lkml.org 
[lkml]   [2020]   [Jan]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[V2 1/3] firmware: arm_sdei: fix possible deadlock
Date
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 | 22 +++++++++++++---------
1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index a479023..37e9bf0 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -45,8 +45,11 @@ static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
static unsigned long sdei_entry_point;

struct sdei_event {
- /* These three are protected by the sdei_list_lock */
+ /* protected by the sdei_list_lock */
struct list_head list;
+
+ spinlock_t sdei_event_lock;
+ /* These two are protected by the sdei_event_lock */
bool reregister;
bool reenable;

@@ -214,6 +217,7 @@ static struct sdei_event *sdei_event_create(u32 event_num,
return ERR_PTR(-ENOMEM);

INIT_LIST_HEAD(&event->list);
+ spin_lock_init(&event->sdei_event_lock);
event->event_num = event_num;

err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
@@ -412,9 +416,9 @@ int sdei_event_enable(u32 event_num)
return -ENOENT;
}

- spin_lock(&sdei_list_lock);
+ spin_lock(&event->sdei_event_lock);
event->reenable = true;
- spin_unlock(&sdei_list_lock);
+ spin_unlock(&event->sdei_event_lock);

if (event->type == SDEI_EVENT_TYPE_SHARED)
err = sdei_api_event_enable(event->event_num);
@@ -491,10 +495,10 @@ static int _sdei_event_unregister(struct sdei_event *event)
{
lockdep_assert_held(&sdei_events_lock);

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

if (event->type == SDEI_EVENT_TYPE_SHARED)
return sdei_api_event_unregister(event->event_num);
@@ -585,9 +589,9 @@ static int _sdei_event_register(struct sdei_event *event)

lockdep_assert_held(&sdei_events_lock);

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

if (event->type == SDEI_EVENT_TYPE_SHARED)
return sdei_api_event_register(event->event_num,
@@ -598,10 +602,10 @@ static int _sdei_event_register(struct sdei_event *event)

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

sdei_do_cross_call(_local_event_unregister, event);
}
--
1.8.3.1
\
 
 \ /
  Last update: 2020-01-16 04:30    [W:0.047 / U:3.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site