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[PATCH] files: rcuref APIs

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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>
This commit is contained in:
Dipankar Sarma
2005-09-09 13:04:09 -07:00
committed by Linus Torvalds
parent 8b6490e5fa
commit c0dfb29051
3 changed files with 308 additions and 0 deletions
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14
kernel/rcupdate.c
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@ -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.