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Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull locking fix from Thomas Gleixner:
 "A single fix to address a race in the static key logic"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/static_key: Fix concurrent static_key_slow_inc()
This commit is contained in:
Linus Torvalds
2016-06-25 06:14:44 -07:00
parent 2de23071f5 4c5ea0a9cd
commit e3b22bc3d7
2 changed files with 46 additions and 6 deletions
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16
include/linux/jump_label.h
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@@ -117,13 +117,18 @@ struct module;
#include <linux/atomic.h>
#ifdef HAVE_JUMP_LABEL
static inline int static_key_count(struct static_key *key)
{
return atomic_read(&key->enabled);
/*
* -1 means the first static_key_slow_inc() is in progress.
* static_key_enabled() must return true, so return 1 here.
*/
int n = atomic_read(&key->enabled);
return n >= 0 ? n : 1;
}
#ifdef HAVE_JUMP_LABEL
#define JUMP_TYPE_FALSE 0UL
#define JUMP_TYPE_TRUE 1UL
#define JUMP_TYPE_MASK 1UL
@@ -162,6 +167,11 @@ extern void jump_label_apply_nops(struct module *mod);
#else /* !HAVE_JUMP_LABEL */
static inline int static_key_count(struct static_key *key)
{
return atomic_read(&key->enabled);
}
static __always_inline void jump_label_init(void)
{
static_key_initialized = true;