| Message ID | 20241018141337.316807-1-danielgeorgem@chromium.org (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | r8152: fix deadlock in usb reset during resume | expand |
Hi, On Fri, Oct 18, 2024 at 7:13 AM George-Daniel Matei <danielgeorgem@chromium.org> wrote: > > rtl8152_system_resume() issues a synchronous usb reset if the device is > inaccessible. __rtl8152_set_mac_address() is called via > rtl8152_post_reset() and it tries to take the same mutex that was already > taken in rtl8152_resume(). Thanks for the fix! I'm 99% certain I tested the original code, but I guess somehow I ran a different code path. I just put my old hacky test patch [1] back on and re-tested this to see what happened. OK, I see. In my case dev_set_mac_address() gets called at resume time but then the address hasn't changed so "ops->ndo_set_mac_address()" (which points to rtl8152_set_mac_address()) never gets called and I don't end up in the deadlock. I wonder why the MAC address changed for you. In any case, the deadlock is real and I agree that this should be fixed. BTW: it would be handy to include the call stack of the deadlock in your commit message. [1] https://crrev.com/c/5543125 > Move the call to reset usb in rtl8152_resume() > outside mutex protection. > > Signed-off-by: George-Daniel Matei <danielgeorgem@chromium.org> Before your Signed-off-by you should have: Fixes: 4933b066fefb ("r8152: If inaccessible at resume time, issue a reset") > --- > drivers/net/usb/r8152.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c > index a5612c799f5e..69d66ce7a5c5 100644 > --- a/drivers/net/usb/r8152.c > +++ b/drivers/net/usb/r8152.c > @@ -8564,19 +8564,6 @@ 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; > } > > @@ -8681,6 +8668,19 @@ static int rtl8152_suspend(struct usb_interface *intf, pm_message_t message) > > 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 (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) > + usb_reset_device(tp->udev); You seem to have moved this to the wrong function. It should be in rtl8152_resume() but you've moved it to rtl8152_suspend(). As you have it here you'll avoid the deadlock but I fear you may end up missing a reset. Maybe you didn't notice this because commit 8c1d92a740c0 ("r8152: Wake up the system if the we need a reset") woke us up quickly enough and the previous reset hadn't expired yet? In any case, please move it to the rtl8152_resume() function, re-test, and post a new version. -Doug
diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index a5612c799f5e..69d66ce7a5c5 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c @@ -8564,19 +8564,6 @@ 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; } @@ -8681,6 +8668,19 @@ static int rtl8152_suspend(struct usb_interface *intf, pm_message_t message) 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 (test_bit(RTL8152_INACCESSIBLE, &tp->flags)) + usb_reset_device(tp->udev); + return ret; }
rtl8152_system_resume() issues a synchronous usb reset if the device is inaccessible. __rtl8152_set_mac_address() is called via rtl8152_post_reset() and it tries to take the same mutex that was already taken in rtl8152_resume(). Move the call to reset usb in rtl8152_resume() outside mutex protection. Signed-off-by: George-Daniel Matei <danielgeorgem@chromium.org> --- drivers/net/usb/r8152.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-)