[RFC PATCH v2 1/1] ALSA: virtio: wait through signals for PCM teardown

[Joonho Lee <mynameisjune111@gmail.com>]

A signal can end the interruptible wait while a STOP or RELEASE request is
still pending. A later teardown may then submit another RELEASE before the
first request completes.

Keep both waits non-interruptible and use the existing message timeout.
Other control requests remain interruptible. Device reset still cancels the
pending request and wakes the waiter.

Assisted-by: LLM
Signed-off-by: Joonho Lee <mynameisjune111@gmail.com>
---
 sound/virtio/virtio_ctl_msg.c | 15 ++++++++++++++-
 sound/virtio/virtio_ctl_msg.h |  3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/sound/virtio/virtio_ctl_msg.c b/sound/virtio/virtio_ctl_msg.c
index 2e0ff15e729d..e50e6c7f3b8d 100644
--- a/sound/virtio/virtio_ctl_msg.c
+++ b/sound/virtio/virtio_ctl_msg.c
@@ -314,7 +314,20 @@ int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg,
 		 */
 		virtsnd_ctl_msg_unref(msg);
 	} else if (!nowait) {
-		rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
+		/*
+		 * Teardown must observe completion even with a pending signal.
+		 * Otherwise a subsequent open can retry RELEASE while the device
+		 * is still processing the previous teardown request.
+		 */
+		switch (le32_to_cpu(request->code)) {
+		case VIRTIO_SND_R_PCM_STOP:
+		case VIRTIO_SND_R_PCM_RELEASE:
+			rc = wait_for_completion_timeout(&msg->notify, js);
+			break;
+		default:
+			rc = wait_for_completion_interruptible_timeout(&msg->notify, js);
+			break;
+		}
 		if (!rc) {
 			dev_err(&vdev->dev,
 				"control message (0x%08x) timeout\n",
diff --git a/sound/virtio/virtio_ctl_msg.h b/sound/virtio/virtio_ctl_msg.h
index f867b9b9233d..d84f0740fcb0 100644
--- a/sound/virtio/virtio_ctl_msg.h
+++ b/sound/virtio/virtio_ctl_msg.h
@@ -47,6 +47,9 @@ int virtsnd_ctl_msg_send(struct virtio_snd *snd, struct virtio_snd_msg *msg,
  * The msg_timeout_ms module parameter defines the message completion timeout.
  * If the message is not completed within this time, the function will return an
  * error.
+ * PCM STOP and RELEASE wait through pending signals within this timeout.
+ * Other requests remain interruptible. Device reset cancels and wakes either
+ * kind of waiter.
  *
  * Context: Any context that permits to sleep.
  * Return: 0 on success, -errno on failure.