diff options
Diffstat (limited to 'src/backend/storage/aio/aio.c')
| -rw-r--r-- | src/backend/storage/aio/aio.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/backend/storage/aio/aio.c b/src/backend/storage/aio/aio.c index 6c6c0a908e2..3643f27ad6e 100644 --- a/src/backend/storage/aio/aio.c +++ b/src/backend/storage/aio/aio.c @@ -556,6 +556,13 @@ bool pgaio_io_was_recycled(PgAioHandle *ioh, uint64 ref_generation, PgAioHandleState *state) { *state = ioh->state; + + /* + * Ensure that we don't see an earlier state of the handle than ioh->state + * due to compiler or CPU reordering. This protects both ->generation as + * directly used here, and other fields in the handle accessed in the + * caller if the handle was not reused. + */ pg_read_barrier(); return ioh->generation != ref_generation; @@ -773,7 +780,12 @@ pgaio_io_wait_for_free(void) * Note that no interrupts are processed between the state check * and the call to reclaim - that's important as otherwise an * interrupt could have already reclaimed the handle. + * + * Need to ensure that there's no reordering, in the more common + * paths, where we wait for IO, that's done by + * pgaio_io_was_recycled(). */ + pg_read_barrier(); pgaio_io_reclaim(ioh); reclaimed++; } @@ -852,7 +864,12 @@ pgaio_io_wait_for_free(void) * check and the call to reclaim - that's important as * otherwise an interrupt could have already reclaimed the * handle. + * + * Need to ensure that there's no reordering, in the more + * common paths, where we wait for IO, that's done by + * pgaio_io_was_recycled(). */ + pg_read_barrier(); pgaio_io_reclaim(ioh); break; } |