[alsa-devel] [PATCH 1/2] ASoC: cs35l32: avoid uninitialized variable access
gcc warns about the possibilty of accessing a property read from devicetree in cs35l32_i2c_probe() when it has not been initialized because CONFIG_OF is disabled:
sound/soc/codecs/cs35l32.c: In function 'cs35l32_i2c_probe': sound/soc/codecs/cs35l32.c:278:2: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]
The code is actually correct because it checks the dev->of_node variable first and we know this is NULL here, but by adding a check for IS_ENABLED(CONFIG_OF), we can let the compiler know as well, and also generate smaller object code.
Signed-off-by: Arnd Bergmann arnd@arndb.de --- sound/soc/codecs/cs35l32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/sound/soc/codecs/cs35l32.c b/sound/soc/codecs/cs35l32.c index 44c30fe3e315..52ffaa8eb02b 100644 --- a/sound/soc/codecs/cs35l32.c +++ b/sound/soc/codecs/cs35l32.c @@ -372,7 +372,7 @@ static int cs35l32_i2c_probe(struct i2c_client *i2c_client, dev_err(&i2c_client->dev, "could not allocate pdata\n"); return -ENOMEM; } - if (i2c_client->dev.of_node) { + if (IS_ENABLED(CONFIG_OF) && i2c_client->dev.of_node) { ret = cs35l32_handle_of_data(i2c_client, &cs35l32->pdata); if (ret != 0)
An older patch to convert the API in the s3c i2s driver ended up passing a const pointer into a function that takes a non-const pointer, so we now get a warning:
sound/soc/samsung/s3c2412-i2s.c: In function 's3c2412_iis_dev_probe': sound/soc/samsung/s3c2412-i2s.c:172:9: error: passing argument 3 of 's3c_i2sv2_register_component' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
However, the s3c_i2sv2_register_component() function again passes the pointer into another function taking a const, so we just need to change its prototype.
Signed-off-by: Arnd Bergmann arnd@arndb.de Fixes: eca3b01d0885 ("ASoC: switch over to use snd_soc_register_component() on s3c i2s") --- sound/soc/samsung/s3c-i2s-v2.c | 2 +- sound/soc/samsung/s3c-i2s-v2.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/soc/samsung/s3c-i2s-v2.c b/sound/soc/samsung/s3c-i2s-v2.c index df65c5b494b1..b6ab3fc5789e 100644 --- a/sound/soc/samsung/s3c-i2s-v2.c +++ b/sound/soc/samsung/s3c-i2s-v2.c @@ -709,7 +709,7 @@ static int s3c2412_i2s_resume(struct snd_soc_dai *dai) #endif
int s3c_i2sv2_register_component(struct device *dev, int id, - struct snd_soc_component_driver *cmp_drv, + const struct snd_soc_component_driver *cmp_drv, struct snd_soc_dai_driver *dai_drv) { struct snd_soc_dai_ops *ops = (struct snd_soc_dai_ops *)dai_drv->ops; diff --git a/sound/soc/samsung/s3c-i2s-v2.h b/sound/soc/samsung/s3c-i2s-v2.h index 90abab364b49..d0684145ed1f 100644 --- a/sound/soc/samsung/s3c-i2s-v2.h +++ b/sound/soc/samsung/s3c-i2s-v2.h @@ -101,7 +101,7 @@ extern int s3c_i2sv2_probe(struct snd_soc_dai *dai, * soc core. */ extern int s3c_i2sv2_register_component(struct device *dev, int id, - struct snd_soc_component_driver *cmp_drv, + const struct snd_soc_component_driver *cmp_drv, struct snd_soc_dai_driver *dai_drv);
#endif /* __SND_SOC_S3C24XX_S3C_I2SV2_I2S_H */
On 26.01.2016 02:07, Arnd Bergmann wrote:
An older patch to convert the API in the s3c i2s driver ended up passing a const pointer into a function that takes a non-const pointer, so we now get a warning:
sound/soc/samsung/s3c2412-i2s.c: In function 's3c2412_iis_dev_probe': sound/soc/samsung/s3c2412-i2s.c:172:9: error: passing argument 3 of 's3c_i2sv2_register_component' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
However, the s3c_i2sv2_register_component() function again passes the pointer into another function taking a const, so we just need to change its prototype.
Signed-off-by: Arnd Bergmann arnd@arndb.de Fixes: eca3b01d0885 ("ASoC: switch over to use snd_soc_register_component() on s3c i2s")
sound/soc/samsung/s3c-i2s-v2.c | 2 +- sound/soc/samsung/s3c-i2s-v2.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
Reviewed-by: Krzysztof Kozlowski k.kozlowski@samsung.com
Best regards, Krzysztof
The patch
ASoC: s3c24xx: use const snd_soc_component_driver pointer
has been applied to the asoc tree at
git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git
All being well this means that it will be integrated into the linux-next tree (usually sometime in the next 24 hours) and sent to Linus during the next merge window (or sooner if it is a bug fix), however if problems are discovered then the patch may be dropped or reverted.
You may get further e-mails resulting from automated or manual testing and review of the tree, please engage with people reporting problems and send followup patches addressing any issues that are reported if needed.
If any updates are required or you are submitting further changes they should be sent as incremental updates against current git, existing patches will not be replaced.
Please add any relevant lists and maintainers to the CCs when replying to this mail.
Thanks, Mark
From ba4bc32eaa39ba7687f0958ae90eec94da613b46 Mon Sep 17 00:00:00 2001
From: Arnd Bergmann arnd@arndb.de Date: Mon, 25 Jan 2016 18:07:33 +0100 Subject: [PATCH] ASoC: s3c24xx: use const snd_soc_component_driver pointer
An older patch to convert the API in the s3c i2s driver ended up passing a const pointer into a function that takes a non-const pointer, so we now get a warning:
sound/soc/samsung/s3c2412-i2s.c: In function 's3c2412_iis_dev_probe': sound/soc/samsung/s3c2412-i2s.c:172:9: error: passing argument 3 of 's3c_i2sv2_register_component' discards 'const' qualifier from pointer target type [-Werror=discarded-qualifiers]
However, the s3c_i2sv2_register_component() function again passes the pointer into another function taking a const, so we just need to change its prototype.
Fixes: eca3b01d0885 ("ASoC: switch over to use snd_soc_register_component() on s3c i2s") Signed-off-by: Arnd Bergmann arnd@arndb.de Reviewed-by: Krzysztof Kozlowski k.kozlowski@samsung.com Signed-off-by: Mark Brown broonie@kernel.org --- sound/soc/samsung/s3c-i2s-v2.c | 2 +- sound/soc/samsung/s3c-i2s-v2.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/sound/soc/samsung/s3c-i2s-v2.c b/sound/soc/samsung/s3c-i2s-v2.c index df65c5b494b1..b6ab3fc5789e 100644 --- a/sound/soc/samsung/s3c-i2s-v2.c +++ b/sound/soc/samsung/s3c-i2s-v2.c @@ -709,7 +709,7 @@ static int s3c2412_i2s_resume(struct snd_soc_dai *dai) #endif
int s3c_i2sv2_register_component(struct device *dev, int id, - struct snd_soc_component_driver *cmp_drv, + const struct snd_soc_component_driver *cmp_drv, struct snd_soc_dai_driver *dai_drv) { struct snd_soc_dai_ops *ops = (struct snd_soc_dai_ops *)dai_drv->ops; diff --git a/sound/soc/samsung/s3c-i2s-v2.h b/sound/soc/samsung/s3c-i2s-v2.h index 90abab364b49..d0684145ed1f 100644 --- a/sound/soc/samsung/s3c-i2s-v2.h +++ b/sound/soc/samsung/s3c-i2s-v2.h @@ -101,7 +101,7 @@ extern int s3c_i2sv2_probe(struct snd_soc_dai *dai, * soc core. */ extern int s3c_i2sv2_register_component(struct device *dev, int id, - struct snd_soc_component_driver *cmp_drv, + const struct snd_soc_component_driver *cmp_drv, struct snd_soc_dai_driver *dai_drv);
#endif /* __SND_SOC_S3C24XX_S3C_I2SV2_I2S_H */
On Jan 25, 2016, at 11:07 AM, Arnd Bergmann <arnd@arndb.demailto:arnd@arndb.de> wrote:
gcc warns about the possibilty of accessing a property read from devicetree in cs35l32_i2c_probe() when it has not been initialized because CONFIG_OF is disabled:
sound/soc/codecs/cs35l32.c: In function 'cs35l32_i2c_probe': sound/soc/codecs/cs35l32.c:278:2: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]
The code is actually correct because it checks the dev->of_node variable first and we know this is NULL here, but by adding a check for IS_ENABLED(CONFIG_OF), we can let the compiler know as well, and also generate smaller object code.
Signed-off-by: Arnd Bergmann <arnd@arndb.demailto:arnd@arndb.de> --- sound/soc/codecs/cs35l32.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Thanks,
Acked-by: Brian Austin <brian.austin@cirrus.commailto:brian.austin@cirrus.com>
On Mon, Jan 25, 2016 at 06:07:32PM +0100, Arnd Bergmann wrote:
if (i2c_client->dev.of_node) {
if (IS_ENABLED(CONFIG_OF) && i2c_client->dev.of_node) {
This feels it's going to be happening a lot and we should probably have a dev_has_of_node() helper that does the IS_ENABLED() check.
On Mon, Jan 25, 2016 at 06:07:32PM +0100, Arnd Bergmann wrote:
gcc warns about the possibilty of accessing a property read from devicetree in cs35l32_i2c_probe() when it has not been initialized because CONFIG_OF is disabled:
sound/soc/codecs/cs35l32.c: In function 'cs35l32_i2c_probe': sound/soc/codecs/cs35l32.c:278:2: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]
The code is actually correct because it checks the dev->of_node variable first and we know this is NULL here, but by adding a check for IS_ENABLED(CONFIG_OF), we can let the compiler know as well, and also generate smaller object code.
No, the code is buggy, and the compiler is very correct in warning about it.
The code there is:
of_property_read_u32(np, "cirrus,boost-manager", &val); switch (val) {
of_property_read_u32() is aliased to of_property_read_u32_array() via:
static inline int of_property_read_u32(const struct device_node *np, const char *propname, u32 *out_value) { return of_property_read_u32_array(np, propname, out_value, 1); }
which does this:
int of_property_read_u32_array(const struct device_node *np, const char *propname, u32 *out_values, size_t sz) { const __be32 *val = of_find_property_value_of_size(np, propname, (sz * sizeof(*out_values)));
if (IS_ERR(val)) return PTR_ERR(val);
while (sz--) *out_values++ = be32_to_cpup(val++); return 0; }
Note that 'out_values' is not written to if of_find_property_value_of_size() returns an error. Therefore, if cirrus,boost-manager is missing, the resulting value of 'val' is left uninitialised.
On Saturday 05 March 2016, Russell King - ARM Linux wrote:
On Mon, Jan 25, 2016 at 06:07:32PM +0100, Arnd Bergmann wrote:
gcc warns about the possibilty of accessing a property read from devicetree in cs35l32_i2c_probe() when it has not been initialized because CONFIG_OF is disabled:
sound/soc/codecs/cs35l32.c: In function 'cs35l32_i2c_probe': sound/soc/codecs/cs35l32.c:278:2: warning: 'val' may be used uninitialized in this function [-Wmaybe-uninitialized]
The code is actually correct because it checks the dev->of_node variable first and we know this is NULL here, but by adding a check for IS_ENABLED(CONFIG_OF), we can let the compiler know as well, and also generate smaller object code.
No, the code is buggy, and the compiler is very correct in warning about it.
...
Note that 'out_values' is not written to if of_find_property_value_of_size() returns an error. Therefore, if cirrus,boost-manager is missing, the resulting value of 'val' is left uninitialised.
You are right, this is an actual bug in the driver, and my patch just hides it. Interestingly, this is not the case that the warning was about, as we get the warning only when CONFIG_OF is disabled and the code is correct (because dev->of_node is guaranteed to be NULL), but we don't get the warning when CONFIG_OF is enabled and we can actually run into the problem.
Fixing the driver to have correct error handling on the property functions will make the warning go away and fix the bug you pointed out, so we should definitely do that and drop my patch.
Arnd
participants (5)
-
Arnd Bergmann -
Austin, Brian -
Krzysztof Kozlowski -
Mark Brown -
Russell King - ARM Linux