[PATCH 7/8] usb, cdc-acm: optimize barrier usage for Rmw atomic bitops

[Davidlohr Bueso]

We can avoid the unnecessary barrier on non LL/SC architectures,
such as x86. Instead, use the smp_mb__after_atomic() call.

Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
---
 drivers/usb/class/cdc-acm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 62f4fb9b362f..0bc4b558f387 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -842,7 +842,7 @@ static void acm_tty_unthrottle(struct tty_struct *tty)
 	clear_bit(ACM_THROTTLED, &acm->flags);
 
 	/* Matches the smp_mb__after_atomic() in acm_read_bulk_callback(). */
-	smp_mb();
+	smp_mb__after_atomic();
 
 	acm_submit_read_urbs(acm, GFP_KERNEL);
 }
-- 
2.16.4