From: Bart Van Assche <bvanassche@acm.org>
Date: Sun, 21 Jun 2020 20:55:04 +0000 (-0700)
Subject: fio: Use atomic_load_acquire() and atomic_store_release() where appropriate
X-Git-Tag: fio-3.21~28^2~4
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=0337173e060e5e6d476312d3780cbb7c39604ed6

fio: Use atomic_load_acquire() and atomic_store_release() where appropriate

The write_barrier() in io_completed() and also the read barriers in
verify.c are misplaced: the write barrier should occur before the flags
update instead of after and the read barriers should occur after the flags
read instead of before. Fix this by using atomic_{load_acquire,
store_release}() instead of read and write barriers.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---

diff --git a/io_u.c b/io_u.c
index ae1438fd..7f50906b 100644
--- a/io_u.c
+++ b/io_u.c
@@ -1934,8 +1934,8 @@ static void io_completed(struct thread_data *td, struct io_u **io_u_ptr,
 		if (io_u->error)
 			unlog_io_piece(td, io_u);
 		else {
-			io_u->ipo->flags &= ~IP_F_IN_FLIGHT;
-			write_barrier();
+			atomic_store_release(&io_u->ipo->flags,
+					io_u->ipo->flags & ~IP_F_IN_FLIGHT);
 		}
 	}
 
diff --git a/verify.c b/verify.c
index b7fa6693..5ee0029d 100644
--- a/verify.c
+++ b/verify.c
@@ -8,6 +8,7 @@
 #include <pthread.h>
 #include <libgen.h>
 
+#include "arch/arch.h"
 #include "fio.h"
 #include "verify.h"
 #include "trim.h"
@@ -1309,8 +1310,7 @@ int get_next_verify(struct thread_data *td, struct io_u *io_u)
 		/*
 		 * Ensure that the associated IO has completed
 		 */
-		read_barrier();
-		if (ipo->flags & IP_F_IN_FLIGHT)
+		if (atomic_load_acquire(&ipo->flags) & IP_F_IN_FLIGHT)
 			goto nothing;
 
 		rb_erase(n, &td->io_hist_tree);
@@ -1322,8 +1322,7 @@ int get_next_verify(struct thread_data *td, struct io_u *io_u)
 		/*
 		 * Ensure that the associated IO has completed
 		 */
-		read_barrier();
-		if (ipo->flags & IP_F_IN_FLIGHT)
+		if (atomic_load_acquire(&ipo->flags) & IP_F_IN_FLIGHT)
 			goto nothing;
 
 		flist_del(&ipo->list);