On Thu, Jun 06, 2019 at 05:52:42PM +0900, Masahiro Yamada wrote: > Kbuild test robot reports outside array bounds warnings. > > This is reproducible for ARCH=sh allmodconfig with the kernel.org > toolchains available at: > > https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/8.1.0/x86_64-gcc-8.1.0-nolibc-sh4-linux.tar.xz > > CC [M] drivers/hwmon/smsc47m1.o > drivers/hwmon/smsc47m1.c: In function 'fan_div_store': > drivers/hwmon/smsc47m1.c:370:49: warning: array subscript [0, 2] is outside array bounds of 'u8[3]' {aka 'unsigned char[3]'} [-Warray-bounds] > tmp = 192 - (old_div * (192 - data->fan_preload[nr]) > ~~~~~~~~~~~~~~~~~^~~~ > drivers/hwmon/smsc47m1.c:372:19: warning: array subscript [0, 2] is outside array bounds of 'u8[3]' {aka 'unsigned char[3]'} [-Warray-bounds] > data->fan_preload[nr] = clamp_val(tmp, 0, 191); > ~~~~~~~~~~~~~~~~~^~~~ > drivers/hwmon/smsc47m1.c:373:53: warning: array subscript [0, 2] is outside array bounds of 'const u8[3]' {aka 'const unsigned char[3]'} [-Warray-bounds] > smsc47m1_write_value(data, SMSC47M1_REG_FAN_PRELOAD[nr], > ~~~~~~~~~~~~~~~~~~~~~~~~^~~~ > > Looking at the code, I believe these are false positives. > > While it is ridiculous to patch our driver to make the insane > compiler happy, clarifying the unreachable path will be helpful > not only for compilers but also for humans. > > Reported-by: kbuild test robot <lkp@xxxxxxxxx> > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> Applied. Thanks, Guenter > --- > > Changes in v2: > - Use unreachable() instead of WARN_ON() > - Mention that the report seems suspicious > > drivers/hwmon/smsc47m1.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c > index cc6aca6e436c..6d366c9cb906 100644 > --- a/drivers/hwmon/smsc47m1.c > +++ b/drivers/hwmon/smsc47m1.c > @@ -351,6 +351,8 @@ static ssize_t fan_div_store(struct device *dev, > tmp |= data->fan_div[2] << 4; > smsc47m1_write_value(data, SMSC47M2_REG_FANDIV3, tmp); > break; > + default: > + unreachable(); > } > > /* Preserve fan min */
