On Fri, Feb 12, 2016 at 05:06:19PM +0100, Arnd Bergmann wrote: > CONFIG_PROFILE_ALL_BRANCHES confuses gcc-5.x to the degree that it prints > incorrect warnings about a lot of variables that it thinks can be used > uninitialized, e.g.: > > i2c/busses/i2c-diolan-u2c.c: In function 'diolan_usb_xfer': > i2c/busses/i2c-diolan-u2c.c:391:16: warning: 'byte' may be used uninitialized in this function > iio/gyro/itg3200_core.c: In function 'itg3200_probe': > iio/gyro/itg3200_core.c:213:6: warning: 'val' may be used uninitialized in this function > leds/leds-lp55xx-common.c: In function 'lp55xx_update_bits': > leds/leds-lp55xx-common.c:350:6: warning: 'tmp' may be used uninitialized in this function > misc/bmp085.c: In function 'show_pressure': > misc/bmp085.c:363:10: warning: 'pressure' may be used uninitialized in this function > power/ds2782_battery.c: In function 'ds2786_get_capacity': > power/ds2782_battery.c:214:17: warning: 'raw' may be used uninitialized in this function > > These are all false positives that either rob someone's time when trying > to figure out whether they are real, or they get people to send wrong > patches to shut up the warnings. > > Nobody normally wants to run a CONFIG_PROFILE_ALL_BRANCHES kernel in > production, so disabling the whole class of warnings for this configuration > has no serious downsides either. > > Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx> Acked-by: Steven Rostedt <rostedt@xxxxxxxxxxx> -- Steve > --- > Makefile | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index 9092c16fa6cf..352f55ccc54e 100644 > --- a/Makefile > +++ b/Makefile > @@ -617,7 +617,11 @@ KBUILD_CFLAGS += $(call cc-option,-fno-delete-null-pointer-checks,) > ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE > KBUILD_CFLAGS += -Os $(call cc-disable-warning,maybe-uninitialized,) > else > -KBUILD_CFLAGS += -O2 > +ifdef CONFIG_PROFILE_ALL_BRANCHES > +KBUILD_CFLAGS += -O2 $(call cc-disable-warning,maybe-uninitialized,) > +else > +KBUILD_CFLAGS += -O2 > +endif > endif > > # Tell gcc to never replace conditional load with a non-conditional one > -- > 2.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
