It looks like a case of "lock held during call up the stack". This is bad for so many reasons. It also makes writing correctly locked drivers a pain in the ass as the moment you unlock the driver before calling ether_input() / ieee80211_input(), you allow things to change state. So no, although you shouldn't use long-held locks to protect things, apparently this is all the rage. iwn(4) does this. ath(4) does not. I'm having a right painful time trying to fine-grain lock things. I'm at the point where I'm about to not care, rip out all the locks and replace with a single ATH_LOCK(). Adrian On 27 July 2012 11:47, Dimitry Andric <dim_at_freebsd.org> wrote: > On 2012-07-26 17:46, David Wolfskill wrote: >> This is at r238795; cut/paste of backtrace: >> >> KDB: enter: panic >> [ thread pid 12 tid 100026 ] >> Stopped at kdb_enter+0x3d: movl $0,kdb_why >> db> bt >> Tracing pid 12 tid 100026 td 0xc6755000 >> kdb_enter(c0f93c5f,c0f93c5f,c0f91e21,f08398f0,c1825c80,...) at kdb_enter+0x3d >> panic(c0f91e21,c66739a0,c0f20db8,371,c6755000,...) at panic+0x1c4 >> _mtx_lock_sleep(c68b8560,c6755000,c0f20db8,c0f20db8,371,...) at _mtx_lock_sleep+0x35e >> _mtx_lock_flags(c68b8560,0,c0f20db8,371,0,...) at _mtx_lock_flags+0xdb >> lem_start(c68ba000,0,c0fa806c,d20,2a,...) at lem_start+0x33 >> if_transmit(c68ba000,c93d9000,6,c6755000,c65da588,...) at if_transmit+0x129 >> ether_output(c68ba000,c93d9000,f0839aa4,0,0,...) at ether_output+0x5df >> arpintr(c93d9000,8,c0f50314,153,0,...) at arpintr+0x108c >> netisr_dispatch_src(7,0,c93d9000,c93d9000,c68ba000,c93d0806) at netisr_dispatch_src+0xa7 >> netisr_dispatch(7,c93d9000,c93d9000,10,3,...) at netisr_dispatch+0x20 >> ether_demux(c68ba000,c93d9000,3,0,3,...) at ether_demux+0x133 >> ether_nh_input(c93d9000,c8f012c8,644d6000,c9492d00,0,...) at ether_nh_input+0x329 >> netisr_dispatch_src(9,0,c93d9000,e2e,2,1) at netisr_dispatch_src+0xa7 >> netisr_dispatch(9,c93d9000) at netisr_dispatch+0x20 >> ether_input(c68ba000,c93d9000,c0f20db8,e2e,c11454c0,...) at ether_input+0x21 >> lem_intr(c68b6000,8,c0f8e00d,561,0,...) at lem_intr+0x567 >> intr_event_execute_handlers(c11454c0,c6626200,c0f8e00d,561,c6755000,...) at intr_event_execute_handlers+0xc5 >> ithread_loop(c6627730,f0839d08,c0f8dd64,3db,0,...) at ithread_loop+0xe2 >> fork_exit(c0a2dcb0,c6627730,f0839d08) at fork_exit+0x7c >> fork_trampoline() at fork_trampoline+0x8 >> --- trap 0, eip = 0, esp = 0xf0839d40, ebp = 0 --- >> db> show locks >> exclusive sleep mutex em0 (EM TX Lock) r = 0 (0xc68b8560) locked _at_ /usr/src/sys/dev/e1000/if_lem.c:1324 >> exclusive sleep mutex em0 (EM Core Lock) r = 0 (0xc68b854c) locked _at_ /usr/src/sys/dev/e1000/if_lem.c:1302 >> db> >> >> I need to head off to a meeting; I can poke at the machine a bit more >> in a couple of hours or so. > > I get the same panic and backtrace here, while running as a VMware > guest. At least, as soon something actually happens with the network. > _______________________________________________ > freebsd-current_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe_at_freebsd.org"Received on Fri Jul 27 2012 - 18:31:55 UTC
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