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Date: Fri, 1 Jan 2016 11:39:40 +0200
From: "Michael S. Tsirkin" <mst@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: Peter Zijlstra <peterz@...radead.org>,
Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
Andrew Cooper <andrew.cooper3@...rix.com>,
virtualization@...ts.linux-foundation.org,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
David Miller <davem@...emloft.net>, linux-ia64@...r.kernel.org,
linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
sparclinux@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-metag@...r.kernel.org, linux-mips@...ux-mips.org,
x86@...nel.org, user-mode-linux-devel@...ts.sourceforge.net,
adi-buildroot-devel@...ts.sourceforge.net,
linux-sh@...r.kernel.org, linux-xtensa@...ux-xtensa.org,
xen-devel@...ts.xenproject.org,
Alexander Duyck <alexander.duyck@...il.com>
Subject: [PATCH v2 30/32] virtio_ring: update weak barriers to use __smp_xxx
virtio ring uses smp_wmb on SMP and wmb on !SMP,
the reason for the later being that it might be
talking to another kernel on the same SMP machine.
This is exactly what __smp_XXX barriers do,
so switch to these instead of homegrown ifdef hacks.
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexander Duyck <alexander.duyck@...il.com>
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
---
include/linux/virtio_ring.h | 25 ++++---------------------
1 file changed, 4 insertions(+), 21 deletions(-)
diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h
index 67e06fe..f3fa55b 100644
--- a/include/linux/virtio_ring.h
+++ b/include/linux/virtio_ring.h
@@ -12,7 +12,7 @@
* anyone care?
*
* For virtio_pci on SMP, we don't need to order with respect to MMIO
- * accesses through relaxed memory I/O windows, so smp_mb() et al are
+ * accesses through relaxed memory I/O windows, so virt_mb() et al are
* sufficient.
*
* For using virtio to talk to real devices (eg. other heterogeneous
@@ -21,11 +21,10 @@
* actually quite cheap.
*/
-#ifdef CONFIG_SMP
static inline void virtio_mb(bool weak_barriers)
{
if (weak_barriers)
- smp_mb();
+ virt_mb();
else
mb();
}
@@ -33,7 +32,7 @@ static inline void virtio_mb(bool weak_barriers)
static inline void virtio_rmb(bool weak_barriers)
{
if (weak_barriers)
- smp_rmb();
+ virt_rmb();
else
rmb();
}
@@ -41,26 +40,10 @@ static inline void virtio_rmb(bool weak_barriers)
static inline void virtio_wmb(bool weak_barriers)
{
if (weak_barriers)
- smp_wmb();
+ virt_wmb();
else
wmb();
}
-#else
-static inline void virtio_mb(bool weak_barriers)
-{
- mb();
-}
-
-static inline void virtio_rmb(bool weak_barriers)
-{
- rmb();
-}
-
-static inline void virtio_wmb(bool weak_barriers)
-{
- wmb();
-}
-#endif
struct virtio_device;
struct virtqueue;
--
MST
--
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