linux-kernel - RE: [PATCH] drm/radeon: remove code that can never get executed

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Date:	Mon, 13 Oct 2014 17:31:12 +0000
From:	"Deucher, Alexander" <Alexander.Deucher@....com>
To:	Henning Schild <henning@...nsch.de>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Rafał Miłecki <zajec5@...il.com>
Subject: RE: [PATCH] drm/radeon: remove code that can never get executed

> -----Original Message-----
> From: Henning Schild [mailto:henning@...nsch.de]
> Sent: Monday, October 13, 2014 12:44 PM
> To: Deucher, Alexander; linux-kernel@...r.kernel.org
> Cc: Rafał Miłecki
> Subject: RE: [PATCH] drm/radeon: remove code that can never get executed
> 
> Well i am not sure what the code actually is supposed to do. That is up to you
> because you know the hardware. I just wanted to point out that right now
> some
> code can never be reached.
> 
> I ran into the whole thing because the pointer (sadp) that gets kfreed was
> never
> initialized (in one of the three cases). My first fix was to initialize it to
> NULL, that way the kfree did not fail even if the allocation did not do
> anything. Then i found the other two copies and decided to follow their
> scheme.
> 
> In your patch you have to make kfree depend on (sad_count > 0) or sadp
> needs to
> be initialized with NULL. Otherwise you will get the dangling pointer kfree
> that
> lead me to read this code.
> 

Ah, ok.  The attached patches should do the trick then.

Alex

> Henning
> 
> > On October 13, 2014 at 6:08 PM "Deucher, Alexander"
> > <Alexander.Deucher@....com> wrote:
> >
> > > -----Original Message-----
> > > From: Henning Schild [mailto:henning@...nsch.de]
> > > Sent: Saturday, October 11, 2014 8:51 AM
> > > To: linux-kernel@...r.kernel.org
> > > Cc: Henning Schild; Deucher, Alexander; Rafał Miłecki
> > > Subject: [PATCH] drm/radeon: remove code that can never get executed
> > >
> > > Removing a code-path that can never be executed ... and its copies. If
> > > drm_edid_to_speaker_allocation returns 0 the callers return. There is no
> > > need to check that condition again.
> >
> > I think we actually want to set the speaker allocation setup to stereo if the
> > speaker allocation block is not present so I think the attached patch is
> > probably the proper fix.
> >
> > Alex
> >
> > >
> > > Signed-off-by: Henning Schild <henning@...nsch.de>
> > > ---
> > > drivers/gpu/drm/radeon/dce3_1_afmt.c | 5 +----
> > > drivers/gpu/drm/radeon/dce6_afmt.c | 5 +----
> > > drivers/gpu/drm/radeon/evergreen_hdmi.c | 5 +----
> > > 3 files changed, 3 insertions(+), 12 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/radeon/dce3_1_afmt.c
> > > b/drivers/gpu/drm/radeon/dce3_1_afmt.c
> > > index cb76074..6d31ed8 100644
> > > --- a/drivers/gpu/drm/radeon/dce3_1_afmt.c
> > > +++ b/drivers/gpu/drm/radeon/dce3_1_afmt.c
> > > @@ -58,10 +58,7 @@ static void
> > > dce3_2_afmt_write_speaker_allocation(struct drm_encoder *encoder)
> > > tmp &= ~(DP_CONNECTION | SPEAKER_ALLOCATION_MASK);
> > > /* set HDMI mode */
> > > tmp |= HDMI_CONNECTION;
> > > - if (sad_count)
> > > - tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > - else
> > > - tmp |= SPEAKER_ALLOCATION(5); /* stereo */
> > > + tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > WREG32(AZ_F0_CODEC_PIN0_CONTROL_CHANNEL_SPEAKER, tmp);
> > >
> > > kfree(sadb);
> > > diff --git a/drivers/gpu/drm/radeon/dce6_afmt.c
> > > b/drivers/gpu/drm/radeon/dce6_afmt.c
> > > index ab29f95..e6b2750 100644
> > > --- a/drivers/gpu/drm/radeon/dce6_afmt.c
> > > +++ b/drivers/gpu/drm/radeon/dce6_afmt.c
> > > @@ -186,10 +186,7 @@ void dce6_afmt_write_speaker_allocation(struct
> > > drm_encoder *encoder)
> > > tmp &= ~(DP_CONNECTION | SPEAKER_ALLOCATION_MASK);
> > > /* set HDMI mode */
> > > tmp |= HDMI_CONNECTION;
> > > - if (sad_count)
> > > - tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > - else
> > > - tmp |= SPEAKER_ALLOCATION(5); /* stereo */
> > > + tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > WREG32_ENDPOINT(offset,
> > > AZ_F0_CODEC_PIN_CONTROL_CHANNEL_SPEAKER, tmp);
> > >
> > > kfree(sadb);
> > > diff --git a/drivers/gpu/drm/radeon/evergreen_hdmi.c
> > > b/drivers/gpu/drm/radeon/evergreen_hdmi.c
> > > index 278c7a1..11a6b65 100644
> > > --- a/drivers/gpu/drm/radeon/evergreen_hdmi.c
> > > +++ b/drivers/gpu/drm/radeon/evergreen_hdmi.c
> > > @@ -128,10 +128,7 @@ static void
> > > dce4_afmt_write_speaker_allocation(struct drm_encoder *encoder)
> > > tmp &= ~(DP_CONNECTION | SPEAKER_ALLOCATION_MASK);
> > > /* set HDMI mode */
> > > tmp |= HDMI_CONNECTION;
> > > - if (sad_count)
> > > - tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > - else
> > > - tmp |= SPEAKER_ALLOCATION(5); /* stereo */
> > > + tmp |= SPEAKER_ALLOCATION(sadb[0]);
> > > WREG32(AZ_F0_CODEC_PIN0_CONTROL_CHANNEL_SPEAKER, tmp);
> > >
> > > kfree(sadb);
> > > --
> > > 2.0.4
> 
> >

Download attachment "0001-drm-radeon-initialize-sadb-to-NULL-in-the-audio-code.patch" of type "application/octet-stream" (2113 bytes)

Download attachment "0002-drm-radeon-fix-speaker-allocation-setup.patch" of type "application/octet-stream" (2640 bytes)