[5/9] ALSA: usb: caiaq: audio: use irqsave() in USB's complete callback

[5/9] ALSA: usb: caiaq: audio: use irqsave() in USB's complete callback

[Sebastian Andrzej Siewior]

From: John Ogness <john.ogness@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@gmail.com>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Takashi Iwai <tiwai@suse.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@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;

[5/9] ALSA: usb: caiaq: audio: use irqsave() in USB's complete callback

[Daniel Mack]

On Tuesday, June 19, 2018 11:55 PM, Sebastian Andrzej Siewior wrote:
> From: John Ogness <john.ogness@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.
Acked-by: Daniel Mack <zonque@gmail.com>


> Cc: Jaroslav Kysela <perex@perex.cz>
> Cc: Takashi Iwai <tiwai@suse.com>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@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;
>
---
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