Re: [PATCH 1/2] nullblk: main: use lock guards

[Jens Axboe <axboe@kernel.dk>]

On 4/17/26 10:38 PM, Ricardo H H Kojo wrote:
> Use guard() and scoped_guard() for handling mutex and spin locks instead of
> manually locking and unlocking. This prevents forgotten locks due to early
> exits and remove the need of gotos.
> 
> Signed-off-by: Ricardo H H Kojo <ricardo.kojo@ime.usp.br>
> Co-developed-by: Ellian Carlos <elliancarlos@gmail.com>
> Signed-off-by: Ellian Carlos <elliancarlos@gmail.com>
> Co-developed-by: Gabriel B L de Oliveira <gabrielblo@ime.usp.br>
> Signed-off-by: Gabriel B L de Oliveira <gabrielblo@ime.usp.br>
> ---
>  drivers/block/null_blk/main.c     | 74 +++++++++++++------------------
>  drivers/block/null_blk/null_blk.h |  1 +
>  2 files changed, 32 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index f8c0fd57e041..fbe34e8a6c93 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -423,9 +423,8 @@ static int nullb_apply_submit_queues(struct nullb_device *dev,
>  {
>  	int ret;
>  
> -	mutex_lock(&lock);
> +	guard(mutex)(&lock);
>  	ret = nullb_update_nr_hw_queues(dev, submit_queues, dev->poll_queues);
> -	mutex_unlock(&lock);
>  
>  	return ret;
>  }

If you're going to use lock guards instead, why on earth is this not
just:

{
	guard(mutex)(&lock);
	return nullb_update_nr_hw_queues(dev, submit_queues, dev->poll_queues);
}

?!

This odd intermediate state you opted for makes no sense.

-- 
Jens Axboe