linux-kernel - [PATCH] media: dvb-frontends/cxd2099: report errors

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Date:   Wed, 22 Jul 2020 06:41:26 -0700
From:   trix@...hat.com
To:     jasmin@....at, mchehab@...nel.org, o.endriss@....de,
        rjkm@...zlerbros.de
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tom Rix <trix@...hat.com>
Subject: [PATCH] media: dvb-frontends/cxd2099: report errors

From: Tom Rix <trix@...hat.com>

Clang static analysis reports this error

drivers/media/dvb-frontends/cxd2099.c:420:2: warning: Undefined
  or garbage value returned to caller
        return val;
        ^~~~~~~~~~

In read_cam_control, the call to read_io can fail.
When it fails val is not set.

The failure status should be returned to the caller,
not the unset val.

Similar problem with read_attribute_mem

Fixes: 0f0b270f905b ("[media] ngene: CXD2099AR Common Interface driver")

Signed-off-by: Tom Rix <trix@...hat.com>
---
 drivers/media/dvb-frontends/cxd2099.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/media/dvb-frontends/cxd2099.c b/drivers/media/dvb-frontends/cxd2099.c
index f88b5355493e..9dfaf18fc4b4 100644
--- a/drivers/media/dvb-frontends/cxd2099.c
+++ b/drivers/media/dvb-frontends/cxd2099.c
@@ -387,12 +387,15 @@ static int read_attribute_mem(struct dvb_ca_en50221 *ca,
 {
 	struct cxd *ci = ca->data;
 	u8 val;
+	int ret;
 
 	mutex_lock(&ci->lock);
 	set_mode(ci, 1);
-	read_pccard(ci, address, &val, 1);
+	ret = read_pccard(ci, address, &val, 1);
+	if (!ret)
+		ret = val;
 	mutex_unlock(&ci->lock);
-	return val;
+	return ret;
 }
 
 static int write_attribute_mem(struct dvb_ca_en50221 *ca, int slot,
@@ -412,12 +415,15 @@ static int read_cam_control(struct dvb_ca_en50221 *ca,
 {
 	struct cxd *ci = ca->data;
 	unsigned int val;
+	int ret;
 
 	mutex_lock(&ci->lock);
 	set_mode(ci, 0);
-	read_io(ci, address, &val);
+	ret = read_io(ci, address, &val);
+	if (!ret)
+		ret = val;
 	mutex_unlock(&ci->lock);
-	return val;
+	return ret;
 }
 
 static int write_cam_control(struct dvb_ca_en50221 *ca, int slot,
-- 
2.18.1