From: Stefan Hajnoczi <stefa...@redhat.com>
This field is accessed by multiple threads without a lock. Use explicit
qatomic_read()/qatomic_set() calls. There is no need for acquire/release
because blk_set_disable_request_queuing() doesn't provide any
guarantees (it helps that it's used at BlockBackend creation time and
not when there is I/O in flight).
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Reviewed-by: Hanna Czenczek <hre...@redhat.com>
Message-Id: <20230307210427.269214-3-stefa...@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <phi...@linaro.org>
Reviewed-by: Kevin Wolf <kw...@redhat.com>
Signed-off-by: Kevin Wolf <kw...@redhat.com>
---
block/block-backend.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/block/block-backend.c b/block/block-backend.c
index 2ae768f24d..8552b6dfd0 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -82,7 +82,7 @@ struct BlockBackend {
int quiesce_counter; /* atomic: written under BQL, read by other threads */
CoQueue queued_requests;
- bool disable_request_queuing;
+ bool disable_request_queuing; /* atomic */
VMChangeStateEntry *vmsh;
bool force_allow_inactivate;
@@ -1232,7 +1232,7 @@ void blk_set_allow_aio_context_change(BlockBackend *blk,
bool allow)
void blk_set_disable_request_queuing(BlockBackend *blk, bool disable)
{
IO_CODE();
- blk->disable_request_queuing = disable;
+ qatomic_set(&blk->disable_request_queuing, disable);
}
static int coroutine_fn GRAPH_RDLOCK
@@ -1271,7 +1271,8 @@ static void coroutine_fn
blk_wait_while_drained(BlockBackend *blk)
{
assert(blk->in_flight > 0);
- if (qatomic_read(&blk->quiesce_counter) && !blk->disable_request_queuing) {
+ if (qatomic_read(&blk->quiesce_counter) &&
+ !qatomic_read(&blk->disable_request_queuing)) {
blk_dec_in_flight(blk);
qemu_co_queue_wait(&blk->queued_requests, NULL);
blk_inc_in_flight(blk);
--
2.40.0
