On Thu, Aug 29, 2019 at 02:12:15PM -0400, Bill Kuzeja wrote:
> The system can hit a deadlock if xhci adapter breaks while initializing.
> The deadlock is between two threads: thread 1 is tearing down the
> adapter and is stuck in usb_unlocked_disable_lpm waiting to lock the
> hcd->handwidth_mutex. Thread 2 is holding this mutex (while still trying
> to add a usb device), but is stuck in xhci_endpoint_reset waiting for a
> stop or config command to complete. A reboot is required to resolve.
>
> It turns out when calling xhci_queue_stop_endpoint and
> xhci_queue_configure_endpoint in xhci_endpoint_reset, the return code is
> not checked for errors. If the timing is right and the adapter dies just
> before either of these commands get issued, we hang indefinitely waiting
> for a completion on a command that didn't get issued.
>
> This wasn't a problem before the following fix because we didn't send
> commands in xhci_endpoint_reset:
>
> commit f5249461b504 ("xhci: Clear the host side toggle manually when endpoint is soft reset")
>
> With the patch I am submitting, a duration test which breaks adapters
> during initialization (and which deadlocks with the standard kernel) runs
> without issue.
>
> Fixes: f5249461b504 ("xhci: Clear the host side toggle manually when endpoint is soft reset")
> Signed-off-by: Bill Kuzeja <william.kuzeja@xxxxxxxxxxx>
> ---
> drivers/usb/host/xhci.c | 22 +++++++++++++++++++---
$ ./scripts/get_maintainer.pl --file drivers/usb/host/xhci.c
Mathias Nyman <mathias.nyman@xxxxxxxxx> (supporter:USB XHCI DRIVER)
Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> (supporter:USB SUBSYSTEM)
linux-usb@xxxxxxxxxxxxxxx (open list:USB XHCI DRIVER)
linux-kernel@xxxxxxxxxxxxxxx (open list)
I think you forgot to send this to the xhci driver maintainer for review
:(
