[alsa-devel] [PATCH 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 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.
Acked-by: 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;
>