[Qemu-devel] qemu-system-x86_64: hw/usb/core.c:720: usb_ep_get: Assertion `dev != NULL' failed

[Qemu-devel] qemu-system-x86_64: hw/usb/core.c:720: usb_ep_get: Assertion `dev != NULL' failed

[Guenter Roeck]

Hi,

I have seen the following problem several times recently. This is with qemu-4.0.

qemu-system-x86_64: hw/usb/core.c:720: usb_ep_get: Assertion `dev != NULL' failed

Backtrace gives me the following call path.

main_loop()
  main_loop_wait()
    glib_pollfds_poll()
      aio_ctx_dispatch()
	aio_dispatch()
	  aio_bh_poll()
            ehci_work_bh()
              ehci_advance_async_state()
                ehci_advance_state()
                  ehci_execute()
                    usb_ep_get()

The problem always happens during shutdown, maybe once every 100 boots.
It seems to be more likely to happen when the system is under heavy load.

...
umount: devtmpfs busy - remounted read-only
[   49.018682] EXT4-fs (sda): re-mounted. Opts: (null)
[   49.028052] sd 6:0:0:0: [sda] Synchronizing SCSI cache
qemu-system-x86_64: hw/usb/core.c:733: usb_ep_get: Assertion `dev != NULL' failed.

Essentially that means that p->queue->dev is NULL in ehci_execute().

Has anyone else seen this problem ? Any idea what I can do to debug
this further ?

Thanks,
Guenter

Re: [Qemu-devel] qemu-system-x86_64: hw/usb/core.c:720: usb_ep_get: Assertion `dev != NULL' failed

[Philippe Mathieu-Daudé]

Cc'ing more people.

On 6/24/19 8:01 PM, Guenter Roeck wrote:
> Hi,
> 
> I have seen the following problem several times recently. This is with qemu-4.0.
> 
> qemu-system-x86_64: hw/usb/core.c:720: usb_ep_get: Assertion `dev != NULL' failed
> 
> Backtrace gives me the following call path.
> 
> main_loop()
>   main_loop_wait()
>     glib_pollfds_poll()
>       aio_ctx_dispatch()
> 	aio_dispatch()
> 	  aio_bh_poll()
>             ehci_work_bh()
>               ehci_advance_async_state()
>                 ehci_advance_state()
>                   ehci_execute()
>                     usb_ep_get()
> 
> The problem always happens during shutdown, maybe once every 100 boots.
> It seems to be more likely to happen when the system is under heavy load.
> 
> ...
> umount: devtmpfs busy - remounted read-only
> [   49.018682] EXT4-fs (sda): re-mounted. Opts: (null)
> [   49.028052] sd 6:0:0:0: [sda] Synchronizing SCSI cache
> qemu-system-x86_64: hw/usb/core.c:733: usb_ep_get: Assertion `dev != NULL' failed.
> 
> Essentially that means that p->queue->dev is NULL in ehci_execute().
> 
> Has anyone else seen this problem ? Any idea what I can do to debug
> this further ?
> 
> Thanks,
> Guenter
>