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SubjectRe: [PATCH 1/3] firmware: arm_sdei: fix possible deadlock
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Hi James,

Sorry for the late reply, this problem was found by code review.


Thanks,

luanshi

在 2019/12/23 22:22, luanshi 写道:
> 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);
>

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