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From: "Michael S. Tsirkin" <mst@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Ohad Ben-Cohen <ohad@wizery.com>,
	Bjorn Andersson <bjorn.andersson@linaro.org>,
	linux-remoteproc@vger.kernel.org,
	Jason Wang <jasowang@redhat.com>,
	virtualization@lists.linux-foundation.org,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: [PATCH] virtio_ring: switch to dma_XX barriers for rpmsg
Date: Thu, 19 Apr 2018 20:35:57 +0300	[thread overview]
Message-ID: <1524159181-351878-1-git-send-email-mst@redhat.com> (raw)

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

             reply	other threads:[~2018-04-19 17:36 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 17:35 Michael S. Tsirkin [this message]
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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