diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2015-01-12 10:51:13 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2015-01-12 10:51:13 +0100 |
| commit | 2f5eaf66e580f64032b365a00157b6b58c266b37 (patch) | |
| tree | 7852017c864f0eb3833782e2a017952bd8531458 /ipc/sem.c | |
| parent | c291ee622165cb2c8d4e7af63fffd499354a23be (diff) | |
| parent | 91d1179212161f220938198b742c328ad38fd0a3 (diff) | |
Merge tag 'irqchip-urgent-3.19' of git://git.infradead.org/users/jcooper/linux into irq/urgent
irqchip urgent fixes for v3.19 from Jason Cooper
- mtk-sysirq: Fix error handling
- hip04: Fix cpu map for 16bit value
- gic-v3-its: Clear a warning regarding decimal constants
- omap-intc: Fix legacy DMA regression
- atmel-aic-common: Retain priority when changing type
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 53c3310f41c..6115146563f 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. */ |