diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-19 06:27:55 -1000 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-07-19 06:27:55 -1000 |
commit | d057190925d994b808e1d07e6c76b90a32caac77 (patch) | |
tree | 1f2d104f879435881d77f0d8d1e48c3224264d53 /include/linux/osq_lock.h | |
parent | d1743b810d7a306d1dd837e086d18124bc38b575 (diff) | |
parent | 9de8033f1bbcce5ed23fe5da9ca1a5060207f7ed (diff) |
Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Thomas Gleixner:
"The locking department delivers:
- A rather large and intrusive bundle of fixes to address serious
performance regressions introduced by the new rwsem / mcs
technology. Simpler solutions have been discussed, but they would
have been ugly bandaids with more risk than doing the right thing.
- Make the rwsem spin on owner technology opt-in for architectures
and enable it only on the known to work ones.
- A few fixes to the lockdep userspace library"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rwsem: Add CONFIG_RWSEM_SPIN_ON_OWNER
locking/mutex: Disable optimistic spinning on some architectures
locking/rwsem: Reduce the size of struct rw_semaphore
locking/rwsem: Rename 'activity' to 'count'
locking/spinlocks/mcs: Micro-optimize osq_unlock()
locking/spinlocks/mcs: Introduce and use init macro and function for osq locks
locking/spinlocks/mcs: Convert osq lock to atomic_t to reduce overhead
locking/spinlocks/mcs: Rename optimistic_spin_queue() to optimistic_spin_node()
locking/rwsem: Allow conservative optimistic spinning when readers have lock
tools/liblockdep: Account for bitfield changes in lockdeps lock_acquire
tools/liblockdep: Remove debug print left over from development
tools/liblockdep: Fix comparison of a boolean value with a value of 2
Diffstat (limited to 'include/linux/osq_lock.h')
-rw-r--r-- | include/linux/osq_lock.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/include/linux/osq_lock.h b/include/linux/osq_lock.h new file mode 100644 index 00000000000..90230d5811c --- /dev/null +++ b/include/linux/osq_lock.h @@ -0,0 +1,27 @@ +#ifndef __LINUX_OSQ_LOCK_H +#define __LINUX_OSQ_LOCK_H + +/* + * An MCS like lock especially tailored for optimistic spinning for sleeping + * lock implementations (mutex, rwsem, etc). + */ + +#define OSQ_UNLOCKED_VAL (0) + +struct optimistic_spin_queue { + /* + * Stores an encoded value of the CPU # of the tail node in the queue. + * If the queue is empty, then it's set to OSQ_UNLOCKED_VAL. + */ + atomic_t tail; +}; + +/* Init macro and function. */ +#define OSQ_LOCK_UNLOCKED { ATOMIC_INIT(OSQ_UNLOCKED_VAL) } + +static inline void osq_lock_init(struct optimistic_spin_queue *lock) +{ + atomic_set(&lock->tail, OSQ_UNLOCKED_VAL); +} + +#endif |