From f2e030dd7aaea5a937a2547dc980fab418fbc5e7 Mon Sep 17 00:00:00 2001 From: Almog Khaikin Date: Tue, 26 Apr 2022 19:34:03 +0300 Subject: [PATCH] io_uring: replace smp_mb() with smp_mb__after_atomic() in io_sq_thread() The IORING_SQ_NEED_WAKEUP flag is now set using atomic_or() which implies a full barrier on some architectures but it is not required to do so. Use the more appropriate smp_mb__after_atomic() which avoids the extra barrier on those architectures. Signed-off-by: Almog Khaikin Link: https://lore.kernel.org/r/20220426163403.112692-1-almogkh@gmail.com Fixes: 8018823e6987 ("io_uring: serialize ctx->rings->sq_flags with atomic_or/and") Signed-off-by: Jens Axboe --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 72cb2d50125c6..1e7466079af7b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8229,7 +8229,7 @@ static int io_sq_thread(void *data) * Ensure the store of the wakeup flag is not * reordered with the load of the SQ tail */ - smp_mb(); + smp_mb__after_atomic(); if (io_sqring_entries(ctx)) { needs_sched = false;