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authorJames Morse <james.morse@arm.com>2020-02-21 16:35:06 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2020-02-27 17:14:12 +0000
commit6ded0b61cf638bf9f8efe60ab8ba23db60ea9763 (patch)
tree5786bb7b077bb3c4ec9573a24863d28d69305a09 /drivers/firmware/arm_sdei.c
parentf8788d86ab28f61f7b46eb6be375f8a726783636 (diff)
firmware: arm_sdei: fix double-lock on hibernate with shared events
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>
Diffstat (limited to 'drivers/firmware/arm_sdei.c')
-rw-r--r--drivers/firmware/arm_sdei.c32
1 files changed, 15 insertions, 17 deletions
diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index a479023fa036..77eaa9a2fd15 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -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);