[alsa-devel] [PATCH] ALSA: x86: Fix spinlock usage in the trigger callback
Ville Syrjälä
ville.syrjala at linux.intel.com
Thu Feb 16 15:46:16 CET 2017
On Wed, Feb 15, 2017 at 10:21:08PM +0100, Takashi Iwai wrote:
> On Wed, 15 Feb 2017 20:15:50 +0100,
> ville.syrjala at linux.intel.com wrote:
> >
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> >
> > Simply doing 'xset dpms force off' while playback is active seems
> > sufficient to anger lockdep [1]. And it's of course correct that it's
> > not safe to use regular spin_lock() outside the irq handler when
> > the irq handler also wants to acquire the same lock. I believe the
> > trigger callback can get called from both irq and non-irq context,
> > so we need to to use spin_lock_irqsave() & co. here.
>
> No, it's just because I used snd_pcm_stop() wrongly. A proper fix
> patch is already in the queue I'm going to submit right now:
> [PATCH 2/8] ALSA: x86: Use snd_pcm_stop_xrun() for connection /
> disconnection paths
OK, cool. I'll have to try this again once I see that land somewhere.
>
>
> thanks,
>
> Takashi
>
>
>
> >
> > The whole locking here looks somewhat suspicious, but I don't feel
> > like digging into further, so here's just the minimal fix.
> >
> > [1]
> > [ 168.303913] [drm:ilk_audio_codec_disable [i915]] Disable audio codec on port B, pipe B
> > [ 168.306245] =================================
> > [ 168.311110] [ INFO: inconsistent lock state ]
> > [ 168.315975] 4.10.0-rc8-ffrd+ #698 Tainted: G W
> > [ 168.322198] ---------------------------------
> > [ 168.327062] inconsistent {IN-HARDIRQ-W} -> {HARDIRQ-ON-W} usage.
> > [ 168.333773] kworker/2:1/44 [HC0[0]:SC0[0]:HE1:SE1] takes:
> > [ 168.339802] (&(&ctx->had_spinlock)->rlock){?.-...}, at: [<ffffffffa02c67e0>] had_pcm_trigger+0x60/0x160 [snd_hdmi_lpe_audio]
> > [ 168.352449] {IN-HARDIRQ-W} state was registered at:
> > [ 168.357901] __lock_acquire+0x7b2/0x16c0
> > [ 168.362378] lock_acquire+0xba/0x220
> > [ 168.366468] _raw_spin_lock_irqsave+0x47/0x60
> > [ 168.371431] had_substream_get+0x23/0x50 [snd_hdmi_lpe_audio]
> > [ 168.377950] display_pipe_interrupt_handler+0x78/0x1a0 [snd_hdmi_lpe_audio]
> > [ 168.385828] __handle_irq_event_percpu+0x3f/0x3a0
> > [ 168.391180] handle_irq_event_percpu+0x24/0x60
> > [ 168.396239] handle_irq_event+0x3a/0x60
> > [ 168.400619] handle_simple_irq+0x79/0xa0
> > [ 168.405096] generic_handle_irq+0x22/0x30
> > [ 168.409718] intel_lpe_audio_irq_handler+0x24/0x80 [i915]
> > [ 168.415878] valleyview_irq_handler+0x1da/0x230 [i915]
> > [ 168.421715] __handle_irq_event_percpu+0x3f/0x3a0
> > [ 168.427067] handle_irq_event_percpu+0x24/0x60
> > [ 168.432126] handle_irq_event+0x3a/0x60
> > [ 168.436505] handle_edge_irq+0x94/0x150
> > [ 168.440886] handle_irq+0xb3/0x190
> > [ 168.444781] do_IRQ+0x69/0x130
> > [ 168.448287] ret_from_intr+0x0/0x19
> > [ 168.452280] cpuidle_enter_state+0xdb/0x360
> > [ 168.457047] cpuidle_enter+0x17/0x20
> > [ 168.461136] call_cpuidle+0x23/0x40
> > [ 168.465126] do_idle+0x18a/0x200
> > [ 168.468826] cpu_startup_entry+0x1d/0x30
> > [ 168.473303] rest_init+0x12c/0x140
> > [ 168.477200] start_kernel+0x402/0x40f
> > [ 168.481385] x86_64_start_reservations+0x2a/0x2c
> > [ 168.486640] x86_64_start_kernel+0xea/0xed
> > [ 168.491313] verify_cpu+0x0/0xfc
> > [ 168.495012] irq event stamp: 28481
> > [ 168.498810] hardirqs last enabled at (28481): [<ffffffff8167feac>] _raw_spin_unlock_irq+0x2c/0x60
> > [ 168.508824] hardirqs last disabled at (28480): [<ffffffff8167fcc8>] _raw_spin_lock_irq+0x18/0x60
> > [ 168.518645] softirqs last enabled at (28442): [<ffffffff815d6cf9>] neigh_periodic_work+0x219/0x320
> > [ 168.528755] softirqs last disabled at (28438): [<ffffffff815d6b19>] neigh_periodic_work+0x39/0x320
> > [ 168.538767]
> > other info that might help us debug this:
> > [ 168.546052] Possible unsafe locking scenario:
> >
> > [ 168.552664] CPU0
> > [ 168.555390] ----
> > [ 168.558116] lock(&(&ctx->had_spinlock)->rlock);
> > [ 168.563371] <Interrupt>
> > [ 168.566291] lock(&(&ctx->had_spinlock)->rlock);
> > [ 168.571741]
> > *** DEADLOCK ***
> >
> > [ 168.578355] 3 locks held by kworker/2:1/44:
> > [ 168.583025] #0: ("events"){.+.+.+}, at: [<ffffffff810a467f>] process_one_work+0x15f/0x6e0
> > [ 168.592357] #1: ((&ctx->hdmi_audio_wq)){+.+.+.}, at: [<ffffffff810a467f>] process_one_work+0x15f/0x6e0
> > [ 168.602959] #2: (&ctx->mutex){+.+.+.}, at: [<ffffffffa02c6ee8>] had_audio_wq+0x48/0x6de [snd_hdmi_lpe_audio]
> > [ 168.614145]
> > stack backtrace:
> > [ 168.619011] CPU: 2 PID: 44 Comm: kworker/2:1 Tainted: G W 4.10.0-rc8-ffrd+ #698
> > [ 168.628441] Hardware name: Intel Corp. VALLEYVIEW C0 PLATFORM/BYT-T FFD8, BIOS BLAKFF81.X64.0088.R10.1403240443 FFD8_X64_R_2014_13_1_00 03/24/2014
> > [ 168.643111] Workqueue: events had_audio_wq [snd_hdmi_lpe_audio]
> > [ 168.649725] Call Trace:
> > [ 168.652448] dump_stack+0x67/0x90
> > [ 168.656149] print_usage_bug+0x20b/0x210
> > [ 168.660530] mark_lock+0x648/0x6c0
> > [ 168.664328] ? print_shortest_lock_dependencies+0x1d0/0x1d0
> > [ 168.670553] __lock_acquire+0x638/0x16c0
> > [ 168.674935] lock_acquire+0xba/0x220
> > [ 168.678929] ? had_pcm_trigger+0x60/0x160 [snd_hdmi_lpe_audio]
> > [ 168.685447] _raw_spin_lock+0x3f/0x50
> > [ 168.689536] ? had_pcm_trigger+0x60/0x160 [snd_hdmi_lpe_audio]
> > [ 168.696054] had_pcm_trigger+0x60/0x160 [snd_hdmi_lpe_audio]
> > [ 168.702383] snd_pcm_do_stop+0x45/0x50 [snd_pcm]
> > [ 168.707545] snd_pcm_action_single+0x32/0x80 [snd_pcm]
> > [ 168.713289] snd_pcm_action+0x118/0x120 [snd_pcm]
> > [ 168.718549] snd_pcm_stop+0x1a/0x20 [snd_pcm]
> > [ 168.723415] had_audio_wq+0x35e/0x6de [snd_hdmi_lpe_audio]
> > [ 168.729545] process_one_work+0x1eb/0x6e0
> > [ 168.734022] ? process_one_work+0x15f/0x6e0
> > [ 168.738693] worker_thread+0x4f/0x4a0
> > [ 168.742781] ? schedule+0x4a/0x90
> > [ 168.746483] ? preempt_count_sub+0xa6/0x110
> > [ 168.751154] kthread+0x10e/0x150
> > [ 168.754757] ? apply_wqattrs_commit+0x90/0x90
> > [ 168.759621] ? kthread_create_on_node+0x40/0x40
> > [ 168.764681] ? umh_complete+0x30/0x30
> > [ 168.768770] ? call_usermodehelper_exec_async+0x13a/0x150
> > [ 168.774802] ret_from_fork+0x2e/0x40
> > [ 168.779412] [drm:intel_disable_pipe [i915]] disabling pipe B
> >
> > Cc: Takashi Iwai <tiwai at suse.de>
> > Cc: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> > sound/x86/intel_hdmi_audio.c | 5 +++--
> > 1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
> > index c0a080e5d1f4..2748766b3f25 100644
> > --- a/sound/x86/intel_hdmi_audio.c
> > +++ b/sound/x86/intel_hdmi_audio.c
> > @@ -1154,6 +1154,7 @@ static int had_pcm_hw_free(struct snd_pcm_substream *substream)
> > static int had_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
> > {
> > int retval = 0;
> > + unsigned long flags;
> > struct snd_intelhad *intelhaddata;
> >
> > intelhaddata = snd_pcm_substream_chip(substream);
> > @@ -1180,12 +1181,12 @@ static int had_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
> > case SNDRV_PCM_TRIGGER_STOP:
> > case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
> > case SNDRV_PCM_TRIGGER_SUSPEND:
> > - spin_lock(&intelhaddata->had_spinlock);
> > + spin_lock_irqsave(&intelhaddata->had_spinlock, flags);
> >
> > /* Stop reporting BUFFER_DONE/UNDERRUN to above layers */
> >
> > intelhaddata->stream_info.running = false;
> > - spin_unlock(&intelhaddata->had_spinlock);
> > + spin_unlock_irqrestore(&intelhaddata->had_spinlock, flags);
> > /* Disable Audio */
> > had_enable_audio(intelhaddata, false);
> > /* Reset buffer pointers */
> > --
> > 2.10.2
> >
--
Ville Syrjälä
Intel OTC
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