Bug 248500
| Summary: | cam_sim_free() sleeping forever | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Bjoern A. Zeeb <bz> |
| Component: | usb | Assignee: | freebsd-usb (Nobody) <usb> |
| Status: | New --- | ||
| Severity: | Affects Some People | CC: | bsdimp, cem, grahamperrin, imp |
| Priority: | --- | Keywords: | cam |
| Version: | CURRENT | ||
| Hardware: | amd64 | ||
| OS: | Any | ||
I don't remember if it was in cam_sim_free, but I've experienced a similar refcount leak when removing a USB device in the past. Eventually something else blocks on one of the deadlocks and the system dies. I did some cursory debugging, but didn't identify the problem: https://reviews.freebsd.org/P300 Since this bug was filed, I've fixed at least one refcont bug. Does it happen in -current? |
Hi, I have a system with a locked USB because cam_sim_free() seems to sleep forever (at least 24 hours by now): # procstat -akk | grep -i usb 15 100045 usb usbus0 mi_switch+0xc1 _cv_wait+0xf2 usb_process+0x101 fork_exit+0x7e fork_trampoline+0xe 15 100046 usb usbus0 mi_switch+0xc1 _cv_wait+0xf2 usb_process+0x101 fork_exit+0x7e fork_trampoline+0xe 15 100047 usb usbus0 mi_switch+0xc1 _cv_wait+0xf2 usb_process+0x101 fork_exit+0x7e fork_trampoline+0xe 15 100048 usb usbus0 mi_switch+0xc1 _sleep+0x1cb cam_sim_free+0x7e umass_detach+0xd8 device_detach+0x185 device_delete_child+0x15 usb_detach_device+0x18f usb_unconfigure+0x2b usb_free_device+0x 11d uhub_explore+0x2ad usb_bus_explore+0x13e usb_process+0x13b fork_exit+0x7e fork_trampoline+0xe 15 100049 usb usbus0 mi_switch+0xc1 _cv_wait+0xf2 usb_process+0x101 fork_exit+0x7e fork_trampoline+0xe 0x2be is in cam_sim_free (/usr/src/head.svn/sys/cam/cam_sim.c:142). 137 if (sim->refcount > 0) { 138 error = msleep(sim, mtx, PRIBIO, "simfree", 0); 139 KASSERT(error == 0, ("invalid error value for msleep(9)")); 140 } 141 KASSERT(sim->refcount == 0, ("sim->refcount == 0")); 142 if (sim->mtx == NULL) 143 mtx_unlock(mtx); 144 145 if (free_devq) 146 cam_simq_free(sim->devq); What should wake us up in this case? Was there a race somewhere? Any ideas?