path: root/arch/powerpc/platforms/powermac/bootx_init.c
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authorNathan Lynch <ntl@pobox.com>2006-08-22 20:36:05 -0500
committerPaul Mackerras <paulus@samba.org>2006-08-23 15:51:18 +1000
commit5db9fa9593e2ff69f2b95f9d59229dc4faaa564d (patch)
treed58ba58c05408edf8993d0da5a31b3ea3df1a053 /arch/powerpc/platforms/powermac/bootx_init.c
parentaa74a30be971c632d734e487df42278b1cf85151 (diff)
[POWERPC] Fix gettimeofday inaccuracies
There are two problems in the powerpc gettimeofday code which can cause incorrect results to be returned. The first is that there is a race between do_gettimeofday and the timer interrupt: 1. do_gettimeofday does get_tb() 2. decrementer exception on boot cpu which runs timer_recalc_offset, which also samples the timebase and updates the do_gtod structure with a greater timebase value. 3. do_gettimeofday calls __do_gettimeofday, which leads to the negative result from tb_val - temp_varp->tb_orig_stamp. The second is caused by taking the boot cpu offline, which can cause the value of tb_last_jiffy to be increased past the currently available timebase, causing the same underflow as above. [paulus@samba.org - define and use data_barrier() instead of mb().] Signed-off-by: Nathan Lynch <ntl@pobox.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
Diffstat (limited to 'arch/powerpc/platforms/powermac/bootx_init.c')
0 files changed, 0 insertions, 0 deletions

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