On 21-05-20 11:42:24, Pawel Laszczak wrote:
> From: Pawel Laszczak <pawell@xxxxxxxxxxx>
>
> Patch fixes the critical issue caused by deadlock which has been detected
> during testing NCM class.
>
> The root cause of issue is spin_lock/spin_unlock instruction instead
> spin_lock_irqsave/spin_lock_irqrestore in cdnsp_thread_irq_handler
> function.
Pawel, would you please explain more about why the deadlock occurs with
current code, and why this patch could fix it?
Peter
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: 3d82904559f4 ("usb: cdnsp: cdns3 Add main part of Cadence USBSSP DRD Driver")
> Signed-off-by: Pawel Laszczak <pawell@xxxxxxxxxxx>
> ---
> drivers/usb/cdns3/cdnsp-ring.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/cdns3/cdnsp-ring.c b/drivers/usb/cdns3/cdnsp-ring.c
> index 5f0513c96c04..68972746e363 100644
> --- a/drivers/usb/cdns3/cdnsp-ring.c
> +++ b/drivers/usb/cdns3/cdnsp-ring.c
> @@ -1517,13 +1517,14 @@ irqreturn_t cdnsp_thread_irq_handler(int irq, void *data)
> {
> struct cdnsp_device *pdev = (struct cdnsp_device *)data;
> union cdnsp_trb *event_ring_deq;
> + unsigned long flags;
> int counter = 0;
>
> - spin_lock(&pdev->lock);
> + spin_lock_irqsave(&pdev->lock, flags);
>
> if (pdev->cdnsp_state & (CDNSP_STATE_HALTED | CDNSP_STATE_DYING)) {
> cdnsp_died(pdev);
> - spin_unlock(&pdev->lock);
> + spin_unlock_irqrestore(&pdev->lock, flags);
> return IRQ_HANDLED;
> }
>
> @@ -1539,7 +1540,7 @@ irqreturn_t cdnsp_thread_irq_handler(int irq, void *data)
>
> cdnsp_update_erst_dequeue(pdev, event_ring_deq, 1);
>
> - spin_unlock(&pdev->lock);
> + spin_unlock_irqrestore(&pdev->lock, flags);
>
> return IRQ_HANDLED;
> }
> --
> 2.25.1
>
--
Thanks,
Peter Chen
