Re: [RFC,PATCH] use rcu for fasync_lock

[OGAWA Hirofumi]

Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> writes:

> --- 2.6/fs/fcntl.c	2003-12-04 19:44:38.000000000 +0100
> +++ build-2.6/fs/fcntl.c	2003-12-24 00:15:16.000000000 +0100
> @@ -609,9 +609,15 @@
> 
>  void kill_fasync(struct fasync_struct **fp, int sig, int band)
>  {
> -	read_lock(&fasync_lock);
> -	__kill_fasync(*fp, sig, band);
> -	read_unlock(&fasync_lock);
> +	/* First a quick test without locking: usually
> +	 * the list is empty.
> +	 */
> +	if (*fp) {
> +		read_lock(&fasync_lock);
> +		/* reread *fp after obtaining the lock */
> +		__kill_fasync(*fp, sig, band);
> +		read_unlock(&fasync_lock);
> +	}
>  }

Looks good to me. This should be the enough effect for usual path.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
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