Re: Chipidea USB device goes infinite loop due to interrupt while hw_ep_prime

[Peter Chen <peter.chen@kernel.org>]

On 21-08-02 17:35:01, Jeaho Hwang wrote:
> Hi.
> 
> We found an infinite loop inside the function hw_ep_set_halt
> (drivers/usb/chipidea/udc.c) if a cablle is repeatedly
> connnected/disconnected while ping through RNDIS with chipidea USB device.
> 
> Using ftrace tracing, we found that hw_ep_set_halt is called due to error
> return of hw_ep_prime(drivers/usb/chipidea/udc.c:202) which is called from
> isr_tr_complete_handler -> isr_setup_status_phase -> _ep_queue.
> 
> The comment of function hw_ep_prime says (execute without interruption) but
> timer interrupt is occurred while hw_ep_prime is executing. We believe that
> the interrupt causes an error return of hw_ep_prime. We tried to protect
> hw_ep_prime from irqs and then no case of the infinite loop is occurred.
> 
> I want ask if it is appropriate way that turning off irq inside (threaded)
> irq handlers. And should we explicitly turn off irqs before calling
> hw_ep_prime?
> 

Jeaho, do you use RT-Linux or standard Linux? The function hw_ep_prime is
only called at udc_irq which is registered as top-half irq handlers.
Why the timer interrupt is occurred when hw_ep_prime is executing?

-- 

Thanks,
Peter Chen