diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/membarrier.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/sched/membarrier.c b/kernel/sched/membarrier.c index 7d98ef5d3bcd..1c278dff4f2d 100644 --- a/kernel/sched/membarrier.c +++ b/kernel/sched/membarrier.c @@ -38,6 +38,23 @@ static void ipi_mb(void *info) smp_mb(); /* IPIs should be serializing but paranoid. */ } +static void ipi_sync_core(void *info) +{ + /* + * The smp_mb() in membarrier after all the IPIs is supposed to + * ensure that memory on remote CPUs that occur before the IPI + * become visible to membarrier()'s caller -- see scenario B in + * the big comment at the top of this file. + * + * A sync_core() would provide this guarantee, but + * sync_core_before_usermode() might end up being deferred until + * after membarrier()'s smp_mb(). + */ + smp_mb(); /* IPIs should be serializing but paranoid. */ + + sync_core_before_usermode(); +} + static void ipi_rseq(void *info) { /* @@ -162,6 +179,7 @@ static int membarrier_private_expedited(int flags, int cpu_id) if (!(atomic_read(&mm->membarrier_state) & MEMBARRIER_STATE_PRIVATE_EXPEDITED_SYNC_CORE_READY)) return -EPERM; + ipi_func = ipi_sync_core; } else if (flags == MEMBARRIER_FLAG_RSEQ) { if (!IS_ENABLED(CONFIG_RSEQ)) return -EINVAL; |