Re: linux-next: manual merge of the drm-misc tree with the origin tree

Re: linux-next: manual merge of the drm-misc tree with the origin tree

[Nathan Chancellor]

Hi Stephen,

On Wed, Nov 16, 2022 at 10:57:02AM +1100, Stephen Rothwell wrote:
> Hi all,
> 
> Today's linux-next merge of the drm-misc tree got a conflict in:
> 
>   drivers/gpu/drm/vc4/vc4_hdmi.c
> 
> between commit:
> 
>   682f99b8ae88 ("drm/vc4: hdmi: Take our lock to reset the link")
> 
> from the origin tree and commits:
> 
>   d218750805a3 ("drm/vc4: hdmi: Pass vc4_hdmi to vc4_hdmi_supports_scrambling()")
>   0a99962c0dbf ("drm/vc4: hdmi: Fix pointer dereference before check")
> 
> from the drm-misc tree.
> 
> I fixed it up (see below) and can carry the fix as necessary. This
> is now fixed as far as linux-next is concerned, but any non trivial
> conflicts should be mentioned to your upstream maintainer when your tree
> is submitted for merging.  You may also want to consider cooperating
> with the maintainer of the conflicting tree to minimise any particularly
> complex conflicts.
> 
> -- 
> Cheers,
> Stephen Rothwell
> 
> diff --cc drivers/gpu/drm/vc4/vc4_hdmi.c
> index d7fcc7a4c082,6b223a5fcf6f..000000000000
> --- a/drivers/gpu/drm/vc4/vc4_hdmi.c
> +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
> @@@ -349,12 -348,9 +348,13 @@@ static int vc4_hdmi_reset_link(struct d
>   	if (!crtc_state->active)
>   		return 0;
>   
>  +	mutex_lock(&vc4_hdmi->mutex);
>  +
> - 	if (!vc4_hdmi_supports_scrambling(encoder)) {
> + 	vc4_hdmi = connector_to_vc4_hdmi(connector);
>  -	if (!vc4_hdmi_supports_scrambling(vc4_hdmi))
> ++	if (!vc4_hdmi_supports_scrambling(vc4_hdmi)) {
>  +		mutex_unlock(&vc4_hdmi->mutex);
>   		return 0;
>  +	}
>   
>   	scrambling_needed = vc4_hdmi_mode_needs_scrambling(&vc4_hdmi->saved_adjusted_mode,
>   							   vc4_hdmi->output_bpc,

This resolution is not quite right, as pointed out by clang:

    drivers/gpu/drm/vc4/vc4_hdmi.c:351:14: error: variable 'vc4_hdmi' is uninitialized when used here [-Werror,-Wuninitialized]
            mutex_lock(&vc4_hdmi->mutex);
                        ^~~~~~~~
    ./include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
    #define mutex_lock(lock) mutex_lock_nested(lock, 0)
                                               ^~~~
    drivers/gpu/drm/vc4/vc4_hdmi.c:322:27: note: initialize the variable 'vc4_hdmi' to silence this warning
            struct vc4_hdmi *vc4_hdmi;
                                     ^
                                      = NULL
    1 error generated.

Obviously, the assignment of vc4_hdmi should be before mutex_lock().

Cheers,
Nathan

Re: linux-next: manual merge of the drm-misc tree with the origin tree

[Stephen Rothwell]

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Hi Nathan,

On Thu, 17 Nov 2022 10:29:33 -0700 Nathan Chancellor <nathan@kernel.org> wrote:
>
> This resolution is not quite right, as pointed out by clang:
> 
>     drivers/gpu/drm/vc4/vc4_hdmi.c:351:14: error: variable 'vc4_hdmi' is uninitialized when used here [-Werror,-Wuninitialized]
>             mutex_lock(&vc4_hdmi->mutex);
>                         ^~~~~~~~
>     ./include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
>     #define mutex_lock(lock) mutex_lock_nested(lock, 0)
>                                                ^~~~
>     drivers/gpu/drm/vc4/vc4_hdmi.c:322:27: note: initialize the variable 'vc4_hdmi' to silence this warning
>             struct vc4_hdmi *vc4_hdmi;
>                                      ^
>                                       = NULL
>     1 error generated.
> 
> Obviously, the assignment of vc4_hdmi should be before mutex_lock().

Thanks for pointing that out (silly me :-) ).  I have fixed up the
resolution for today.

-- 
Cheers,
Stephen Rothwell

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Re: linux-next: manual merge of the drm-misc tree with the origin tree

[Nathan Chancellor]

On Fri, Nov 18, 2022 at 09:06:36AM +1100, Stephen Rothwell wrote:
> Hi Nathan,
> 
> On Thu, 17 Nov 2022 10:29:33 -0700 Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > This resolution is not quite right, as pointed out by clang:
> > 
> >     drivers/gpu/drm/vc4/vc4_hdmi.c:351:14: error: variable 'vc4_hdmi' is uninitialized when used here [-Werror,-Wuninitialized]
> >             mutex_lock(&vc4_hdmi->mutex);
> >                         ^~~~~~~~
> >     ./include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
> >     #define mutex_lock(lock) mutex_lock_nested(lock, 0)
> >                                                ^~~~
> >     drivers/gpu/drm/vc4/vc4_hdmi.c:322:27: note: initialize the variable 'vc4_hdmi' to silence this warning
> >             struct vc4_hdmi *vc4_hdmi;
> >                                      ^
> >                                       = NULL
> >     1 error generated.
> > 
> > Obviously, the assignment of vc4_hdmi should be before mutex_lock().
> 
> Thanks for pointing that out (silly me :-) ).  I have fixed up the
> resolution for today.

Great, thank you so much! One less warning to worry about :)

Cheers,
Nathan

Re: linux-next: manual merge of the drm-misc tree with the origin tree

[Maxime Ripard]

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On Thu, Nov 17, 2022 at 05:01:08PM -0700, Nathan Chancellor wrote:
> On Fri, Nov 18, 2022 at 09:06:36AM +1100, Stephen Rothwell wrote:
> > Hi Nathan,
> > 
> > On Thu, 17 Nov 2022 10:29:33 -0700 Nathan Chancellor <nathan@kernel.org> wrote:
> > >
> > > This resolution is not quite right, as pointed out by clang:
> > > 
> > >     drivers/gpu/drm/vc4/vc4_hdmi.c:351:14: error: variable 'vc4_hdmi' is uninitialized when used here [-Werror,-Wuninitialized]
> > >             mutex_lock(&vc4_hdmi->mutex);
> > >                         ^~~~~~~~
> > >     ./include/linux/mutex.h:187:44: note: expanded from macro 'mutex_lock'
> > >     #define mutex_lock(lock) mutex_lock_nested(lock, 0)
> > >                                                ^~~~
> > >     drivers/gpu/drm/vc4/vc4_hdmi.c:322:27: note: initialize the variable 'vc4_hdmi' to silence this warning
> > >             struct vc4_hdmi *vc4_hdmi;
> > >                                      ^
> > >                                       = NULL
> > >     1 error generated.
> > > 
> > > Obviously, the assignment of vc4_hdmi should be before mutex_lock().
> > 
> > Thanks for pointing that out (silly me :-) ).  I have fixed up the
> > resolution for today.
> 
> Great, thank you so much! One less warning to worry about :)

I actually did the same conflict resolution in drm-tip. I've fixed it up
too, thanks for your report :)

Maxime

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