Commit 23492754 authored Dec 27, 2015 by Michael S. Tsirkin

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>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

parent 506b02eb

drivers/xen/events/events_fifo.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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];
		}