linux-kernel - [PATCH 4.14 51/52] media: dvb-core: always call invoke_release() in fe

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Date:   Fri, 15 Dec 2017 10:52:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Daniel Scheller <d.scheller@....net>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 4.14 51/52] media: dvb-core: always call invoke_release() in fe_free()

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Scheller <d.scheller@....net>

commit 62229de19ff2b7f3e0ebf4d48ad99061127d0281 upstream.

Follow-up to: ead666000a5f ("media: dvb_frontend: only use kref after initialized")

The aforementioned commit fixed refcount OOPSes when demod driver attaching
succeeded but tuner driver didn't. However, the use count of the attached
demod drivers don't go back to zero and thus couldn't be cleanly unloaded.
Improve on this by calling dvb_frontend_invoke_release() in
__dvb_frontend_free() regardless of fepriv being NULL, instead of returning
when fepriv is NULL. This is safe to do since _invoke_release() will check
for passed pointers being valid before calling the .release() function.

[mchehab@...pensource.com: changed the logic a little bit to reduce
 conflicts with another bug fix patch under review]
Fixes: ead666000a5f ("media: dvb_frontend: only use kref after initialized")
Signed-off-by: Daniel Scheller <d.scheller@....net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...pensource.com>
Cc: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/media/dvb-core/dvb_frontend.c |    9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

--- a/drivers/media/dvb-core/dvb_frontend.c
+++ b/drivers/media/dvb-core/dvb_frontend.c
@@ -145,13 +145,14 @@ static void __dvb_frontend_free(struct d
 {
 	struct dvb_frontend_private *fepriv = fe->frontend_priv;
 
-	if (!fepriv)
-		return;
-
-	dvb_free_device(fepriv->dvbdev);
+	if (fepriv)
+		dvb_free_device(fepriv->dvbdev);
 
 	dvb_frontend_invoke_release(fe, fe->ops.release);
 
+	if (!fepriv)
+		return;
+
 	kfree(fepriv);
 	fe->frontend_priv = NULL;
 }