aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/scsi/libfc/fc_exch.c
blob: d261e982a2fae5a0c8b13ef098cc3265ebb2ebc5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
/*
 * Copyright(c) 2007 Intel Corporation. All rights reserved.
 * Copyright(c) 2008 Red Hat, Inc.  All rights reserved.
 * Copyright(c) 2008 Mike Christie
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained at www.Open-FCoE.org
 */

/*
 * Fibre Channel exchange and sequence handling.
 */

#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/err.h>

#include <scsi/fc/fc_fc2.h>

#include <scsi/libfc.h>
#include <scsi/fc_encode.h>

#include "fc_libfc.h"

u16	fc_cpu_mask;		/* cpu mask for possible cpus */
EXPORT_SYMBOL(fc_cpu_mask);
static u16	fc_cpu_order;	/* 2's power to represent total possible cpus */
static struct kmem_cache *fc_em_cachep;	       /* cache for exchanges */
static struct workqueue_struct *fc_exch_workqueue;

/*
 * Structure and function definitions for managing Fibre Channel Exchanges
 * and Sequences.
 *
 * The three primary structures used here are fc_exch_mgr, fc_exch, and fc_seq.
 *
 * fc_exch_mgr holds the exchange state for an N port
 *
 * fc_exch holds state for one exchange and links to its active sequence.
 *
 * fc_seq holds the state for an individual sequence.
 */

/**
 * struct fc_exch_pool - Per cpu exchange pool
 * @next_index:	  Next possible free exchange index
 * @total_exches: Total allocated exchanges
 * @lock:	  Exch pool lock
 * @ex_list:	  List of exchanges
 *
 * This structure manages per cpu exchanges in array of exchange pointers.
 * This array is allocated followed by struct fc_exch_pool memory for
 * assigned range of exchanges to per cpu pool.
 */
struct fc_exch_pool {
	u16		 next_index;
	u16		 total_exches;

	/* two cache of free slot in exch array */
	u16		 left;
	u16		 right;

	spinlock_t	 lock;
	struct list_head ex_list;
};

/**
 * struct fc_exch_mgr - The Exchange Manager (EM).
 * @class:	    Default class for new sequences
 * @kref:	    Reference counter
 * @min_xid:	    Minimum exchange ID
 * @max_xid:	    Maximum exchange ID
 * @ep_pool:	    Reserved exchange pointers
 * @pool_max_index: Max exch array index in exch pool
 * @pool:	    Per cpu exch pool
 * @stats:	    Statistics structure
 *
 * This structure is the center for creating exchanges and sequences.
 * It manages the allocation of exchange IDs.
 */
struct fc_exch_mgr {
	enum fc_class	class;
	struct kref	kref;
	u16		min_xid;
	u16		max_xid;
	mempool_t	*ep_pool;
	u16		pool_max_index;
	struct fc_exch_pool *pool;

	/*
	 * currently exchange mgr stats are updated but not used.
	 * either stats can be expose via sysfs or remove them
	 * all together if not used XXX
	 */
	struct {
		atomic_t no_free_exch;
		atomic_t no_free_exch_xid;
		atomic_t xid_not_found;
		atomic_t xid_busy;
		atomic_t seq_not_found;
		atomic_t non_bls_resp;
	} stats;
};

/**
 * struct fc_exch_mgr_anchor - primary structure for list of EMs
 * @ema_list: Exchange Manager Anchor list
 * @mp:	      Exchange Manager associated with this anchor
 * @match:    Routine to determine if this anchor's EM should be used
 *
 * When walking the list of anchors the match routine will be called
 * for each anchor to determine if that EM should be used. The last
 * anchor in the list will always match to handle any exchanges not
 * handled by other EMs. The non-default EMs would be added to the
 * anchor list by HW that provides FCoE offloads.
 */
struct fc_exch_mgr_anchor {
	struct list_head ema_list;
	struct fc_exch_mgr *mp;
	bool (*match)(struct fc_frame *);
};

static void fc_exch_rrq(struct fc_exch *);
static void fc_seq_ls_acc(struct fc_frame *);
static void fc_seq_ls_rjt(struct fc_frame *, enum fc_els_rjt_reason,
			  enum fc_els_rjt_explan);
static void fc_exch_els_rec(struct fc_frame *);
static void fc_exch_els_rrq(struct fc_frame *);

/*
 * Internal implementation notes.
 *
 * The exchange manager is one by default in libfc but LLD may choose
 * to have one per CPU. The sequence manager is one per exchange manager
 * and currently never separated.
 *
 * Section 9.8 in FC-FS-2 specifies:  "The SEQ_ID is a one-byte field
 * assigned by the Sequence Initiator that shall be unique for a specific
 * D_ID and S_ID pair while the Sequence is open."   Note that it isn't
 * qualified by exchange ID, which one might think it would be.
 * In practice this limits the number of open sequences and exchanges to 256
 * per session.	 For most targets we could treat this limit as per exchange.
 *
 * The exchange and its sequence are freed when the last sequence is received.
 * It's possible for the remote port to leave an exchange open without
 * sending any sequences.
 *
 * Notes on reference counts:
 *
 * Exchanges are reference counted and exchange gets freed when the reference
 * count becomes zero.
 *
 * Timeouts:
 * Sequences are timed out for E_D_TOV and R_A_TOV.
 *
 * Sequence event handling:
 *
 * The following events may occur on initiator sequences:
 *
 *	Send.
 *	    For now, the whole thing is sent.
 *	Receive ACK
 *	    This applies only to class F.
 *	    The sequence is marked complete.
 *	ULP completion.
 *	    The upper layer calls fc_exch_done() when done
 *	    with exchange and sequence tuple.
 *	RX-inferred completion.
 *	    When we receive the next sequence on the same exchange, we can
 *	    retire the previous sequence ID.  (XXX not implemented).
 *	Timeout.
 *	    R_A_TOV frees the sequence ID.  If we're waiting for ACK,
 *	    E_D_TOV causes abort and calls upper layer response handler
 *	    with FC_EX_TIMEOUT error.
 *	Receive RJT
 *	    XXX defer.
 *	Send ABTS
 *	    On timeout.
 *
 * The following events may occur on recipient sequences:
 *
 *	Receive
 *	    Allocate sequence for first frame received.
 *	    Hold during receive handler.
 *	    Release when final frame received.
 *	    Keep status of last N of these for the ELS RES command.  XXX TBD.
 *	Receive ABTS
 *	    Deallocate sequence
 *	Send RJT
 *	    Deallocate
 *
 * For now, we neglect conditions where only part of a sequence was
 * received or transmitted, or where out-of-order receipt is detected.
 */

/*
 * Locking notes:
 *
 * The EM code run in a per-CPU worker thread.
 *
 * To protect against concurrency between a worker thread code and timers,
 * sequence allocation and deallocation must be locked.
 *  - exchange refcnt can be done atomicly without locks.
 *  - sequence allocation must be locked by exch lock.
 *  - If the EM pool lock and ex_lock must be taken at the same time, then the
 *    EM pool lock must be taken before the ex_lock.
 */

/*
 * opcode names for debugging.
 */
static char *fc_exch_rctl_names[] = FC_RCTL_NAMES_INIT;

/**
 * fc_exch_name_lookup() - Lookup name by opcode
 * @op:	       Opcode to be looked up
 * @table:     Opcode/name table
 * @max_index: Index not to be exceeded
 *
 * This routine is used to determine a human-readable string identifying
 * a R_CTL opcode.
 */
static inline const char *fc_exch_name_lookup(unsigned int op, char **table,
					      unsigned int max_index)
{
	const char *name = NULL;

	if (op < max_index)
		name = table[op];
	if (!name)
		name = "unknown";
	return name;
}

/**
 * fc_exch_rctl_name() - Wrapper routine for fc_exch_name_lookup()
 * @op: The opcode to be looked up
 */
static const char *fc_exch_rctl_name(unsigned int op)
{
	return fc_exch_name_lookup(op, fc_exch_rctl_names,
				   ARRAY_SIZE(fc_exch_rctl_names));
}

/**
 * fc_exch_hold() - Increment an exchange's reference count
 * @ep: Echange to be held
 */
static inline void fc_exch_hold(struct fc_exch *ep)
{
	atomic_inc(&ep->ex_refcnt);
}

/**
 * fc_exch_setup_hdr() - Initialize a FC header by initializing some fields
 *			 and determine SOF and EOF.
 * @ep:	   The exchange to that will use the header
 * @fp:	   The frame whose header is to be modified
 * @f_ctl: F_CTL bits that will be used for the frame header
 *
 * The fields initialized by this routine are: fh_ox_id, fh_rx_id,
 * fh_seq_id, fh_seq_cnt and the SOF and EOF.
 */
static void fc_exch_setup_hdr(struct fc_exch *ep, struct fc_frame *fp,
			      u32 f_ctl)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	u16 fill;

	fr_sof(fp) = ep->class;
	if (ep->seq.cnt)
		fr_sof(fp) = fc_sof_normal(ep->class);

	if (f_ctl & FC_FC_END_SEQ) {
		fr_eof(fp) = FC_EOF_T;
		if (fc_sof_needs_ack(ep->class))
			fr_eof(fp) = FC_EOF_N;
		/*
		 * From F_CTL.
		 * The number of fill bytes to make the length a 4-byte
		 * multiple is the low order 2-bits of the f_ctl.
		 * The fill itself will have been cleared by the frame
		 * allocation.
		 * After this, the length will be even, as expected by
		 * the transport.
		 */
		fill = fr_len(fp) & 3;
		if (fill) {
			fill = 4 - fill;
			/* TODO, this may be a problem with fragmented skb */
			skb_put(fp_skb(fp), fill);
			hton24(fh->fh_f_ctl, f_ctl | fill);
		}
	} else {
		WARN_ON(fr_len(fp) % 4 != 0);	/* no pad to non last frame */
		fr_eof(fp) = FC_EOF_N;
	}

	/*
	 * Initialize remainig fh fields
	 * from fc_fill_fc_hdr
	 */
	fh->fh_ox_id = htons(ep->oxid);
	fh->fh_rx_id = htons(ep->rxid);
	fh->fh_seq_id = ep->seq.id;
	fh->fh_seq_cnt = htons(ep->seq.cnt);
}

/**
 * fc_exch_release() - Decrement an exchange's reference count
 * @ep: Exchange to be released
 *
 * If the reference count reaches zero and the exchange is complete,
 * it is freed.
 */
static void fc_exch_release(struct fc_exch *ep)
{
	struct fc_exch_mgr *mp;

	if (atomic_dec_and_test(&ep->ex_refcnt)) {
		mp = ep->em;
		if (ep->destructor)
			ep->destructor(&ep->seq, ep->arg);
		WARN_ON(!(ep->esb_stat & ESB_ST_COMPLETE));
		mempool_free(ep, mp->ep_pool);
	}
}

/**
 * fc_exch_done_locked() - Complete an exchange with the exchange lock held
 * @ep: The exchange that is complete
 */
static int fc_exch_done_locked(struct fc_exch *ep)
{
	int rc = 1;

	/*
	 * We must check for completion in case there are two threads
	 * tyring to complete this. But the rrq code will reuse the
	 * ep, and in that case we only clear the resp and set it as
	 * complete, so it can be reused by the timer to send the rrq.
	 */
	ep->resp = NULL;
	if (ep->state & FC_EX_DONE)
		return rc;
	ep->esb_stat |= ESB_ST_COMPLETE;

	if (!(ep->esb_stat & ESB_ST_REC_QUAL)) {
		ep->state |= FC_EX_DONE;
		if (cancel_delayed_work(&ep->timeout_work))
			atomic_dec(&ep->ex_refcnt); /* drop hold for timer */
		rc = 0;
	}
	return rc;
}

/**
 * fc_exch_ptr_get() - Return an exchange from an exchange pool
 * @pool:  Exchange Pool to get an exchange from
 * @index: Index of the exchange within the pool
 *
 * Use the index to get an exchange from within an exchange pool. exches
 * will point to an array of exchange pointers. The index will select
 * the exchange within the array.
 */
static inline struct fc_exch *fc_exch_ptr_get(struct fc_exch_pool *pool,
					      u16 index)
{
	struct fc_exch **exches = (struct fc_exch **)(pool + 1);
	return exches[index];
}

/**
 * fc_exch_ptr_set() - Assign an exchange to a slot in an exchange pool
 * @pool:  The pool to assign the exchange to
 * @index: The index in the pool where the exchange will be assigned
 * @ep:	   The exchange to assign to the pool
 */
static inline void fc_exch_ptr_set(struct fc_exch_pool *pool, u16 index,
				   struct fc_exch *ep)
{
	((struct fc_exch **)(pool + 1))[index] = ep;
}

/**
 * fc_exch_delete() - Delete an exchange
 * @ep: The exchange to be deleted
 */
static void fc_exch_delete(struct fc_exch *ep)
{
	struct fc_exch_pool *pool;
	u16 index;

	pool = ep->pool;
	spin_lock_bh(&pool->lock);
	WARN_ON(pool->total_exches <= 0);
	pool->total_exches--;

	/* update cache of free slot */
	index = (ep->xid - ep->em->min_xid) >> fc_cpu_order;
	if (pool->left == FC_XID_UNKNOWN)
		pool->left = index;
	else if (pool->right == FC_XID_UNKNOWN)
		pool->right = index;
	else
		pool->next_index = index;

	fc_exch_ptr_set(pool, index, NULL);
	list_del(&ep->ex_list);
	spin_unlock_bh(&pool->lock);
	fc_exch_release(ep);	/* drop hold for exch in mp */
}

/**
 * fc_exch_timer_set_locked() - Start a timer for an exchange w/ the
 *				the exchange lock held
 * @ep:		The exchange whose timer will start
 * @timer_msec: The timeout period
 *
 * Used for upper level protocols to time out the exchange.
 * The timer is cancelled when it fires or when the exchange completes.
 */
static inline void fc_exch_timer_set_locked(struct fc_exch *ep,
					    unsigned int timer_msec)
{
	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE))
		return;

	FC_EXCH_DBG(ep, "Exchange timer armed\n");

	if (queue_delayed_work(fc_exch_workqueue, &ep->timeout_work,
			       msecs_to_jiffies(timer_msec)))
		fc_exch_hold(ep);		/* hold for timer */
}

/**
 * fc_exch_timer_set() - Lock the exchange and set the timer
 * @ep:		The exchange whose timer will start
 * @timer_msec: The timeout period
 */
static void fc_exch_timer_set(struct fc_exch *ep, unsigned int timer_msec)
{
	spin_lock_bh(&ep->ex_lock);
	fc_exch_timer_set_locked(ep, timer_msec);
	spin_unlock_bh(&ep->ex_lock);
}

/**
 * fc_seq_send() - Send a frame using existing sequence/exchange pair
 * @lport: The local port that the exchange will be sent on
 * @sp:	   The sequence to be sent
 * @fp:	   The frame to be sent on the exchange
 */
static int fc_seq_send(struct fc_lport *lport, struct fc_seq *sp,
		       struct fc_frame *fp)
{
	struct fc_exch *ep;
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	int error;
	u32 f_ctl;

	ep = fc_seq_exch(sp);
	WARN_ON((ep->esb_stat & ESB_ST_SEQ_INIT) != ESB_ST_SEQ_INIT);

	f_ctl = ntoh24(fh->fh_f_ctl);
	fc_exch_setup_hdr(ep, fp, f_ctl);
	fr_encaps(fp) = ep->encaps;

	/*
	 * update sequence count if this frame is carrying
	 * multiple FC frames when sequence offload is enabled
	 * by LLD.
	 */
	if (fr_max_payload(fp))
		sp->cnt += DIV_ROUND_UP((fr_len(fp) - sizeof(*fh)),
					fr_max_payload(fp));
	else
		sp->cnt++;

	/*
	 * Send the frame.
	 */
	error = lport->tt.frame_send(lport, fp);

	if (fh->fh_type == FC_TYPE_BLS)
		return error;

	/*
	 * Update the exchange and sequence flags,
	 * assuming all frames for the sequence have been sent.
	 * We can only be called to send once for each sequence.
	 */
	spin_lock_bh(&ep->ex_lock);
	ep->f_ctl = f_ctl & ~FC_FC_FIRST_SEQ;	/* not first seq */
	if (f_ctl & FC_FC_SEQ_INIT)
		ep->esb_stat &= ~ESB_ST_SEQ_INIT;
	spin_unlock_bh(&ep->ex_lock);
	return error;
}

/**
 * fc_seq_alloc() - Allocate a sequence for a given exchange
 * @ep:	    The exchange to allocate a new sequence for
 * @seq_id: The sequence ID to be used
 *
 * We don't support multiple originated sequences on the same exchange.
 * By implication, any previously originated sequence on this exchange
 * is complete, and we reallocate the same sequence.
 */
static struct fc_seq *fc_seq_alloc(struct fc_exch *ep, u8 seq_id)
{
	struct fc_seq *sp;

	sp = &ep->seq;
	sp->ssb_stat = 0;
	sp->cnt = 0;
	sp->id = seq_id;
	return sp;
}

/**
 * fc_seq_start_next_locked() - Allocate a new sequence on the same
 *				exchange as the supplied sequence
 * @sp: The sequence/exchange to get a new sequence for
 */
static struct fc_seq *fc_seq_start_next_locked(struct fc_seq *sp)
{
	struct fc_exch *ep = fc_seq_exch(sp);

	sp = fc_seq_alloc(ep, ep->seq_id++);
	FC_EXCH_DBG(ep, "f_ctl %6x seq %2x\n",
		    ep->f_ctl, sp->id);
	return sp;
}

/**
 * fc_seq_start_next() - Lock the exchange and get a new sequence
 *			 for a given sequence/exchange pair
 * @sp: The sequence/exchange to get a new exchange for
 */
static struct fc_seq *fc_seq_start_next(struct fc_seq *sp)
{
	struct fc_exch *ep = fc_seq_exch(sp);

	spin_lock_bh(&ep->ex_lock);
	sp = fc_seq_start_next_locked(sp);
	spin_unlock_bh(&ep->ex_lock);

	return sp;
}

/*
 * Set the response handler for the exchange associated with a sequence.
 */
static void fc_seq_set_resp(struct fc_seq *sp,
			    void (*resp)(struct fc_seq *, struct fc_frame *,
					 void *),
			    void *arg)
{
	struct fc_exch *ep = fc_seq_exch(sp);

	spin_lock_bh(&ep->ex_lock);
	ep->resp = resp;
	ep->arg = arg;
	spin_unlock_bh(&ep->ex_lock);
}

/**
 * fc_exch_abort_locked() - Abort an exchange
 * @ep:	The exchange to be aborted
 * @timer_msec: The period of time to wait before aborting
 *
 * Locking notes:  Called with exch lock held
 *
 * Return value: 0 on success else error code
 */
static int fc_exch_abort_locked(struct fc_exch *ep,
				unsigned int timer_msec)
{
	struct fc_seq *sp;
	struct fc_frame *fp;
	int error;

	if (ep->esb_stat & (ESB_ST_COMPLETE | ESB_ST_ABNORMAL) ||
	    ep->state & (FC_EX_DONE | FC_EX_RST_CLEANUP))
		return -ENXIO;

	/*
	 * Send the abort on a new sequence if possible.
	 */
	sp = fc_seq_start_next_locked(&ep->seq);
	if (!sp)
		return -ENOMEM;

	ep->esb_stat |= ESB_ST_SEQ_INIT | ESB_ST_ABNORMAL;
	if (timer_msec)
		fc_exch_timer_set_locked(ep, timer_msec);

	/*
	 * If not logged into the fabric, don't send ABTS but leave
	 * sequence active until next timeout.
	 */
	if (!ep->sid)
		return 0;

	/*
	 * Send an abort for the sequence that timed out.
	 */
	fp = fc_frame_alloc(ep->lp, 0);
	if (fp) {
		fc_fill_fc_hdr(fp, FC_RCTL_BA_ABTS, ep->did, ep->sid,
			       FC_TYPE_BLS, FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);
		error = fc_seq_send(ep->lp, sp, fp);
	} else
		error = -ENOBUFS;
	return error;
}

/**
 * fc_seq_exch_abort() - Abort an exchange and sequence
 * @req_sp:	The sequence to be aborted
 * @timer_msec: The period of time to wait before aborting
 *
 * Generally called because of a timeout or an abort from the upper layer.
 *
 * Return value: 0 on success else error code
 */
static int fc_seq_exch_abort(const struct fc_seq *req_sp,
			     unsigned int timer_msec)
{
	struct fc_exch *ep;
	int error;

	ep = fc_seq_exch(req_sp);
	spin_lock_bh(&ep->ex_lock);
	error = fc_exch_abort_locked(ep, timer_msec);
	spin_unlock_bh(&ep->ex_lock);
	return error;
}

/**
 * fc_exch_timeout() - Handle exchange timer expiration
 * @work: The work_struct identifying the exchange that timed out
 */
static void fc_exch_timeout(struct work_struct *work)
{
	struct fc_exch *ep = container_of(work, struct fc_exch,
					  timeout_work.work);
	struct fc_seq *sp = &ep->seq;
	void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg);
	void *arg;
	u32 e_stat;
	int rc = 1;

	FC_EXCH_DBG(ep, "Exchange timed out\n");

	spin_lock_bh(&ep->ex_lock);
	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE))
		goto unlock;

	e_stat = ep->esb_stat;
	if (e_stat & ESB_ST_COMPLETE) {
		ep->esb_stat = e_stat & ~ESB_ST_REC_QUAL;
		spin_unlock_bh(&ep->ex_lock);
		if (e_stat & ESB_ST_REC_QUAL)
			fc_exch_rrq(ep);
		goto done;
	} else {
		resp = ep->resp;
		arg = ep->arg;
		ep->resp = NULL;
		if (e_stat & ESB_ST_ABNORMAL)
			rc = fc_exch_done_locked(ep);
		spin_unlock_bh(&ep->ex_lock);
		if (!rc)
			fc_exch_delete(ep);
		if (resp)
			resp(sp, ERR_PTR(-FC_EX_TIMEOUT), arg);
		fc_seq_exch_abort(sp, 2 * ep->r_a_tov);
		goto done;
	}
unlock:
	spin_unlock_bh(&ep->ex_lock);
done:
	/*
	 * This release matches the hold taken when the timer was set.
	 */
	fc_exch_release(ep);
}

/**
 * fc_exch_em_alloc() - Allocate an exchange from a specified EM.
 * @lport: The local port that the exchange is for
 * @mp:	   The exchange manager that will allocate the exchange
 *
 * Returns pointer to allocated fc_exch with exch lock held.
 */
static struct fc_exch *fc_exch_em_alloc(struct fc_lport *lport,
					struct fc_exch_mgr *mp)
{
	struct fc_exch *ep;
	unsigned int cpu;
	u16 index;
	struct fc_exch_pool *pool;

	/* allocate memory for exchange */
	ep = mempool_alloc(mp->ep_pool, GFP_ATOMIC);
	if (!ep) {
		atomic_inc(&mp->stats.no_free_exch);
		goto out;
	}
	memset(ep, 0, sizeof(*ep));

	cpu = get_cpu();
	pool = per_cpu_ptr(mp->pool, cpu);
	spin_lock_bh(&pool->lock);
	put_cpu();

	/* peek cache of free slot */
	if (pool->left != FC_XID_UNKNOWN) {
		index = pool->left;
		pool->left = FC_XID_UNKNOWN;
		goto hit;
	}
	if (pool->right != FC_XID_UNKNOWN) {
		index = pool->right;
		pool->right = FC_XID_UNKNOWN;
		goto hit;
	}

	index = pool->next_index;
	/* allocate new exch from pool */
	while (fc_exch_ptr_get(pool, index)) {
		index = index == mp->pool_max_index ? 0 : index + 1;
		if (index == pool->next_index)
			goto err;
	}
	pool->next_index = index == mp->pool_max_index ? 0 : index + 1;
hit:
	fc_exch_hold(ep);	/* hold for exch in mp */
	spin_lock_init(&ep->ex_lock);
	/*
	 * Hold exch lock for caller to prevent fc_exch_reset()
	 * from releasing exch	while fc_exch_alloc() caller is
	 * still working on exch.
	 */
	spin_lock_bh(&ep->ex_lock);

	fc_exch_ptr_set(pool, index, ep);
	list_add_tail(&ep->ex_list, &pool->ex_list);
	fc_seq_alloc(ep, ep->seq_id++);
	pool->total_exches++;
	spin_unlock_bh(&pool->lock);

	/*
	 *  update exchange
	 */
	ep->oxid = ep->xid = (index << fc_cpu_order | cpu) + mp->min_xid;
	ep->em = mp;
	ep->pool = pool;
	ep->lp = lport;
	ep->f_ctl = FC_FC_FIRST_SEQ;	/* next seq is first seq */
	ep->rxid = FC_XID_UNKNOWN;
	ep->class = mp->class;
	INIT_DELAYED_WORK(&ep->timeout_work, fc_exch_timeout);
out:
	return ep;
err:
	spin_unlock_bh(&pool->lock);
	atomic_inc(&mp->stats.no_free_exch_xid);
	mempool_free(ep, mp->ep_pool);
	return NULL;
}

/**
 * fc_exch_alloc() - Allocate an exchange from an EM on a
 *		     local port's list of EMs.
 * @lport: The local port that will own the exchange
 * @fp:	   The FC frame that the exchange will be for
 *
 * This function walks the list of exchange manager(EM)
 * anchors to select an EM for a new exchange allocation. The
 * EM is selected when a NULL match function pointer is encountered
 * or when a call to a match function returns true.
 */
static inline struct fc_exch *fc_exch_alloc(struct fc_lport *lport,
					    struct fc_frame *fp)
{
	struct fc_exch_mgr_anchor *ema;

	list_for_each_entry(ema, &lport->ema_list, ema_list)
		if (!ema->match || ema->match(fp))
			return fc_exch_em_alloc(lport, ema->mp);
	return NULL;
}

/**
 * fc_exch_find() - Lookup and hold an exchange
 * @mp:	 The exchange manager to lookup the exchange from
 * @xid: The XID of the exchange to look up
 */
static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid)
{
	struct fc_exch_pool *pool;
	struct fc_exch *ep = NULL;

	if ((xid >= mp->min_xid) && (xid <= mp->max_xid)) {
		pool = per_cpu_ptr(mp->pool, xid & fc_cpu_mask);
		spin_lock_bh(&pool->lock);
		ep = fc_exch_ptr_get(pool, (xid - mp->min_xid) >> fc_cpu_order);
		if (ep && ep->xid == xid)
			fc_exch_hold(ep);
		spin_unlock_bh(&pool->lock);
	}
	return ep;
}


/**
 * fc_exch_done() - Indicate that an exchange/sequence tuple is complete and
 *		    the memory allocated for the related objects may be freed.
 * @sp: The sequence that has completed
 */
static void fc_exch_done(struct fc_seq *sp)
{
	struct fc_exch *ep = fc_seq_exch(sp);
	int rc;

	spin_lock_bh(&ep->ex_lock);
	rc = fc_exch_done_locked(ep);
	spin_unlock_bh(&ep->ex_lock);
	if (!rc)
		fc_exch_delete(ep);
}

/**
 * fc_exch_resp() - Allocate a new exchange for a response frame
 * @lport: The local port that the exchange was for
 * @mp:	   The exchange manager to allocate the exchange from
 * @fp:	   The response frame
 *
 * Sets the responder ID in the frame header.
 */
static struct fc_exch *fc_exch_resp(struct fc_lport *lport,
				    struct fc_exch_mgr *mp,
				    struct fc_frame *fp)
{
	struct fc_exch *ep;
	struct fc_frame_header *fh;

	ep = fc_exch_alloc(lport, fp);
	if (ep) {
		ep->class = fc_frame_class(fp);

		/*
		 * Set EX_CTX indicating we're responding on this exchange.
		 */
		ep->f_ctl |= FC_FC_EX_CTX;	/* we're responding */
		ep->f_ctl &= ~FC_FC_FIRST_SEQ;	/* not new */
		fh = fc_frame_header_get(fp);
		ep->sid = ntoh24(fh->fh_d_id);
		ep->did = ntoh24(fh->fh_s_id);
		ep->oid = ep->did;

		/*
		 * Allocated exchange has placed the XID in the
		 * originator field. Move it to the responder field,
		 * and set the originator XID from the frame.
		 */
		ep->rxid = ep->xid;
		ep->oxid = ntohs(fh->fh_ox_id);
		ep->esb_stat |= ESB_ST_RESP | ESB_ST_SEQ_INIT;
		if ((ntoh24(fh->fh_f_ctl) & FC_FC_SEQ_INIT) == 0)
			ep->esb_stat &= ~ESB_ST_SEQ_INIT;

		fc_exch_hold(ep);	/* hold for caller */
		spin_unlock_bh(&ep->ex_lock);	/* lock from fc_exch_alloc */
	}
	return ep;
}

/**
 * fc_seq_lookup_recip() - Find a sequence where the other end
 *			   originated the sequence
 * @lport: The local port that the frame was sent to
 * @mp:	   The Exchange Manager to lookup the exchange from
 * @fp:	   The frame associated with the sequence we're looking for
 *
 * If fc_pf_rjt_reason is FC_RJT_NONE then this function will have a hold
 * on the ep that should be released by the caller.
 */
static enum fc_pf_rjt_reason fc_seq_lookup_recip(struct fc_lport *lport,
						 struct fc_exch_mgr *mp,
						 struct fc_frame *fp)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	struct fc_exch *ep = NULL;
	struct fc_seq *sp = NULL;
	enum fc_pf_rjt_reason reject = FC_RJT_NONE;
	u32 f_ctl;
	u16 xid;

	f_ctl = ntoh24(fh->fh_f_ctl);
	WARN_ON((f_ctl & FC_FC_SEQ_CTX) != 0);

	/*
	 * Lookup or create the exchange if we will be creating the sequence.
	 */
	if (f_ctl & FC_FC_EX_CTX) {
		xid = ntohs(fh->fh_ox_id);	/* we originated exch */
		ep = fc_exch_find(mp, xid);
		if (!ep) {
			atomic_inc(&mp->stats.xid_not_found);
			reject = FC_RJT_OX_ID;
			goto out;
		}
		if (ep->rxid == FC_XID_UNKNOWN)
			ep->rxid = ntohs(fh->fh_rx_id);
		else if (ep->rxid != ntohs(fh->fh_rx_id)) {
			reject = FC_RJT_OX_ID;
			goto rel;
		}
	} else {
		xid = ntohs(fh->fh_rx_id);	/* we are the responder */

		/*
		 * Special case for MDS issuing an ELS TEST with a
		 * bad rxid of 0.
		 * XXX take this out once we do the proper reject.
		 */
		if (xid == 0 && fh->fh_r_ctl == FC_RCTL_ELS_REQ &&
		    fc_frame_payload_op(fp) == ELS_TEST) {
			fh->fh_rx_id = htons(FC_XID_UNKNOWN);
			xid = FC_XID_UNKNOWN;
		}

		/*
		 * new sequence - find the exchange
		 */
		ep = fc_exch_find(mp, xid);
		if ((f_ctl & FC_FC_FIRST_SEQ) && fc_sof_is_init(fr_sof(fp))) {
			if (ep) {
				atomic_inc(&mp->stats.xid_busy);
				reject = FC_RJT_RX_ID;
				goto rel;
			}
			ep = fc_exch_resp(lport, mp, fp);
			if (!ep) {
				reject = FC_RJT_EXCH_EST;	/* XXX */
				goto out;
			}
			xid = ep->xid;	/* get our XID */
		} else if (!ep) {
			atomic_inc(&mp->stats.xid_not_found);
			reject = FC_RJT_RX_ID;	/* XID not found */
			goto out;
		}
	}

	/*
	 * At this point, we have the exchange held.
	 * Find or create the sequence.
	 */
	if (fc_sof_is_init(fr_sof(fp))) {
		sp = &ep->seq;
		sp->ssb_stat |= SSB_ST_RESP;
		sp->id = fh->fh_seq_id;
	} else {
		sp = &ep->seq;
		if (sp->id != fh->fh_seq_id) {
			atomic_inc(&mp->stats.seq_not_found);
			if (f_ctl & FC_FC_END_SEQ) {
				/*
				 * Update sequence_id based on incoming last
				 * frame of sequence exchange. This is needed
				 * for FCoE target where DDP has been used
				 * on target where, stack is indicated only
				 * about last frame's (payload _header) header.
				 * Whereas "seq_id" which is part of
				 * frame_header is allocated by initiator
				 * which is totally different from "seq_id"
				 * allocated when XFER_RDY was sent by target.
				 * To avoid false -ve which results into not
				 * sending RSP, hence write request on other
				 * end never finishes.
				 */
				spin_lock_bh(&ep->ex_lock);
				sp->ssb_stat |= SSB_ST_RESP;
				sp->id = fh->fh_seq_id;
				spin_unlock_bh(&ep->ex_lock);
			} else {
				/* sequence/exch should exist */
				reject = FC_RJT_SEQ_ID;
				goto rel;
			}
		}
	}
	WARN_ON(ep != fc_seq_exch(sp));

	if (f_ctl & FC_FC_SEQ_INIT)
		ep->esb_stat |= ESB_ST_SEQ_INIT;

	fr_seq(fp) = sp;
out:
	return reject;
rel:
	fc_exch_done(&ep->seq);
	fc_exch_release(ep);	/* hold from fc_exch_find/fc_exch_resp */
	return reject;
}

/**
 * fc_seq_lookup_orig() - Find a sequence where this end
 *			  originated the sequence
 * @mp:	   The Exchange Manager to lookup the exchange from
 * @fp:	   The frame associated with the sequence we're looking for
 *
 * Does not hold the sequence for the caller.
 */
static struct fc_seq *fc_seq_lookup_orig(struct fc_exch_mgr *mp,
					 struct fc_frame *fp)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	struct fc_exch *ep;
	struct fc_seq *sp = NULL;
	u32 f_ctl;
	u16 xid;

	f_ctl = ntoh24(fh->fh_f_ctl);
	WARN_ON((f_ctl & FC_FC_SEQ_CTX) != FC_FC_SEQ_CTX);
	xid = ntohs((f_ctl & FC_FC_EX_CTX) ? fh->fh_ox_id : fh->fh_rx_id);
	ep = fc_exch_find(mp, xid);
	if (!ep)
		return NULL;
	if (ep->seq.id == fh->fh_seq_id) {
		/*
		 * Save the RX_ID if we didn't previously know it.
		 */
		sp = &ep->seq;
		if ((f_ctl & FC_FC_EX_CTX) != 0 &&
		    ep->rxid == FC_XID_UNKNOWN) {
			ep->rxid = ntohs(fh->fh_rx_id);
		}
	}
	fc_exch_release(ep);
	return sp;
}

/**
 * fc_exch_set_addr() - Set the source and destination IDs for an exchange
 * @ep:	     The exchange to set the addresses for
 * @orig_id: The originator's ID
 * @resp_id: The responder's ID
 *
 * Note this must be done before the first sequence of the exchange is sent.
 */
static void fc_exch_set_addr(struct fc_exch *ep,
			     u32 orig_id, u32 resp_id)
{
	ep->oid = orig_id;
	if (ep->esb_stat & ESB_ST_RESP) {
		ep->sid = resp_id;
		ep->did = orig_id;
	} else {
		ep->sid = orig_id;
		ep->did = resp_id;
	}
}

/**
 * fc_seq_els_rsp_send() - Send an ELS response using information from
 *			   the existing sequence/exchange.
 * @fp:	      The received frame
 * @els_cmd:  The ELS command to be sent
 * @els_data: The ELS data to be sent
 *
 * The received frame is not freed.
 */
static void fc_seq_els_rsp_send(struct fc_frame *fp, enum fc_els_cmd els_cmd,
				struct fc_seq_els_data *els_data)
{
	switch (els_cmd) {
	case ELS_LS_RJT:
		fc_seq_ls_rjt(fp, els_data->reason, els_data->explan);
		break;
	case ELS_LS_ACC:
		fc_seq_ls_acc(fp);
		break;
	case ELS_RRQ:
		fc_exch_els_rrq(fp);
		break;
	case ELS_REC:
		fc_exch_els_rec(fp);
		break;
	default:
		FC_LPORT_DBG(fr_dev(fp), "Invalid ELS CMD:%x\n", els_cmd);
	}
}

/**
 * fc_seq_send_last() - Send a sequence that is the last in the exchange
 * @sp:	     The sequence that is to be sent
 * @fp:	     The frame that will be sent on the sequence
 * @rctl:    The R_CTL information to be sent
 * @fh_type: The frame header type
 */
static void fc_seq_send_last(struct fc_seq *sp, struct fc_frame *fp,
			     enum fc_rctl rctl, enum fc_fh_type fh_type)
{
	u32 f_ctl;
	struct fc_exch *ep = fc_seq_exch(sp);

	f_ctl = FC_FC_LAST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT;
	f_ctl |= ep->f_ctl;
	fc_fill_fc_hdr(fp, rctl, ep->did, ep->sid, fh_type, f_ctl, 0);
	fc_seq_send(ep->lp, sp, fp);
}

/**
 * fc_seq_send_ack() - Send an acknowledgement that we've received a frame
 * @sp:	   The sequence to send the ACK on
 * @rx_fp: The received frame that is being acknoledged
 *
 * Send ACK_1 (or equiv.) indicating we received something.
 */
static void fc_seq_send_ack(struct fc_seq *sp, const struct fc_frame *rx_fp)
{
	struct fc_frame *fp;
	struct fc_frame_header *rx_fh;
	struct fc_frame_header *fh;
	struct fc_exch *ep = fc_seq_exch(sp);
	struct fc_lport *lport = ep->lp;
	unsigned int f_ctl;

	/*
	 * Don't send ACKs for class 3.
	 */
	if (fc_sof_needs_ack(fr_sof(rx_fp))) {
		fp = fc_frame_alloc(lport, 0);
		if (!fp)
			return;

		fh = fc_frame_header_get(fp);
		fh->fh_r_ctl = FC_RCTL_ACK_1;
		fh->fh_type = FC_TYPE_BLS;

		/*
		 * Form f_ctl by inverting EX_CTX and SEQ_CTX (bits 23, 22).
		 * Echo FIRST_SEQ, LAST_SEQ, END_SEQ, END_CONN, SEQ_INIT.
		 * Bits 9-8 are meaningful (retransmitted or unidirectional).
		 * Last ACK uses bits 7-6 (continue sequence),
		 * bits 5-4 are meaningful (what kind of ACK to use).
		 */
		rx_fh = fc_frame_header_get(rx_fp);
		f_ctl = ntoh24(rx_fh->fh_f_ctl);
		f_ctl &= FC_FC_EX_CTX | FC_FC_SEQ_CTX |
			FC_FC_FIRST_SEQ | FC_FC_LAST_SEQ |
			FC_FC_END_SEQ | FC_FC_END_CONN | FC_FC_SEQ_INIT |
			FC_FC_RETX_SEQ | FC_FC_UNI_TX;
		f_ctl ^= FC_FC_EX_CTX | FC_FC_SEQ_CTX;
		hton24(fh->fh_f_ctl, f_ctl);

		fc_exch_setup_hdr(ep, fp, f_ctl);
		fh->fh_seq_id = rx_fh->fh_seq_id;
		fh->fh_seq_cnt = rx_fh->fh_seq_cnt;
		fh->fh_parm_offset = htonl(1);	/* ack single frame */

		fr_sof(fp) = fr_sof(rx_fp);
		if (f_ctl & FC_FC_END_SEQ)
			fr_eof(fp) = FC_EOF_T;
		else
			fr_eof(fp) = FC_EOF_N;

		lport->tt.frame_send(lport, fp);
	}
}

/**
 * fc_exch_send_ba_rjt() - Send BLS Reject
 * @rx_fp:  The frame being rejected
 * @reason: The reason the frame is being rejected
 * @explan: The explanation for the rejection
 *
 * This is for rejecting BA_ABTS only.
 */
static void fc_exch_send_ba_rjt(struct fc_frame *rx_fp,
				enum fc_ba_rjt_reason reason,
				enum fc_ba_rjt_explan explan)
{
	struct fc_frame *fp;
	struct fc_frame_header *rx_fh;
	struct fc_frame_header *fh;
	struct fc_ba_rjt *rp;
	struct fc_lport *lport;
	unsigned int f_ctl;

	lport = fr_dev(rx_fp);
	fp = fc_frame_alloc(lport, sizeof(*rp));
	if (!fp)
		return;
	fh = fc_frame_header_get(fp);
	rx_fh = fc_frame_header_get(rx_fp);

	memset(fh, 0, sizeof(*fh) + sizeof(*rp));

	rp = fc_frame_payload_get(fp, sizeof(*rp));
	rp->br_reason = reason;
	rp->br_explan = explan;

	/*
	 * seq_id, cs_ctl, df_ctl and param/offset are zero.
	 */
	memcpy(fh->fh_s_id, rx_fh->fh_d_id, 3);
	memcpy(fh->fh_d_id, rx_fh->fh_s_id, 3);
	fh->fh_ox_id = rx_fh->fh_ox_id;
	fh->fh_rx_id = rx_fh->fh_rx_id;
	fh->fh_seq_cnt = rx_fh->fh_seq_cnt;
	fh->fh_r_ctl = FC_RCTL_BA_RJT;
	fh->fh_type = FC_TYPE_BLS;

	/*
	 * Form f_ctl by inverting EX_CTX and SEQ_CTX (bits 23, 22).
	 * Echo FIRST_SEQ, LAST_SEQ, END_SEQ, END_CONN, SEQ_INIT.
	 * Bits 9-8 are meaningful (retransmitted or unidirectional).
	 * Last ACK uses bits 7-6 (continue sequence),
	 * bits 5-4 are meaningful (what kind of ACK to use).
	 * Always set LAST_SEQ, END_SEQ.
	 */
	f_ctl = ntoh24(rx_fh->fh_f_ctl);
	f_ctl &= FC_FC_EX_CTX | FC_FC_SEQ_CTX |
		FC_FC_END_CONN | FC_FC_SEQ_INIT |
		FC_FC_RETX_SEQ | FC_FC_UNI_TX;
	f_ctl ^= FC_FC_EX_CTX | FC_FC_SEQ_CTX;
	f_ctl |= FC_FC_LAST_SEQ | FC_FC_END_SEQ;
	f_ctl &= ~FC_FC_FIRST_SEQ;
	hton24(fh->fh_f_ctl, f_ctl);

	fr_sof(fp) = fc_sof_class(fr_sof(rx_fp));
	fr_eof(fp) = FC_EOF_T;
	if (fc_sof_needs_ack(fr_sof(fp)))
		fr_eof(fp) = FC_EOF_N;

	lport->tt.frame_send(lport, fp);
}

/**
 * fc_exch_recv_abts() - Handle an incoming ABTS
 * @ep:	   The exchange the abort was on
 * @rx_fp: The ABTS frame
 *
 * This would be for target mode usually, but could be due to lost
 * FCP transfer ready, confirm or RRQ. We always handle this as an
 * exchange abort, ignoring the parameter.
 */
static void fc_exch_recv_abts(struct fc_exch *ep, struct fc_frame *rx_fp)
{
	struct fc_frame *fp;
	struct fc_ba_acc *ap;
	struct fc_frame_header *fh;
	struct fc_seq *sp;

	if (!ep)
		goto reject;
	spin_lock_bh(&ep->ex_lock);
	if (ep->esb_stat & ESB_ST_COMPLETE) {
		spin_unlock_bh(&ep->ex_lock);
		goto reject;
	}
	if (!(ep->esb_stat & ESB_ST_REC_QUAL))
		fc_exch_hold(ep);		/* hold for REC_QUAL */
	ep->esb_stat |= ESB_ST_ABNORMAL | ESB_ST_REC_QUAL;
	fc_exch_timer_set_locked(ep, ep->r_a_tov);

	fp = fc_frame_alloc(ep->lp, sizeof(*ap));
	if (!fp) {
		spin_unlock_bh(&ep->ex_lock);
		goto free;
	}
	fh = fc_frame_header_get(fp);
	ap = fc_frame_payload_get(fp, sizeof(*ap));
	memset(ap, 0, sizeof(*ap));
	sp = &ep->seq;
	ap->ba_high_seq_cnt = htons(0xffff);
	if (sp->ssb_stat & SSB_ST_RESP) {
		ap->ba_seq_id = sp->id;
		ap->ba_seq_id_val = FC_BA_SEQ_ID_VAL;
		ap->ba_high_seq_cnt = fh->fh_seq_cnt;
		ap->ba_low_seq_cnt = htons(sp->cnt);
	}
	sp = fc_seq_start_next_locked(sp);
	spin_unlock_bh(&ep->ex_lock);
	fc_seq_send_last(sp, fp, FC_RCTL_BA_ACC, FC_TYPE_BLS);
	fc_frame_free(rx_fp);
	return;

reject:
	fc_exch_send_ba_rjt(rx_fp, FC_BA_RJT_UNABLE, FC_BA_RJT_INV_XID);
free:
	fc_frame_free(rx_fp);
}

/**
 * fc_seq_assign() - Assign exchange and sequence for incoming request
 * @lport: The local port that received the request
 * @fp:    The request frame
 *
 * On success, the sequence pointer will be returned and also in fr_seq(@fp).
 * A reference will be held on the exchange/sequence for the caller, which
 * must call fc_seq_release().
 */
static struct fc_seq *fc_seq_assign(struct fc_lport *lport, struct fc_frame *fp)
{
	struct fc_exch_mgr_anchor *ema;

	WARN_ON(lport != fr_dev(fp));
	WARN_ON(fr_seq(fp));
	fr_seq(fp) = NULL;

	list_for_each_entry(ema, &lport->ema_list, ema_list)
		if ((!ema->match || ema->match(fp)) &&
		    fc_seq_lookup_recip(lport, ema->mp, fp) == FC_RJT_NONE)
			break;
	return fr_seq(fp);
}

/**
 * fc_seq_release() - Release the hold
 * @sp:    The sequence.
 */
static void fc_seq_release(struct fc_seq *sp)
{
	fc_exch_release(fc_seq_exch(sp));
}

/**
 * fc_exch_recv_req() - Handler for an incoming request
 * @lport: The local port that received the request
 * @mp:	   The EM that the exchange is on
 * @fp:	   The request frame
 *
 * This is used when the other end is originating the exchange
 * and the sequence.
 */
static void fc_exch_recv_req(struct fc_lport *lport, struct fc_exch_mgr *mp,
			     struct fc_frame *fp)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	struct fc_seq *sp = NULL;
	struct fc_exch *ep = NULL;
	enum fc_pf_rjt_reason reject;

	/* We can have the wrong fc_lport at this point with NPIV, which is a
	 * problem now that we know a new exchange needs to be allocated
	 */
	lport = fc_vport_id_lookup(lport, ntoh24(fh->fh_d_id));
	if (!lport) {
		fc_frame_free(fp);
		return;
	}
	fr_dev(fp) = lport;

	BUG_ON(fr_seq(fp));		/* XXX remove later */

	/*
	 * If the RX_ID is 0xffff, don't allocate an exchange.
	 * The upper-level protocol may request one later, if needed.
	 */
	if (fh->fh_rx_id == htons(FC_XID_UNKNOWN))
		return lport->tt.lport_recv(lport, fp);

	reject = fc_seq_lookup_recip(lport, mp, fp);
	if (reject == FC_RJT_NONE) {
		sp = fr_seq(fp);	/* sequence will be held */
		ep = fc_seq_exch(sp);
		fc_seq_send_ack(sp, fp);
		ep->encaps = fr_encaps(fp);

		/*
		 * Call the receive function.
		 *
		 * The receive function may allocate a new sequence
		 * over the old one, so we shouldn't change the
		 * sequence after this.
		 *
		 * The frame will be freed by the receive function.
		 * If new exch resp handler is valid then call that
		 * first.
		 */
		if (ep->resp)
			ep->resp(sp, fp, ep->arg);
		else
			lport->tt.lport_recv(lport, fp);
		fc_exch_release(ep);	/* release from lookup */
	} else {
		FC_LPORT_DBG(lport, "exch/seq lookup failed: reject %x\n",
			     reject);
		fc_frame_free(fp);
	}
}

/**
 * fc_exch_recv_seq_resp() - Handler for an incoming response where the other
 *			     end is the originator of the sequence that is a
 *			     response to our initial exchange
 * @mp: The EM that the exchange is on
 * @fp: The response frame
 */
static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	struct fc_seq *sp;
	struct fc_exch *ep;
	enum fc_sof sof;
	u32 f_ctl;
	void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg);
	void *ex_resp_arg;
	int rc;

	ep = fc_exch_find(mp, ntohs(fh->fh_ox_id));
	if (!ep) {
		atomic_inc(&mp->stats.xid_not_found);
		goto out;
	}
	if (ep->esb_stat & ESB_ST_COMPLETE) {
		atomic_inc(&mp->stats.xid_not_found);
		goto rel;
	}
	if (ep->rxid == FC_XID_UNKNOWN)
		ep->rxid = ntohs(fh->fh_rx_id);
	if (ep->sid != 0 && ep->sid != ntoh24(fh->fh_d_id)) {
		atomic_inc(&mp->stats.xid_not_found);
		goto rel;
	}
	if (ep->did != ntoh24(fh->fh_s_id) &&
	    ep->did != FC_FID_FLOGI) {
		atomic_inc(&mp->stats.xid_not_found);
		goto rel;
	}
	sof = fr_sof(fp);
	sp = &ep->seq;
	if (fc_sof_is_init(sof)) {
		sp->ssb_stat |= SSB_ST_RESP;
		sp->id = fh->fh_seq_id;
	} else if (sp->id != fh->fh_seq_id) {
		atomic_inc(&mp->stats.seq_not_found);
		goto rel;
	}

	f_ctl = ntoh24(fh->fh_f_ctl);
	fr_seq(fp) = sp;
	if (f_ctl & FC_FC_SEQ_INIT)
		ep->esb_stat |= ESB_ST_SEQ_INIT;

	if (fc_sof_needs_ack(sof))
		fc_seq_send_ack(sp, fp);
	resp = ep->resp;
	ex_resp_arg = ep->arg;

	if (fh->fh_type != FC_TYPE_FCP && fr_eof(fp) == FC_EOF_T &&
	    (f_ctl & (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) ==
	    (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) {
		spin_lock_bh(&ep->ex_lock);
		resp = ep->resp;
		rc = fc_exch_done_locked(ep);
		WARN_ON(fc_seq_exch(sp) != ep);
		spin_unlock_bh(&ep->ex_lock);
		if (!rc)
			fc_exch_delete(ep);
	}

	/*
	 * Call the receive function.
	 * The sequence is held (has a refcnt) for us,
	 * but not for the receive function.
	 *
	 * The receive function may allocate a new sequence
	 * over the old one, so we shouldn't change the
	 * sequence after this.
	 *
	 * The frame will be freed by the receive function.
	 * If new exch resp handler is valid then call that
	 * first.
	 */
	if (resp)
		resp(sp, fp, ex_resp_arg);
	else
		fc_frame_free(fp);
	fc_exch_release(ep);
	return;
rel:
	fc_exch_release(ep);
out:
	fc_frame_free(fp);
}

/**
 * fc_exch_recv_resp() - Handler for a sequence where other end is
 *			 responding to our sequence
 * @mp: The EM that the exchange is on
 * @fp: The response frame
 */
static void fc_exch_recv_resp(struct fc_exch_mgr *mp, struct fc_frame *fp)
{
	struct fc_seq *sp;

	sp = fc_seq_lookup_orig(mp, fp);	/* doesn't hold sequence */

	if (!sp)
		atomic_inc(&mp->stats.xid_not_found);
	else
		atomic_inc(&mp->stats.non_bls_resp);

	fc_frame_free(fp);
}

/**
 * fc_exch_abts_resp() - Handler for a response to an ABT
 * @ep: The exchange that the frame is on
 * @fp: The response frame
 *
 * This response would be to an ABTS cancelling an exchange or sequence.
 * The response can be either BA_ACC or BA_RJT
 */
static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp)
{
	void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg);
	void *ex_resp_arg;
	struct fc_frame_header *fh;
	struct fc_ba_acc *ap;
	struct fc_seq *sp;
	u16 low;
	u16 high;
	int rc = 1, has_rec = 0;

	fh = fc_frame_header_get(fp);
	FC_EXCH_DBG(ep, "exch: BLS rctl %x - %s\n", fh->fh_r_ctl,
		    fc_exch_rctl_name(fh->fh_r_ctl));

	if (cancel_delayed_work_sync(&ep->timeout_work))
		fc_exch_release(ep);	/* release from pending timer hold */

	spin_lock_bh(&ep->ex_lock);
	switch (fh->fh_r_ctl) {
	case FC_RCTL_BA_ACC:
		ap = fc_frame_payload_get(fp, sizeof(*ap));
		if (!ap)
			break;

		/*
		 * Decide whether to establish a Recovery Qualifier.
		 * We do this if there is a non-empty SEQ_CNT range and
		 * SEQ_ID is the same as the one we aborted.
		 */
		low = ntohs(ap->ba_low_seq_cnt);
		high = ntohs(ap->ba_high_seq_cnt);
		if ((ep->esb_stat & ESB_ST_REC_QUAL) == 0 &&
		    (ap->ba_seq_id_val != FC_BA_SEQ_ID_VAL ||
		     ap->ba_seq_id == ep->seq_id) && low != high) {
			ep->esb_stat |= ESB_ST_REC_QUAL;
			fc_exch_hold(ep);  /* hold for recovery qualifier */
			has_rec = 1;
		}
		break;
	case FC_RCTL_BA_RJT:
		break;
	default:
		break;
	}

	resp = ep->resp;
	ex_resp_arg = ep->arg;

	/* do we need to do some other checks here. Can we reuse more of
	 * fc_exch_recv_seq_resp
	 */
	sp = &ep->seq;
	/*
	 * do we want to check END_SEQ as well as LAST_SEQ here?
	 */
	if (ep->fh_type != FC_TYPE_FCP &&
	    ntoh24(fh->fh_f_ctl) & FC_FC_LAST_SEQ)
		rc = fc_exch_done_locked(ep);
	spin_unlock_bh(&ep->ex_lock);
	if (!rc)
		fc_exch_delete(ep);

	if (resp)
		resp(sp, fp, ex_resp_arg);
	else
		fc_frame_free(fp);

	if (has_rec)
		fc_exch_timer_set(ep, ep->r_a_tov);

}

/**
 * fc_exch_recv_bls() - Handler for a BLS sequence
 * @mp: The EM that the exchange is on
 * @fp: The request frame
 *
 * The BLS frame is always a sequence initiated by the remote side.
 * We may be either the originator or recipient of the exchange.
 */
static void fc_exch_recv_bls(struct fc_exch_mgr *mp, struct fc_frame *fp)
{
	struct fc_frame_header *fh;
	struct fc_exch *ep;
	u32 f_ctl;

	fh = fc_frame_header_get(fp);
	f_ctl = ntoh24(fh->fh_f_ctl);
	fr_seq(fp) = NULL;

	ep = fc_exch_find(mp, (f_ctl & FC_FC_EX_CTX) ?
			  ntohs(fh->fh_ox_id) : ntohs(fh->fh_rx_id));
	if (ep && (f_ctl & FC_FC_SEQ_INIT)) {
		spin_lock_bh(&ep->ex_lock);
		ep->esb_stat |= ESB_ST_SEQ_INIT;
		spin_unlock_bh(&ep->ex_lock);
	}
	if (f_ctl & FC_FC_SEQ_CTX) {
		/*
		 * A response to a sequence we initiated.
		 * This should only be ACKs for class 2 or F.
		 */
		switch (fh->fh_r_ctl) {
		case FC_RCTL_ACK_1:
		case FC_RCTL_ACK_0:
			break;
		default:
			FC_EXCH_DBG(ep, "BLS rctl %x - %s received",
				    fh->fh_r_ctl,
				    fc_exch_rctl_name(fh->fh_r_ctl));
			break;
		}
		fc_frame_free(fp);
	} else {
		switch (fh->fh_r_ctl) {
		case FC_RCTL_BA_RJT:
		case FC_RCTL_BA_ACC:
			if (ep)
				fc_exch_abts_resp(ep, fp);
			else
				fc_frame_free(fp);
			break;
		case FC_RCTL_BA_ABTS:
			fc_exch_recv_abts(ep, fp);
			break;
		default:			/* ignore junk */
			fc_frame_free(fp);
			break;
		}
	}
	if (ep)
		fc_exch_release(ep);	/* release hold taken by fc_exch_find */
}

/**
 * fc_seq_ls_acc() - Accept sequence with LS_ACC
 * @rx_fp: The received frame, not freed here.
 *
 * If this fails due to allocation or transmit congestion, assume the
 * originator will repeat the sequence.
 */
static void fc_seq_ls_acc(struct fc_frame *rx_fp)
{
	struct fc_lport *lport;
	struct fc_els_ls_acc *acc;
	struct fc_frame *fp;

	lport = fr_dev(rx_fp);
	fp = fc_frame_alloc(lport, sizeof(*acc));
	if (!fp)
		return;
	acc = fc_frame_payload_get(fp, sizeof(*acc));
	memset(acc, 0, sizeof(*acc));
	acc->la_cmd = ELS_LS_ACC;
	fc_fill_reply_hdr(fp, rx_fp, FC_RCTL_ELS_REP, 0);
	lport->tt.frame_send(lport, fp);
}

/**
 * fc_seq_ls_rjt() - Reject a sequence with ELS LS_RJT
 * @rx_fp: The received frame, not freed here.
 * @reason: The reason the sequence is being rejected
 * @explan: The explanation for the rejection
 *
 * If this fails due to allocation or transmit congestion, assume the
 * originator will repeat the sequence.
 */
static void fc_seq_ls_rjt(struct fc_frame *rx_fp, enum fc_els_rjt_reason reason,
			  enum fc_els_rjt_explan explan)
{
	struct fc_lport *lport;
	struct fc_els_ls_rjt *rjt;
	struct fc_frame *fp;

	lport = fr_dev(rx_fp);
	fp = fc_frame_alloc(lport, sizeof(*rjt));
	if (!fp)
		return;
	rjt = fc_frame_payload_get(fp, sizeof(*rjt));
	memset(rjt, 0, sizeof(*rjt));
	rjt->er_cmd = ELS_LS_RJT;
	rjt->er_reason = reason;
	rjt->er_explan = explan;
	fc_fill_reply_hdr(fp, rx_fp, FC_RCTL_ELS_REP, 0);
	lport->tt.frame_send(lport, fp);
}

/**
 * fc_exch_reset() - Reset an exchange
 * @ep: The exchange to be reset
 */
static void fc_exch_reset(struct fc_exch *ep)
{
	struct fc_seq *sp;
	void (*resp)(struct fc_seq *, struct fc_frame *, void *);
	void *arg;
	int rc = 1;

	spin_lock_bh(&ep->ex_lock);
	fc_exch_abort_locked(ep, 0);
	ep->state |= FC_EX_RST_CLEANUP;
	if (cancel_delayed_work(&ep->timeout_work))
		atomic_dec(&ep->ex_refcnt);	/* drop hold for timer */
	resp = ep->resp;
	ep->resp = NULL;
	if (ep->esb_stat & ESB_ST_REC_QUAL)
		atomic_dec(&ep->ex_refcnt);	/* drop hold for rec_qual */
	ep->esb_stat &= ~ESB_ST_REC_QUAL;
	arg = ep->arg;
	sp = &ep->seq;
	rc = fc_exch_done_locked(ep);
	spin_unlock_bh(&ep->ex_lock);
	if (!rc)
		fc_exch_delete(ep);

	if (resp)
		resp(sp, ERR_PTR(-FC_EX_CLOSED), arg);
}

/**
 * fc_exch_pool_reset() - Reset a per cpu exchange pool
 * @lport: The local port that the exchange pool is on
 * @pool:  The exchange pool to be reset
 * @sid:   The source ID
 * @did:   The destination ID
 *
 * Resets a per cpu exches pool, releasing all of its sequences
 * and exchanges. If sid is non-zero then reset only exchanges
 * we sourced from the local port's FID. If did is non-zero then
 * only reset exchanges destined for the local port's FID.
 */
static void fc_exch_pool_reset(struct fc_lport *lport,
			       struct fc_exch_pool *pool,
			       u32 sid, u32 did)
{
	struct fc_exch *ep;
	struct fc_exch *next;

	spin_lock_bh(&pool->lock);
restart:
	list_for_each_entry_safe(ep, next, &pool->ex_list, ex_list) {
		if ((lport == ep->lp) &&
		    (sid == 0 || sid == ep->sid) &&
		    (did == 0 || did == ep->did)) {
			fc_exch_hold(ep);
			spin_unlock_bh(&pool->lock);

			fc_exch_reset(ep);

			fc_exch_release(ep);
			spin_lock_bh(&pool->lock);

			/*
			 * must restart loop incase while lock
			 * was down multiple eps were released.
			 */
			goto restart;
		}
	}
	spin_unlock_bh(&pool->lock);
}

/**
 * fc_exch_mgr_reset() - Reset all EMs of a local port
 * @lport: The local port whose EMs are to be reset
 * @sid:   The source ID
 * @did:   The destination ID
 *
 * Reset all EMs associated with a given local port. Release all
 * sequences and exchanges. If sid is non-zero then reset only the
 * exchanges sent from the local port's FID. If did is non-zero then
 * reset only exchanges destined for the local port's FID.
 */
void fc_exch_mgr_reset(struct fc_lport *lport, u32 sid, u32 did)
{
	struct fc_exch_mgr_anchor *ema;
	unsigned int cpu;

	list_for_each_entry(ema, &lport->ema_list, ema_list) {
		for_each_possible_cpu(cpu)
			fc_exch_pool_reset(lport,
					   per_cpu_ptr(ema->mp->pool, cpu),
					   sid, did);
	}
}
EXPORT_SYMBOL(fc_exch_mgr_reset);

/**
 * fc_exch_lookup() - find an exchange
 * @lport: The local port
 * @xid: The exchange ID
 *
 * Returns exchange pointer with hold for caller, or NULL if not found.
 */
static struct fc_exch *fc_exch_lookup(struct fc_lport *lport, u32 xid)
{
	struct fc_exch_mgr_anchor *ema;

	list_for_each_entry(ema, &lport->ema_list, ema_list)
		if (ema->mp->min_xid <= xid && xid <= ema->mp->max_xid)
			return fc_exch_find(ema->mp, xid);
	return NULL;
}

/**
 * fc_exch_els_rec() - Handler for ELS REC (Read Exchange Concise) requests
 * @rfp: The REC frame, not freed here.
 *
 * Note that the requesting port may be different than the S_ID in the request.
 */
static void fc_exch_els_rec(struct fc_frame *rfp)
{
	struct fc_lport *lport;
	struct fc_frame *fp;
	struct fc_exch *ep;
	struct fc_els_rec *rp;
	struct fc_els_rec_acc *acc;
	enum fc_els_rjt_reason reason = ELS_RJT_LOGIC;
	enum fc_els_rjt_explan explan;
	u32 sid;
	u16 rxid;
	u16 oxid;

	lport = fr_dev(rfp);
	rp = fc_frame_payload_get(rfp, sizeof(*rp));
	explan = ELS_EXPL_INV_LEN;
	if (!rp)
		goto reject;
	sid = ntoh24(rp->rec_s_id);
	rxid = ntohs(rp->rec_rx_id);
	oxid = ntohs(rp->rec_ox_id);

	ep = fc_exch_lookup(lport,
			    sid == fc_host_port_id(lport->host) ? oxid : rxid);
	explan = ELS_EXPL_OXID_RXID;
	if (!ep)
		goto reject;
	if (ep->oid != sid || oxid != ep->oxid)
		goto rel;
	if (rxid != FC_XID_UNKNOWN && rxid != ep->rxid)
		goto rel;
	fp = fc_frame_alloc(lport, sizeof(*acc));
	if (!fp)
		goto out;

	acc = fc_frame_payload_get(fp, sizeof(*acc));
	memset(acc, 0, sizeof(*acc));
	acc->reca_cmd = ELS_LS_ACC;
	acc->reca_ox_id = rp->rec_ox_id;
	memcpy(acc->reca_ofid, rp->rec_s_id, 3);
	acc->reca_rx_id = htons(ep->rxid);
	if (ep->sid == ep->oid)
		hton24(acc->reca_rfid, ep->did);
	else
		hton24(acc->reca_rfid, ep->sid);
	acc->reca_fc4value = htonl(ep->seq.rec_data);
	acc->reca_e_stat = htonl(ep->esb_stat & (ESB_ST_RESP |
						 ESB_ST_SEQ_INIT |
						 ESB_ST_COMPLETE));
	fc_fill_reply_hdr(fp, rfp, FC_RCTL_ELS_REP, 0);
	lport->tt.frame_send(lport, fp);
out:
	fc_exch_release(ep);
	return;

rel:
	fc_exch_release(ep);
reject:
	fc_seq_ls_rjt(rfp, reason, explan);
}

/**
 * fc_exch_rrq_resp() - Handler for RRQ responses
 * @sp:	 The sequence that the RRQ is on
 * @fp:	 The RRQ frame
 * @arg: The exchange that the RRQ is on
 *
 * TODO: fix error handler.
 */
static void fc_exch_rrq_resp(struct fc_seq *sp, struct fc_frame *fp, void *arg)
{
	struct fc_exch *aborted_ep = arg;
	unsigned int op;

	if (IS_ERR(fp)) {
		int err = PTR_ERR(fp);

		if (err == -FC_EX_CLOSED || err == -FC_EX_TIMEOUT)
			goto cleanup;
		FC_EXCH_DBG(aborted_ep, "Cannot process RRQ, "
			    "frame error %d\n", err);
		return;
	}

	op = fc_frame_payload_op(fp);
	fc_frame_free(fp);

	switch (op) {
	case ELS_LS_RJT:
		FC_EXCH_DBG(aborted_ep, "LS_RJT for RRQ");
		/* fall through */
	case ELS_LS_ACC:
		goto cleanup;
	default:
		FC_EXCH_DBG(aborted_ep, "unexpected response op %x "
			    "for RRQ", op);
		return;
	}

cleanup:
	fc_exch_done(&aborted_ep->seq);
	/* drop hold for rec qual */
	fc_exch_release(aborted_ep);
}


/**
 * fc_exch_seq_send() - Send a frame using a new exchange and sequence
 * @lport:	The local port to send the frame on
 * @fp:		The frame to be sent
 * @resp:	The response handler for this request
 * @destructor: The destructor for the exchange
 * @arg:	The argument to be passed to the response handler
 * @timer_msec: The timeout period for the exchange
 *
 * The frame pointer with some of the header's fields must be
 * filled before calling this routine, those fields are:
 *
 * - routing control
 * - FC port did
 * - FC port sid
 * - FC header type
 * - frame control
 * - parameter or relative offset
 */
static struct fc_seq *fc_exch_seq_send(struct fc_lport *lport,
				       struct fc_frame *fp,
				       void (*resp)(struct fc_seq *,
						    struct fc_frame *fp,
						    void *arg),
				       void (*destructor)(struct fc_seq *,
							  void *),
				       void *arg, u32 timer_msec)
{
	struct fc_exch *ep;
	struct fc_seq *sp = NULL;
	struct fc_frame_header *fh;
	struct fc_fcp_pkt *fsp = NULL;
	int rc = 1;

	ep = fc_exch_alloc(lport, fp);
	if (!ep) {
		fc_frame_free(fp);
		return NULL;
	}
	ep->esb_stat |= ESB_ST_SEQ_INIT;
	fh = fc_frame_header_get(fp);
	fc_exch_set_addr(ep, ntoh24(fh->fh_s_id), ntoh24(fh->fh_d_id));
	ep->resp = resp;
	ep->destructor = destructor;
	ep->arg = arg;
	ep->r_a_tov = FC_DEF_R_A_TOV;
	ep->lp = lport;
	sp = &ep->seq;

	ep->fh_type = fh->fh_type; /* save for possbile timeout handling */
	ep->f_ctl = ntoh24(fh->fh_f_ctl);
	fc_exch_setup_hdr(ep, fp, ep->f_ctl);
	sp->cnt++;

	if (ep->xid <= lport->lro_xid && fh->fh_r_ctl == FC_RCTL_DD_UNSOL_CMD) {
		fsp = fr_fsp(fp);
		fc_fcp_ddp_setup(fr_fsp(fp), ep->xid);
	}

	if (unlikely(lport->tt.frame_send(lport, fp)))
		goto err;

	if (timer_msec)
		fc_exch_timer_set_locked(ep, timer_msec);
	ep->f_ctl &= ~FC_FC_FIRST_SEQ;	/* not first seq */

	if (ep->f_ctl & FC_FC_SEQ_INIT)
		ep->esb_stat &= ~ESB_ST_SEQ_INIT;
	spin_unlock_bh(&ep->ex_lock);
	return sp;
err:
	if (fsp)
		fc_fcp_ddp_done(fsp);
	rc = fc_exch_done_locked(ep);
	spin_unlock_bh(&ep->ex_lock);
	if (!rc)
		fc_exch_delete(ep);
	return NULL;
}

/**
 * fc_exch_rrq() - Send an ELS RRQ (Reinstate Recovery Qualifier) command
 * @ep: The exchange to send the RRQ on
 *
 * This tells the remote port to stop blocking the use of
 * the exchange and the seq_cnt range.
 */
static void fc_exch_rrq(struct fc_exch *ep)
{
	struct fc_lport *lport;
	struct fc_els_rrq *rrq;
	struct fc_frame *fp;
	u32 did;

	lport = ep->lp;

	fp = fc_frame_alloc(lport, sizeof(*rrq));
	if (!fp)
		goto retry;

	rrq = fc_frame_payload_get(fp, sizeof(*rrq));
	memset(rrq, 0, sizeof(*rrq));
	rrq->rrq_cmd = ELS_RRQ;
	hton24(rrq->rrq_s_id, ep->sid);
	rrq->rrq_ox_id = htons(ep->oxid);
	rrq->rrq_rx_id = htons(ep->rxid);

	did = ep->did;
	if (ep->esb_stat & ESB_ST_RESP)
		did = ep->sid;

	fc_fill_fc_hdr(fp, FC_RCTL_ELS_REQ, did,
		       lport->port_id, FC_TYPE_ELS,
		       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);

	if (fc_exch_seq_send(lport, fp, fc_exch_rrq_resp, NULL, ep,
			     lport->e_d_tov))
		return;

retry:
	spin_lock_bh(&ep->ex_lock);
	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE)) {
		spin_unlock_bh(&ep->ex_lock);
		/* drop hold for rec qual */
		fc_exch_release(ep);
		return;
	}
	ep->esb_stat |= ESB_ST_REC_QUAL;
	fc_exch_timer_set_locked(ep, ep->r_a_tov);
	spin_unlock_bh(&ep->ex_lock);
}

/**
 * fc_exch_els_rrq() - Handler for ELS RRQ (Reset Recovery Qualifier) requests
 * @fp: The RRQ frame, not freed here.
 */
static void fc_exch_els_rrq(struct fc_frame *fp)
{
	struct fc_lport *lport;
	struct fc_exch *ep = NULL;	/* request or subject exchange */
	struct fc_els_rrq *rp;
	u32 sid;
	u16 xid;
	enum fc_els_rjt_explan explan;

	lport = fr_dev(fp);
	rp = fc_frame_payload_get(fp, sizeof(*rp));
	explan = ELS_EXPL_INV_LEN;
	if (!rp)
		goto reject;

	/*
	 * lookup subject exchange.
	 */
	sid = ntoh24(rp->rrq_s_id);		/* subject source */
	xid = fc_host_port_id(lport->host) == sid ?
			ntohs(rp->rrq_ox_id) : ntohs(rp->rrq_rx_id);
	ep = fc_exch_lookup(lport, xid);
	explan = ELS_EXPL_OXID_RXID;
	if (!ep)
		goto reject;
	spin_lock_bh(&ep->ex_lock);
	if (ep->oxid != ntohs(rp->rrq_ox_id))
		goto unlock_reject;
	if (ep->rxid != ntohs(rp->rrq_rx_id) &&
	    ep->rxid != FC_XID_UNKNOWN)
		goto unlock_reject;
	explan = ELS_EXPL_SID;
	if (ep->sid != sid)
		goto unlock_reject;

	/*
	 * Clear Recovery Qualifier state, and cancel timer if complete.
	 */
	if (ep->esb_stat & ESB_ST_REC_QUAL) {
		ep->esb_stat &= ~ESB_ST_REC_QUAL;
		atomic_dec(&ep->ex_refcnt);	/* drop hold for rec qual */
	}
	if (ep->esb_stat & ESB_ST_COMPLETE) {
		if (cancel_delayed_work(&ep->timeout_work))
			atomic_dec(&ep->ex_refcnt);	/* drop timer hold */
	}

	spin_unlock_bh(&ep->ex_lock);

	/*
	 * Send LS_ACC.
	 */
	fc_seq_ls_acc(fp);
	goto out;

unlock_reject:
	spin_unlock_bh(&ep->ex_lock);
reject:
	fc_seq_ls_rjt(fp, ELS_RJT_LOGIC, explan);
out:
	if (ep)
		fc_exch_release(ep);	/* drop hold from fc_exch_find */
}

/**
 * fc_exch_mgr_add() - Add an exchange manager to a local port's list of EMs
 * @lport: The local port to add the exchange manager to
 * @mp:	   The exchange manager to be added to the local port
 * @match: The match routine that indicates when this EM should be used
 */
struct fc_exch_mgr_anchor *fc_exch_mgr_add(struct fc_lport *lport,
					   struct fc_exch_mgr *mp,
					   bool (*match)(struct fc_frame *))
{
	struct fc_exch_mgr_anchor *ema;

	ema = kmalloc(sizeof(*ema), GFP_ATOMIC);
	if (!ema)
		return ema;

	ema->mp = mp;
	ema->match = match;
	/* add EM anchor to EM anchors list */
	list_add_tail(&ema->ema_list, &lport->ema_list);
	kref_get(&mp->kref);
	return ema;
}
EXPORT_SYMBOL(fc_exch_mgr_add);

/**
 * fc_exch_mgr_destroy() - Destroy an exchange manager
 * @kref: The reference to the EM to be destroyed
 */
static void fc_exch_mgr_destroy(struct kref *kref)
{
	struct fc_exch_mgr *mp = container_of(kref, struct fc_exch_mgr, kref);

	mempool_destroy(mp->ep_pool);
	free_percpu(mp->pool);
	kfree(mp);
}

/**
 * fc_exch_mgr_del() - Delete an EM from a local port's list
 * @ema: The exchange manager anchor identifying the EM to be deleted
 */
void fc_exch_mgr_del(struct fc_exch_mgr_anchor *ema)
{
	/* remove EM anchor from EM anchors list */
	list_del(&ema->ema_list);
	kref_put(&ema->mp->kref, fc_exch_mgr_destroy);
	kfree(ema);
}
EXPORT_SYMBOL(fc_exch_mgr_del);

/**
 * fc_exch_mgr_list_clone() - Share all exchange manager objects
 * @src: Source lport to clone exchange managers from
 * @dst: New lport that takes references to all the exchange managers
 */
int fc_exch_mgr_list_clone(struct fc_lport *src, struct fc_lport *dst)
{
	struct fc_exch_mgr_anchor *ema, *tmp;

	list_for_each_entry(ema, &src->ema_list, ema_list) {
		if (!fc_exch_mgr_add(dst, ema->mp, ema->match))
			goto err;
	}
	return 0;
err:
	list_for_each_entry_safe(ema, tmp, &dst->ema_list, ema_list)
		fc_exch_mgr_del(ema);
	return -ENOMEM;
}
EXPORT_SYMBOL(fc_exch_mgr_list_clone);

/**
 * fc_exch_mgr_alloc() - Allocate an exchange manager
 * @lport:   The local port that the new EM will be associated with
 * @class:   The default FC class for new exchanges
 * @min_xid: The minimum XID for exchanges from the new EM
 * @max_xid: The maximum XID for exchanges from the new EM
 * @match:   The match routine for the new EM
 */
struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lport,
				      enum fc_class class,
				      u16 min_xid, u16 max_xid,
				      bool (*match)(struct fc_frame *))
{
	struct fc_exch_mgr *mp;
	u16 pool_exch_range;
	size_t pool_size;
	unsigned int cpu;
	struct fc_exch_pool *pool;

	if (max_xid <= min_xid || max_xid == FC_XID_UNKNOWN ||
	    (min_xid & fc_cpu_mask) != 0) {
		FC_LPORT_DBG(lport, "Invalid min_xid 0x:%x and max_xid 0x:%x\n",
			     min_xid, max_xid);
		return NULL;
	}

	/*
	 * allocate memory for EM
	 */
	mp = kzalloc(sizeof(struct fc_exch_mgr), GFP_ATOMIC);
	if (!mp)
		return NULL;

	mp->class = class;
	/* adjust em exch xid range for offload */
	mp->min_xid = min_xid;
	mp->max_xid = max_xid;

	mp->ep_pool = mempool_create_slab_pool(2, fc_em_cachep);
	if (!mp->ep_pool)
		goto free_mp;

	/*
	 * Setup per cpu exch pool with entire exchange id range equally
	 * divided across all cpus. The exch pointers array memory is
	 * allocated for exch range per pool.
	 */
	pool_exch_range = (mp->max_xid - mp->min_xid + 1) / (fc_cpu_mask + 1);
	mp->pool_max_index = pool_exch_range - 1;

	/*
	 * Allocate and initialize per cpu exch pool
	 */
	pool_size = sizeof(*pool) + pool_exch_range * sizeof(struct fc_exch *);
	mp->pool = __alloc_percpu(pool_size, __alignof__(struct fc_exch_pool));
	if (!mp->pool)
		goto free_mempool;
	for_each_possible_cpu(cpu) {
		pool = per_cpu_ptr(mp->pool, cpu);
		pool->left = FC_XID_UNKNOWN;
		pool->right = FC_XID_UNKNOWN;
		spin_lock_init(&pool->lock);
		INIT_LIST_HEAD(&pool->ex_list);
	}

	kref_init(&mp->kref);
	if (!fc_exch_mgr_add(lport, mp, match)) {
		free_percpu(mp->pool);
		goto free_mempool;
	}

	/*
	 * Above kref_init() sets mp->kref to 1 and then
	 * call to fc_exch_mgr_add incremented mp->kref again,
	 * so adjust that extra increment.
	 */
	kref_put(&mp->kref, fc_exch_mgr_destroy);
	return mp;

free_mempool:
	mempool_destroy(mp->ep_pool);
free_mp:
	kfree(mp);
	return NULL;
}
EXPORT_SYMBOL(fc_exch_mgr_alloc);

/**
 * fc_exch_mgr_free() - Free all exchange managers on a local port
 * @lport: The local port whose EMs are to be freed
 */
void fc_exch_mgr_free(struct fc_lport *lport)
{
	struct fc_exch_mgr_anchor *ema, *next;

	flush_workqueue(fc_exch_workqueue);
	list_for_each_entry_safe(ema, next, &lport->ema_list, ema_list)
		fc_exch_mgr_del(ema);
}
EXPORT_SYMBOL(fc_exch_mgr_free);

/**
 * fc_find_ema() - Lookup and return appropriate Exchange Manager Anchor depending
 * upon 'xid'.
 * @f_ctl: f_ctl
 * @lport: The local port the frame was received on
 * @fh: The received frame header
 */
static struct fc_exch_mgr_anchor *fc_find_ema(u32 f_ctl,
					      struct fc_lport *lport,
					      struct fc_frame_header *fh)
{
	struct fc_exch_mgr_anchor *ema;
	u16 xid;

	if (f_ctl & FC_FC_EX_CTX)
		xid = ntohs(fh->fh_ox_id);
	else {
		xid = ntohs(fh->fh_rx_id);
		if (xid == FC_XID_UNKNOWN)
			return list_entry(lport->ema_list.prev,
					  typeof(*ema), ema_list);
	}

	list_for_each_entry(ema, &lport->ema_list, ema_list) {
		if ((xid >= ema->mp->min_xid) &&
		    (xid <= ema->mp->max_xid))
			return ema;
	}
	return NULL;
}
/**
 * fc_exch_recv() - Handler for received frames
 * @lport: The local port the frame was received on
 * @fp:	The received frame
 */
void fc_exch_recv(struct fc_lport *lport, struct fc_frame *fp)
{
	struct fc_frame_header *fh = fc_frame_header_get(fp);
	struct fc_exch_mgr_anchor *ema;
	u32 f_ctl;

	/* lport lock ? */
	if (!lport || lport->state == LPORT_ST_DISABLED) {
		FC_LPORT_DBG(lport, "Receiving frames for an lport that "
			     "has not been initialized correctly\n");
		fc_frame_free(fp);
		return;
	}

	f_ctl = ntoh24(fh->fh_f_ctl);
	ema = fc_find_ema(f_ctl, lport, fh);
	if (!ema) {
		FC_LPORT_DBG(lport, "Unable to find Exchange Manager Anchor,"
				    "fc_ctl <0x%x>, xid <0x%x>\n",
				     f_ctl,
				     (f_ctl & FC_FC_EX_CTX) ?
				     ntohs(fh->fh_ox_id) :
				     ntohs(fh->fh_rx_id));
		fc_frame_free(fp);
		return;
	}

	/*
	 * If frame is marked invalid, just drop it.
	 */
	switch (fr_eof(fp)) {
	case FC_EOF_T:
		if (f_ctl & FC_FC_END_SEQ)
			skb_trim(fp_skb(fp), fr_len(fp) - FC_FC_FILL(f_ctl));
		/* fall through */
	case FC_EOF_N:
		if (fh->fh_type == FC_TYPE_BLS)
			fc_exch_recv_bls(ema->mp, fp);
		else if ((f_ctl & (FC_FC_EX_CTX | FC_FC_SEQ_CTX)) ==
			 FC_FC_EX_CTX)
			fc_exch_recv_seq_resp(ema->mp, fp);
		else if (f_ctl & FC_FC_SEQ_CTX)
			fc_exch_recv_resp(ema->mp, fp);
		else	/* no EX_CTX and no SEQ_CTX */
			fc_exch_recv_req(lport, ema->mp, fp);
		break;
	default:
		FC_LPORT_DBG(lport, "dropping invalid frame (eof %x)",
			     fr_eof(fp));
		fc_frame_free(fp);
	}
}
EXPORT_SYMBOL(fc_exch_recv);

/**
 * fc_exch_init() - Initialize the exchange layer for a local port
 * @lport: The local port to initialize the exchange layer for
 */
int fc_exch_init(struct fc_lport *lport)
{
	if (!lport->tt.seq_start_next)
		lport->tt.seq_start_next = fc_seq_start_next;

	if (!lport->tt.seq_set_resp)
		lport->tt.seq_set_resp = fc_seq_set_resp;

	if (!lport->tt.exch_seq_send)
		lport->tt.exch_seq_send = fc_exch_seq_send;

	if (!lport->tt.seq_send)
		lport->tt.seq_send = fc_seq_send;

	if (!lport->tt.seq_els_rsp_send)
		lport->tt.seq_els_rsp_send = fc_seq_els_rsp_send;

	if (!lport->tt.exch_done)
		lport->tt.exch_done = fc_exch_done;

	if (!lport->tt.exch_mgr_reset)
		lport->tt.exch_mgr_reset = fc_exch_mgr_reset;

	if (!lport->tt.seq_exch_abort)
		lport->tt.seq_exch_abort = fc_seq_exch_abort;

	if (!lport->tt.seq_assign)
		lport->tt.seq_assign = fc_seq_assign;

	if (!lport->tt.seq_release)
		lport->tt.seq_release = fc_seq_release;

	return 0;
}
EXPORT_SYMBOL(fc_exch_init);

/**
 * fc_setup_exch_mgr() - Setup an exchange manager
 */
int fc_setup_exch_mgr(void)
{
	fc_em_cachep = kmem_cache_create("libfc_em", sizeof(struct fc_exch),
					 0, SLAB_HWCACHE_ALIGN, NULL);
	if (!fc_em_cachep)
		return -ENOMEM;

	/*
	 * Initialize fc_cpu_mask and fc_cpu_order. The
	 * fc_cpu_mask is set for nr_cpu_ids rounded up
	 * to order of 2's * power and order is stored
	 * in fc_cpu_order as this is later required in
	 * mapping between an exch id and exch array index
	 * in per cpu exch pool.
	 *
	 * This round up is required to align fc_cpu_mask
	 * to exchange id's lower bits such that all incoming
	 * frames of an exchange gets delivered to the same
	 * cpu on which exchange originated by simple bitwise
	 * AND operation between fc_cpu_mask and exchange id.
	 */
	fc_cpu_mask = 1;
	fc_cpu_order = 0;
	while (fc_cpu_mask < nr_cpu_ids) {
		fc_cpu_mask <<= 1;
		fc_cpu_order++;
	}
	fc_cpu_mask--;

	fc_exch_workqueue = create_singlethread_workqueue("fc_exch_workqueue");
	if (!fc_exch_workqueue)
		goto err;
	return 0;
err:
	kmem_cache_destroy(fc_em_cachep);
	return -ENOMEM;
}

/**
 * fc_destroy_exch_mgr() - Destroy an exchange manager
 */
void fc_destroy_exch_mgr(void)
{
	destroy_workqueue(fc_exch_workqueue);
	kmem_cache_destroy(fc_em_cachep);
}

Privacy Policy