linux-kernel - [PATCH] extcon: Release locking when sending the notification of connector state

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Message-id: <1528949687-32002-1-git-send-email-cw00.choi@samsung.com>
Date:   Thu, 14 Jun 2018 13:14:47 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     linux-kernel@...r.kernel.org
Cc:     cw00.choi@...sung.com, chanwoo@...nel.org,
        myungjoo.ham@...sung.com, stable@...r.kernel.org,
        Roger Quadros <rogerq@...com>,
        Kishon Vijay Abraham I <kishon@...com>
Subject: [PATCH] extcon: Release locking when sending the notification of
 connector state

Previously, extcon used the spinlock before calling the notifier_call_chain
to prevent the scheduled out of task and to prevent the notification delay.
When spinlock is locked for sending the notification, deadlock issue
occured on the side of extcon consumer device. To fix this issue,
extcon consumer device should always use the work. it is always not
reasonable to use work.

To fix this issue on extcon consumer device, release locking when sending
the notification of connector state.

Fixes: ab11af049f88 ("extcon: Add the synchronization extcon APIs to support the notification")
Cc: stable@...r.kernel.org
Cc: Roger Quadros <rogerq@...com>
Cc: Kishon Vijay Abraham I <kishon@...com>
Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
---
 drivers/extcon/extcon.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
index 8bff5fd18185..f75b08a45d4e 100644
--- a/drivers/extcon/extcon.c
+++ b/drivers/extcon/extcon.c
@@ -433,8 +433,8 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id)
 		return index;
 
 	spin_lock_irqsave(&edev->lock, flags);
-
 	state = !!(edev->state & BIT(index));
+	spin_unlock_irqrestore(&edev->lock, flags);
 
 	/*
 	 * Call functions in a raw notifier chain for the specific one
@@ -448,6 +448,7 @@ int extcon_sync(struct extcon_dev *edev, unsigned int id)
 	 */
 	raw_notifier_call_chain(&edev->nh_all, state, edev);
 
+	spin_lock_irqsave(&edev->lock, flags);
 	/* This could be in interrupt handler */
 	prop_buf = (char *)get_zeroed_page(GFP_ATOMIC);
 	if (!prop_buf) {
-- 
1.9.1