Re: ASoC: nau8825: cross talk suppression measurement function

Re: ASoC: nau8825: cross talk suppression measurement function

[Dan Carpenter]

Hello John Hsu,

The patch b50455fab459: "ASoC: nau8825: cross talk suppression
measurement function" from Jun 7, 2016, leads to the following static
checker warning:

	sound/soc/codecs/nau8825.c:265 nau8825_sema_acquire()
	warn: 'sem:&nau8825->xtalk_sem' is sometimes locked here and sometimes unlocked.


sound/soc/codecs/nau8825.c
   240  /**
   241   * nau8825_sema_acquire - acquire the semaphore of nau88l25
   242   * @nau8825:  component to register the codec private data with
   243   * @timeout: how long in jiffies to wait before failure or zero to wait
   244   * until release
   245   *
   246   * Attempts to acquire the semaphore with number of jiffies. If no more
   247   * tasks are allowed to acquire the semaphore, calling this function will
   248   * put the task to sleep. If the semaphore is not released within the
   249   * specified number of jiffies, this function returns.
   250   * Acquires the semaphore without jiffies. If no more tasks are allowed
   251   * to acquire the semaphore, calling this function will put the task to
   252   * sleep until the semaphore is released.
   253   * It returns if the semaphore was acquired.

Sometimes it returns without the lock held.

   254   */
   255  static void nau8825_sema_acquire(struct nau8825 *nau8825, long timeout)
   256  {
   257          int ret;
   258  
   259          if (timeout)
   260                  ret = down_timeout(&nau8825->xtalk_sem, timeout);
   261          else
   262                  ret = down_interruptible(&nau8825->xtalk_sem);
   263  
   264          if (ret < 0)
   265                  dev_warn(nau8825->dev, "Acquire semaphone fail\n");

This function makes me sad.  Warn and corrupt is my least favourite
anti-pattern.

   266  }

regards,
dan carpenter

Re: ASoC: nau8825: cross talk suppression measurement function

[John Hsu]

Hi Dan,

On 6/15/2016 8:33 PM, Dan Carpenter wrote:
> Hello John Hsu,
>
> The patch b50455fab459: "ASoC: nau8825: cross talk suppression
> measurement function" from Jun 7, 2016, leads to the following static
> checker warning:
>
> 	sound/soc/codecs/nau8825.c:265 nau8825_sema_acquire()
> 	warn: 'sem:&nau8825->xtalk_sem' is sometimes locked here and sometimes unlocked.
>
>
> sound/soc/codecs/nau8825.c
>    240  /**
>    241   * nau8825_sema_acquire - acquire the semaphore of nau88l25
>    242   * @nau8825:  component to register the codec private data with
>    243   * @timeout: how long in jiffies to wait before failure or zero to wait
>    244   * until release
>    245   *
>    246   * Attempts to acquire the semaphore with number of jiffies. If no more
>    247   * tasks are allowed to acquire the semaphore, calling this function will
>    248   * put the task to sleep. If the semaphore is not released within the
>    249   * specified number of jiffies, this function returns.
>    250   * Acquires the semaphore without jiffies. If no more tasks are allowed
>    251   * to acquire the semaphore, calling this function will put the task to
>    252   * sleep until the semaphore is released.
>    253   * It returns if the semaphore was acquired.
>
> Sometimes it returns without the lock held.
>
>    254   */
>    255  static void nau8825_sema_acquire(struct nau8825 *nau8825, long timeout)
>    256  {
>    257          int ret;
>    258  
>    259          if (timeout)
>    260                  ret = down_timeout(&nau8825->xtalk_sem, timeout);
>    261          else
>    262                  ret = down_interruptible(&nau8825->xtalk_sem);
>    263  
>    264          if (ret < 0)
>    265                  dev_warn(nau8825->dev, "Acquire semaphone fail\n");
>
> This function makes me sad.  Warn and corrupt is my least favourite
> anti-pattern.
>   

Is it better to separate this function to two case, one locked with
timeout and the other not? Do you have any suggestion about it?
Thank you.

Re: ASoC: nau8825: cross talk suppression measurement function

[Dan Carpenter]

On Mon, Jun 20, 2016 at 09:51:28AM +0800, John Hsu wrote:
> Is it better to separate this function to two case, one locked with
> timeout and the other not? Do you have any suggestion about it?
> Thank you.

It should return the error code and the callers should handle it.  We
always have to know if we have the lock or not.

regards,
dan carpenter

Re: ASoC: nau8825: cross talk suppression measurement function

[John Hsu]

Hi,

On 6/20/2016 6:00 PM, Dan Carpenter wrote:
> On Mon, Jun 20, 2016 at 09:51:28AM +0800, John Hsu wrote:
>   
>> Is it better to separate this function to two case, one locked with
>> timeout and the other not? Do you have any suggestion about it?
>> Thank you.
>>     
>
> It should return the error code and the callers should handle it.  We
> always have to know if we have the lock or not.
>
> regards,
> dan carpenter
>
> .
>
>   

I see and we'll modify it. Thanks for your suggestion.

BR.
John