On Fri, 2008-11-07 at 10:12 +0100, Clemens Ladisch wrote: > Fernando Lopez-Lezcano wrote: > > I'm seeing a realtime patch related hard hang in the kernel alsa > > subsystem (MIDI input/output). In a nutshell: > > > > - alsa rawmidi works (ie: "rawmidi -v -i hw:0" outputs a stream of > > messages when pointed to a midi capable card that has an external > > keyboard connected). > > > > - the alsa sequencer interface works (ie: aplaymidi connected to > > aseqdump transfers data just fine). > > > > - BOTH combined do NOT work (ie: use aconnect to connect the port that > > corresponds to the external midi interface to aseqdump: aseqdump hangs > > forever after transferring the first message and the only way out is a > > reboot). > > Please try the snd-virmidi driver, then we'd have a test case that does > not require MIDI hardware. > > > ... including the output of a "echo t >/proc/sysrq-trigger" that > > should show where aseqdump currently hangs (or so I think). > > It hangs in tasklet_kill(), which gets called while it tries to close > the rawmidi port. > > The rawmidi framework uses this tasklet to notify the sequencer that new > MIDI data is available. The handler function is > snd_rawmidi_input_event_tasklet() in sound/core/rawmidi.c; the sequencer > callback that gets called from there is snd_midi_input_event() in > core/seq/seq_midi.c. > > You say that the first event gets delivered, so it might be possible > that the tasklet never finishes executing. Please check whether the > call to snd_seq_kernel_client_dispatch() in snd_midi_input_event() > ever returns. I added a printk before and after the call, it looks like it gets called and it returns (but only _once_... aseqdump hangs in an unkillable state as before). But the hang is different, I'll reboot and retry to see if it is repeatable: -------- Nov 7 10:05:36 host kernel: ======================= Nov 7 10:05:36 host kernel: aseqdump S [f2e5c330] f78df0f0 0 5256 5185 Nov 7 10:05:36 host kernel: f2cffbd4 00000086 f2cffb88 f78df0f0 00000003 f2e5c330 f2e5c5c4 c4847700 Nov 7 10:05:36 host kernel: 00000001 c4847700 ef1ba352 0000002c c4844054 00000000 fffe5e91 00000246 Nov 7 10:05:36 host kernel: f57fc274 00000000 00000000 00000000 ffffffff 00000000 7fffffff f2cffe98 Nov 7 10:05:36 host kernel: Call Trace: Nov 7 10:05:36 host kernel: [<c0643ba5>] schedule+0xbf/0xd8 Nov 7 10:05:36 host kernel: [<c0643c72>] schedule_timeout+0x17/0xbc Nov 7 10:05:36 host kernel: [<c0496c8f>] ? __pollwait+0xad/0xb6 Nov 7 10:05:36 host kernel: [<f8971b34>] ? snd_seq_fifo_poll_wait +0x18/0x25 [snd_seq] Nov 7 10:05:36 host kernel: [<f896efad>] ? snd_seq_poll+0x4d/0x9f [snd_seq] Nov 7 10:05:36 host kernel: [<c0495d92>] do_sys_poll+0x292/0x348 Nov 7 10:05:36 host kernel: [<c0496be2>] ? __pollwait+0x0/0xb6 Nov 7 10:05:36 host kernel: [<c0425c81>] ? default_wake_function +0x0/0x12 Nov 7 10:05:36 host kernel: [<c0645736>] ? rt_spin_lock+0x38/0x3b Nov 7 10:05:36 host kernel: [<c04752f7>] ? page_address+0x88/0xaa Nov 7 10:05:36 host kernel: [<c047596d>] ? kmap_high+0x421/0x42a Nov 7 10:05:36 host kernel: [<c04ff574>] ? radix_valid_always+0x0/0xa Nov 7 10:05:36 host kernel: [<c046430b>] ? __rcu_read_unlock+0x6d/0x72 Nov 7 10:05:36 host kernel: [<c04699ec>] ? find_get_page+0xfa/0x120 Nov 7 10:05:36 host kernel: [<c06456c1>] ? __rt_spin_lock+0x24/0x61 Nov 7 10:05:36 host kernel: [<c0645736>] ? rt_spin_lock+0x38/0x3b Nov 7 10:05:36 host kernel: [<c0420afc>] ? __enqueue_entity+0xe3/0xeb Nov 7 10:05:36 host kernel: [<c041f87b>] ? task_rq_lock+0x44/0x6e Nov 7 10:05:36 host kernel: [<c0425c76>] ? try_to_wake_up+0x212/0x21d Nov 7 10:05:36 host kernel: [<c0425c91>] ? default_wake_function +0x10/0x12 Nov 7 10:05:36 host kernel: [<c041ddd8>] ? __wake_up_common+0x35/0x5b Nov 7 10:05:36 host kernel: [<c0423172>] ? __wake_up+0x28/0x32 Nov 7 10:05:36 host kernel: [<c0554f2e>] ? n_tty_receive_buf +0xfa9/0xff7 Nov 7 10:05:36 host kernel: [<c0554f2e>] ? n_tty_receive_buf +0xfa9/0xff7 Nov 7 10:05:36 host kernel: [<c0447cef>] ? rt_mutex_up_read+0x1b7/0x25d Nov 7 10:05:36 host kernel: [<c0448f40>] ? rt_up_read+0x8/0xa Nov 7 10:05:36 host kernel: [<c0647c26>] ? do_page_fault+0x45f/0x7d8 Nov 7 10:05:36 host kernel: [<c0502f6c>] ? copy_to_user+0x36/0x106 Nov 7 10:05:36 host kernel: [<c0644770>] ? rt_spin_lock_slowlock +0x1bd/0x1d8 Nov 7 10:05:36 host kernel: [<c06456c1>] ? __rt_spin_lock+0x24/0x61 Nov 7 10:05:36 host kernel: [<c0645736>] ? rt_spin_lock+0x38/0x3b Nov 7 10:05:36 host kernel: [<f8971c46>] ? snd_seq_fifo_cell_out +0x47/0xee [snd_seq] Nov 7 10:05:36 host kernel: [<c0425c81>] ? default_wake_function +0x0/0x12 Nov 7 10:05:36 host kernel: [<f896f041>] ? snd_seq_read+0x0/0x1d8 [snd_seq] Nov 7 10:05:36 host kernel: [<f896f11e>] ? snd_seq_read+0xdd/0x1d8 [snd_seq] Nov 7 10:05:36 host kernel: [<c04d73d3>] ? security_file_permission +0xf/0x11 Nov 7 10:05:36 host kernel: [<c045e231>] ? audit_syscall_entry +0xf9/0x123 Nov 7 10:05:36 host kernel: [<c049606a>] sys_poll+0x3a/0x6a Nov 7 10:05:36 host kernel: [<c0404be6>] syscall_call+0x7/0xb Nov 7 10:05:36 host kernel: ======================= -------- # cat /proc/5256/status Name: aseqdump State: D (disk sleep) Tgid: 5256 Pid: 5256 PPid: 5185 TracerPid: 0 Uid: 743 743 743 743 Gid: 10 10 10 10 FDSize: 32 Groups: 10 11 30 31 400 VmPeak: 3104 kB VmSize: 3048 kB VmLck: 0 kB VmHWM: 884 kB VmRSS: 884 kB VmData: 172 kB VmStk: 84 kB VmExe: 12 kB VmLib: 2700 kB VmPTE: 20 kB Threads: 1 SigQ: 1/32768 SigPnd: 0000000000000000 ShdPnd: 0000000000004000 SigBlk: 0000000000000000 SigIgn: 0000000000000000 SigCgt: 0000000180004002 CapInh: 0000000000000000 CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffffffffffff Cpus_allowed: 0000000f Cpus_allowed_list: 0-3 Mems_allowed: 1 Mems_allowed_list: 0 voluntary_ctxt_switches: 66283 nonvoluntary_ctxt_switches: 4 # cat /proc/5256/wchan msleep -- Fernando _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
