linux-kernel - Re: [PATCH 3/7] kernfs: Refactor kernfs_get_open

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Date:   Tue, 23 Aug 2022 13:16:41 +0800
From:   Chengming Zhou <zhouchengming@...edance.com>
To:     Tejun Heo <tj@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Johannes Weiner <hannes@...xchg.org>,
        Imran Khan <imran.f.khan@...cle.com>, kernel-team@...com
Subject: Re: [PATCH 3/7] kernfs: Refactor kernfs_get_open_node()

On 2022/8/20 08:05, Tejun Heo wrote:
> Factor out commont part. This is cleaner and should help with future
> changes. No functional changes.
> 

Reviewed-by: Chengming Zhou <zhouchengming@...edance.com>

Thanks.

> Signed-off-by: Tejun Heo <tj@...nel.org>
> ---
>  fs/kernfs/file.c | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
> index 6437f7c7162d..7060a2a714b8 100644
> --- a/fs/kernfs/file.c
> +++ b/fs/kernfs/file.c
> @@ -554,31 +554,28 @@ static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma)
>  static int kernfs_get_open_node(struct kernfs_node *kn,
>  				struct kernfs_open_file *of)
>  {
> -	struct kernfs_open_node *on, *new_on = NULL;
> +	struct kernfs_open_node *on;
>  	struct mutex *mutex;
>  
>  	mutex = kernfs_open_file_mutex_lock(kn);
>  	on = kernfs_deref_open_node_locked(kn);
>  
> -	if (on) {
> -		list_add_tail(&of->list, &on->files);
> -		mutex_unlock(mutex);
> -		return 0;
> -	} else {
> +	if (!on) {
>  		/* not there, initialize a new one */
> -		new_on = kmalloc(sizeof(*new_on), GFP_KERNEL);
> -		if (!new_on) {
> +		on = kmalloc(sizeof(*on), GFP_KERNEL);
> +		if (!on) {
>  			mutex_unlock(mutex);
>  			return -ENOMEM;
>  		}
> -		atomic_set(&new_on->event, 1);
> -		init_waitqueue_head(&new_on->poll);
> -		INIT_LIST_HEAD(&new_on->files);
> -		list_add_tail(&of->list, &new_on->files);
> -		rcu_assign_pointer(kn->attr.open, new_on);
> +		atomic_set(&on->event, 1);
> +		init_waitqueue_head(&on->poll);
> +		INIT_LIST_HEAD(&on->files);
> +		rcu_assign_pointer(kn->attr.open, on);
>  	}
> -	mutex_unlock(mutex);
>  
> +	list_add_tail(&of->list, &on->files);
> +
> +	mutex_unlock(mutex);
>  	return 0;
>  }
>