[dm-devel] multipathd: move 'filter_devnode' under vector lock

[Benjamin Marzinski]

On Wed, May 11, 2016 at 12:35:41PM +0200, Hannes Reinecke wrote:
> Ben Marzinski pointed out that filter_devnode() is used
> without any lock or configuration settings in uev_trigger(),
> and hence might be invalid when processing events during
> reconfiguration.
> So move it into the individual functions and handle it
> with the vector lock held.

ACK

-Ben

> 
> Signed-off-by: Hannes Reinecke <hare at suse.com>
> ---
>  multipathd/main.c | 45 +++++++++++++++++++++++++++------------------
>  1 file changed, 27 insertions(+), 18 deletions(-)
> 
> diff --git a/multipathd/main.c b/multipathd/main.c
> index 58e8854..2c7486d 100644
> --- a/multipathd/main.c
> +++ b/multipathd/main.c
> @@ -580,6 +580,11 @@ uev_add_path (struct uevent *uev, struct vectors * vecs)
>  	pthread_cleanup_push(cleanup_lock, &vecs->lock);
>  	lock(vecs->lock);
>  	pthread_testcancel();
> +	if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
> +			   uev->kernel) > 0) {
> +		ret = 0;
> +		goto out_unlock;
> +	}
>  	pp = find_path_by_dev(vecs->pathvec, uev->kernel);
>  	if (pp) {
>  		int r;
> @@ -637,6 +642,7 @@ uev_add_path (struct uevent *uev, struct vectors * vecs)
>  		free_path(pp);
>  		ret = 1;
>  	}
> +out_unlock:
>  	lock_cleanup_pop(vecs->lock);
>  	return ret;
>  }
> @@ -780,22 +786,23 @@ fail:
>  static int
>  uev_remove_path (struct uevent *uev, struct vectors * vecs)
>  {
> -	struct path *pp;
> -	int ret;
> +	struct path *pp = NULL;
> +	int ret = 0;
>  
>  	condlog(2, "%s: remove path (uevent)", uev->kernel);
>  	pthread_cleanup_push(cleanup_lock, &vecs->lock);
>  	lock(vecs->lock);
>  	pthread_testcancel();
> -	pp = find_path_by_dev(vecs->pathvec, uev->kernel);
> -	if (pp)
> -		ret = ev_remove_path(pp, vecs);
> -	lock_cleanup_pop(vecs->lock);
> -	if (!pp) {
> -		/* Not an error; path might have been purged earlier */
> -		condlog(0, "%s: path already removed", uev->kernel);
> -		return 0;
> +	if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
> +			   uev->kernel) == 0) {
> +		pp = find_path_by_dev(vecs->pathvec, uev->kernel);
> +		if (pp)
> +			ret = ev_remove_path(pp, vecs);
> +		else
> +			/* Not an error; path might have been purged earlier */
> +			condlog(0, "%s: path already removed", uev->kernel);
>  	}
> +	lock_cleanup_pop(vecs->lock);
>  	return ret;
>  }
>  
> @@ -905,7 +912,7 @@ uev_update_path (struct uevent *uev, struct vectors * vecs)
>  	ro = uevent_get_disk_ro(uev);
>  
>  	if (ro >= 0) {
> -		struct path * pp;
> +		struct path * pp = NULL;
>  		struct multipath *mpp = NULL;
>  
>  		condlog(2, "%s: update path write_protect to '%d' (uevent)",
> @@ -918,6 +925,10 @@ uev_update_path (struct uevent *uev, struct vectors * vecs)
>  		 * need to be at the same indentation level, hence
>  		 * this slightly convoluted codepath.
>  		 */
> +		if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
> +				   uev->kernel) > 0) {
> +			goto out_unlock;
> +		}
>  		pp = find_path_by_dev(vecs->pathvec, uev->kernel);
>  		if (pp) {
>  			if (pp->initialized == INIT_REQUESTED_UDEV) {
> @@ -937,11 +948,13 @@ uev_update_path (struct uevent *uev, struct vectors * vecs)
>  					uev->kernel, mpp->alias, retval);
>  			}
>  		}
> +	out_unlock:
>  		lock_cleanup_pop(vecs->lock);
>  		if (!pp) {
> -			condlog(0, "%s: spurious uevent, path not found",
> -				uev->kernel);
> -			return 1;
> +			if (retval)
> +				condlog(0, "%s: spurious uevent, path not found",
> +					uev->kernel);
> +			return retval;
>  		}
>  		if (retval == 2)
>  			return uev_add_path(uev, vecs);
> @@ -1059,10 +1072,6 @@ uev_trigger (struct uevent * uev, void * trigger_data)
>  	/*
>  	 * path add/remove event
>  	 */
> -	if (filter_devnode(conf->blist_devnode, conf->elist_devnode,
> -			   uev->kernel) > 0)
> -		goto out;
> -
>  	if (!strncmp(uev->action, "add", 3)) {
>  		r = uev_add_path(uev, vecs);
>  		goto out;
> -- 
> 2.6.6