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authorDipankar Sarma <dipankar@in.ibm.com>2005-09-09 13:04:09 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-09 13:57:54 -0700
commitc0dfb2905126e9e94edebbce8d3e05001301f52d (patch)
treedb31f15f7e5dea0c812992c2ca87a1151507ed9c /kernel
parent8b6490e5faafb3a16ea45654fb55f9ff086f1495 (diff)
[PATCH] files: rcuref APIs
Adds a set of primitives to do reference counting for objects that are looked up without locks using RCU. Signed-off-by: Ravikiran Thirumalai <kiran_th@gmail.com> Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcupdate.c14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c
index f436993bd590..bef3b6901b76 100644
--- a/kernel/rcupdate.c
+++ b/kernel/rcupdate.c
@@ -45,6 +45,7 @@
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/rcupdate.h>
+#include <linux/rcuref.h>
#include <linux/cpu.h>
/* Definition for rcupdate control block. */
@@ -72,6 +73,19 @@ DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L };
static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL};
static int maxbatch = 10;
+#ifndef __HAVE_ARCH_CMPXCHG
+/*
+ * We use an array of spinlocks for the rcurefs -- similar to ones in sparc
+ * 32 bit atomic_t implementations, and a hash function similar to that
+ * for our refcounting needs.
+ * Can't help multiprocessors which donot have cmpxchg :(
+ */
+
+spinlock_t __rcuref_hash[RCUREF_HASH_SIZE] = {
+ [0 ... (RCUREF_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED
+};
+#endif
+
/**
* call_rcu - Queue an RCU callback for invocation after a grace period.
* @head: structure to be used for queueing the RCU updates.

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