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authorRusty Russell <rusty@rustcorp.com.au>2010-02-24 14:22:22 -0600
committerRusty Russell <rusty@rustcorp.com.au>2010-02-24 14:22:24 +1030
commit97a545ab6ce922a0f868d192718a48a0091ebc5e (patch)
tree1593d2a0f0ff19c4deb731d6079997e79989c8b1
parent28ff4ef71795fe6f6c0cc06a04911c9ca09c2c11 (diff)
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 <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
-rw-r--r--drivers/virtio/virtio_ring.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index fbd2ecde93e..1ee97d402a4 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 { \