linux-kernel - [PATCH AUTOSEL 4.14 22/66] media: cec-core: first mark device unregistered, then wake up fhs

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Date:   Tue, 22 Dec 2020 21:22:08 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>, linux-media@...r.kernel.org
Subject: [PATCH AUTOSEL 4.14 22/66] media: cec-core: first mark device unregistered, then wake up fhs

From: Hans Verkuil <hverkuil-cisco@...all.nl>

[ Upstream commit e91c255733d9bbb4978a372f44fb5ed689ccdbd1 ]

If a CEC device node is unregistered, then it should be marked as
unregistered before waking up any filehandles that are waiting for
an event.

This ensures that there is no race condition where an application can
call CEC_DQEVENT and have the ioctl return 0 instead of ENODEV.

Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/cec/cec-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/media/cec/cec-core.c b/drivers/media/cec/cec-core.c
index 648136e552d5b..7c585e05c6311 100644
--- a/drivers/media/cec/cec-core.c
+++ b/drivers/media/cec/cec-core.c
@@ -175,12 +175,12 @@ static void cec_devnode_unregister(struct cec_devnode *devnode)
 		mutex_unlock(&devnode->lock);
 		return;
 	}
+	devnode->registered = false;
+	devnode->unregistered = true;
 
 	list_for_each_entry(fh, &devnode->fhs, list)
 		wake_up_interruptible(&fh->wait);
 
-	devnode->registered = false;
-	devnode->unregistered = true;
 	mutex_unlock(&devnode->lock);
 
 	cdev_device_del(&devnode->cdev, &devnode->dev);
-- 
2.27.0