diff options
Diffstat (limited to 'src/backend/port/unix_latch.c')
| -rw-r--r-- | src/backend/port/unix_latch.c | 16 |
1 files changed, 7 insertions, 9 deletions
diff --git a/src/backend/port/unix_latch.c b/src/backend/port/unix_latch.c index 92ae7801583..147e22cee4e 100644 --- a/src/backend/port/unix_latch.c +++ b/src/backend/port/unix_latch.c @@ -51,6 +51,7 @@ #include "miscadmin.h" #include "portability/instr_time.h" #include "postmaster/postmaster.h" +#include "storage/barrier.h" #include "storage/latch.h" #include "storage/pmsignal.h" #include "storage/shmem.h" @@ -515,12 +516,11 @@ SetLatch(volatile Latch *latch) pid_t owner_pid; /* - * XXX there really ought to be a memory barrier operation right here, to - * ensure that any flag variables we might have changed get flushed to - * main memory before we check/set is_set. Without that, we have to - * require that callers provide their own synchronization for machines - * with weak memory ordering (see latch.h). + * The memory barrier has be to be placed here to ensure that any flag + * variables possibly changed by this process have been flushed to main + * memory, before we check/set is_set. */ + pg_memory_barrier(); /* Quick exit if already set */ if (latch->is_set) @@ -574,14 +574,12 @@ ResetLatch(volatile Latch *latch) latch->is_set = false; /* - * XXX there really ought to be a memory barrier operation right here, to - * ensure that the write to is_set gets flushed to main memory before we + * Ensure that the write to is_set gets flushed to main memory before we * examine any flag variables. Otherwise a concurrent SetLatch might * falsely conclude that it needn't signal us, even though we have missed * seeing some flag updates that SetLatch was supposed to inform us of. - * For the moment, callers must supply their own synchronization of flag - * variables (see latch.h). */ + pg_memory_barrier(); } /* |