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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-24 17:36:18 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-03-24 17:36:18 +0100 |
| commit | 19d6f04cd374b886b98d7b070ebf287c93bff7ac (patch) | |
| tree | 26414711c808fbfd736423dfd5b1498abb256b37 /include | |
| parent | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net (diff) | |
| parent | bitops: Do not default to __clear_bit() for __clear_bit_unlock() (diff) | |
| download | linux-19d6f04cd374b886b98d7b070ebf287c93bff7ac.tar.xz linux-19d6f04cd374b886b98d7b070ebf287c93bff7ac.zip | |
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Ingo Molnar:
"Documentation updates and a bitops ordering fix"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
bitops: Do not default to __clear_bit() for __clear_bit_unlock()
documentation: Clarify compiler store-fusion example
documentation: Transitivity is not cumulativity
documentation: Add alternative release-acquire outcome
documentation: Distinguish between local and global transitivity
documentation: Subsequent writes ordered by rcu_dereference()
documentation: Remove obsolete reference to RCU-protected indexes
documentation: Fix memory-barriers.txt section references
documentation: Fix control dependency and identical stores
Diffstat (limited to 'include')
| -rw-r--r-- | include/asm-generic/bitops/lock.h | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/include/asm-generic/bitops/lock.h b/include/asm-generic/bitops/lock.h index c30266e94806..8ef0ccbf8167 100644 --- a/include/asm-generic/bitops/lock.h +++ b/include/asm-generic/bitops/lock.h @@ -29,16 +29,16 @@ do { \ * @nr: the bit to set * @addr: the address to start counting from * - * This operation is like clear_bit_unlock, however it is not atomic. - * It does provide release barrier semantics so it can be used to unlock - * a bit lock, however it would only be used if no other CPU can modify - * any bits in the memory until the lock is released (a good example is - * if the bit lock itself protects access to the other bits in the word). + * A weaker form of clear_bit_unlock() as used by __bit_lock_unlock(). If all + * the bits in the word are protected by this lock some archs can use weaker + * ops to safely unlock. + * + * See for example x86's implementation. */ #define __clear_bit_unlock(nr, addr) \ do { \ - smp_mb(); \ - __clear_bit(nr, addr); \ + smp_mb__before_atomic(); \ + clear_bit(nr, addr); \ } while (0) #endif /* _ASM_GENERIC_BITOPS_LOCK_H_ */ |