On 8/1/12, Attilio Rao <atti...@freebsd.org> wrote: > On 8/1/12, John Baldwin <j...@freebsd.org> wrote: >> On Tuesday, July 31, 2012 4:51:19 pm Attilio Rao wrote: >>> On 7/31/12, John Baldwin <j...@freebsd.org> wrote: >>> > On Thursday, July 19, 2012 7:58:14 pm Sean Bruno wrote: >>> >> Working on the Dell R420 today, got most of it working, even the >>> >> broadcom ethernet cards! However, I get the following when I reboot >>> >> the >>> >> system: >>> >> >>> >> Syncing disks, vnodes remaining...4 Sleeping thread (tid 100107, pid >>> >> 9) >>> >> owns a non-sleepable lock >>> >> KDB: stack backtrace of thread 100107: >>> >> sched_switch() at sched_switch+0x19f >>> >> mi_switch() at mi_switch+0x208 >>> >> sleepq_switch() at sleepq_switch+0xfc >>> >> sleepq_wait() at sleepq_wait+0x4d >>> >> _sleep() at _sleep+0x3f6 >>> >> ipmi_submit_driver_request() at ipmi_submit_driver_request+0x97 >>> >> ipmi_set_watchdog() at ipmi_set_watchdog+0xb1 >>> >> ipmi_wd_event() at ipmi_wd_event+0x8f >>> >> kern_do_pat() at kern_do_pat+0x10f >>> >> sched_sync() at sched_sync+0x1ea >>> >> fork_exit() at fork_exit+0x135 >>> >> fork_trampoline() at fork_trampoline+0xe >>> > >>> > Hmmm, the watchdog pat should probably happen without holding locks if >>> > possible. This is related to the IPMI watchdog being special and >>> > wanting >>> > to schedule a thread to work. >>> >>> The watchdog pat without the locks is not easy to do because we >>> register the watchdog callbacks in eventhandlers, which are indeed >>> locked (and you may also end up racing against watchdog detach, if you >>> don't use any lock at all). >> >> No, eventhandlers go through several hoops to not hold any locks while >> the eventhandler functions are running. It seems in this case that a >> lock is held in a higher layer (sched_sync()) and that is what I was >> talking about. Yes, it is the 'sync_mtx' that is held. Something like >> this > > No, EVENTHANDLER_INVOKE() acquires eventhandler internal locks. > Look at eventhandler_find_list() for details.
Oh, but I guess you misunderstood me -- I didn't mean to say that eventhandler callbacks run with eventhandlers lock held, I meant to say that that it would be nice if EVENTHANDLER_INVOKE() could run lockless. This would have avoided some issues in special context (I recall I had some issues at work years ago, but they could have been predating the STOP_SCHEDULER() patch and in DDB). Attilio -- Peace can only be achieved by understanding - A. Einstein _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
