diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-13 13:00:36 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-13 13:00:36 -0800 |
| commit | 78a45c6f067824cf5d0a9fedea7339ac2e28603c (patch) | |
| tree | b4f78c8b6b9059ddace0a18c11629b8d2045f793 /ipc/sem.c | |
| parent | f96fe225677b3efb74346ebd56fafe3997b02afa (diff) | |
| parent | 29d293b6007b91a4463f05bc8d0b26e0e65c5816 (diff) | |
Merge branch 'akpm' (second patch-bomb from Andrew)
Merge second patchbomb from Andrew Morton:
- the rest of MM
- misc fs fixes
- add execveat() syscall
- new ratelimit feature for fault-injection
- decompressor updates
- ipc/ updates
- fallocate feature creep
- fsnotify cleanups
- a few other misc things
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (99 commits)
cgroups: Documentation: fix trivial typos and wrong paragraph numberings
parisc: percpu: update comments referring to __get_cpu_var
percpu: update local_ops.txt to reflect this_cpu operations
percpu: remove __get_cpu_var and __raw_get_cpu_var macros
fsnotify: remove destroy_list from fsnotify_mark
fsnotify: unify inode and mount marks handling
fallocate: create FAN_MODIFY and IN_MODIFY events
mm/cma: make kmemleak ignore CMA regions
slub: fix cpuset check in get_any_partial
slab: fix cpuset check in fallback_alloc
shmdt: use i_size_read() instead of ->i_size
ipc/shm.c: fix overly aggressive shmdt() when calls span multiple segments
ipc/msg: increase MSGMNI, remove scaling
ipc/sem.c: increase SEMMSL, SEMMNI, SEMOPM
ipc/sem.c: change memory barrier in sem_lock() to smp_rmb()
lib/decompress.c: consistency of compress formats for kernel image
decompress_bunzip2: off by one in get_next_block()
usr/Kconfig: make initrd compression algorithm selection not expert
fault-inject: add ratelimit option
ratelimit: add initialization macro
...
Diffstat (limited to 'ipc/sem.c')
| -rw-r--r-- | ipc/sem.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/ipc/sem.c b/ipc/sem.c index 53c3310f41c6..6115146563f9 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -326,10 +326,17 @@ static inline int sem_lock(struct sem_array *sma, struct sembuf *sops, /* Then check that the global lock is free */ if (!spin_is_locked(&sma->sem_perm.lock)) { - /* spin_is_locked() is not a memory barrier */ - smp_mb(); + /* + * The ipc object lock check must be visible on all + * cores before rechecking the complex count. Otherwise + * we can race with another thread that does: + * complex_count++; + * spin_unlock(sem_perm.lock); + */ + smp_rmb(); - /* Now repeat the test of complex_count: + /* + * Now repeat the test of complex_count: * It can't change anymore until we drop sem->lock. * Thus: if is now 0, then it will stay 0. */ |