firmware: arm_sdei: fix double-lock on hibernate with shared events (6ded0b61) · Commits · 戴 / test

SDEI has private events that must be registered on each CPU. When CPUs come and go they must re-register and re-enable their private events. Each event has flags to indicate whether this should happen to protect against an event being registered on a CPU coming online, while all the others are unregistering the event. These flags are protected by the sdei_list_lock spinlock, because the cpuhp callbacks can't take the mutex. Hibernate needs to unregister all events, but keep the in-memory re-register and re-enable as they are. sdei_unregister_shared() takes the spinlock to walk the list, then calls _sdei_event_unregister() on each shared event. _sdei_event_unregister() tries to take the same spinlock to update re-register and re-enable. This doesn't go so well. Push the re-register and re-enable updates out to their callers. sdei_unregister_shared() doesn't want these values updated, so doesn't need to do anything. This also fixes shared events getting lost over hibernate as this path made them look unregistered. Fixes: ("firmware: arm_sdei: Add support for CPU and system power states") Reported-by:

Liguang Zhang <zhangliguang@linux.alibaba.com> Signed-off-by:

James Morse <james.morse@arm.com> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

drivers/firmware/arm_sdei.c

+15 −17

Original line number	Diff line number	Diff line
		@@ -491,11 +491,6 @@ static int _sdei_event_unregister(struct sdei_event *event)
		{
		lockdep_assert_held(&sdei_events_lock);

		spin_lock(&sdei_list_lock);
		event->reregister = false;
		event->reenable = false;
		spin_unlock(&sdei_list_lock);

		if (event->type == SDEI_EVENT_TYPE_SHARED)
		return sdei_api_event_unregister(event->event_num);

		@@ -518,6 +513,11 @@ int sdei_event_unregister(u32 event_num)
		break;
		}

		spin_lock(&sdei_list_lock);
		event->reregister = false;
		event->reenable = false;
		spin_unlock(&sdei_list_lock);

		err = _sdei_event_unregister(event);
		if (err)
		break;
		@@ -585,26 +585,15 @@ static int _sdei_event_register(struct sdei_event *event)

		lockdep_assert_held(&sdei_events_lock);

		spin_lock(&sdei_list_lock);
		event->reregister = true;
		spin_unlock(&sdei_list_lock);

		if (event->type == SDEI_EVENT_TYPE_SHARED)
		return sdei_api_event_register(event->event_num,
		sdei_entry_point,
		event->registered,
		SDEI_EVENT_REGISTER_RM_ANY, 0);


		err = sdei_do_cross_call(_local_event_register, event);
		if (err) {
		spin_lock(&sdei_list_lock);
		event->reregister = false;
		event->reenable = false;
		spin_unlock(&sdei_list_lock);

		if (err)
		sdei_do_cross_call(_local_event_unregister, event);
		}

		return err;
		}
		@@ -632,8 +621,17 @@ int sdei_event_register(u32 event_num, sdei_event_callback cb, void arg)
		break;
		}

		spin_lock(&sdei_list_lock);
		event->reregister = true;
		spin_unlock(&sdei_list_lock);

		err = _sdei_event_register(event);
		if (err) {
		spin_lock(&sdei_list_lock);
		event->reregister = false;
		event->reenable = false;
		spin_unlock(&sdei_list_lock);

		sdei_event_destroy(event);
		pr_warn("Failed to register event %u: %d\n", event_num,
		err);

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