From ef80ec5067d7ca5b46e5b88be1be33cddfd33551 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 7 Mar 2023 16:04:26 -0500 Subject: [PATCH] block: make BlockBackend->disable_request_queuing atomic MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Hanna Czenczek Message-Id: <20230307210427.269214-3-stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Kevin Wolf Signed-off-by: Kevin Wolf --- 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); -- 2.11.0