Messages in this thread | | | Date | Thu, 28 Jan 2016 11:15:53 +0000 | From | Lee Jones <> | Subject | Re: [PATCH] mfd: db8500: avoid uninitialized variable reference |
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On Mon, 25 Jan 2016, Arnd Bergmann wrote:
> The prcmu_config_clkout() function ensures that the 'clkout' argument > can only be '0' or '1' using an appropriate BUG_ON(), so the compiler > should know that the div_mask, mask, and bits variables are always > initialized later on. However, it doesn't understand this in gcc-5.2 > and produces a false positive warning instead: > > drivers/mfd/db8500-prcmu.c: In function 'prcmu_config_clkout': > drivers/mfd/db8500-prcmu.c:762:10: error: 'div_mask' may be used uninitialized in this function [-Werror=maybe-uninitialized] > if (val & div_mask) { > ^ > drivers/mfd/db8500-prcmu.c:769:13: error: 'mask' may be used uninitialized in this function [-Werror=maybe-uninitialized] > if ((val & mask & ~div_mask) != bits) { > ^ > drivers/mfd/db8500-prcmu.c:757:7: error: 'bits' may be used uninitialized in this function [-Werror=maybe-uninitialized] > > Replacing the switch() statement with an equivalent if() lets > gcc figure this out reliably and avoids the warnings. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/mfd/db8500-prcmu.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-)
Applied, thanks.
> diff --git a/drivers/mfd/db8500-prcmu.c b/drivers/mfd/db8500-prcmu.c > index 12099b09a9a7..c0a86aeb1733 100644 > --- a/drivers/mfd/db8500-prcmu.c > +++ b/drivers/mfd/db8500-prcmu.c > @@ -739,20 +739,17 @@ int prcmu_config_clkout(u8 clkout, u8 source, u8 div) > if (!div && !requests[clkout]) > return -EINVAL; > > - switch (clkout) { > - case 0: > + if (clkout == 0) { > div_mask = PRCM_CLKOCR_CLKODIV0_MASK; > mask = (PRCM_CLKOCR_CLKODIV0_MASK | PRCM_CLKOCR_CLKOSEL0_MASK); > bits = ((source << PRCM_CLKOCR_CLKOSEL0_SHIFT) | > (div << PRCM_CLKOCR_CLKODIV0_SHIFT)); > - break; > - case 1: > + } else { > div_mask = PRCM_CLKOCR_CLKODIV1_MASK; > mask = (PRCM_CLKOCR_CLKODIV1_MASK | PRCM_CLKOCR_CLKOSEL1_MASK | > PRCM_CLKOCR_CLK1TYPE); > bits = ((source << PRCM_CLKOCR_CLKOSEL1_SHIFT) | > (div << PRCM_CLKOCR_CLKODIV1_SHIFT)); > - break; > } > bits &= mask; >
-- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
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