From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Hennerich Date: Mon, 23 Nov 2015 13:53:11 +0000 Subject: Re: [PATCH] backlight: adp88x0: fix uninitialized variable use Message-Id: <56531A47.5000508@analog.com> List-Id: References: <3850346.cL1ocQLBvP@wuerfel> In-Reply-To: <3850346.cL1ocQLBvP@wuerfel> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On 11/23/2015 02:44 PM, Arnd Bergmann wrote: > gcc correctly warns about both the adp8860 and adp8870 backlight > drivers using an uninitialized variable in their error handling > path: > > drivers/video/backlight/adp8870_bl.c: In function 'adp8870_bl_ambient_light_zone_store': > drivers/video/backlight/adp8870_bl.c:811:11: warning: 'reg_val' may be used uninitialized in this function > > This changes the code to only write back the data if it was > correctly read to start with. > > As a side-note, the drivers are mostly identical, so I think they > should really be merged into one file to avoid having to fix every > bug twice. > > Signed-off-by: Arnd Bergmann Acked-by: Michael Hennerich > > diff --git a/drivers/video/backlight/adp8860_bl.c b/drivers/video/backlight/adp8860_bl.c > index 98ffe71e8af2..f0d4c0324580 100644 > --- a/drivers/video/backlight/adp8860_bl.c > +++ b/drivers/video/backlight/adp8860_bl.c > @@ -621,10 +621,12 @@ static ssize_t adp8860_bl_ambient_light_zone_store(struct device *dev, > > /* Set user supplied ambient light zone */ > mutex_lock(&data->lock); > - adp8860_read(data->client, ADP8860_CFGR, ®_val); > - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT); > - reg_val |= (val - 1) << CFGR_BLV_SHIFT; > - adp8860_write(data->client, ADP8860_CFGR, reg_val); > + ret = adp8860_read(data->client, ADP8860_CFGR, ®_val); > + if (!ret) { > + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT); > + reg_val |= (val - 1) << CFGR_BLV_SHIFT; > + adp8860_write(data->client, ADP8860_CFGR, reg_val); > + } > mutex_unlock(&data->lock); > } > > diff --git a/drivers/video/backlight/adp8870_bl.c b/drivers/video/backlight/adp8870_bl.c > index 9d738352d7d4..21acac90fd77 100644 > --- a/drivers/video/backlight/adp8870_bl.c > +++ b/drivers/video/backlight/adp8870_bl.c > @@ -807,10 +807,12 @@ static ssize_t adp8870_bl_ambient_light_zone_store(struct device *dev, > > /* Set user supplied ambient light zone */ > mutex_lock(&data->lock); > - adp8870_read(data->client, ADP8870_CFGR, ®_val); > - reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT); > - reg_val |= (val - 1) << CFGR_BLV_SHIFT; > - adp8870_write(data->client, ADP8870_CFGR, reg_val); > + ret = adp8870_read(data->client, ADP8870_CFGR, ®_val); > + if (!ret) { > + reg_val &= ~(CFGR_BLV_MASK << CFGR_BLV_SHIFT); > + reg_val |= (val - 1) << CFGR_BLV_SHIFT; > + adp8870_write(data->client, ADP8870_CFGR, reg_val); > + } > mutex_unlock(&data->lock); > } > > -- Greetings, Michael -- Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368; Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. Martin, Margaret Seif