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Message-ID: <s5ho83yldu3.wl-tiwai@suse.de>
Date: Wed, 26 Jan 2022 16:24:36 +0100
From: Takashi Iwai <tiwai@...e.de>
To: Alexander Sergeyev <sergeev917@...il.com>
Cc: Jeremy Szu <jeremy.szu@...onical.com>, tiwai@...e.com,
"moderated list:SOUND" <alsa-devel@...a-project.org>,
Kailang Yang <kailang@...ltek.com>,
open list <linux-kernel@...r.kernel.org>,
Huacai Chen <chenhuacai@...nel.org>,
Jian-Hong Pan <jhp@...lessos.org>,
Hui Wang <hui.wang@...onical.com>,
PeiSen Hou <pshou@...ltek.com>
Subject: Re: [PATCH 1/4] ALSA: hda/realtek: fix mute/micmute LEDs for HP 855 G8
On Sat, 22 Jan 2022 21:56:37 +0100,
Alexander Sergeyev wrote:
>
> On Sat, Jan 22, 2022 at 10:05:24PM +0300, Alexander Sergeyev wrote:
> > I'm not sure about kernel log buffering or maybe the device support for
> > pipelining, but is it okay that alc_update_coefex_idx() seem to overlap?
>
> Given that the CPU number is the same in alc_update_coefex_idx(), it seems
> these calls execution is interrupted and interleaved on the same core.
>
> And, actually, there are two LEDs to set (mute and micmute). Am I onto
> something here?
That's an interesting finding, and yes, such a race is quite
possible. Below is a quick fix as an attempt to cover it.
Could you give it a try?
BTW, the fix for the unbind problem was submitted. It's a slightly
more simplified version than what I posted here beforehand.
thanks,
Takashi
-- 8< --
From: Takashi Iwai <tiwai@...e.de>
Subject: [PATCH] ALSA: hda: realtek: Fix race at concurrent COEF updates
The COEF access is done with two steps: setting the index then read or
write the data. When multiple COEF accesses are performed
concurrently, the index and data might be paired unexpectedly.
In most cases, this isn't a big problem as the COEF setup is done at
the initialization, but some dynamic changes like the mute LED may hit
such a race.
For avoiding the racy COEF accesses, this patch introduces a new
mutex coef_mutex to alc_spec, and wrap the COEF accessing functions
with it.
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
sound/pci/hda/patch_realtek.c | 61 ++++++++++++++++++++++++++++-------
1 file changed, 50 insertions(+), 11 deletions(-)
diff --git a/sound/pci/hda/patch_realtek.c b/sound/pci/hda/patch_realtek.c
index 668274e52674..a5677be0a405 100644
--- a/sound/pci/hda/patch_realtek.c
+++ b/sound/pci/hda/patch_realtek.c
@@ -98,6 +98,7 @@ struct alc_spec {
unsigned int gpio_mic_led_mask;
struct alc_coef_led mute_led_coef;
struct alc_coef_led mic_led_coef;
+ struct mutex coef_mutex;
hda_nid_t headset_mic_pin;
hda_nid_t headphone_mic_pin;
@@ -137,8 +138,8 @@ struct alc_spec {
* COEF access helper functions
*/
-static int alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
- unsigned int coef_idx)
+static int __alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
+ unsigned int coef_idx)
{
unsigned int val;
@@ -147,28 +148,61 @@ static int alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
return val;
}
+static int alc_read_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
+ unsigned int coef_idx)
+{
+ struct alc_spec *spec = codec->spec;
+ unsigned int val;
+
+ mutex_lock(&spec->coef_mutex);
+ val = __alc_read_coefex_idx(codec, nid, coef_idx);
+ mutex_unlock(&spec->coef_mutex);
+ return val;
+}
+
#define alc_read_coef_idx(codec, coef_idx) \
alc_read_coefex_idx(codec, 0x20, coef_idx)
-static void alc_write_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
- unsigned int coef_idx, unsigned int coef_val)
+static void __alc_write_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
+ unsigned int coef_idx, unsigned int coef_val)
{
snd_hda_codec_write(codec, nid, 0, AC_VERB_SET_COEF_INDEX, coef_idx);
snd_hda_codec_write(codec, nid, 0, AC_VERB_SET_PROC_COEF, coef_val);
}
+static void alc_write_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
+ unsigned int coef_idx, unsigned int coef_val)
+{
+ struct alc_spec *spec = codec->spec;
+
+ mutex_lock(&spec->coef_mutex);
+ __alc_write_coefex_idx(codec, nid, coef_idx, coef_val);
+ mutex_unlock(&spec->coef_mutex);
+}
+
#define alc_write_coef_idx(codec, coef_idx, coef_val) \
alc_write_coefex_idx(codec, 0x20, coef_idx, coef_val)
+static void __alc_update_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
+ unsigned int coef_idx, unsigned int mask,
+ unsigned int bits_set)
+{
+ unsigned int val = __alc_read_coefex_idx(codec, nid, coef_idx);
+
+ if (val != -1)
+ __alc_write_coefex_idx(codec, nid, coef_idx,
+ (val & ~mask) | bits_set);
+}
+
static void alc_update_coefex_idx(struct hda_codec *codec, hda_nid_t nid,
unsigned int coef_idx, unsigned int mask,
unsigned int bits_set)
{
- unsigned int val = alc_read_coefex_idx(codec, nid, coef_idx);
+ struct alc_spec *spec = codec->spec;
- if (val != -1)
- alc_write_coefex_idx(codec, nid, coef_idx,
- (val & ~mask) | bits_set);
+ mutex_lock(&spec->coef_mutex);
+ __alc_update_coefex_idx(codec, nid, coef_idx, mask, bits_set);
+ mutex_unlock(&spec->coef_mutex);
}
#define alc_update_coef_idx(codec, coef_idx, mask, bits_set) \
@@ -201,13 +235,17 @@ struct coef_fw {
static void alc_process_coef_fw(struct hda_codec *codec,
const struct coef_fw *fw)
{
+ struct alc_spec *spec = codec->spec;
+
+ mutex_lock(&spec->coef_mutex);
for (; fw->nid; fw++) {
if (fw->mask == (unsigned short)-1)
- alc_write_coefex_idx(codec, fw->nid, fw->idx, fw->val);
+ __alc_write_coefex_idx(codec, fw->nid, fw->idx, fw->val);
else
- alc_update_coefex_idx(codec, fw->nid, fw->idx,
- fw->mask, fw->val);
+ __alc_update_coefex_idx(codec, fw->nid, fw->idx,
+ fw->mask, fw->val);
}
+ mutex_unlock(&spec->coef_mutex);
}
/*
@@ -1153,6 +1191,7 @@ static int alc_alloc_spec(struct hda_codec *codec, hda_nid_t mixer_nid)
codec->spdif_status_reset = 1;
codec->forced_resume = 1;
codec->patch_ops = alc_patch_ops;
+ mutex_init(&spec->coef_mutex);
err = alc_codec_rename_from_preset(codec);
if (err < 0) {
--
2.31.1
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