diff --git a/include/sound/seq_virmidi.h b/include/sound/seq_virmidi.h index 56a3f38df8c3..359cb363369d 100644 --- a/include/sound/seq_virmidi.h +++ b/include/sound/seq_virmidi.h @@ -46,7 +46,6 @@ struct snd_virmidi_dev { int client; /* created/attached client */ int port; /* created/attached port */ unsigned int flags; /* SNDRV_VIRMIDI_* */ - rwlock_t filelist_lock; struct rw_semaphore filelist_sem; struct list_head filelist; }; diff --git a/sound/core/seq/seq_virmidi.c b/sound/core/seq/seq_virmidi.c index 982828650d41..6208bf7f57bf 100644 --- a/sound/core/seq/seq_virmidi.c +++ b/sound/core/seq/seq_virmidi.c @@ -78,10 +78,11 @@ static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev, int len; if (atomic) - read_lock(&rdev->filelist_lock); + rcu_read_lock(); else down_read(&rdev->filelist_sem); - list_for_each_entry(vmidi, &rdev->filelist, list) { + list_for_each_entry_rcu(vmidi, &rdev->filelist, list, + lockdep_is_held(&rdev->filelist_sem)) { if (!READ_ONCE(vmidi->trigger)) continue; if (ev->type == SNDRV_SEQ_EVENT_SYSEX) { @@ -96,7 +97,7 @@ static int snd_virmidi_dev_receive_event(struct snd_virmidi_dev *rdev, } } if (atomic) - read_unlock(&rdev->filelist_lock); + rcu_read_unlock(); else up_read(&rdev->filelist_sem); @@ -200,8 +201,7 @@ static int snd_virmidi_input_open(struct snd_rawmidi_substream *substream) vmidi->port = rdev->port; runtime->private_data = vmidi; scoped_guard(rwsem_write, &rdev->filelist_sem) { - guard(write_lock_irq)(&rdev->filelist_lock); - list_add_tail(&vmidi->list, &rdev->filelist); + list_add_tail_rcu(&vmidi->list, &rdev->filelist); } vmidi->rdev = rdev; return 0; @@ -243,9 +243,13 @@ static int snd_virmidi_input_close(struct snd_rawmidi_substream *substream) struct snd_virmidi *vmidi = substream->runtime->private_data; scoped_guard(rwsem_write, &rdev->filelist_sem) { - guard(write_lock_irq)(&rdev->filelist_lock); - list_del(&vmidi->list); + list_del_rcu(&vmidi->list); } + /* wait for a grace period so that lockless readers in the atomic + * delivery path (snd_virmidi_dev_receive_event()) are no longer + * traversing this entry before its parser and memory are freed + */ + synchronize_rcu(); snd_midi_event_free(vmidi->parser); substream->runtime->private_data = NULL; kfree(vmidi); @@ -508,7 +512,6 @@ int snd_virmidi_new(struct snd_card *card, int device, struct snd_rawmidi **rrmi rdev->device = device; rdev->client = -1; init_rwsem(&rdev->filelist_sem); - rwlock_init(&rdev->filelist_lock); INIT_LIST_HEAD(&rdev->filelist); rdev->seq_mode = SNDRV_VIRMIDI_SEQ_DISPATCH; rmidi->private_data = rdev;