[alsa-devel] [PATCH REPOST 1/2] ALSA: usb: caiaq: audio: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

From: John Ogness <john.ogness at linutronix.de>

The USB completion callback does not disable interrupts while acquiring
the lock. We want to remove the local_irq_disable() invocation from
__usb_hcd_giveback_urb() and therefore it is required for the callback
handler to disable the interrupts while acquiring the lock.
The callback may be invoked either in IRQ or BH context depending on the
USB host controller.
Use the _irqsave() variant of the locking primitives.

Cc: Daniel Mack <zonque at gmail.com>
Cc: Jaroslav Kysela <perex at perex.cz>
Cc: Takashi Iwai <tiwai at suse.com>
Signed-off-by: John Ogness <john.ogness at linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
---
 sound/usb/caiaq/audio.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sound/usb/caiaq/audio.c b/sound/usb/caiaq/audio.c
index f35d29f49ffe..15344d39a6cd 100644
--- a/sound/usb/caiaq/audio.c
+++ b/sound/usb/caiaq/audio.c
@@ -636,6 +636,7 @@ static void read_completed(struct urb *urb)
 	struct device *dev;
 	struct urb *out = NULL;
 	int i, frame, len, send_it = 0, outframe = 0;
+	unsigned long flags;
 	size_t offset = 0;
 
 	if (urb->status || !info)
@@ -672,10 +673,10 @@ static void read_completed(struct urb *urb)
 		offset += len;
 
 		if (len > 0) {
-			spin_lock(&cdev->spinlock);
+			spin_lock_irqsave(&cdev->spinlock, flags);
 			fill_out_urb(cdev, out, &out->iso_frame_desc[outframe]);
 			read_in_urb(cdev, urb, &urb->iso_frame_desc[frame]);
-			spin_unlock(&cdev->spinlock);
+			spin_unlock_irqrestore(&cdev->spinlock, flags);
 			check_for_elapsed_periods(cdev, cdev->sub_playback);
 			check_for_elapsed_periods(cdev, cdev->sub_capture);
 			send_it = 1;
-- 
2.18.0