[PATCH REPOST net-next 1/2] r8152: If inaccessible at resume time, issue a reset

From: Douglas Anderson
Date: Thu May 30 2024 - 19:43:41 EST


If we happened to get a USB transfer error during the transition to
suspend then the usb_queue_reset_device() that r8152_control_msg()
calls will get dropped on the floor. This is because
usb_lock_device_for_reset() (which usb_queue_reset_device() uses)
silently fails if it's called when a device is suspended or if too
much time passes.

Let's resolve this by resetting the device ourselves in r8152's
resume() function.

NOTE: due to timing, it's _possible_ that we could end up with two USB
resets: the one queued previously and the one called from the resume()
patch. This didn't happen in test cases I ran, though it's conceivably
possible. We can't easily know if this happened since
usb_queue_reset_device() can just silently drop the reset request. In
any case, it's not expected that this is a problem since the two
resets can't run at the same time (because of the device lock) and it
should be OK to reset the device twice. If somehow the double-reset
causes problems we could prevent resets from being queued up while
suspend is running.

Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
---
Reposting now that the merge window is open as per [1].

[1] https://lore.kernel.org/r/75651199a933427a7fc3980ef8a2139f5f1f1695.camel@xxxxxxxxxx

drivers/net/usb/r8152.c | 13 +++++++++++++
1 file changed, 13 insertions(+)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 19df1cd9f072..6a3f4b2114ee 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -8554,6 +8554,19 @@ static int rtl8152_system_resume(struct r8152 *tp)
usb_submit_urb(tp->intr_urb, GFP_NOIO);
}

+ /* If the device is RTL8152_INACCESSIBLE here then we should do a
+ * reset. This is important because the usb_lock_device_for_reset()
+ * that happens as a result of usb_queue_reset_device() will silently
+ * fail if the device was suspended or if too much time passed.
+ *
+ * NOTE: The device is locked here so we can directly do the reset.
+ * We don't need usb_lock_device_for_reset() because that's just a
+ * wrapper over device_lock() and device_resume() (which calls us)
+ * does that for us.
+ */
+ if (test_bit(RTL8152_INACCESSIBLE, &tp->flags))
+ usb_reset_device(tp->udev);
+
return 0;
}

--
2.45.1.288.g0e0cd299f1-goog