Re: [PATCH] Regulator: Suppress compiler warnings

[Keith Busch]

On Tue, 1 Sep 2015, Mark Brown wrote:

On Tue, Sep 01, 2015 at 09:52:13AM +0900, Krzysztof Kozlowski wrote:

2015-09-01 1:41 GMT+09:00 Keith Busch :

 int regulator_is_enabled_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;

ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );



This is quite common pattern so such work-around should be added to
many other functions leading to code obfuscation. Which compiler do
you have in mind?


Right, plus this will shut up valid compiler warnings which is poor
practice anyway.  I'd say this is a bug in the compiler.


Using gcc 4.7.2 with '-Os'. The warning does not happen when that option
is not used, i.e. disable CONFIG_CC_OPTIMIZE_FOR_SIZE.

I will certainly try other gcc versions with the same config and see
what happens.
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Re: [PATCH] Regulator: Suppress compiler warnings

[Mark Brown]

On Tue, Sep 01, 2015 at 09:52:13AM +0900, Krzysztof Kozlowski wrote:
> 2015-09-01 1:41 GMT+09:00 Keith Busch :
> > Some compilers complain of possible uninitialized variable usage, like
> > the following:

> >   drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
> >   drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used 
> > uninitialized in this function [-Wuninitialized]

> > The code is safe though, and only uses the variables if they were
> > successfully set, so suppressing the warning with uninitialized_val.

> >  int regulator_is_enabled_regmap(struct regulator_dev *rdev)
> >  {
> > -   unsigned int val;
> > +   unsigned int uninitialized_var(val);
> > int ret;
> >
> > ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );

> This is quite common pattern so such work-around should be added to
> many other functions leading to code obfuscation. Which compiler do
> you have in mind?

Right, plus this will shut up valid compiler warnings which is poor
practice anyway.  I'd say this is a bug in the compiler.


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Re: [PATCH] Regulator: Suppress compiler warnings

[Keith Busch]

On Tue, 1 Sep 2015, Mark Brown wrote:

On Tue, Sep 01, 2015 at 09:52:13AM +0900, Krzysztof Kozlowski wrote:

2015-09-01 1:41 GMT+09:00 Keith Busch :

 int regulator_is_enabled_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;

ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );



This is quite common pattern so such work-around should be added to
many other functions leading to code obfuscation. Which compiler do
you have in mind?


Right, plus this will shut up valid compiler warnings which is poor
practice anyway.  I'd say this is a bug in the compiler.


Using gcc 4.7.2 with '-Os'. The warning does not happen when that option
is not used, i.e. disable CONFIG_CC_OPTIMIZE_FOR_SIZE.

I will certainly try other gcc versions with the same config and see
what happens.
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To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
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Re: [PATCH] Regulator: Suppress compiler warnings

[Mark Brown]

On Tue, Sep 01, 2015 at 09:52:13AM +0900, Krzysztof Kozlowski wrote:
> 2015-09-01 1:41 GMT+09:00 Keith Busch :
> > Some compilers complain of possible uninitialized variable usage, like
> > the following:

> >   drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
> >   drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used 
> > uninitialized in this function [-Wuninitialized]

> > The code is safe though, and only uses the variables if they were
> > successfully set, so suppressing the warning with uninitialized_val.

> >  int regulator_is_enabled_regmap(struct regulator_dev *rdev)
> >  {
> > -   unsigned int val;
> > +   unsigned int uninitialized_var(val);
> > int ret;
> >
> > ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );

> This is quite common pattern so such work-around should be added to
> many other functions leading to code obfuscation. Which compiler do
> you have in mind?

Right, plus this will shut up valid compiler warnings which is poor
practice anyway.  I'd say this is a bug in the compiler.


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Description: Digital signature

Re: [PATCH] Regulator: Suppress compiler warnings

[Krzysztof Kozlowski]

2015-09-01 1:41 GMT+09:00 Keith Busch :
> Some compilers complain of possible uninitialized variable usage, like
> the following:
>
>   drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
>   drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used 
> uninitialized in this function [-Wuninitialized]
>
> The code is safe though, and only uses the variables if they were
> successfully set, so suppressing the warning with uninitialized_val.
>
> Signed-off-by: Keith Busch 
> ---
>  drivers/regulator/helpers.c |6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
> index 3bbb326..bb5b22a 100644
> --- a/drivers/regulator/helpers.c
> +++ b/drivers/regulator/helpers.c
> @@ -30,7 +30,7 @@
>   */
>  int regulator_is_enabled_regmap(struct regulator_dev *rdev)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );

This is quite common pattern so such work-around should be added to
many other functions leading to code obfuscation. Which compiler do
you have in mind?

Best regards,
Krzysztof

> @@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(regulator_disable_regmap);
>   */
>  int regulator_get_voltage_sel_regmap(struct regulator_dev *rdev)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, );
> @@ -453,7 +453,7 @@ EXPORT_SYMBOL_GPL(regulator_set_bypass_regmap);
>   */
>  int regulator_get_bypass_regmap(struct regulator_dev *rdev, bool *enable)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->bypass_reg, );
> --
> 1.7.10.4
>
> --
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[PATCH] Regulator: Suppress compiler warnings

[Keith Busch]

Some compilers complain of possible uninitialized variable usage, like
the following:

  drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
  drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used uninitialized 
in this function [-Wuninitialized]

The code is safe though, and only uses the variables if they were
successfully set, so suppressing the warning with uninitialized_val.

Signed-off-by: Keith Busch 
---
 drivers/regulator/helpers.c |6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
index 3bbb326..bb5b22a 100644
--- a/drivers/regulator/helpers.c
+++ b/drivers/regulator/helpers.c
@@ -30,7 +30,7 @@
  */
 int regulator_is_enabled_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );
@@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(regulator_disable_regmap);
  */
 int regulator_get_voltage_sel_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, );
@@ -453,7 +453,7 @@ EXPORT_SYMBOL_GPL(regulator_set_bypass_regmap);
  */
 int regulator_get_bypass_regmap(struct regulator_dev *rdev, bool *enable)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->bypass_reg, );
-- 
1.7.10.4

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[PATCH] Regulator: Suppress compiler warnings

[Keith Busch]

Some compilers complain of possible uninitialized variable usage, like
the following:

  drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
  drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used uninitialized 
in this function [-Wuninitialized]

The code is safe though, and only uses the variables if they were
successfully set, so suppressing the warning with uninitialized_val.

Signed-off-by: Keith Busch 
---
 drivers/regulator/helpers.c |6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
index 3bbb326..bb5b22a 100644
--- a/drivers/regulator/helpers.c
+++ b/drivers/regulator/helpers.c
@@ -30,7 +30,7 @@
  */
 int regulator_is_enabled_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );
@@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(regulator_disable_regmap);
  */
 int regulator_get_voltage_sel_regmap(struct regulator_dev *rdev)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, );
@@ -453,7 +453,7 @@ EXPORT_SYMBOL_GPL(regulator_set_bypass_regmap);
  */
 int regulator_get_bypass_regmap(struct regulator_dev *rdev, bool *enable)
 {
-   unsigned int val;
+   unsigned int uninitialized_var(val);
int ret;
 
ret = regmap_read(rdev->regmap, rdev->desc->bypass_reg, );
-- 
1.7.10.4

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Re: [PATCH] Regulator: Suppress compiler warnings

[Krzysztof Kozlowski]

2015-09-01 1:41 GMT+09:00 Keith Busch :
> Some compilers complain of possible uninitialized variable usage, like
> the following:
>
>   drivers/regulator/helpers.c: In function ‘regulator_get_bypass_regmap’:
>   drivers/regulator/helpers.c:463:16: warning: ‘val’ may be used 
> uninitialized in this function [-Wuninitialized]
>
> The code is safe though, and only uses the variables if they were
> successfully set, so suppressing the warning with uninitialized_val.
>
> Signed-off-by: Keith Busch 
> ---
>  drivers/regulator/helpers.c |6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/regulator/helpers.c b/drivers/regulator/helpers.c
> index 3bbb326..bb5b22a 100644
> --- a/drivers/regulator/helpers.c
> +++ b/drivers/regulator/helpers.c
> @@ -30,7 +30,7 @@
>   */
>  int regulator_is_enabled_regmap(struct regulator_dev *rdev)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->enable_reg, );

This is quite common pattern so such work-around should be added to
many other functions leading to code obfuscation. Which compiler do
you have in mind?

Best regards,
Krzysztof

> @@ -114,7 +114,7 @@ EXPORT_SYMBOL_GPL(regulator_disable_regmap);
>   */
>  int regulator_get_voltage_sel_regmap(struct regulator_dev *rdev)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->vsel_reg, );
> @@ -453,7 +453,7 @@ EXPORT_SYMBOL_GPL(regulator_set_bypass_regmap);
>   */
>  int regulator_get_bypass_regmap(struct regulator_dev *rdev, bool *enable)
>  {
> -   unsigned int val;
> +   unsigned int uninitialized_var(val);
> int ret;
>
> ret = regmap_read(rdev->regmap, rdev->desc->bypass_reg, );
> --
> 1.7.10.4
>
> --
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