From b532526a07ef3b903ead2e055fe6cc87b41057a3 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Fri, 3 Mar 2023 11:03:52 +0100 Subject: [PATCH] aio-wait: switch to smp_mb__after_rmw() The barrier comes after an atomic increment, so it is enough to use smp_mb__after_rmw(); this avoids a double barrier on x86 systems. Reviewed-by: Richard Henderson Reviewed-by: David Hildenbrand Signed-off-by: Paolo Bonzini --- include/block/aio-wait.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/block/aio-wait.h b/include/block/aio-wait.h index dd9a7f6461..da13357bb8 100644 --- a/include/block/aio-wait.h +++ b/include/block/aio-wait.h @@ -85,7 +85,7 @@ extern AioWait global_aio_wait; /* Increment wait_->num_waiters before evaluating cond. */ \ qatomic_inc(&wait_->num_waiters); \ /* Paired with smp_mb in aio_wait_kick(). */ \ - smp_mb(); \ + smp_mb__after_rmw(); \ if (ctx_ && in_aio_context_home_thread(ctx_)) { \ while ((cond)) { \ aio_poll(ctx_, true); \