usb: host: Flush hub workqueue before stopping controller

when xhci platform driver is removed with a usb device
connected there is a possibility of race between xhci
platform driver remove context and device disconnect hub
event work context. This results into

use after free: xhci_mem_clean() called from xhci_plat_remove()
freeing the xhci virtual device when a structure member is
being accessed by xhci_alloc_virt_device() after virtual device
allocation as part of connect hub event.

deadlock: Upon device disconnect if stop endpoint command remains
pending xhci_mem_cleanup() frees xhci virtual device which also
frees up endpoint stop_cmd_timer. udev->dev lock is held until
cancelled urb is not given back to class driver. In a different
context xhci platform remove calls usb_disconnect() on children of
root hub which tries to acquire the same udev->dev lock this results
into a dead lock condition.

Fix issues by making sure hub events are flushed before xhci is
stopped.

Change-Id: I86d414bca17464d1dff3346ec668d8b3efec1652
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>

0 files changed, 0 insertions, 0 deletions