[PATCH 06/11] ALSA: caiaq: Fix races at MIDI URB and trigger accesses

[Takashi Iwai <tiwai@suse.de>]

URB completion and rawmidi trigger callbacks can race with each other,
which may put the state inconsistent, causing double submissions, etc.

Guard both with a new spinlock for avoiding the races.

Fixes: f3f80a9205da ("ALSA: caiaq - Fix Oops with MIDI")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 sound/usb/caiaq/device.c | 1 +
 sound/usb/caiaq/device.h | 3 ++-
 sound/usb/caiaq/midi.c   | 2 ++
 3 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c
index c68ed16d7ac4..634dc36f2ead 100644
--- a/sound/usb/caiaq/device.c
+++ b/sound/usb/caiaq/device.c
@@ -455,6 +455,7 @@ static int create_card(struct usb_device *usb_dev,
 	cdev->chip.usb_id = USB_ID(le16_to_cpu(usb_dev->descriptor.idVendor),
 				  le16_to_cpu(usb_dev->descriptor.idProduct));
 	spin_lock_init(&cdev->spinlock);
+	spin_lock_init(&cdev->midi_lock);
 	mutex_init(&cdev->ep1_out_mutex);
 
 	*cardp = card;
diff --git a/sound/usb/caiaq/device.h b/sound/usb/caiaq/device.h
index dd726ca68e80..16f65e7867d1 100644
--- a/sound/usb/caiaq/device.h
+++ b/sound/usb/caiaq/device.h
@@ -77,7 +77,8 @@ struct snd_usb_caiaqdev {
 	unsigned char midi_out_buf[EP1_BUFSIZE];
 
 	struct caiaq_device_spec spec;
-	spinlock_t spinlock;
+	spinlock_t spinlock;	/* for PCM audio */
+	spinlock_t midi_lock;	/* midi_x_stream, midi_out_active */
 	wait_queue_head_t ep1_wait_queue;
 	wait_queue_head_t prepare_wait_queue;
 	int spec_received, audio_parm_answer;
diff --git a/sound/usb/caiaq/midi.c b/sound/usb/caiaq/midi.c
index 18529484c8dc..b7d7d24937a7 100644
--- a/sound/usb/caiaq/midi.c
+++ b/sound/usb/caiaq/midi.c
@@ -79,6 +79,7 @@ static void snd_usb_caiaq_midi_output_trigger(struct snd_rawmidi_substream *subs
 {
 	struct snd_usb_caiaqdev *cdev = substream->rmidi->private_data;
 
+	guard(spinlock_irqsave)(&cdev->midi_lock);
 	if (up) {
 		cdev->midi_out_substream = substream;
 		if (!cdev->midi_out_active)
@@ -151,6 +152,7 @@ void snd_usb_caiaq_midi_output_done(struct urb* urb)
 {
 	struct snd_usb_caiaqdev *cdev = urb->context;
 
+	guard(spinlock_irqsave)(&cdev->midi_lock);
 	cdev->midi_out_active = 0;
 	if (urb->status != 0)
 		return;
-- 
2.55.0