* [PATCH] pwm: fix undefined behavior in stm32_pwm_apply
@ 2017-01-25 22:31 Arnd Bergmann
2017-01-26 12:16 ` Lee Jones
0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2017-01-25 22:31 UTC (permalink / raw)
To: Thierry Reding
Cc: Arnd Bergmann, Maxime Coquelin, Alexandre Torgue, Lee Jones,
Benjamin Gaignard, linux-pwm, linux-arm-kernel, linux-kernel
The stm32_pwm_apply randomly sets the polarity or doesn't,
as pointed out by this gcc warning:
drivers/pwm/pwm-stm32.c: In function 'stm32_pwm_apply':
drivers/pwm/pwm-stm32.c:204:33: error: 'curstate.polarity' may be used uninitialized in this function [-Werror=maybe-uninitialized]
I assume it was meant to compare the new state to the current
state rather than an uninitialized stack variable, so let's
do that instead.
Fixes: bafffb6e7bd1 ("pwm: Add driver for STM32 plaftorm")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
drivers/pwm/pwm-stm32.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index ce6232ebefe1..6139512aab7b 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -189,7 +189,6 @@ static void stm32_pwm_disable(struct stm32_pwm *priv, int ch)
static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
- struct pwm_state curstate;
bool enabled;
struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
int ret;
@@ -201,7 +200,7 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
return 0;
}
- if (state->polarity != curstate.polarity)
+ if (state->polarity != pwm->state.polarity)
stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
ret = stm32_pwm_config(priv, pwm->hwpwm,
--
2.9.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] pwm: fix undefined behavior in stm32_pwm_apply
2017-01-25 22:31 [PATCH] pwm: fix undefined behavior in stm32_pwm_apply Arnd Bergmann
@ 2017-01-26 12:16 ` Lee Jones
0 siblings, 0 replies; 2+ messages in thread
From: Lee Jones @ 2017-01-26 12:16 UTC (permalink / raw)
To: Arnd Bergmann
Cc: Thierry Reding, Maxime Coquelin, Alexandre Torgue,
Benjamin Gaignard, linux-pwm, linux-arm-kernel, linux-kernel
On Wed, 25 Jan 2017, Arnd Bergmann wrote:
> The stm32_pwm_apply randomly sets the polarity or doesn't,
> as pointed out by this gcc warning:
>
> drivers/pwm/pwm-stm32.c: In function 'stm32_pwm_apply':
> drivers/pwm/pwm-stm32.c:204:33: error: 'curstate.polarity' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>
> I assume it was meant to compare the new state to the current
> state rather than an uninitialized stack variable, so let's
> do that instead.
>
> Fixes: bafffb6e7bd1 ("pwm: Add driver for STM32 plaftorm")
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/pwm/pwm-stm32.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
Fix from the author already applied.
> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
> index ce6232ebefe1..6139512aab7b 100644
> --- a/drivers/pwm/pwm-stm32.c
> +++ b/drivers/pwm/pwm-stm32.c
> @@ -189,7 +189,6 @@ static void stm32_pwm_disable(struct stm32_pwm *priv, int ch)
> static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> struct pwm_state *state)
> {
> - struct pwm_state curstate;
> bool enabled;
> struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
> int ret;
> @@ -201,7 +200,7 @@ static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> return 0;
> }
>
> - if (state->polarity != curstate.polarity)
> + if (state->polarity != pwm->state.polarity)
> stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
>
> ret = stm32_pwm_config(priv, pwm->hwpwm,
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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