linux/sound/firewire
Takashi Sakamoto 4a9bfafc64 ALSA: firewire-lib: Fix stall of process context at packet error
At Linux v3.5, packet processing can be done in process context of ALSA
PCM application as well as software IRQ context for OHCI 1394. Below is
an example of the callgraph (some calls are omitted).

ioctl(2) with e.g. HWSYNC
(sound/core/pcm_native.c)
->snd_pcm_common_ioctl1()
  ->snd_pcm_hwsync()
    ->snd_pcm_stream_lock_irq
    (sound/core/pcm_lib.c)
    ->snd_pcm_update_hw_ptr()
      ->snd_pcm_udpate_hw_ptr0()
        ->struct snd_pcm_ops.pointer()
        (sound/firewire/*)
        = Each handler on drivers in ALSA firewire stack
          (sound/firewire/amdtp-stream.c)
          ->amdtp_stream_pcm_pointer()
            (drivers/firewire/core-iso.c)
            ->fw_iso_context_flush_completions()
              ->struct fw_card_driver.flush_iso_completion()
              (drivers/firewire/ohci.c)
              = flush_iso_completions()
                ->struct fw_iso_context.callback.sc
                (sound/firewire/amdtp-stream.c)
                = in_stream_callback() or out_stream_callback()
                  ->...
    ->snd_pcm_stream_unlock_irq

When packet queueing error occurs or detecting invalid packets in
'in_stream_callback()' or 'out_stream_callback()', 'snd_pcm_stop_xrun()'
is called on local CPU with disabled IRQ.

(sound/firewire/amdtp-stream.c)
in_stream_callback() or out_stream_callback()
->amdtp_stream_pcm_abort()
  ->snd_pcm_stop_xrun()
    ->snd_pcm_stream_lock_irqsave()
    ->snd_pcm_stop()
    ->snd_pcm_stream_unlock_irqrestore()

The process is stalled on the CPU due to attempt to acquire recursive lock.

[  562.630853] INFO: rcu_sched detected stalls on CPUs/tasks:
[  562.630861]      2-...: (1 GPs behind) idle=37d/140000000000000/0 softirq=38323/38323 fqs=7140
[  562.630862]      (detected by 3, t=15002 jiffies, g=21036, c=21035, q=5933)
[  562.630866] Task dump for CPU 2:
[  562.630867] alsa-source-OXF R  running task        0  6619      1 0x00000008
[  562.630870] Call Trace:
[  562.630876]  ? vt_console_print+0x79/0x3e0
[  562.630880]  ? msg_print_text+0x9d/0x100
[  562.630883]  ? up+0x32/0x50
[  562.630885]  ? irq_work_queue+0x8d/0xa0
[  562.630886]  ? console_unlock+0x2b6/0x4b0
[  562.630888]  ? vprintk_emit+0x312/0x4a0
[  562.630892]  ? dev_vprintk_emit+0xbf/0x230
[  562.630895]  ? do_sys_poll+0x37a/0x550
[  562.630897]  ? dev_printk_emit+0x4e/0x70
[  562.630900]  ? __dev_printk+0x3c/0x80
[  562.630903]  ? _raw_spin_lock+0x20/0x30
[  562.630909]  ? snd_pcm_stream_lock+0x31/0x50 [snd_pcm]
[  562.630914]  ? _snd_pcm_stream_lock_irqsave+0x2e/0x40 [snd_pcm]
[  562.630918]  ? snd_pcm_stop_xrun+0x16/0x70 [snd_pcm]
[  562.630922]  ? in_stream_callback+0x3e6/0x450 [snd_firewire_lib]
[  562.630925]  ? handle_ir_packet_per_buffer+0x8e/0x1a0 [firewire_ohci]
[  562.630928]  ? ohci_flush_iso_completions+0xa3/0x130 [firewire_ohci]
[  562.630932]  ? fw_iso_context_flush_completions+0x15/0x20 [firewire_core]
[  562.630935]  ? amdtp_stream_pcm_pointer+0x2d/0x40 [snd_firewire_lib]
[  562.630938]  ? pcm_capture_pointer+0x19/0x20 [snd_oxfw]
[  562.630943]  ? snd_pcm_update_hw_ptr0+0x47/0x3d0 [snd_pcm]
[  562.630945]  ? poll_select_copy_remaining+0x150/0x150
[  562.630947]  ? poll_select_copy_remaining+0x150/0x150
[  562.630952]  ? snd_pcm_update_hw_ptr+0x10/0x20 [snd_pcm]
[  562.630956]  ? snd_pcm_hwsync+0x45/0xb0 [snd_pcm]
[  562.630960]  ? snd_pcm_common_ioctl1+0x1ff/0xc90 [snd_pcm]
[  562.630962]  ? futex_wake+0x90/0x170
[  562.630966]  ? snd_pcm_capture_ioctl1+0x136/0x260 [snd_pcm]
[  562.630970]  ? snd_pcm_capture_ioctl+0x27/0x40 [snd_pcm]
[  562.630972]  ? do_vfs_ioctl+0xa3/0x610
[  562.630974]  ? vfs_read+0x11b/0x130
[  562.630976]  ? SyS_ioctl+0x79/0x90
[  562.630978]  ? entry_SYSCALL_64_fastpath+0x1e/0xad

This commit fixes the above bug. This assumes two cases:
1. Any error is detected in software IRQ context of OHCI 1394 context.
In this case, PCM substream should be aborted in packet handler. On the
other hand, it should not be done in any process context. TO distinguish
these two context, use 'in_interrupt()' macro.
2. Any error is detect in process context of ALSA PCM application.
In this case, PCM substream should not be aborted in packet handler
because PCM substream lock is acquired. The task to abort PCM substream
should be done in ALSA PCM core. For this purpose, SNDRV_PCM_POS_XRUN is
returned at 'struct snd_pcm_ops.pointer()'.

Suggested-by: Clemens Ladisch <clemens@ladisch.de>
Fixes: e9148dddc3c7("ALSA: firewire-lib: flush completed packets when reading PCM position")
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2017-06-19 17:47:18 +02:00
..
bebob ALSA: firewire-lib/bebob/oxfw: improve response evaluation for AV/C commands 2017-04-05 21:37:23 +02:00
dice sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
digi00x ALSA: firewire-digi00x: remove transaction handler for unknown purpose 2017-04-05 21:34:13 +02:00
fireface ALSA: fireface: obsolete usage of ktime_set() for zero assignment 2017-04-20 15:00:54 +02:00
fireworks sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h> 2017-03-02 08:42:32 +01:00
motu ALSA: firewire-motu: mark trace helpers as __maybe_unused 2017-04-20 12:50:45 +02:00
oxfw Merge branch 'for-linus' into for-next 2017-04-12 07:16:07 +02:00
tascam ALSA: firewire-tascam: support drain callback for MIDI playback substream 2017-04-14 14:50:43 +02:00
amdtp-am824.c ALSA: firewire-lib: process_rx_data_blocks() can be static 2015-09-29 16:52:52 +02:00
amdtp-am824.h ALSA: firewire-lib: complete AM824 data block processing layer 2015-09-29 12:51:20 +02:00
amdtp-stream-trace.h ALSA: firewire_lib: add tracepoints for packets without CIP headers 2017-04-11 08:30:43 +02:00
amdtp-stream.c ALSA: firewire-lib: Fix stall of process context at packet error 2017-06-19 17:47:18 +02:00
amdtp-stream.h ALSA: firewire-lib: Fix stall of process context at packet error 2017-06-19 17:47:18 +02:00
cmp.c ALSA: firewire-lib: fix kerneldoc errors 2014-11-18 18:10:23 +01:00
cmp.h ALSA: firewire-lib: Add a new function to check others' connection 2014-05-26 14:22:46 +02:00
fcp.c ALSA: firewire-lib/bebob/oxfw: improve response evaluation for AV/C commands 2017-04-05 21:37:23 +02:00
fcp.h ALSA: firewire-lib: Add some AV/C general commands 2014-05-26 14:23:13 +02:00
isight.c ALSA: pcm: Add snd_pcm_stop_xrun() helper 2014-11-09 18:20:40 +01:00
iso-resources.c ALSA: firewire-lib: leave unit reference counting completely 2015-03-10 15:27:19 +01:00
iso-resources.h firewire: octlet AT payloads can be stack-allocated 2011-05-10 22:53:44 +02:00
Kconfig ALSA: fireface: add support for Fireface 400 2017-04-05 21:31:54 +02:00
lib.c ALSA: firewire-lib/firewire-tascam: localize async midi port 2017-04-14 14:50:26 +02:00
lib.h ALSA: firewire-lib/firewire-tascam: localize async midi port 2017-04-14 14:50:26 +02:00
Makefile ALSA: fireface: add skeleton for RME Fireface series 2017-04-05 21:31:24 +02:00
packets-buffer.c sound: Add export.h for THIS_MODULE/EXPORT_SYMBOL where needed 2011-10-31 19:31:22 -04:00
packets-buffer.h