[PATCH v1] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[PATCH v1] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[Minjie Du]

Make IS_ERR() judge the debugfs_create_dir() function return
in ath5k_debug_init_device().

Signed-off-by: Minjie Du <duminjie@vivo.com>
---
 drivers/net/wireless/ath/ath5k/debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath5k/debug.c b/drivers/net/wireless/ath/ath5k/debug.c
index 4b41160e5..08058b3f7 100644
--- a/drivers/net/wireless/ath/ath5k/debug.c
+++ b/drivers/net/wireless/ath/ath5k/debug.c
@@ -982,7 +982,7 @@ ath5k_debug_init_device(struct ath5k_hw *ah)
 	ah->debug.level = ath5k_debug;
 
 	phydir = debugfs_create_dir("ath5k", ah->hw->wiphy->debugfsdir);
-	if (!phydir)
+	if (IS_ERR(phydir))
 		return;
 
 	debugfs_create_file("debug", 0600, phydir, ah, &fops_debug);
-- 
2.39.0

Re: [PATCH v1] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[Luis Chamberlain]

On Wed, Jul 12, 2023 at 08:42:59PM +0800, Minjie Du wrote:
> Make IS_ERR() judge the debugfs_create_dir() function return
> in ath5k_debug_init_device().
> 
> Signed-off-by: Minjie Du <duminjie@vivo.com>
> ---
>  drivers/net/wireless/ath/ath5k/debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath5k/debug.c b/drivers/net/wireless/ath/ath5k/debug.c
> index 4b41160e5..08058b3f7 100644
> --- a/drivers/net/wireless/ath/ath5k/debug.c
> +++ b/drivers/net/wireless/ath/ath5k/debug.c
> @@ -982,7 +982,7 @@ ath5k_debug_init_device(struct ath5k_hw *ah)
>  	ah->debug.level = ath5k_debug;
>  
>  	phydir = debugfs_create_dir("ath5k", ah->hw->wiphy->debugfsdir);
> -	if (!phydir)
> +	if (IS_ERR(phydir))

Please use IS_ERR_OR_NULL() instead.

With that change added:

Acked-by: Luis Chamberlain <mcgrof@kernel.org>

  Luis

Re: [PATCH] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[Jiri Slaby]

On 12. 07. 23, 21:07, Markus Elfring wrote:
>>> +++ b/drivers/net/wireless/ath/ath5k/debug.c
>>> @@ -982,7 +982,7 @@ ath5k_debug_init_device(struct ath5k_hw *ah)
>>>   	ah->debug.level = ath5k_debug;
>>>
>>>   	phydir = debugfs_create_dir("ath5k", ah->hw->wiphy->debugfsdir);
>> -	if (!phydir)
>>> +	if (IS_ERR(phydir))
>>
>> Please use IS_ERR_OR_NULL() instead.
> 
> I find your support for consistent error detection interesting here.
> Contributors for other Linux software components provide different
> development views.

IS_ERR_OR_NULL() is almost never correct. It is used exceptionally in 
cases where one needs to distinct three states. It's not the case for 
sysfs/debugfs interfaces.

> Would a subject like “[PATCH v2] ath5k: Fix an error check in ath5k_debug_init_device()”
> be more appropriate?

Yes (pointing out specifically "()" at the end). And add the "why" part 
to the message log too, please.

thanks,
-- 
js
suse labs

Re: [PATCH v1] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[Jeff Johnson]

subject prefix should be "wifi: ath5k: "

On 7/12/2023 5:42 AM, Minjie Du wrote:
> Make IS_ERR() judge the debugfs_create_dir() function return
> in ath5k_debug_init_device().
> 
> Signed-off-by: Minjie Du <duminjie@vivo.com>
> ---
>   drivers/net/wireless/ath/ath5k/debug.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath5k/debug.c b/drivers/net/wireless/ath/ath5k/debug.c
> index 4b41160e5..08058b3f7 100644
> --- a/drivers/net/wireless/ath/ath5k/debug.c
> +++ b/drivers/net/wireless/ath/ath5k/debug.c
> @@ -982,7 +982,7 @@ ath5k_debug_init_device(struct ath5k_hw *ah)
>   	ah->debug.level = ath5k_debug;
>   
>   	phydir = debugfs_create_dir("ath5k", ah->hw->wiphy->debugfsdir);
> -	if (!phydir)
> +	if (IS_ERR(phydir))
>   		return;
>   
>   	debugfs_create_file("debug", 0600, phydir, ah, &fops_debug);

Re: [PATCH] drivers: wireless: ath5k: fix parameter check in ath5k_debug_init_device

[Dan Carpenter]

On Thu, Jul 13, 2023 at 07:47:53AM +0200, Jiri Slaby wrote:
> On 12. 07. 23, 21:07, Markus Elfring wrote:
> > > > +++ b/drivers/net/wireless/ath/ath5k/debug.c
> > > > @@ -982,7 +982,7 @@ ath5k_debug_init_device(struct ath5k_hw *ah)
> > > >   	ah->debug.level = ath5k_debug;
> > > > 
> > > >   	phydir = debugfs_create_dir("ath5k", ah->hw->wiphy->debugfsdir);
> > > -	if (!phydir)
> > > > +	if (IS_ERR(phydir))
> > > 
> > > Please use IS_ERR_OR_NULL() instead.

The correct thing for debugfs is to delete the error handling entirely.
Checking for NULL is harmless but checking for IS_ERR() will break the
driver if debugfs is turned off.

Debugfs is a special case where the error handling was deliberately
written so that it's basically impossible to do it correctly.  Because
as I said at the start, the correct thing is to delete it.

regards,
dan carpenter