From 97a545ab6ce922a0f868d192718a48a0091ebc5e Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 24 Feb 2010 14:22:22 -0600 Subject: [PATCH] virtio: remove bogus barriers from DEBUG version of virtio_ring.c With DEBUG defined, we add an ->in_use flag to detect if the caller invokes two virtio methods in parallel. The barriers attempt to ensure timely update of the ->in_use flag. But they're voodoo: if we need these barriers it implies that the calling code doesn't have sufficient synchronization to ensure the code paths aren't invoked at the same time anyway, and we want to detect it. Also, adding barriers changes timing, so turning on debug has more chance of hiding real problems. Thanks to MST for drawing my attention to this code... CC: Michael S. Tsirkin Signed-off-by: Rusty Russell --- drivers/virtio/virtio_ring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index fbd2ecde93e4..1ee97d402a48 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -36,10 +36,9 @@ panic("%s:in_use = %i\n", \ (_vq)->vq.name, (_vq)->in_use); \ (_vq)->in_use = __LINE__; \ - mb(); \ } while (0) #define END_USE(_vq) \ - do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; mb(); } while(0) + do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0) #else #define BAD_RING(_vq, fmt, args...) \ do { \ -- 2.20.1