linux-kernel - [Patch v3 1/1] media: am437x-vpfe: Fix a race condition during release

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Message-ID: <1435612716-3952-1-git-send-email-bparrot@ti.com>
Date:	Mon, 29 Jun 2015 16:18:36 -0500
From:	Benoit Parrot <bparrot@...com>
To:	Hans Verkuil <hverkuil@...all.nl>
CC:	Prabhakar Lad <prabhakar.csengg@...il.com>,
	<linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	Benoit Parrot <bparrot@...com>, <stable@...r.kernel.org>
Subject: [Patch v3 1/1] media: am437x-vpfe: Fix a race condition during release

There was a race condition where during cleanup/release operation
on-going streaming would cause a kernel panic because the hardware
module was disabled prematurely with IRQ still pending.

Fixes: 417d2e507edc ("[media] media: platform: add VPFE capture driver support for AM437X")
Cc: <stable@...r.kernel.org> # v4.0+
Signed-off-by: Benoit Parrot <bparrot@...com>
---
Changes since v2:
- fix the stable commit reference syntax

 drivers/media/platform/am437x/am437x-vpfe.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/am437x/am437x-vpfe.c b/drivers/media/platform/am437x/am437x-vpfe.c
index a30cc2f7e4f1..eb25c43da126 100644
--- a/drivers/media/platform/am437x/am437x-vpfe.c
+++ b/drivers/media/platform/am437x/am437x-vpfe.c
@@ -1185,14 +1185,21 @@ static int vpfe_initialize_device(struct vpfe_device *vpfe)
 static int vpfe_release(struct file *file)
 {
 	struct vpfe_device *vpfe = video_drvdata(file);
+	bool fh_singular = v4l2_fh_is_singular_file(file);
 	int ret;
 
 	mutex_lock(&vpfe->lock);
 
-	if (v4l2_fh_is_singular_file(file))
-		vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
+	/* the release helper will cleanup any on-going streaming */
 	ret = _vb2_fop_release(file, NULL);
 
+	/*
+	 * If this was the last open file.
+	 * Then de-initialize hw module.
+	 */
+	if (fh_singular)
+		vpfe_ccdc_close(&vpfe->ccdc, vpfe->pdev);
+
 	mutex_unlock(&vpfe->lock);
 
 	return ret;
-- 
1.8.5.1

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