Files
linux-stable-mirror/drivers/usb/host
Michal Pecio 11559d14ed Revert "usb: xhci: Avoid Stop Endpoint retry loop if the endpoint seems Running"
[ Upstream commit 08fa726e66 ]

This reverts commit 28a76fcc4c.

No actual HW bugs are known where Endpoint Context shows Running state
but Stop Endpoint fails repeatedly with Context State Error and leaves
the endpoint state unchanged. Stop Endpoint retries on Running EPs have
been performed since early 2021 with no such issues reported so far.

Trying to handle this hypothetical case brings a more realistic danger:
if Stop Endpoint fails on an endpoint which hasn't yet started after a
doorbell ring and enough latency occurs before this completion event is
handled, the driver may time out and begin removing cancelled TDs from
a running endpoint, even though one more retry would stop it reliably.

Such high latency is rare but not impossible, and removing TDs from a
running endpoint can cause more damage than not giving back a cancelled
URB (which wasn't happening anyway). So err on the side of caution and
revert to the old policy of always retrying if the EP appears running.

[Remove stable tag as we are dealing with theoretical cases -Mathias]

Fixes: 28a76fcc4c ("usb: xhci: Avoid Stop Endpoint retry loop if the endpoint seems Running")
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20250917210726.97100-2-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-10-15 12:00:13 +02:00
..