Re: [PATCH 1/3] md: call del_gendisk in control path

[Bart Van Assche <bvanassche@acm.org>]

On 6/11/25 12:31 AM, Xiao Ni wrote:
>   static inline int mddev_trylock(struct mddev *mddev)
>   {
> -	return mutex_trylock(&mddev->reconfig_mutex);
> +	int ret;
> +
> +	ret = mutex_trylock(&mddev->reconfig_mutex);
> +	if (!ret && test_bit(MD_DELETED, &mddev->flags)) {
> +		ret = -ENODEV;
> +		mutex_unlock(&mddev->reconfig_mutex);
> +	}
> +	return ret;
>   }

This change seems wrong to me. This change will cause mutex_unlock() to
be called if mutex_trylock() *failed*. Additionally, returning -ENODEV
from the failure path will cause the caller to call mutex_unlock() a
second time if mutex_trylock() failed. Please fix this!

As a reminder, from include/linux/mutex.h:

/*
  * NOTE: mutex_trylock() follows the spin_trylock() convention,
  *       not the down_trylock() convention!
  *
  * Returns 1 if the mutex has been acquired successfully, and 0 on 
contention.
  */

Bart.