Re: [PATCH] net: usb: r8152: fix resume reset deadlock
From: Doug Anderson <dianders@chromium.org>
Date: 2026-01-28 18:05:58
Also in:
linux-usb, lkml
Hi, On Tue, Jan 27, 2026 at 11:02 PM Sergey Senozhatsky [off-list ref] wrote:
rtl8152 can trigger device reset during reset which
potentially can result in a deadlock:
**** DPM device timeout after 10 seconds; 15 seconds until panic ****
Call Trace:
<TASK>
schedule+0x483/0x1370
schedule_preempt_disabled+0x15/0x30
__mutex_lock_common+0x1fd/0x470
__rtl8152_set_mac_address+0x80/0x1f0
dev_set_mac_address+0x7f/0x150
rtl8152_post_reset+0x72/0x150
usb_reset_device+0x1d0/0x220
rtl8152_resume+0x99/0xc0
usb_resume_interface+0x3e/0xc0
usb_resume_both+0x104/0x150
usb_resume+0x22/0x110
The problem is that rtl8152 resume calls reset under
tp->control mutex while reset basically re-enters rtl8152
and attempts to acquire the same tp->control lock once
again.
Reset INACCESSIBLE device outside of tp->control mutex
scope to avoid recursive mutex_lock() deadlock.
Fixes: 4933b066fefb ("r8152: If inaccessible at resume time, issue a reset")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
---
drivers/net/usb/r8152.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)This is effectively v2 of: https://lore.kernel.org/r/20241018141337.316807-1-danielgeorgem@chromium.org/ (local) ...and you've incorporated my feedback there. Thanks! :-)
quoted hunk ↗ jump to hunk
@@ -8674,6 +8662,19 @@ static int rtl8152_resume(struct usb_interface *intf) mutex_unlock(&tp->control); + /* 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 (system_resume && test_bit(RTL8152_INACCESSIBLE, &tp->flags)) + ret = usb_reset_device(tp->udev); + return ret;
Question when looking at the above again: have you thought about the consequences of clobbering `ret` above? I guess it's fine since rtl8152_system_resume() always returns 0, but it looks a little awkward. It's been long enough since I thought through all this code that I'm not 100% sure what it _should_ do if rtl8152_system_resume() was ever changed to return an error. Shouldn't it honor the existing error instead of trying to reset the device and clearing the error? Also: I guess you've added the `system_resume` variable here, which is different than the earlier patch. It seems fine to me, though maybe you want to consistently use the `system_resume` variable earlier in the function too? In any case, both of the above are pretty nitty, so I'm OK with: Reviewed-by: Douglas Anderson <dianders@chromium.org>