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firmware: arm_sdei: fix double-lock on hibernate with shared events

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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: da351827240e ("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>
This commit is contained in:
James Morse 2020-02-21 16:35:06 +00:00 committed by Catalin Marinas
parent f8788d86ab
commit 6ded0b61cf
1 changed files with 15 additions and 17 deletions
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32
drivers/firmware/arm_sdei.c
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@ -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);