| Message ID | 1452426622-4471-40-git-send-email-mst@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 10/01/16 14:21, Michael S. Tsirkin wrote: > 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> Acked-by: David Vrabel <david.vrabel@citrix.com> David
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]; }
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> --- drivers/xen/events/events_fifo.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)