| Message ID | 20161116141841.2030776-1-arnd@arndb.de |
|---|---|
| State | New |
| Headers | show |
On Wed, Nov 16, 2016 at 3:18 PM, Arnd Bergmann <arnd@arndb.de> wrote: > gcc warns about a way that it could use an uninitialized variable: > > drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': > drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > This cannot really happen except if 'freq' is UINT_MAX and 'clock' is > zero, and both of these are forbidden. To shut up the warning anyway, > this changes the logic to initialize the return code to the first > divider value before looking at the others. > > Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Patch applied. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Arnd, On Wed, Nov 16, 2016 at 03:18:18PM +0100, Arnd Bergmann wrote: > gcc warns about a way that it could use an uninitialized variable: > > drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': > drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > This cannot really happen except if 'freq' is UINT_MAX and 'clock' is > zero, and both of these are forbidden. To shut up the warning anyway, > this changes the logic to initialize the return code to the first > divider value before looking at the others. > > Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Thanks for that patch. Just out of curiosity, which gcc gives those warnings? I have 6.2 and it didn't output anything.. Maxime
On Wed, Nov 16, 2016 at 9:33 PM, Maxime Ripard <maxime.ripard@free-electrons.com> wrote: > On Wed, Nov 16, 2016 at 03:18:18PM +0100, Arnd Bergmann wrote: >> gcc warns about a way that it could use an uninitialized variable: >> >> drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': >> drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] >> >> This cannot really happen except if 'freq' is UINT_MAX and 'clock' is >> zero, and both of these are forbidden. To shut up the warning anyway, >> this changes the logic to initialize the return code to the first >> divider value before looking at the others. >> >> Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Thanks for that patch. > > Just out of curiosity, which gcc gives those warnings? I have 6.2 and > it didn't output anything.. Context: Arnd re-enabled -Werror=maybe-uninitialized in the kernel build and this kind of stuff started to appear so it needs to be fixed up. Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thursday, November 17, 2016 10:08:28 AM CET Linus Walleij wrote: > On Wed, Nov 16, 2016 at 9:33 PM, Maxime Ripard > <maxime.ripard@free-electrons.com> wrote: > > > On Wed, Nov 16, 2016 at 03:18:18PM +0100, Arnd Bergmann wrote: > >> gcc warns about a way that it could use an uninitialized variable: > >> > >> drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': > >> drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] > >> > >> This cannot really happen except if 'freq' is UINT_MAX and 'clock' is > >> zero, and both of these are forbidden. To shut up the warning anyway, > >> this changes the logic to initialize the return code to the first > >> divider value before looking at the others. > >> > >> Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") > >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > > Thanks for that patch. > > > > Just out of curiosity, which gcc gives those warnings? I have 6.2 and > > it didn't output anything.. > > Context: Arnd re-enabled -Werror=maybe-uninitialized > in the kernel build and this kind of stuff started to appear so > it needs to be fixed up. Right, it was disabled from linux-4.8-rc1 to linux-4.9-rc4 and is now back in the default builds when using gcc-4.9 or higher. You should get the warning if you test with linux-next or -rc4. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 17, 2016 at 10:08:28AM +0100, Linus Walleij wrote: > On Wed, Nov 16, 2016 at 9:33 PM, Maxime Ripard > <maxime.ripard@free-electrons.com> wrote: > > > On Wed, Nov 16, 2016 at 03:18:18PM +0100, Arnd Bergmann wrote: > >> gcc warns about a way that it could use an uninitialized variable: > >> > >> drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': > >> drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] > >> > >> This cannot really happen except if 'freq' is UINT_MAX and 'clock' is > >> zero, and both of these are forbidden. To shut up the warning anyway, > >> this changes the logic to initialize the return code to the first > >> divider value before looking at the others. > >> > >> Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") > >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > > > Thanks for that patch. > > > > Just out of curiosity, which gcc gives those warnings? I have 6.2 and > > it didn't output anything.. > > Context: Arnd re-enabled -Werror=maybe-uninitialized > in the kernel build and this kind of stuff started to appear so > it needs to be fixed up. Ah, that makes sense. Thanks! Maxime
diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c index 2339d4718b4d..6b7953da4228 100644 --- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c +++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c @@ -1125,10 +1125,13 @@ static int sunxi_pinctrl_build_state(struct platform_device *pdev) static int sunxi_pinctrl_get_debounce_div(struct clk *clk, int freq, int *diff) { unsigned long clock = clk_get_rate(clk); - unsigned int best_diff = ~0, best_div; + unsigned int best_diff, best_div; int i; - for (i = 0; i < 8; i++) { + best_diff = abs(freq - clock); + best_div = 0; + + for (i = 1; i < 8; i++) { int cur_diff = abs(freq - (clock >> i)); if (cur_diff < best_diff) {
gcc warns about a way that it could use an uninitialized variable: drivers/pinctrl/sunxi/pinctrl-sunxi.c: In function 'sunxi_pinctrl_init': drivers/pinctrl/sunxi/pinctrl-sunxi.c:1191:8: error: 'best_div' may be used uninitialized in this function [-Werror=maybe-uninitialized] This cannot really happen except if 'freq' is UINT_MAX and 'clock' is zero, and both of these are forbidden. To shut up the warning anyway, this changes the logic to initialize the return code to the first divider value before looking at the others. Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/pinctrl/sunxi/pinctrl-sunxi.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)