https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=252165
--- Comment #24 from Ali Abdallah <ali.abdal...@suse.com> --- Created attachment 236901 --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=236901&action=edit dtrace ure usb traces I got another machine on which I didn't apply the workaround, running 13.1, with a USB Lan adapter that uses if_ure, I used the following dtrace probes. dtrace -n 'fbt:miibus:mii_pollstat:*,fbt:uether:ue_tick_task:*,fbt:if_ure:ure_tick:*,fbt:if_ure:ure_ifmedia_sts:*,fbt:miibus:mii_tick:*,fbt:miibus:miibus_linkchg:*, fbt:usb:* { printf("%p", curthread); }' You can see from the attached debug log (numbered lines) 1 48573 ure_ifmedia_sts:entry fffffe00dc75c720 1 48475 mii_pollstat:entry fffffe00dc75c720 But before exit entry of re_ifmedia_sts:return of thread fffffe00dc75c720, you can see: 1052 0 48573 ure_ifmedia_sts:entry fffffe00e00271e0 1053 2 27791 usb_command_wrapper:entry fffffe0082a17ac0 1054 2 27738 usbd_callback_wrapper:entry fffffe0082a17ac0 1055 0 48475 mii_pollstat:entry fffffe00e00271e0 And that exactly when the link up/down happened. So thread fffffe00e00271e0 managed to go ahead and call mii_pollstat, acquiring the sc mutex, despite that thread fffffe00dc75c720 didn't release it yet, you can see that the return from "polling the media state" on thread fffffe00dc75c720 comes way after the ure_ifmedia_sts:entry of thread fffffe00e00271e0 1517 3 48476 mii_pollstat:return fffffe00dc75c720 1518 3 48574 ure_ifmedia_sts:return fffffe00dc75c720 __snip if_ure__ ure_ifmedia_sts { ... URE_LOCK(sc); mii_pollstat(mii); ifmr->ifm_active = mii->mii_media_active; ifmr->ifm_status = mii->mii_media_status; URE_UNLOCK(sc); } __snip__ The mutex locked/released by URE_LOCK, is the same mutex used in if_ure, USB xfer and USB transfer, so I guess something is not playing well in the release/acquire sequence... Will try if time permits to dig more into the USB transfer/process code, but I have to say that I'm extremely surprised that this bug didn't attract much attention, it actually renders any USB Ethernet device unusable on FreeBSD... -- You are receiving this mail because: You are the assignee for the bug.
