On Tue, 29 Oct 2019 20:10:50 +0100,
Ville Syrjälä wrote:
>
> Hi Takashi,
>
> I just got this deadlock when I tried to modprobe i915 on an ELK:
>
> [ 203.716416] ============================================
> [ 203.716417] WARNING: possible recursive locking detected
> [ 203.716418] 5.4.0-rc5-elk+ #206 Not tainted
> [ 203.716419] --------------------------------------------
> [ 203.716420] kworker/0:1/12 is trying to acquire lock:
> [ 203.716421] efb1c138 (&spec->pcm_lock){+.+.}, at: generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
> [ 203.716426]
> but task is already holding lock:
> [ 203.716427] efb1c138 (&spec->pcm_lock){+.+.}, at: check_presence_and_report+0x67/0xb0 [snd_hda_codec_hdmi]
> [ 203.716430]
> other info that might help us debug this:
> [ 203.716431] Possible unsafe locking scenario:
>
> [ 203.716431] CPU0
> [ 203.716432] ----
> [ 203.716432] lock(&spec->pcm_lock);
> [ 203.716433] lock(&spec->pcm_lock);
> [ 203.716434]
> *** DEADLOCK ***
>
> [ 203.716435] May be due to missing lock nesting notation
>
> [ 203.716436] 3 locks held by kworker/0:1/12:
> [ 203.716436] #0: f14096a0 ((wq_completion)events){+.+.}, at: process_one_work+0x1b8/0x530
> [ 203.716442] #1: f14dbf4c ((work_completion)(&bus->unsol_work)){+.+.}, at: process_one_work+0x1b8/0x530
> [ 203.716444] #2: efb1c138 (&spec->pcm_lock){+.+.}, at: check_presence_and_report+0x67/0xb0 [snd_hda_codec_hdmi]
> [ 203.716448]
> stack backtrace:
> [ 203.716449] CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.4.0-rc5-elk+ #206
> [ 203.716450] Hardware name: System manufacturer P5Q-EM/P5Q-EM, BIOS 2203 07/08/2009
> [ 203.716457] Workqueue: events snd_hdac_bus_process_unsol_events [snd_hda_core]
> [ 203.716459] Call Trace:
> [ 203.716463] dump_stack+0x66/0x8e
> [ 203.716466] __lock_acquire.cold.62+0x3bf/0x3c7
> [ 203.716468] ? mark_held_locks+0x3f/0x60
> [ 203.716470] ? _raw_spin_unlock_irq+0x22/0x30
> [ 203.716478] ? azx_rirb_get_response+0xd7/0x220 [snd_hda_codec]
> [ 203.716479] ? lockdep_hardirqs_on+0xec/0x1a0
> [ 203.716480] ? _raw_spin_unlock_irq+0x22/0x30
> [ 203.716483] ? trace_hardirqs_on+0x4a/0xf0
> [ 203.716484] ? find_held_lock+0x26/0xb0
> [ 203.716486] lock_acquire+0x74/0x150
> [ 203.716488] ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
> [ 203.716490] __mutex_lock+0x60/0x810
> [ 203.716492] ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
> [ 203.716496] ? snd_hdac_exec_verb+0x16/0x40 [snd_hda_core]
> [ 203.716499] ? codec_read+0x29/0x40 [snd_hda_core]
> [ 203.716501] mutex_lock_nested+0x14/0x20
> [ 203.716503] ? generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
> [ 203.716505] generic_hdmi_init+0x21/0x140 [snd_hda_codec_hdmi]
> [ 203.716507] generic_hdmi_resume+0x18/0x60 [snd_hda_codec_hdmi]
> [ 203.716512] hda_call_codec_resume+0xc2/0x130 [snd_hda_codec]
> [ 203.716517] hda_codec_runtime_resume+0x2a/0x60 [snd_hda_codec]
> [ 203.716520] __rpm_callback+0x7a/0x140
> [ 203.716524] ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
> [ 203.716529] ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
> [ 203.716531] rpm_callback+0x1a/0x70
> [ 203.716535] ? snd_hda_codec_device_new+0x2a0/0x2a0 [snd_hda_codec]
> [ 203.716537] rpm_resume+0x52c/0x700
> [ 203.716538] ? _raw_spin_lock_irqsave+0x32/0x40
> [ 203.716540] __pm_runtime_resume+0x43/0x90
> [ 203.716543] snd_hdac_power_up_pm+0x4d/0x50 [snd_hda_core]
> [ 203.716546] hdmi_present_sense+0x34/0x340 [snd_hda_codec_hdmi]
> [ 203.716548] ? finish_task_switch+0x89/0x210
> [ 203.716550] check_presence_and_report+0x7a/0xb0 [snd_hda_codec_hdmi]
> [ 203.716553] hdmi_unsol_event+0x57/0x60 [snd_hda_codec_hdmi]
> [ 203.716557] ? hda_codec_match+0x70/0x70 [snd_hda_codec]
> [ 203.716561] hda_codec_unsol_event+0x12/0x20 [snd_hda_codec]
> [ 203.716564] snd_hdac_bus_process_unsol_events+0x51/0x60 [snd_hda_core]
> [ 203.716566] process_one_work+0x230/0x530
> [ 203.716567] worker_thread+0x37/0x410
> [ 203.716569] kthread+0xf5/0x110
> [ 203.716570] ? process_one_work+0x530/0x530
> [ 203.716572] ? kthread_create_worker_on_cpu+0x20/0x20
> [ 203.716574] ret_from_fork+0x2e/0x38
>
> Looks like commit ade49db337a9 ("ALSA: hda/hdmi - Allow audio
> component for AMD/ATI and Nvidia HDMI") introduced pcm_lock
> to generic_hdmi_init().
Indeed, that can lead to a deadlock.
The patch below should address the issue. I'm going to queue it
later.
thanks,
Takashi
-- 8< --
From: Takashi Iwai <tiwai@xxxxxxx>
Subject: [PATCH] ALSA: hda - Fix mutex deadlock in HDMI codec driver
The commit ade49db337a9 ("ALSA: hda/hdmi - Allow audio component for
AMD/ATI and Nvidia HDMI") introduced the spec->pcm_lock mutex lock to
the whole generic_hdmi_init() function for avoiding the race with the
audio component registration. However, this caused a dead lock when
the unsolicited event is handled without the audio component, as the
codec gets runtime-resumed in hdmi_present_sense() which is already
inside the spec->pcm_lock in its caller.
For avoiding this deadlock, add a new mutex only for the audio
component binding that is used in both generic_hdmi_init() and the
audio notifier registration where the jack callbacks are handled /
re-registered.
Fixes: ade49db337a9 ("ALSA: hda/hdmi - Allow audio component for AMD/ATI and Nvidia HDMI")
Reported-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/pci/hda/patch_hdmi.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 795cbda32cbb..d9b5ba361409 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -145,6 +145,7 @@ struct hdmi_spec {
struct snd_array pins; /* struct hdmi_spec_per_pin */
struct hdmi_pcm pcm_rec[16];
struct mutex pcm_lock;
+ struct mutex bind_lock; /* for audio component binding */
/* pcm_bitmap means which pcms have been assigned to pins*/
unsigned long pcm_bitmap;
int pcm_used; /* counter of pcm_rec[] */
@@ -2258,7 +2259,7 @@ static int generic_hdmi_init(struct hda_codec *codec)
struct hdmi_spec *spec = codec->spec;
int pin_idx;
- mutex_lock(&spec->pcm_lock);
+ mutex_lock(&spec->bind_lock);
spec->use_jack_detect = !codec->jackpoll_interval;
for (pin_idx = 0; pin_idx < spec->num_pins; pin_idx++) {
struct hdmi_spec_per_pin *per_pin = get_pin(spec, pin_idx);
@@ -2275,7 +2276,7 @@ static int generic_hdmi_init(struct hda_codec *codec)
snd_hda_jack_detect_enable_callback(codec, pin_nid,
jack_callback);
}
- mutex_unlock(&spec->pcm_lock);
+ mutex_unlock(&spec->bind_lock);
return 0;
}
@@ -2451,7 +2452,7 @@ static void generic_acomp_notifier_set(struct drm_audio_component *acomp,
int i;
spec = container_of(acomp->audio_ops, struct hdmi_spec, drm_audio_ops);
- mutex_lock(&spec->pcm_lock);
+ mutex_lock(&spec->bind_lock);
spec->use_acomp_notifier = use_acomp;
spec->codec->relaxed_resume = use_acomp;
/* reprogram each jack detection logic depending on the notifier */
@@ -2461,7 +2462,7 @@ static void generic_acomp_notifier_set(struct drm_audio_component *acomp,
get_pin(spec, i)->pin_nid,
use_acomp);
}
- mutex_unlock(&spec->pcm_lock);
+ mutex_unlock(&spec->bind_lock);
}
/* enable / disable the notifier via master bind / unbind */
--
2.16.4
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