2014-10-16 21:00:49

by Boris Ostrovsky

Subject: [PATCH] xen/time: Fix incorrect per_cpu accessor in xen_clocksource_read()

Commit 89cbc76768c2 ("x86: Replace __get_cpu_var uses") replaced
__get_cpu_var() with this_cpu_ptr() in xen_clocksource_read() in such a
way that instead of accessing a structure pointed to by a per-cpu pointer
we are trying to get to a per-cpu structure.

__this_cpu_read() of the pointer is the more appropriate accessor.

Signed-off-by: Boris Ostrovsky <[email protected]>
---
arch/x86/xen/time.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index a1d430b..f473d26 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -158,7 +158,7 @@ cycle_t xen_clocksource_read(void)
cycle_t ret;

preempt_disable_notrace();
- src = this_cpu_ptr(&xen_vcpu->time);
+ src = &__this_cpu_read(xen_vcpu)->time;
ret = pvclock_clocksource_read(src);
preempt_enable_notrace();
return ret;
--
1.8.1.4

2014-10-17 12:45:51

by David Vrabel

Subject: Re: [Xen-devel] [PATCH] xen/time: Fix incorrect per_cpu accessor in xen_clocksource_read()

On 16/10/14 22:02, Boris Ostrovsky wrote:
> Commit 89cbc76768c2 ("x86: Replace __get_cpu_var uses") replaced
> __get_cpu_var() with this_cpu_ptr() in xen_clocksource_read() in such a
> way that instead of accessing a structure pointed to by a per-cpu pointer
> we are trying to get to a per-cpu structure.
>
> __this_cpu_read() of the pointer is the more appropriate accessor.

Applied, thanks.

David