diff mbox series

[7/9] net: macb: avoid uninitialized variables

Message ID 1453903507-3427225-8-git-send-email-arnd@arndb.de
State New
Headers show
Series None | expand

Commit Message

Arnd Bergmann Jan. 27, 2016, 2:04 p.m. UTC
The macb_clk_init function returns three clock pointers, unless
the it fails to get the first ones. We correctly handle the
failure case by propagating the error from macb_probe, but
gcc does not realize this and incorrectly warns about a later
use of those:

In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:
drivers/net/ethernet/cadence/macb.c: In function 'macb_probe':
include/linux/clk.h:484:2: error: 'tx_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  clk_disable(clk);
  ^
drivers/net/ethernet/cadence/macb.c:2822:28: note: 'tx_clk' was declared here
  struct clk *pclk, *hclk, *tx_clk;
                            ^
In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:
include/linux/clk.h:484:2: error: 'hclk' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  clk_disable(clk);
  ^
drivers/net/ethernet/cadence/macb.c:2822:21: note: 'hclk' was declared here
  struct clk *pclk, *hclk, *tx_clk;
                     ^

This shuts up the misleading warnings by ensuring that the
macb_clk_init() always stores something into all three pointers.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 drivers/net/ethernet/cadence/macb.c | 1 +
 1 file changed, 1 insertion(+)

-- 
2.7.0

Comments

Nicolas Ferre Jan. 27, 2016, 3:51 p.m. UTC | #1
Le 27/01/2016 15:04, Arnd Bergmann a écrit :
> The macb_clk_init function returns three clock pointers, unless

> the it fails to get the first ones. We correctly handle the

> failure case by propagating the error from macb_probe, but

> gcc does not realize this and incorrectly warns about a later

> use of those:

> 

> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

> drivers/net/ethernet/cadence/macb.c: In function 'macb_probe':

> include/linux/clk.h:484:2: error: 'tx_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>   clk_disable(clk);

>   ^

> drivers/net/ethernet/cadence/macb.c:2822:28: note: 'tx_clk' was declared here

>   struct clk *pclk, *hclk, *tx_clk;

>                             ^

> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

> include/linux/clk.h:484:2: error: 'hclk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>   clk_disable(clk);

>   ^

> drivers/net/ethernet/cadence/macb.c:2822:21: note: 'hclk' was declared here

>   struct clk *pclk, *hclk, *tx_clk;

>                      ^

> 

> This shuts up the misleading warnings by ensuring that the

> macb_clk_init() always stores something into all three pointers.

> 

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


Okay Arnd, thanks!

Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>


> ---

>  drivers/net/ethernet/cadence/macb.c | 1 +

>  1 file changed, 1 insertion(+)

> 

> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c

> index 9d9984a87d42..d3aa74f9db79 100644

> --- a/drivers/net/ethernet/cadence/macb.c

> +++ b/drivers/net/ethernet/cadence/macb.c

> @@ -2268,6 +2268,7 @@ static int macb_clk_init(struct platform_device *pdev, struct clk **pclk,

>  {

>  	int err;

>  

> +	*tx_clk = *hclk = NULL;

>  	*pclk = devm_clk_get(&pdev->dev, "pclk");

>  	if (IS_ERR(*pclk)) {

>  		err = PTR_ERR(*pclk);

> 



-- 
Nicolas Ferre
Nicolas Ferre Jan. 27, 2016, 4:04 p.m. UTC | #2
Le 27/01/2016 16:51, Nicolas Ferre a écrit :
> Le 27/01/2016 15:04, Arnd Bergmann a écrit :

>> The macb_clk_init function returns three clock pointers, unless

>> the it fails to get the first ones. We correctly handle the

>> failure case by propagating the error from macb_probe, but

>> gcc does not realize this and incorrectly warns about a later

>> use of those:

>>

>> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

>> drivers/net/ethernet/cadence/macb.c: In function 'macb_probe':

>> include/linux/clk.h:484:2: error: 'tx_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>>   clk_disable(clk);

>>   ^

>> drivers/net/ethernet/cadence/macb.c:2822:28: note: 'tx_clk' was declared here

>>   struct clk *pclk, *hclk, *tx_clk;

>>                             ^

>> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

>> include/linux/clk.h:484:2: error: 'hclk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>>   clk_disable(clk);

>>   ^

>> drivers/net/ethernet/cadence/macb.c:2822:21: note: 'hclk' was declared here

>>   struct clk *pclk, *hclk, *tx_clk;

>>                      ^

>>

>> This shuts up the misleading warnings by ensuring that the

>> macb_clk_init() always stores something into all three pointers.

>>

>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

> 

> Okay Arnd, thanks!

> 

> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>


Oh, crap: actually this warning has just been fixed by Sudip Mukherjee
and is already queued by David here:
https://patchwork.ozlabs.org/patch/572610/

So, sorry, I've shot too fast: NACK...

Bye,

>> ---

>>  drivers/net/ethernet/cadence/macb.c | 1 +

>>  1 file changed, 1 insertion(+)

>>

>> diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c

>> index 9d9984a87d42..d3aa74f9db79 100644

>> --- a/drivers/net/ethernet/cadence/macb.c

>> +++ b/drivers/net/ethernet/cadence/macb.c

>> @@ -2268,6 +2268,7 @@ static int macb_clk_init(struct platform_device *pdev, struct clk **pclk,

>>  {

>>  	int err;

>>  

>> +	*tx_clk = *hclk = NULL;

>>  	*pclk = devm_clk_get(&pdev->dev, "pclk");

>>  	if (IS_ERR(*pclk)) {

>>  		err = PTR_ERR(*pclk);

>>

> 

> 



-- 
Nicolas Ferre
Sergei Shtylyov Jan. 28, 2016, 1:27 p.m. UTC | #3
Hello.

On 1/27/2016 5:04 PM, Arnd Bergmann wrote:

> The macb_clk_init function returns three clock pointers, unless

> the it fails to get the first ones. We correctly handle the


    s/the//.

> failure case by propagating the error from macb_probe, but

> gcc does not realize this and incorrectly warns about a later

> use of those:

>

> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

> drivers/net/ethernet/cadence/macb.c: In function 'macb_probe':


    Hm, didn't these 2 lines get swapped by chance?

> include/linux/clk.h:484:2: error: 'tx_clk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>    clk_disable(clk);

>    ^

> drivers/net/ethernet/cadence/macb.c:2822:28: note: 'tx_clk' was declared here

>    struct clk *pclk, *hclk, *tx_clk;

>                              ^

> In file included from /git/arm-soc/drivers/net/ethernet/cadence/macb.c:12:0:

> include/linux/clk.h:484:2: error: 'hclk' may be used uninitialized in this function [-Werror=maybe-uninitialized]

>    clk_disable(clk);

>    ^

> drivers/net/ethernet/cadence/macb.c:2822:21: note: 'hclk' was declared here

>    struct clk *pclk, *hclk, *tx_clk;

>                       ^

>

> This shuts up the misleading warnings by ensuring that the

> macb_clk_init() always stores something into all three pointers.

>

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>


[...]

MBR, Sergei
Arnd Bergmann Jan. 28, 2016, 4:32 p.m. UTC | #4
On Wednesday 27 January 2016 17:04:47 Nicolas Ferre wrote:
> > 

> > Okay Arnd, thanks!

> > 

> > Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

> 

> Oh, crap: actually this warning has just been fixed by Sudip Mukherjee

> and is already queued by David here:

> https://patchwork.ozlabs.org/patch/572610/

> 

> So, sorry, I've shot too fast: NACK...


Ok, thanks for pointing this out.

	Arnd
diff mbox series

Patch

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 9d9984a87d42..d3aa74f9db79 100644
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -2268,6 +2268,7 @@  static int macb_clk_init(struct platform_device *pdev, struct clk **pclk,
 {
 	int err;
 
+	*tx_clk = *hclk = NULL;
 	*pclk = devm_clk_get(&pdev->dev, "pclk");
 	if (IS_ERR(*pclk)) {
 		err = PTR_ERR(*pclk);