[PATCH] clockevents: Match the CPU when unbinding devices via sysfs

[Avi Weiss]

Clockevent devices belonging to different CPUs can share the same
name. The sysfs unbind handler selects the first matching name from
the global device list, which can cause a request for one CPU to
unbind another CPU's device or incorrectly return -EBUSY.

Check the device's CPU mask when selecting the clockevent to unbind
so that the request targets a device eligible for the specified CPU.

Fixes: 03e13cf5ee60 ("clockevents: Implement unbind functionality")
Signed-off-by: Avi Weiss <thnkslprpt@xxxxxxxxx>
---
 kernel/time/clockevents.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c
index 62ad7c000386..05e9d966b024 100644
--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -756,7 +756,8 @@ static ssize_t unbind_device_store(struct device *dev,
 	mutex_lock(&clockevents_mutex);
 	raw_spin_lock_irq(&clockevents_lock);
 	list_for_each_entry(iter, &clockevent_devices, list) {
-		if (!strcmp(iter->name, name)) {
+		if (!strcmp(iter->name, name) &&
+		    cpumask_test_cpu(dev->id, iter->cpumask)) {
 			ret = __clockevents_try_unbind(iter, dev->id);
 			ce = iter;
 			break;

base-commit: cbbddb6b08cc9900a87cccaa9b22bbe06aa4f50a
-- 
2.53.0