FAILED: patch "[PATCH] extcon: Release locking when sending the notification of" failed to apply to 4.9-stable tree

FAILED: patch "[PATCH] extcon: Release locking when sending the notification of" failed to apply to 4.9-stable tree

[gregkh]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

>From 8a9dbb779fe882325b9a0238494a7afaff2eb444 Mon Sep 17 00:00:00 2001
From: Chanwoo Choi <cw00.choi@samsung.com>
Date: Thu, 14 Jun 2018 11:16:29 +0900
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@vger.kernel.org
Cc: Roger Quadros <rogerq@ti.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

diff --git a/drivers/extcon/extcon.c b/drivers/extcon/extcon.c
index af83ad58819c..b9d27c8fe57e 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) {