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* [PATCH] virtio_ring: switch to dma_XX barriers for rpmsg
@ 2018-04-19 17:35 Michael S. Tsirkin
  2018-04-19 17:39 ` Paolo Bonzini
                   ` (2 more replies)
  0 siblings, 3 replies; 9+ messages in thread
From: Michael S. Tsirkin @ 2018-04-19 17:35 UTC (permalink / raw)
  To: linux-kernel
  Cc: Ohad Ben-Cohen, Bjorn Andersson, linux-remoteproc, Jason Wang,
	virtualization, Paolo Bonzini

virtio is using barriers to order memory accesses, thus
dma_wmb/rmb is a good match.

Build-tested on x86: Before

[mst@tuck linux]$ size drivers/virtio/virtio_ring.o
   text    data     bss     dec     hex filename
  11392     820       0   12212    2fb4 drivers/virtio/virtio_ring.o

After
mst@tuck linux]$ size drivers/virtio/virtio_ring.o
   text    data     bss     dec     hex filename
  11284     820       0   12104    2f48 drivers/virtio/virtio_ring.o

Cc: Ohad Ben-Cohen <ohad@wizery.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: linux-remoteproc@vger.kernel.org
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

It's good in theory, but could one of RPMSG maintainers please review
and ack this patch? Or even better test it?

All these barriers are useless on Intel anyway ...

 include/linux/virtio_ring.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index bbf3252..fab0213 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -35,7 +35,7 @@ static inline void virtio_rmb(bool weak_barriers)
 	if (weak_barriers)
 		virt_rmb();
 	else
-		rmb();
+		dma_rmb();
 }
 
 static inline void virtio_wmb(bool weak_barriers)
@@ -43,7 +43,7 @@ static inline void virtio_wmb(bool weak_barriers)
 	if (weak_barriers)
 		virt_wmb();
 	else
-		wmb();
+		dma_wmb();
 }
 
 static inline void virtio_store_mb(bool weak_barriers,
-- 
MST

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2018-06-04 20:16 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-04-19 17:35 [PATCH] virtio_ring: switch to dma_XX barriers for rpmsg Michael S. Tsirkin
2018-04-19 17:39 ` Paolo Bonzini
2018-04-19 17:46   ` Michael S. Tsirkin
2018-04-19 17:48     ` Paolo Bonzini
2018-04-19 18:10       ` Michael S. Tsirkin
2018-05-30 14:10       ` Michael S. Tsirkin
2018-06-04 20:16       ` Bjorn Andersson
2018-04-20  3:04 ` Jason Wang
2018-06-04 20:02 ` Bjorn Andersson

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