lkml.org 
[lkml]   [2016]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] xen/events: use virt_xxx barriers
drivers/xen/events/events_fifo.c uses rmb() to communicate with the
other side.

For guests compiled with CONFIG_SMP, smp_rmb would be sufficient, so
rmb() here is only needed if a non-SMP guest runs on an SMP host.

Switch to the virt_rmb barrier which serves this exact purpose.

Pull in asm/barrier.h here to make sure the file is self-contained.

Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---

This is on top of my series:
arch: barrier cleanup + barriers for virt
and will be included in v3 of the series.

drivers/xen/events/events_fifo.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 96a1b8d..eff2b88 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -41,6 +41,7 @@
#include <linux/percpu.h>
#include <linux/cpu.h>

+#include <asm/barrier.h>
#include <asm/sync_bitops.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
@@ -296,7 +297,7 @@ static void consume_one_event(unsigned cpu,
* control block.
*/
if (head == 0) {
- rmb(); /* Ensure word is up-to-date before reading head. */
+ virt_rmb(); /* Ensure word is up-to-date before reading head. */
head = control_block->head[priority];
}

--
MST

\
 
 \ /
  Last update: 2016-01-04 13:41    [W:0.041 / U:0.676 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site