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Subject[PATCH 1/3] firmware: arm_sdei: fix possible deadlock
Date
From: Liguang Zhang <zhangliguang@linux.alibaba.com>

We call sdei_reregister_event() with sdei_list_lock held but
_sdei_event_register() and sdei_event_destroy() also acquires
sdei_list_lock thus creating A-A deadlock.

Fixes: da351827240e ("firmware: arm_sdei: Add support for CPU and system power states")
Signed-off-by: Liguang Zhang <zhangliguang@linux.alibaba.com>
---
drivers/firmware/arm_sdei.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index a479023..b122927 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -651,20 +651,19 @@ static int sdei_reregister_event(struct sdei_event *event)

lockdep_assert_held(&sdei_events_lock);

- err = _sdei_event_register(event);
+ err = sdei_api_event_register(event->event_num,
+ sdei_entry_point,
+ event->registered,
+ SDEI_EVENT_REGISTER_RM_ANY, 0);
if (err) {
pr_err("Failed to re-register event %u\n", event->event_num);
- sdei_event_destroy(event);
+ list_del(&event->list);
+ kfree(event->registered);
return err;
}

- if (event->reenable) {
- if (event->type == SDEI_EVENT_TYPE_SHARED)
- err = sdei_api_event_enable(event->event_num);
- else
- err = sdei_do_cross_call(_local_event_enable, event);
- }
-
+ if (event->reenable)
+ err = sdei_api_event_enable(event->event_num);
if (err)
pr_err("Failed to re-enable event %u\n", event->event_num);

--
1.8.3.1
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