| Message ID | 20130308130100.f0db69f823e6451e5ed06c9f@linux-foundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Mar 8, 2013 at 4:01 PM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Fri, 8 Mar 2013 14:31:07 -0500 Devendra Naga <devendra.aaru@gmail.com> wrote: > >> while compiling with make W=1 (gcc gcc (GCC) 4.7.2 20121109 (Red Hat 4.7.2-8)) >> >> found the following warning >> >> drivers/video/backlight/adp5520_bl.c: In function ___adp5520_show___: >> drivers/video/backlight/adp5520_bl.c:146:6: warning: variable ___error___ set but not used [-Wunused-but-set-variable] >> >> fixed by removing the variable >> >> ... >> >> --- a/drivers/video/backlight/adp5520_bl.c >> +++ b/drivers/video/backlight/adp5520_bl.c >> @@ -143,11 +143,10 @@ static int adp5520_bl_setup(struct backlight_device *bl) >> static ssize_t adp5520_show(struct device *dev, char *buf, int reg) >> { >> struct adp5520_bl *data = dev_get_drvdata(dev); >> - int error; >> uint8_t reg_val; >> >> mutex_lock(&data->lock); >> - error = adp5520_read(data->master, reg, ®_val); >> + adp5520_read(data->master, reg, ®_val); >> mutex_unlock(&data->lock); >> >> return sprintf(buf, "%u\n", reg_val); > > We shouldn't just ignore the error; with the code as it stands, a > adp5520_read() failure will result in the kernel displaying > uninitialised garbage. > > So it would be better to propagate the adp5520_read() return value back > to the caller if it's negative. > > > (This assumes that the i2c layer returns a sane return value - if it > does, that would make i2c pretty unique :( We could get paranoid and > return a hard-wired -EIO, but it would be bad of us to overwrite things > like -ENOMEM). > > So I'd suggest this: > > --- a/drivers/video/backlight/adp5520_bl.c~video-backlight-adp5520-fix-compiler-warning-in-adp5520_show > +++ a/drivers/video/backlight/adp5520_bl.c > @@ -143,13 +143,15 @@ static int adp5520_bl_setup(struct backl > static ssize_t adp5520_show(struct device *dev, char *buf, int reg) > { > struct adp5520_bl *data = dev_get_drvdata(dev); > - int error; > + int ret; > uint8_t reg_val; > > mutex_lock(&data->lock); > - error = adp5520_read(data->master, reg, ®_val); > + ret = adp5520_read(data->master, reg, ®_val); > mutex_unlock(&data->lock); > > + if (ret < 0) > + return ret; > return sprintf(buf, "%u\n", reg_val); > } > Thanks for the suggestion, i will do the same and i will send you a patch sooner. or you can merge your change with my Acked By too :). > _ > -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
--- a/drivers/video/backlight/adp5520_bl.c~video-backlight-adp5520-fix-compiler-warning-in-adp5520_show +++ a/drivers/video/backlight/adp5520_bl.c @@ -143,13 +143,15 @@ static int adp5520_bl_setup(struct backl static ssize_t adp5520_show(struct device *dev, char *buf, int reg) { struct adp5520_bl *data = dev_get_drvdata(dev); - int error; + int ret; uint8_t reg_val; mutex_lock(&data->lock); - error = adp5520_read(data->master, reg, ®_val); + ret = adp5520_read(data->master, reg, ®_val); mutex_unlock(&data->lock); + if (ret < 0) + return ret; return sprintf(buf, "%u\n", reg_val); }