[Xen-devel] [PATCH 4/7] xen/arm: When CPU dies, free percpu area immediatelly

[Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>]

Freeing percpu area is done when a non-boot CPU is disabled upon suspend.
This use to be scheduled for execution after a period of time, what caused
the following racing issues. If CPU is enabled after it is disabled and
before the freeing of percpu area is performed, Xen would crash upon
initializing percpu area because per cpu offset is not marked as
INVALID_PERCPU_AREA (this suppose to happen when cpu area is freed).
To resolve the racing issue, free percpu area right away instead
scheduling it for later.

Signed-off-by: Mirela Simonovic <mirela.simonovic@xxxxxxxxxx>
---
 xen/arch/arm/percpu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/percpu.c b/xen/arch/arm/percpu.c
index 25442c48fe..e4e8405f43 100644
--- a/xen/arch/arm/percpu.c
+++ b/xen/arch/arm/percpu.c
@@ -46,7 +46,7 @@ static void free_percpu_area(unsigned int cpu)
 {
     struct free_info *info = &per_cpu(free_info, cpu);
     info->cpu = cpu;
-    call_rcu(&info->rcu, _free_percpu_area);
+    _free_percpu_area(&info->rcu);
 }
 
 static int cpu_percpu_callback(
-- 
2.13.0


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel