[linux-dvb] ifconfig locks on down - B2C2 flexcop.

[Johannes Stezenbach]

stonewall at inebraska.com wrote:
> Johannes - here is the dmesg output before I did a Ctrl-C to break out of the 
> errant ifconfig:
> 
> SysRq : Show State
> 
>  ifconfig      S 00000008     0  8226   8216                     (NOTLB)
> f4f0fdbc 00000082 f4f0fdac 00000008 00000001 f7f10000 00000208 c03d1c00
>        00000000 00004240 00000000 00001fff 00004240 00000000 20a35fff c2000520
>        00000000 000034eb e61ca35d 00000268 00000040 f7f1b020 f7f1b144 f8e76d9d
> Call Trace:
>  [<c0370b28>] __down_interruptible+0xa8/0x128
>  [<c0370bc2>] __down_failed_interruptible+0xa/0x10
>  [<f8f1d801>] .text.lock.dvb_demux+0x1fb/0x31a [dvb_core]
>  [<f8f1cfbb>] dmx_section_feed_release_filter+0xab/0xd0 [dvb_core]
>  [<f8f23afa>] dvb_net_feed_stop+0x7a/0x1e0 [dvb_core]
>  [<c0304821>] dev_close+0xb1/0xc0
>  [<c0305f98>] dev_change_flags+0x58/0x130
>  [<c0348cc4>] devinet_ioctl+0x254/0x5c0
>  [<c034b194>] inet_ioctl+0x64/0xb0
>  [<c02faf98>] sock_ioctl+0xd8/0x210
>  [<c0171b31>] do_ioctl+0x81/0xa0
>  [<c0171d02>] vfs_ioctl+0x62/0x1d0
>  [<c0171eb1>] sys_ioctl+0x41/0x70
>  [<c01033b9>] syscall_call+0x7/0xb

Hm, now the question is who's holding the dvb_demux mutex.

What other tasks are in SysRq-T output? If you grep for
.text.lock.dvb_demux, does anything show up? Or at least
any other process with "dvb_" or "dmx_" in the call trace?

If not, I have no clue. I just looked through dvb_demux.c
and I can't see any case where a function could exit without
releasing the mutex. (Memory corruption could cause this
kind of lockup, but that's more difficult to check.)

Johannes