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Groups > linux.kernel > #1335473 > unrolled thread

[PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

Started byArnd Bergmann <arnd@arndb.de>
First post2016-02-16 15:50 +0100
Last post2016-02-17 10:50 +0100
Articles 14 — 3 participants

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Contents

  [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 15:50 +0100
    Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-16 16:50 +0100
      Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 17:20 +0100
        Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-16 17:20 +0100
          Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack'  pointer Mark Brown <broonie@kernel.org> - 2016-02-16 17:40 +0100
            Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-16 17:50 +0100
            Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 18:00 +0100
              Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 18:20 +0100
              Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-16 18:20 +0100
                Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 18:30 +0100
                  Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-16 23:10 +0100
                    Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-17 10:10 +0100
                      Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Takashi Iwai <tiwai@suse.de> - 2016-02-17 10:40 +0100
                        Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer Arnd Bergmann <arnd@arndb.de> - 2016-02-17 10:50 +0100

#1335473 — [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 15:50 +0100
Subject[PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer
Message-ID<r2P6V-Gk-7@gated-at.bofh.it>
When CONFIG_SND_JACK is disabled, the hdmi driver tries to create
a new output jack structure and dereferences it even though
the pointer is never assigned:

sound/pci/hda/patch_hdmi.c: In function 'generic_hdmi_build_jack':
sound/pci/hda/patch_hdmi.c:2534:30: error: 'jack' may be used uninitialized in this function [-Werror=maybe-uninitialized]
sound/pci/hda/patch_hdmi.c:2526:19: note: 'jack' was declared here

This uses a compile-time check to avoid calling a nonworking
snd_jack_new() function, and sets an explicit NULL pointer instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 788d441a164c ("ALSA: hda - Use component ops for i915 HDMI/DP audio jack handling")
---
 sound/pci/hda/patch_hdmi.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index f4443b5fbf6e..c0872ad80aa0 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -2526,6 +2526,11 @@ static int add_hdmi_jack_kctl(struct hda_codec *codec,
 	struct snd_jack *jack;
 	int err;
 
+	if (!IS_ENABLED(CONFIG_SND_JACK)) {
+		spec->pcm_rec[pcm_idx].jack = NULL;
+		return 0;
+	}
+
 	err = snd_jack_new(codec->card, name, SND_JACK_AVOUT, &jack,
 			   true, false);
 	if (err < 0)
-- 
2.7.0

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#1335560

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-16 16:50 +0100
Message-ID<r2Q30-1iJ-19@gated-at.bofh.it>
In reply to#1335473
On Tue, 16 Feb 2016 15:47:28 +0100,
Arnd Bergmann wrote:
> 
> When CONFIG_SND_JACK is disabled, the hdmi driver tries to create
> a new output jack structure and dereferences it even though
> the pointer is never assigned:
> 
> sound/pci/hda/patch_hdmi.c: In function 'generic_hdmi_build_jack':
> sound/pci/hda/patch_hdmi.c:2534:30: error: 'jack' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> sound/pci/hda/patch_hdmi.c:2526:19: note: 'jack' was declared here
> 
> This uses a compile-time check to avoid calling a nonworking
> snd_jack_new() function, and sets an explicit NULL pointer instead.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Fixes: 788d441a164c ("ALSA: hda - Use component ops for i915 HDMI/DP audio jack handling")

Thanks for the patch.  But I think it's cleaner to fix Kconfig.

Thinking more of it, maybe splitting jack stuff as a separate module
and does reverse-select to CONFIG_INPUT would be better.  Then its
users can select simply SND_JACK, and everything would fit.

An untested patch is below.  Mark, what do you think?


Takashi

---
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index a2a1e24becc6..cf4058dde959 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -24,11 +24,9 @@ config SND_RAWMIDI
 config SND_COMPRESS_OFFLOAD
 	tristate
 
-# To be effective this also requires INPUT - users should say:
-#    select SND_JACK if INPUT=y || INPUT=SND
-# to avoid having to force INPUT on.
 config SND_JACK
-	bool
+	tristate
+	select INPUT
 
 config SND_SEQUENCER
 	tristate "Sequencer support"
diff --git a/sound/core/Makefile b/sound/core/Makefile
index 48ab4b8f8279..d16e2b0ba4fb 100644
--- a/sound/core/Makefile
+++ b/sound/core/Makefile
@@ -11,7 +11,8 @@ endif
 snd-$(CONFIG_ISA_DMA_API) += isadma.o
 snd-$(CONFIG_SND_OSSEMUL) += sound_oss.o
 snd-$(CONFIG_SND_VMASTER) += vmaster.o
-snd-$(CONFIG_SND_JACK)	  += ctljack.o jack.o
+
+snd-jack-objs	:= ctljack.o jack.o
 
 snd-pcm-y := pcm.o pcm_native.o pcm_lib.o pcm_misc.o \
 		pcm_memory.o memalloc.o
@@ -41,6 +42,7 @@ obj-$(CONFIG_SND_RTCTIMER)	+= snd-rtctimer.o
 obj-$(CONFIG_SND_PCM)		+= snd-pcm.o
 obj-$(CONFIG_SND_DMAENGINE_PCM)	+= snd-pcm-dmaengine.o
 obj-$(CONFIG_SND_RAWMIDI)	+= snd-rawmidi.o
+obj-$(CONFIG_SND_JACK)		+= snd-jack.o
 
 obj-$(CONFIG_SND_OSSEMUL)	+= oss/
 obj-$(CONFIG_SND_SEQUENCER)	+= seq/
diff --git a/sound/pci/Kconfig b/sound/pci/Kconfig
index 8f6594a7d37f..32151d8c6bb8 100644
--- a/sound/pci/Kconfig
+++ b/sound/pci/Kconfig
@@ -866,7 +866,7 @@ config SND_VIRTUOSO
 	select SND_OXYGEN_LIB
 	select SND_PCM
 	select SND_MPU401_UART
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	help
 	  Say Y here to include support for sound cards based on the
 	  Asus AV66/AV100/AV200 chips, i.e., Xonar D1, DX, D2, D2X, DS, DSX,
diff --git a/sound/pci/hda/Kconfig b/sound/pci/hda/Kconfig
index e94cfd5c69f7..bb02c2d48fd5 100644
--- a/sound/pci/hda/Kconfig
+++ b/sound/pci/hda/Kconfig
@@ -4,7 +4,7 @@ config SND_HDA
 	tristate
 	select SND_PCM
 	select SND_VMASTER
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select SND_HDA_CORE
 
 config SND_HDA_INTEL
diff --git a/sound/soc/Kconfig b/sound/soc/Kconfig
index 7ea66ee3653f..182d92efc7c8 100644
--- a/sound/soc/Kconfig
+++ b/sound/soc/Kconfig
@@ -6,7 +6,7 @@ menuconfig SND_SOC
 	tristate "ALSA for SoC audio support"
 	select SND_PCM
 	select AC97_BUS if SND_SOC_AC97_BUS
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select REGMAP_I2C if I2C
 	select REGMAP_SPI if SPI_MASTER
 	---help---

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#1335596

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 17:20 +0100
Message-ID<r2Qw1-1LV-5@gated-at.bofh.it>
In reply to#1335560
On Tuesday 16 February 2016 16:49:42 Takashi Iwai wrote:
> 
> Thanks for the patch.  But I think it's cleaner to fix Kconfig.
> 
> Thinking more of it, maybe splitting jack stuff as a separate module
> and does reverse-select to CONFIG_INPUT would be better.  Then its
> users can select simply SND_JACK, and everything would fit.
> 
> 

Adding 'select INPUT' is rather nasty, I think that can lead to circular
dependencies, and would likely upset users of small embedded systems
that want to use audio but don't want to use input.

Generally speaking, I would recommend never using 'select' on a user
visible Kconfig symbol.

Another option might would be to change snd_jack_new() to return
an error if that SND_JACK is disabled, and then require all users
to handle the error gracefully, i.e. not fail the probe() function
but just not use the jack.

	Arnd

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#1335603

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-16 17:20 +0100
Message-ID<r2Qw2-1LV-23@gated-at.bofh.it>
In reply to#1335596
On Tue, 16 Feb 2016 17:09:43 +0100,
Arnd Bergmann wrote:
> 
> On Tuesday 16 February 2016 16:49:42 Takashi Iwai wrote:
> > 
> > Thanks for the patch.  But I think it's cleaner to fix Kconfig.
> > 
> > Thinking more of it, maybe splitting jack stuff as a separate module
> > and does reverse-select to CONFIG_INPUT would be better.  Then its
> > users can select simply SND_JACK, and everything would fit.
> > 
> > 
> 
> Adding 'select INPUT' is rather nasty, I think that can lead to circular
> dependencies, and would likely upset users of small embedded systems
> that want to use audio but don't want to use input.

Fair enough.

> Generally speaking, I would recommend never using 'select' on a user
> visible Kconfig symbol.
>
> Another option might would be to change snd_jack_new() to return
> an error if that SND_JACK is disabled, and then require all users
> to handle the error gracefully, i.e. not fail the probe() function
> but just not use the jack.

Yes, I thought of that, too.  If select is no good option, it's a good
alternative, indeed.


Takashi

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#1335616 — Re: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer

FromMark Brown <broonie@kernel.org>
Date2016-02-16 17:40 +0100
SubjectRe: [PATCH] sound: hdmi: avoid dereferencing uninitialized 'jack' pointer
Message-ID<r2QPo-1Uv-9@gated-at.bofh.it>
In reply to#1335603

[Multipart message — attachments visible in raw view] — view raw

On Tue, Feb 16, 2016 at 05:18:29PM +0100, Takashi Iwai wrote:
> Arnd Bergmann wrote:

> > Another option might would be to change snd_jack_new() to return
> > an error if that SND_JACK is disabled, and then require all users
> > to handle the error gracefully, i.e. not fail the probe() function
> > but just not use the jack.

> Yes, I thought of that, too.  If select is no good option, it's a good
> alternative, indeed.

It's going to be a bunch of work to implement though.

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#1335630

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-16 17:50 +0100
Message-ID<r2QZ4-1Yc-19@gated-at.bofh.it>
In reply to#1335616
On Tue, 16 Feb 2016 17:38:40 +0100,
Mark Brown wrote:
> 
> On Tue, Feb 16, 2016 at 05:18:29PM +0100, Takashi Iwai wrote:
> > Arnd Bergmann wrote:
> 
> > > Another option might would be to change snd_jack_new() to return
> > > an error if that SND_JACK is disabled, and then require all users
> > > to handle the error gracefully, i.e. not fail the probe() function
> > > but just not use the jack.
> 
> > Yes, I thought of that, too.  If select is no good option, it's a good
> > alternative, indeed.
> 
> It's going to be a bunch of work to implement though.

Is it?  Which driver would be broken?  Many ASoC drivers just ignore
the return error completely.  Some treats as a fatal error, and the
behavior would change, yes.  But I don't think that such a driver
would work without CONFIG_SND_JACK properly in anyway.


Takashi

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#1335637

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 18:00 +0100
Message-ID<r2R8K-21y-11@gated-at.bofh.it>
In reply to#1335616
On Tuesday 16 February 2016 16:38:40 Mark Brown wrote:
> On Tue, Feb 16, 2016 at 05:18:29PM +0100, Takashi Iwai wrote:
> > Arnd Bergmann wrote:
> 
> > > Another option might would be to change snd_jack_new() to return
> > > an error if that SND_JACK is disabled, and then require all users
> > > to handle the error gracefully, i.e. not fail the probe() function
> > > but just not use the jack.
> 
> > Yes, I thought of that, too.  If select is no good option, it's a good
> > alternative, indeed.
> 
> It's going to be a bunch of work to implement though.
> 

I've already sent a v2 to change the snd_jack_new() function, feel free
to ignore that. I also saw now that the same bug is present in hda_jack.c,
but I think the other drivers are fine.

How about this approach below? That should also make it possible to
use the jack APIs without using a error return.

	Arnd

diff --git a/sound/pci/hda/hda_jack.c b/sound/pci/hda/hda_jack.c
index a33234e04d4f..2f72b3c09d92 100644
--- a/sound/pci/hda/hda_jack.c
+++ b/sound/pci/hda/hda_jack.c
@@ -403,8 +403,10 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,
 
 	jack->phantom_jack = !!phantom_jack;
 	jack->type = type;
-	jack->jack->private_data = jack;
-	jack->jack->private_free = hda_free_jack_priv;
+	if (IS_ENABLED(CONFIG_SND_JACK)) {
+		jack->jack->private_data = jack;
+		jack->jack->private_free = hda_free_jack_priv;
+	}
 	state = snd_hda_jack_detect(codec, nid);
 	snd_jack_report(jack->jack, state ? jack->type : 0);
 
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index f4443b5fbf6e..e9a0f67c92ca 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -2532,8 +2532,10 @@ static int add_hdmi_jack_kctl(struct hda_codec *codec,
 		return err;
 
 	spec->pcm_rec[pcm_idx].jack = jack;
-	jack->private_data = &spec->pcm_rec[pcm_idx];
-	jack->private_free = free_hdmi_jack_priv;
+	if (IS_ENABLED(CONFIG_SND_JACK)) {
+		jack->private_data = &spec->pcm_rec[pcm_idx];
+		jack->private_free = free_hdmi_jack_priv;
+	}
 	return 0;
 }

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#1335644

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 18:20 +0100
Message-ID<r2Rs5-2q8-1@gated-at.bofh.it>
In reply to#1335637
On Tuesday 16 February 2016 17:59:04 Arnd Bergmann wrote:
> --- a/sound/pci/hda/hda_jack.c
> +++ b/sound/pci/hda/hda_jack.c
> @@ -403,8 +403,10 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,
>  
>         jack->phantom_jack = !!phantom_jack;
>         jack->type = type;
> -       jack->jack->private_data = jack;
> -       jack->jack->private_free = hda_free_jack_priv;
> +       if (IS_ENABLED(CONFIG_SND_JACK)) {
> +               jack->jack->private_data = jack;
> +               jack->jack->private_free = hda_free_jack_priv;
> +       }
>         state = snd_hda_jack_detect(codec, nid);
>         snd_jack_report(jack->jack, state ? jack->type : 0);
>  

Or another idea: if we pass private_{data,free} into snd_jack_new()
as arguments, the snd_jack structure can become private to
sound/core/jack.c, so we can be sure to never hit this bug
again.

	Arnd

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#1335649

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-16 18:20 +0100
Message-ID<r2Rs6-2q8-33@gated-at.bofh.it>
In reply to#1335637
On Tue, 16 Feb 2016 17:59:04 +0100,
Arnd Bergmann wrote:
> 
> On Tuesday 16 February 2016 16:38:40 Mark Brown wrote:
> > On Tue, Feb 16, 2016 at 05:18:29PM +0100, Takashi Iwai wrote:
> > > Arnd Bergmann wrote:
> > 
> > > > Another option might would be to change snd_jack_new() to return
> > > > an error if that SND_JACK is disabled, and then require all users
> > > > to handle the error gracefully, i.e. not fail the probe() function
> > > > but just not use the jack.
> > 
> > > Yes, I thought of that, too.  If select is no good option, it's a good
> > > alternative, indeed.
> > 
> > It's going to be a bunch of work to implement though.
> > 
> 
> I've already sent a v2 to change the snd_jack_new() function, feel free
> to ignore that. I also saw now that the same bug is present in hda_jack.c,
> but I think the other drivers are fine.
> 
> How about this approach below? That should also make it possible to
> use the jack APIs without using a error return.

I prefer setting NULL explicitly in snd_jack_new(), and let callers
checking NULL.  Then we can avoid ugly IS_ENABLE() while the compiler
should be still capable to optimize out.

OTOH, I think it'd be a waste of time to bikeshedding too much, so I
don't care so much which to take :)


Takashi

---
diff --git a/include/sound/jack.h b/include/sound/jack.h
index 23bede121c78..a27c253a3207 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -99,6 +99,7 @@ void snd_jack_report(struct snd_jack *jack, int status);
 static inline int snd_jack_new(struct snd_card *card, const char *id, int type,
 			       struct snd_jack **jack, bool initial_kctl, bool phantom_jack)
 {
+	*jack = NULL;
 	return 0;
 }
 
diff --git a/sound/pci/hda/hda_jack.c b/sound/pci/hda/hda_jack.c
index a33234e04d4f..babd3a8864a1 100644
--- a/sound/pci/hda/hda_jack.c
+++ b/sound/pci/hda/hda_jack.c
@@ -403,10 +403,12 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,
 
 	jack->phantom_jack = !!phantom_jack;
 	jack->type = type;
-	jack->jack->private_data = jack;
-	jack->jack->private_free = hda_free_jack_priv;
-	state = snd_hda_jack_detect(codec, nid);
-	snd_jack_report(jack->jack, state ? jack->type : 0);
+	if (jack->jack) {
+		jack->jack->private_data = jack;
+		jack->jack->private_free = hda_free_jack_priv;
+		state = snd_hda_jack_detect(codec, nid);
+		snd_jack_report(jack->jack, state ? jack->type : 0);
+	}
 
 	return 0;
 }
diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
index 8ee78dbd4c60..34a7b3aaba11 100644
--- a/sound/pci/hda/patch_hdmi.c
+++ b/sound/pci/hda/patch_hdmi.c
@@ -2158,8 +2158,10 @@ static int add_acomp_jack_kctl(struct hda_codec *codec,
 	if (err < 0)
 		return err;
 	per_pin->acomp_jack = jack;
-	jack->private_data = per_pin;
-	jack->private_free = free_acomp_jack_priv;
+	if (jack) {
+		jack->private_data = per_pin;
+		jack->private_free = free_acomp_jack_priv;
+	}
 	return 0;
 }

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#1335659

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 18:30 +0100
Message-ID<r2RBM-2tA-11@gated-at.bofh.it>
In reply to#1335649
On Tuesday 16 February 2016 18:10:02 Takashi Iwai wrote:
> diff --git a/include/sound/jack.h b/include/sound/jack.h
> index 23bede121c78..a27c253a3207 100644
> --- a/include/sound/jack.h
> +++ b/include/sound/jack.h
> @@ -99,6 +99,7 @@ void snd_jack_report(struct snd_jack *jack, int status);
>  static inline int snd_jack_new(struct snd_card *card, const char *id, int type,
>                                struct snd_jack **jack, bool initial_kctl, bool phantom_jack)
>  {
> +       *jack = NULL;
>         return 0;
>  }
>  
> diff --git a/sound/pci/hda/hda_jack.c b/sound/pci/hda/hda_jack.c
> index a33234e04d4f..babd3a8864a1 100644
> --- a/sound/pci/hda/hda_jack.c
> +++ b/sound/pci/hda/hda_jack.c
> @@ -403,10 +403,12 @@ int snd_hda_jack_add_kctl(struct hda_codec *codec, hda_nid_t nid,
>  
>         jack->phantom_jack = !!phantom_jack;
>         jack->type = type;
> -       jack->jack->private_data = jack;
> -       jack->jack->private_free = hda_free_jack_priv;
> -       state = snd_hda_jack_detect(codec, nid);
> -       snd_jack_report(jack->jack, state ? jack->type : 0);
> +       if (jack->jack) {
> +               jack->jack->private_data = jack;
> +               jack->jack->private_free = hda_free_jack_priv;
> +               state = snd_hda_jack_detect(codec, nid);
> +               snd_jack_report(jack->jack, state ? jack->type : 0);
> +       }
>  
>         return 0;
>  }
> diff --git a/sound/pci/hda/patch_hdmi.c b/sound/pci/hda/patch_hdmi.c
> index 8ee78dbd4c60..34a7b3aaba11 100644
> --- a/sound/pci/hda/patch_hdmi.c
> +++ b/sound/pci/hda/patch_hdmi.c
> @@ -2158,8 +2158,10 @@ static int add_acomp_jack_kctl(struct hda_codec *codec,
>         if (err < 0)
>                 return err;
>         per_pin->acomp_jack = jack;
> -       jack->private_data = per_pin;
> -       jack->private_free = free_acomp_jack_priv;
> +       if (jack) {
> +               jack->private_data = per_pin;
> +               jack->private_free = free_acomp_jack_priv;
> +       }
>         return 0;
>  }
> 
Looks good to me.

Acked-by: Arnd Bergmann <arnd@arndb.de>

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#1335889

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-16 23:10 +0100
Message-ID<r2VYM-5w0-35@gated-at.bofh.it>
In reply to#1335659
On Tuesday 16 February 2016 18:26:09 Arnd Bergmann wrote:
> >                 return err;
> >         per_pin->acomp_jack = jack;
> > -       jack->private_data = per_pin;
> > -       jack->private_free = free_acomp_jack_priv;
> > +       if (jack) {
> > +               jack->private_data = per_pin;
> > +               jack->private_free = free_acomp_jack_priv;
> > +       }
> >         return 0;
> >  }
> > 
> Looks good to me.
> 
> Acked-by: Arnd Bergmann <arnd@arndb.de>
> 

Actually, on second thought, there is one notable downside
of this approach: 'jack' is guaranteed to be NULL here, so gcc
won't produce a warning if another driver makes the same mistake:

By default, we only get a warning for uses of uninitialized
variables, but not those that are known to be NULL. I think
some compiler warnings are able to warn about that too, but I
forgot the details.

	Arnd

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#1336153

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-17 10:10 +0100
Message-ID<r36hs-4dm-3@gated-at.bofh.it>
In reply to#1335889
On Tue, 16 Feb 2016 23:08:13 +0100,
Arnd Bergmann wrote:
> 
> On Tuesday 16 February 2016 18:26:09 Arnd Bergmann wrote:
> > >                 return err;
> > >         per_pin->acomp_jack = jack;
> > > -       jack->private_data = per_pin;
> > > -       jack->private_free = free_acomp_jack_priv;
> > > +       if (jack) {
> > > +               jack->private_data = per_pin;
> > > +               jack->private_free = free_acomp_jack_priv;
> > > +       }
> > >         return 0;
> > >  }
> > > 
> > Looks good to me.
> > 
> > Acked-by: Arnd Bergmann <arnd@arndb.de>
> > 
> 
> Actually, on second thought, there is one notable downside
> of this approach: 'jack' is guaranteed to be NULL here, so gcc
> won't produce a warning if another driver makes the same mistake:
> 
> By default, we only get a warning for uses of uninitialized
> variables, but not those that are known to be NULL. I think
> some compiler warnings are able to warn about that too, but I
> forgot the details.

Yes, that is a good point.

On third thought, we should look back how this issue came out.

Originally HD-audio driver had another jack implementation using ctl
API, and this could be unconditionally enabled.  The kctl jack was
unified into the input jack layer later, and the dependency issue came
out.  In that sense, the problem is that SND_JACK dependency is still
present although it's not needed -- namely, the jack layer itself can
be implemented in kctl even without input devices.

So, the missing piece is the conditional build of jack.c & co without
CONFIG_INPUT.  Then the dependency in the user's side can be ignored.

Below is the patch to do that.


Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH] ALSA: jack: Allow building the jack layer without input
 device

Since the recent integration of kctl jack and input jack layers, we
can basically build the jack layer even without input devices.  That
is, the jack layer itself can be built with conditional to enable the
input device support or not, while the users may enable always
CONFIG_SND_JACK unconditionally.

For achieving it, this patch changes the following:
- A new Kconfig, CONFIG_SND_JACK_INPUT_DEV, was introduced to indicate
  whether the jack layer supports the input device,
- A few items in snd_jack struct and relevant codes are conditionally
  built upon CONFIG_SND_JACK_INPUT_DEV,
- The users of CONFIG_SND_JACK drop the messy dependency on
  CONFIG_INPUT, but just select SND_JACK.

This change also automagically fixes a potential bug in HD-audio
driver Arnd reported, where the NULL or uninitialized jack instance is
dereferenced.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 include/sound/jack.h  | 23 ++++++++++++++---------
 sound/core/Kconfig    |  9 ++++++---
 sound/core/jack.c     | 23 ++++++++++++++++++++---
 sound/pci/Kconfig     |  2 +-
 sound/pci/hda/Kconfig |  2 +-
 sound/soc/Kconfig     |  2 +-
 6 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/include/sound/jack.h b/include/sound/jack.h
index 23bede121c78..1e84bfb553cf 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -72,14 +72,16 @@ enum snd_jack_types {
 #define SND_JACK_SWITCH_TYPES 6
 
 struct snd_jack {
-	struct input_dev *input_dev;
 	struct list_head kctl_list;
 	struct snd_card *card;
+	const char *id;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	struct input_dev *input_dev;
 	int registered;
 	int type;
-	const char *id;
 	char name[100];
 	unsigned int key[6];   /* Keep in sync with definitions above */
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	void *private_data;
 	void (*private_free)(struct snd_jack *);
 };
@@ -89,10 +91,11 @@ struct snd_jack {
 int snd_jack_new(struct snd_card *card, const char *id, int type,
 		 struct snd_jack **jack, bool initial_kctl, bool phantom_jack);
 int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name, int mask);
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 void snd_jack_set_parent(struct snd_jack *jack, struct device *parent);
 int snd_jack_set_key(struct snd_jack *jack, enum snd_jack_types type,
 		     int keytype);
-
+#endif
 void snd_jack_report(struct snd_jack *jack, int status);
 
 #else
@@ -107,6 +110,13 @@ static inline int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name
 	return 0;
 }
 
+static inline void snd_jack_report(struct snd_jack *jack, int status)
+{
+}
+
+#endif
+
+#if !defined(CONFIG_SND_JACK) || !defined(CONFIG_SND_JACK_INPUT_DEV)
 static inline void snd_jack_set_parent(struct snd_jack *jack,
 				       struct device *parent)
 {
@@ -118,11 +128,6 @@ static inline int snd_jack_set_key(struct snd_jack *jack,
 {
 	return 0;
 }
-
-static inline void snd_jack_report(struct snd_jack *jack, int status)
-{
-}
-
-#endif
+#endif /* !CONFIG_SND_JACK || !CONFIG_SND_JACK_INPUT_DEV */
 
 #endif
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index a2a1e24becc6..8b71e15898cd 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -24,11 +24,14 @@ config SND_RAWMIDI
 config SND_COMPRESS_OFFLOAD
 	tristate
 
-# To be effective this also requires INPUT - users should say:
-#    select SND_JACK if INPUT=y || INPUT=SND
-# to avoid having to force INPUT on.
 config SND_JACK
+	tristate
+
+# enable input device support in jack layer
+config SND_JACK_INPUT_DEV
 	bool
+	depends on SND_JACK
+	default y if INPUT=y || INPUT=SND
 
 config SND_SEQUENCER
 	tristate "Sequencer support"
diff --git a/sound/core/jack.c b/sound/core/jack.c
index 7237acbdcbbc..f652e90efd7e 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -32,6 +32,7 @@ struct snd_jack_kctl {
 	unsigned int mask_bits; /* only masked status bits are reported via kctl */
 };
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
 	SW_HEADPHONE_INSERT,
 	SW_MICROPHONE_INSERT,
@@ -40,9 +41,11 @@ static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
 	SW_VIDEOOUT_INSERT,
 	SW_LINEIN_INSERT,
 };
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 static int snd_jack_dev_disconnect(struct snd_device *device)
 {
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	struct snd_jack *jack = device->device_data;
 
 	if (!jack->input_dev)
@@ -55,6 +58,7 @@ static int snd_jack_dev_disconnect(struct snd_device *device)
 	else
 		input_free_device(jack->input_dev);
 	jack->input_dev = NULL;
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	return 0;
 }
 
@@ -79,6 +83,7 @@ static int snd_jack_dev_free(struct snd_device *device)
 	return 0;
 }
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 static int snd_jack_dev_register(struct snd_device *device)
 {
 	struct snd_jack *jack = device->device_data;
@@ -116,6 +121,7 @@ static int snd_jack_dev_register(struct snd_device *device)
 
 	return err;
 }
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 static void snd_jack_kctl_private_free(struct snd_kcontrol *kctl)
 {
@@ -209,11 +215,12 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 	struct snd_jack *jack;
 	struct snd_jack_kctl *jack_kctl = NULL;
 	int err;
-	int i;
 	static struct snd_device_ops ops = {
 		.dev_free = snd_jack_dev_free,
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 		.dev_register = snd_jack_dev_register,
 		.dev_disconnect = snd_jack_dev_disconnect,
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	};
 
 	if (initial_kctl) {
@@ -230,6 +237,9 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 
 	/* don't creat input device for phantom jack */
 	if (!phantom_jack) {
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+		int i;
+
 		jack->input_dev = input_allocate_device();
 		if (jack->input_dev == NULL) {
 			err = -ENOMEM;
@@ -245,6 +255,7 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 				input_set_capability(jack->input_dev, EV_SW,
 						     jack_switch_types[i]);
 
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	}
 
 	err = snd_device_new(card, SNDRV_DEV_JACK, jack, &ops);
@@ -262,13 +273,16 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 	return 0;
 
 fail_input:
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	input_free_device(jack->input_dev);
+#endif
 	kfree(jack->id);
 	kfree(jack);
 	return err;
 }
 EXPORT_SYMBOL(snd_jack_new);
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 /**
  * snd_jack_set_parent - Set the parent device for a jack
  *
@@ -326,10 +340,10 @@ int snd_jack_set_key(struct snd_jack *jack, enum snd_jack_types type,
 
 	jack->type |= type;
 	jack->key[key] = keytype;
-
 	return 0;
 }
 EXPORT_SYMBOL(snd_jack_set_key);
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 /**
  * snd_jack_report - Report the current status of a jack
@@ -340,7 +354,9 @@ EXPORT_SYMBOL(snd_jack_set_key);
 void snd_jack_report(struct snd_jack *jack, int status)
 {
 	struct snd_jack_kctl *jack_kctl;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	int i;
+#endif
 
 	if (!jack)
 		return;
@@ -349,6 +365,7 @@ void snd_jack_report(struct snd_jack *jack, int status)
 		snd_kctl_jack_report(jack->card, jack_kctl->kctl,
 					    status & jack_kctl->mask_bits);
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	if (!jack->input_dev)
 		return;
 
@@ -369,6 +386,6 @@ void snd_jack_report(struct snd_jack *jack, int status)
 	}
 
 	input_sync(jack->input_dev);
-
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 }
 EXPORT_SYMBOL(snd_jack_report);
diff --git a/sound/pci/Kconfig b/sound/pci/Kconfig
index 8f6594a7d37f..32151d8c6bb8 100644
--- a/sound/pci/Kconfig
+++ b/sound/pci/Kconfig
@@ -866,7 +866,7 @@ config SND_VIRTUOSO
 	select SND_OXYGEN_LIB
 	select SND_PCM
 	select SND_MPU401_UART
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	help
 	  Say Y here to include support for sound cards based on the
 	  Asus AV66/AV100/AV200 chips, i.e., Xonar D1, DX, D2, D2X, DS, DSX,
diff --git a/sound/pci/hda/Kconfig b/sound/pci/hda/Kconfig
index e94cfd5c69f7..bb02c2d48fd5 100644
--- a/sound/pci/hda/Kconfig
+++ b/sound/pci/hda/Kconfig
@@ -4,7 +4,7 @@ config SND_HDA
 	tristate
 	select SND_PCM
 	select SND_VMASTER
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select SND_HDA_CORE
 
 config SND_HDA_INTEL
diff --git a/sound/soc/Kconfig b/sound/soc/Kconfig
index 7ea66ee3653f..182d92efc7c8 100644
--- a/sound/soc/Kconfig
+++ b/sound/soc/Kconfig
@@ -6,7 +6,7 @@ menuconfig SND_SOC
 	tristate "ALSA for SoC audio support"
 	select SND_PCM
 	select AC97_BUS if SND_SOC_AC97_BUS
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select REGMAP_I2C if I2C
 	select REGMAP_SPI if SPI_MASTER
 	---help---
-- 
2.7.1

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#1336173

FromTakashi Iwai <tiwai@suse.de>
Date2016-02-17 10:40 +0100
Message-ID<r36Ku-4qr-31@gated-at.bofh.it>
In reply to#1336153
On Wed, 17 Feb 2016 10:03:50 +0100,
Takashi Iwai wrote:
> --- a/sound/core/Kconfig
> +++ b/sound/core/Kconfig
> @@ -24,11 +24,14 @@ config SND_RAWMIDI
>  config SND_COMPRESS_OFFLOAD
>  	tristate
>  
> -# To be effective this also requires INPUT - users should say:
> -#    select SND_JACK if INPUT=y || INPUT=SND
> -# to avoid having to force INPUT on.
>  config SND_JACK
> +	tristate

Oops, some unintentional change slipped in.  This must be bool.

Below is the revised patch.


Takashi

-- 8< --
From: Takashi Iwai <tiwai@suse.de>
Subject: [PATCH v2] ALSA: jack: Allow building the jack layer without
 input device

Since the recent integration of kctl jack and input jack layers, we
can basically build the jack layer even without input devices.  That
is, the jack layer itself can be built with conditional to enable the
input device support or not, while the users may enable always
CONFIG_SND_JACK unconditionally.

For achieving it, this patch changes the following:
- A new Kconfig, CONFIG_SND_JACK_INPUT_DEV, was introduced to indicate
  whether the jack layer supports the input device,
- A few items in snd_jack struct and relevant codes are conditionally
  built upon CONFIG_SND_JACK_INPUT_DEV,
- The users of CONFIG_SND_JACK drop the messy dependency on
  CONFIG_INPUT.

This change also automagically fixes a potential bug in HD-audio
driver Arnd reported, where the NULL or uninitialized jack instance is
dereferenced.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---
 include/sound/jack.h  | 23 ++++++++++++++---------
 sound/core/Kconfig    |  9 ++++++---
 sound/core/jack.c     | 23 ++++++++++++++++++++---
 sound/pci/Kconfig     |  2 +-
 sound/pci/hda/Kconfig |  2 +-
 sound/soc/Kconfig     |  2 +-
 6 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/include/sound/jack.h b/include/sound/jack.h
index 23bede121c78..1e84bfb553cf 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -72,14 +72,16 @@ enum snd_jack_types {
 #define SND_JACK_SWITCH_TYPES 6
 
 struct snd_jack {
-	struct input_dev *input_dev;
 	struct list_head kctl_list;
 	struct snd_card *card;
+	const char *id;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+	struct input_dev *input_dev;
 	int registered;
 	int type;
-	const char *id;
 	char name[100];
 	unsigned int key[6];   /* Keep in sync with definitions above */
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	void *private_data;
 	void (*private_free)(struct snd_jack *);
 };
@@ -89,10 +91,11 @@ struct snd_jack {
 int snd_jack_new(struct snd_card *card, const char *id, int type,
 		 struct snd_jack **jack, bool initial_kctl, bool phantom_jack);
 int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name, int mask);
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 void snd_jack_set_parent(struct snd_jack *jack, struct device *parent);
 int snd_jack_set_key(struct snd_jack *jack, enum snd_jack_types type,
 		     int keytype);
-
+#endif
 void snd_jack_report(struct snd_jack *jack, int status);
 
 #else
@@ -107,6 +110,13 @@ static inline int snd_jack_add_new_kctl(struct snd_jack *jack, const char * name
 	return 0;
 }
 
+static inline void snd_jack_report(struct snd_jack *jack, int status)
+{
+}
+
+#endif
+
+#if !defined(CONFIG_SND_JACK) || !defined(CONFIG_SND_JACK_INPUT_DEV)
 static inline void snd_jack_set_parent(struct snd_jack *jack,
 				       struct device *parent)
 {
@@ -118,11 +128,6 @@ static inline int snd_jack_set_key(struct snd_jack *jack,
 {
 	return 0;
 }
-
-static inline void snd_jack_report(struct snd_jack *jack, int status)
-{
-}
-
-#endif
+#endif /* !CONFIG_SND_JACK || !CONFIG_SND_JACK_INPUT_DEV */
 
 #endif
diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index a2a1e24becc6..6d12ca9bcb80 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -24,12 +24,15 @@ config SND_RAWMIDI
 config SND_COMPRESS_OFFLOAD
 	tristate
 
-# To be effective this also requires INPUT - users should say:
-#    select SND_JACK if INPUT=y || INPUT=SND
-# to avoid having to force INPUT on.
 config SND_JACK
 	bool
 
+# enable input device support in jack layer
+config SND_JACK_INPUT_DEV
+	bool
+	depends on SND_JACK
+	default y if INPUT=y || INPUT=SND
+
 config SND_SEQUENCER
 	tristate "Sequencer support"
 	select SND_TIMER
diff --git a/sound/core/jack.c b/sound/core/jack.c
index 7237acbdcbbc..f652e90efd7e 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -32,6 +32,7 @@ struct snd_jack_kctl {
 	unsigned int mask_bits; /* only masked status bits are reported via kctl */
 };
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
 	SW_HEADPHONE_INSERT,
 	SW_MICROPHONE_INSERT,
@@ -40,9 +41,11 @@ static int jack_switch_types[SND_JACK_SWITCH_TYPES] = {
 	SW_VIDEOOUT_INSERT,
 	SW_LINEIN_INSERT,
 };
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 static int snd_jack_dev_disconnect(struct snd_device *device)
 {
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	struct snd_jack *jack = device->device_data;
 
 	if (!jack->input_dev)
@@ -55,6 +58,7 @@ static int snd_jack_dev_disconnect(struct snd_device *device)
 	else
 		input_free_device(jack->input_dev);
 	jack->input_dev = NULL;
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	return 0;
 }
 
@@ -79,6 +83,7 @@ static int snd_jack_dev_free(struct snd_device *device)
 	return 0;
 }
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 static int snd_jack_dev_register(struct snd_device *device)
 {
 	struct snd_jack *jack = device->device_data;
@@ -116,6 +121,7 @@ static int snd_jack_dev_register(struct snd_device *device)
 
 	return err;
 }
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 static void snd_jack_kctl_private_free(struct snd_kcontrol *kctl)
 {
@@ -209,11 +215,12 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 	struct snd_jack *jack;
 	struct snd_jack_kctl *jack_kctl = NULL;
 	int err;
-	int i;
 	static struct snd_device_ops ops = {
 		.dev_free = snd_jack_dev_free,
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 		.dev_register = snd_jack_dev_register,
 		.dev_disconnect = snd_jack_dev_disconnect,
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	};
 
 	if (initial_kctl) {
@@ -230,6 +237,9 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 
 	/* don't creat input device for phantom jack */
 	if (!phantom_jack) {
+#ifdef CONFIG_SND_JACK_INPUT_DEV
+		int i;
+
 		jack->input_dev = input_allocate_device();
 		if (jack->input_dev == NULL) {
 			err = -ENOMEM;
@@ -245,6 +255,7 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 				input_set_capability(jack->input_dev, EV_SW,
 						     jack_switch_types[i]);
 
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 	}
 
 	err = snd_device_new(card, SNDRV_DEV_JACK, jack, &ops);
@@ -262,13 +273,16 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
 	return 0;
 
 fail_input:
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	input_free_device(jack->input_dev);
+#endif
 	kfree(jack->id);
 	kfree(jack);
 	return err;
 }
 EXPORT_SYMBOL(snd_jack_new);
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 /**
  * snd_jack_set_parent - Set the parent device for a jack
  *
@@ -326,10 +340,10 @@ int snd_jack_set_key(struct snd_jack *jack, enum snd_jack_types type,
 
 	jack->type |= type;
 	jack->key[key] = keytype;
-
 	return 0;
 }
 EXPORT_SYMBOL(snd_jack_set_key);
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 
 /**
  * snd_jack_report - Report the current status of a jack
@@ -340,7 +354,9 @@ EXPORT_SYMBOL(snd_jack_set_key);
 void snd_jack_report(struct snd_jack *jack, int status)
 {
 	struct snd_jack_kctl *jack_kctl;
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	int i;
+#endif
 
 	if (!jack)
 		return;
@@ -349,6 +365,7 @@ void snd_jack_report(struct snd_jack *jack, int status)
 		snd_kctl_jack_report(jack->card, jack_kctl->kctl,
 					    status & jack_kctl->mask_bits);
 
+#ifdef CONFIG_SND_JACK_INPUT_DEV
 	if (!jack->input_dev)
 		return;
 
@@ -369,6 +386,6 @@ void snd_jack_report(struct snd_jack *jack, int status)
 	}
 
 	input_sync(jack->input_dev);
-
+#endif /* CONFIG_SND_JACK_INPUT_DEV */
 }
 EXPORT_SYMBOL(snd_jack_report);
diff --git a/sound/pci/Kconfig b/sound/pci/Kconfig
index 8f6594a7d37f..32151d8c6bb8 100644
--- a/sound/pci/Kconfig
+++ b/sound/pci/Kconfig
@@ -866,7 +866,7 @@ config SND_VIRTUOSO
 	select SND_OXYGEN_LIB
 	select SND_PCM
 	select SND_MPU401_UART
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	help
 	  Say Y here to include support for sound cards based on the
 	  Asus AV66/AV100/AV200 chips, i.e., Xonar D1, DX, D2, D2X, DS, DSX,
diff --git a/sound/pci/hda/Kconfig b/sound/pci/hda/Kconfig
index e94cfd5c69f7..bb02c2d48fd5 100644
--- a/sound/pci/hda/Kconfig
+++ b/sound/pci/hda/Kconfig
@@ -4,7 +4,7 @@ config SND_HDA
 	tristate
 	select SND_PCM
 	select SND_VMASTER
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select SND_HDA_CORE
 
 config SND_HDA_INTEL
diff --git a/sound/soc/Kconfig b/sound/soc/Kconfig
index 7ea66ee3653f..182d92efc7c8 100644
--- a/sound/soc/Kconfig
+++ b/sound/soc/Kconfig
@@ -6,7 +6,7 @@ menuconfig SND_SOC
 	tristate "ALSA for SoC audio support"
 	select SND_PCM
 	select AC97_BUS if SND_SOC_AC97_BUS
-	select SND_JACK if INPUT=y || INPUT=SND
+	select SND_JACK
 	select REGMAP_I2C if I2C
 	select REGMAP_SPI if SPI_MASTER
 	---help---
-- 
2.7.1

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#1336181

FromArnd Bergmann <arnd@arndb.de>
Date2016-02-17 10:50 +0100
Message-ID<r36Ua-4uj-17@gated-at.bofh.it>
In reply to#1336173
On Wednesday 17 February 2016 10:35:40 Takashi Iwai wrote:
> From: Takashi Iwai <tiwai@suse.de>
> Subject: [PATCH v2] ALSA: jack: Allow building the jack layer without
>  input device
> 
> Since the recent integration of kctl jack and input jack layers, we
> can basically build the jack layer even without input devices.  That
> is, the jack layer itself can be built with conditional to enable the
> input device support or not, while the users may enable always
> CONFIG_SND_JACK unconditionally.
> 
> For achieving it, this patch changes the following:
> - A new Kconfig, CONFIG_SND_JACK_INPUT_DEV, was introduced to indicate
>   whether the jack layer supports the input device,
> - A few items in snd_jack struct and relevant codes are conditionally
>   built upon CONFIG_SND_JACK_INPUT_DEV,
> - The users of CONFIG_SND_JACK drop the messy dependency on
>   CONFIG_INPUT.
> 
> This change also automagically fixes a potential bug in HD-audio
> driver Arnd reported, where the NULL or uninitialized jack instance is
> dereferenced.
> 
> Reported-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Takashi Iwai <tiwai@suse.de>
> 

Looks great, that indeed takes care of the issue I reported and
makes the code more useful and more robust overall.

Acked-by: Arnd Bergmann <arnd@arndb.de>

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