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author | Linus Torvalds | 2016-07-25 21:41:29 +0200 |
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committer | Linus Torvalds | 2016-07-25 21:41:29 +0200 |
commit | c86ad14d305d2429c3da19462440bac50c183def (patch) | |
tree | bd794cd72476661faf82c440063c217bb978ce44 /ipc | |
parent | Merge branch 'efi-core-for-linus' of git://git.kernel.org/pub/scm/linux/kerne... (diff) | |
parent | locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API (diff) | |
download | kernel-qcow2-linux-c86ad14d305d2429c3da19462440bac50c183def.tar.gz kernel-qcow2-linux-c86ad14d305d2429c3da19462440bac50c183def.tar.xz kernel-qcow2-linux-c86ad14d305d2429c3da19462440bac50c183def.zip |
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
"The locking tree was busier in this cycle than the usual pattern - a
couple of major projects happened to coincide.
The main changes are:
- implement the atomic_fetch_{add,sub,and,or,xor}() API natively
across all SMP architectures (Peter Zijlstra)
- add atomic_fetch_{inc/dec}() as well, using the generic primitives
(Davidlohr Bueso)
- optimize various aspects of rwsems (Jason Low, Davidlohr Bueso,
Waiman Long)
- optimize smp_cond_load_acquire() on arm64 and implement LSE based
atomic{,64}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()
on arm64 (Will Deacon)
- introduce smp_acquire__after_ctrl_dep() and fix various barrier
mis-uses and bugs (Peter Zijlstra)
- after discovering ancient spin_unlock_wait() barrier bugs in its
implementation and usage, strengthen its semantics and update/fix
usage sites (Peter Zijlstra)
- optimize mutex_trylock() fastpath (Peter Zijlstra)
- ... misc fixes and cleanups"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (67 commits)
locking/atomic: Introduce inc/dec variants for the atomic_fetch_$op() API
locking/barriers, arch/arm64: Implement LDXR+WFE based smp_cond_load_acquire()
locking/static_keys: Fix non static symbol Sparse warning
locking/qspinlock: Use __this_cpu_dec() instead of full-blown this_cpu_dec()
locking/atomic, arch/tile: Fix tilepro build
locking/atomic, arch/m68k: Remove comment
locking/atomic, arch/arc: Fix build
locking/Documentation: Clarify limited control-dependency scope
locking/atomic, arch/rwsem: Employ atomic_long_fetch_add()
locking/atomic, arch/qrwlock: Employ atomic_fetch_add_acquire()
locking/atomic, arch/mips: Convert to _relaxed atomics
locking/atomic, arch/alpha: Convert to _relaxed atomics
locking/atomic: Remove the deprecated atomic_{set,clear}_mask() functions
locking/atomic: Remove linux/atomic.h:atomic_fetch_or()
locking/atomic: Implement atomic{,64,_long}_fetch_{add,sub,and,andnot,or,xor}{,_relaxed,_acquire,_release}()
locking/atomic: Fix atomic64_relaxed() bits
locking/atomic, arch/xtensa: Implement atomic_fetch_{add,sub,and,or,xor}()
locking/atomic, arch/x86: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
locking/atomic, arch/tile: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
locking/atomic, arch/sparc: Implement atomic{,64}_fetch_{add,sub,and,or,xor}()
...
Diffstat (limited to 'ipc')
-rw-r--r-- | ipc/sem.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index b3757ea0694b..ae72b3cddc8d 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -260,16 +260,6 @@ static void sem_rcu_free(struct rcu_head *head) } /* - * spin_unlock_wait() and !spin_is_locked() are not memory barriers, they - * are only control barriers. - * The code must pair with spin_unlock(&sem->lock) or - * spin_unlock(&sem_perm.lock), thus just the control barrier is insufficient. - * - * smp_rmb() is sufficient, as writes cannot pass the control barrier. - */ -#define ipc_smp_acquire__after_spin_is_unlocked() smp_rmb() - -/* * Wait until all currently ongoing simple ops have completed. * Caller must own sem_perm.lock. * New simple ops cannot start, because simple ops first check @@ -292,7 +282,6 @@ static void sem_wait_array(struct sem_array *sma) sem = sma->sem_base + i; spin_unlock_wait(&sem->lock); } - ipc_smp_acquire__after_spin_is_unlocked(); } /* @@ -350,7 +339,7 @@ static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, * complex_count++; * spin_unlock(sem_perm.lock); */ - ipc_smp_acquire__after_spin_is_unlocked(); + smp_acquire__after_ctrl_dep(); /* * Now repeat the test of complex_count: |