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From:   luanshi <zhangliguang@linux.alibaba.com>
To:     James Morse <james.morse@arm.com>
Cc:     linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        Liguang Zhang <zhangliguang@linux.alibaba.com>
Subject: [PATCH 1/3] firmware: arm_sdei: fix possible deadlock
Date:   Mon, 23 Dec 2019 22:22:53 +0800
Message-Id: <1577110975-54782-1-git-send-email-zhangliguang@linux.alibaba.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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);
 
-- 
1.8.3.1