Re: [PATCH] sound: convert snd_seq_subscribers.ref_count from atomic_t to refcount_t

From: Peter Zijlstra
Date: Tue Feb 21 2017 - 10:43:13 EST


On Tue, Feb 21, 2017 at 05:27:10PM +0200, Elena Reshetova wrote:
> diff --git a/sound/core/seq/seq_ports.c b/sound/core/seq/seq_ports.c
> index fe686ee..1ca896b 100644
> --- a/sound/core/seq/seq_ports.c
> +++ b/sound/core/seq/seq_ports.c

> @@ -520,7 +520,6 @@ static int check_and_subscribe_port(struct snd_seq_client *client,
> else
> list_add_tail(&subs->dest_list, &grp->list_head);
> grp->exclusive = exclusive;
> - atomic_inc(&subs->ref_count);
> write_unlock_irq(&grp->list_lock);
> err = 0;
>
> @@ -570,7 +569,6 @@ int snd_seq_port_connect(struct snd_seq_client *connector,
> return -ENOMEM;
>
> subs->info = *info;
> - atomic_set(&subs->ref_count, 0);
> INIT_LIST_HEAD(&subs->src_list);
> INIT_LIST_HEAD(&subs->dest_list);
>
> @@ -587,6 +585,7 @@ int snd_seq_port_connect(struct snd_seq_client *connector,
> if (err < 0)
> goto error_dest;
>
> + refcount_set(&subs->ref_count, 2);
> return 0;
>
> error_dest:
> @@ -613,7 +612,7 @@ int snd_seq_port_disconnect(struct snd_seq_client *connector,
> /* look for the connection */
> list_for_each_entry(subs, &src->list_head, src_list) {
> if (match_subs_info(info, &subs->info)) {
> - atomic_dec(&subs->ref_count); /* mark as not ready */
> + refcount_dec(&subs->ref_count); /* mark as not ready */
> err = 0;
> break;
> }

This looks dodgy... someone should look hard at this.