[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[jianqi.ren.cn]

From: Wayne Lin <wayne.lin@amd.com>

[ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]

[Why]
When unplug one of monitors connected after mst hub, encounter null pointer dereference.

It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
commit new state which directly referring to info stored in dc_sink will cause null pointer
dereference.

[how]
Remove redundant checking condition. Relevant condition should already be covered by checking
if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 1acef5f3838f..a1619f4569cf 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -183,6 +183,8 @@ amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
 		dc_sink_release(dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 	}
 
 	aconnector->mst_status = MST_STATUS_DEFAULT;
@@ -487,6 +489,8 @@ dm_dp_mst_detect(struct drm_connector *connector,
 		dc_sink_release(aconnector->dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
 			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
-- 
2.25.1

Re: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: fcf6a49d79923a234844b8efe830a61f3f0584e4

WARNING: Author mismatch between patch and upstream commit:
Backport author: <jianqi.ren.cn@windriver.com>
Commit author: Wayne Lin <wayne.lin@amd.com>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: c7e65cab54a8)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  fcf6a49d79923 ! 1:  bb340e15684fc drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    @@ Metadata
      ## Commit message ##
         drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
     
    +    [ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
    +
         [Why]
         When unplug one of monitors connected after mst hub, encounter null pointer dereference.
     
    @@ Commit message
         Signed-off-by: Wayne Lin <wayne.lin@amd.com>
         Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
         Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    +    Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
     
      ## drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c ##
     @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
    @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: dm_dp_mst_detect(st
      
      		amdgpu_dm_set_mst_status(&aconnector->mst_status,
      			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
    -@@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: static bool is_dsc_need_re_compute(
    - 		if (!aconnector || !aconnector->dsc_aux)
    - 			continue;
    - 
    --		/*
    --		 *	check if cached virtual MST DSC caps are available and DSC is supported
    --		 *	as per specifications in their Virtual DPCD registers.
    --		*/
    --		if (!(aconnector->dc_sink->dsc_caps.dsc_dec_caps.is_dsc_supported ||
    --			aconnector->dc_link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT))
    --			continue;
    --
    - 		stream_on_link[new_stream_on_link_num] = aconnector;
    - 		new_stream_on_link_num++;
    - 
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |

Re: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

[Greg KH]

On Wed, Dec 11, 2024 at 06:15:44PM +0800, jianqi.ren.cn@windriver.com wrote:
> From: Wayne Lin <wayne.lin@amd.com>
> 
> [ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
> 
> [Why]
> When unplug one of monitors connected after mst hub, encounter null pointer dereference.
> 
> It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
> commit new state which directly referring to info stored in dc_sink will cause null pointer
> dereference.
> 
> [how]
> Remove redundant checking condition. Relevant condition should already be covered by checking
> if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.
> 
> Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
> Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
> Signed-off-by: Wayne Lin <wayne.lin@amd.com>
> Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
> Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
> ---
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
>  1 file changed, 4 insertions(+)

You sent this 3 times, all different, so I have no idea what to do.

Ok, I give up.  I'm deleting ALL of your pending stable patches from my
review queue now due to all of the problems that these have had.

Please work with a more experienced kernel developer at your company to
get these backports correct, and complete, and send them as a patch
series with the correct information and documentation as to what is
going on, so that we have a chance to get this right.

thanks,

greg k-h

Patch "[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute" has been added to the 5.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-don-t-refer-to-dc_sink-in-is_dsc_need_re_compute.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From jianqi.ren.cn@windriver.com  Thu Dec 12 13:11:21 2024
From: <jianqi.ren.cn@windriver.com>
Date: Wed, 11 Dec 2024 18:15:44 +0800
Subject: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
To: <wayne.lin@amd.com>, <gregkh@linuxfoundation.org>
Cc: <patches@lists.linux.dev>, <jerry.zuo@amd.com>, <zaeem.mohamed@amd.com>, <daniel.wheeler@amd.com>, <alexander.deucher@amd.com>, <stable@vger.kernel.org>, <harry.wentland@amd.com>, <sunpeng.li@amd.com>, <Rodrigo.Siqueira@amd.com>, <christian.koenig@amd.com>, <airlied@gmail.com>, <daniel@ffwll.ch>, <Jerry.Zuo@amd.com>, <amd-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
Message-ID: <20241211101544.2121147-1-jianqi.ren.cn@windriver.com>


From: Wayne Lin <wayne.lin@amd.com>

[ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]

[Why]
When unplug one of monitors connected after mst hub, encounter null pointer dereference.

It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
commit new state which directly referring to info stored in dc_sink will cause null pointer
dereference.

[how]
Remove redundant checking condition. Relevant condition should already be covered by checking
if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 1acef5f3838f..a1619f4569cf 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -183,6 +183,8 @@ amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
 		dc_sink_release(dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 	}
 
 	aconnector->mst_status = MST_STATUS_DEFAULT;
@@ -487,6 +489,8 @@ dm_dp_mst_detect(struct drm_connector *connector,
 		dc_sink_release(aconnector->dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
 			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
-- 
2.25.1



Patches currently in stable-queue which might be from jianqi.ren.cn@windriver.com are

queue-5.4/drm-amd-display-don-t-refer-to-dc_sink-in-is_dsc_need_re_compute.patch

Patch "[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute" has been added to the 5.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-don-t-refer-to-dc_sink-in-is_dsc_need_re_compute.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From jianqi.ren.cn@windriver.com  Thu Dec 12 13:11:21 2024
From: <jianqi.ren.cn@windriver.com>
Date: Wed, 11 Dec 2024 18:15:44 +0800
Subject: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
To: <wayne.lin@amd.com>, <gregkh@linuxfoundation.org>
Cc: <patches@lists.linux.dev>, <jerry.zuo@amd.com>, <zaeem.mohamed@amd.com>, <daniel.wheeler@amd.com>, <alexander.deucher@amd.com>, <stable@vger.kernel.org>, <harry.wentland@amd.com>, <sunpeng.li@amd.com>, <Rodrigo.Siqueira@amd.com>, <christian.koenig@amd.com>, <airlied@gmail.com>, <daniel@ffwll.ch>, <Jerry.Zuo@amd.com>, <amd-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
Message-ID: <20241211101544.2121147-1-jianqi.ren.cn@windriver.com>


From: Wayne Lin <wayne.lin@amd.com>

[ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]

[Why]
When unplug one of monitors connected after mst hub, encounter null pointer dereference.

It's due to dc_sink get released immediately in early_unregister() or detect_ctx(). When
commit new state which directly referring to info stored in dc_sink will cause null pointer
dereference.

[how]
Remove redundant checking condition. Relevant condition should already be covered by checking
if dsc_aux is null or not. Also reset dsc_aux to NULL when the connector is disconnected.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
index 1acef5f3838f..a1619f4569cf 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c
@@ -183,6 +183,8 @@ amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
 		dc_sink_release(dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 	}
 
 	aconnector->mst_status = MST_STATUS_DEFAULT;
@@ -487,6 +489,8 @@ dm_dp_mst_detect(struct drm_connector *connector,
 		dc_sink_release(aconnector->dc_sink);
 		aconnector->dc_sink = NULL;
 		aconnector->edid = NULL;
+		aconnector->dsc_aux = NULL;
+		port->passthrough_aux = NULL;
 
 		amdgpu_dm_set_mst_status(&aconnector->mst_status,
 			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
-- 
2.25.1



Patches currently in stable-queue which might be from jianqi.ren.cn@windriver.com are

queue-5.4/drm-amd-display-don-t-refer-to-dc_sink-in-is_dsc_need_re_compute.patch

Re: Patch "[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute" has been added to the 5.4-stable tree

[Sasha Levin]

[ Sasha's backport helper bot ]

Hi,

The upstream commit SHA1 provided is correct: fcf6a49d79923a234844b8efe830a61f3f0584e4

WARNING: Author mismatch between patch and upstream commit:
Backport author: <gregkh@linuxfoundation.org>
Commit author: Wayne Lin <wayne.lin@amd.com>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.6.y | Present (different SHA1: c7e65cab54a8)
6.1.y | Not found

Note: The patch differs from the upstream commit:
---
1:  fcf6a49d79923 ! 1:  79f06b6c107fd drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    @@
      ## Metadata ##
    -Author: Wayne Lin <wayne.lin@amd.com>
    +Author: gregkh@linuxfoundation.org <gregkh@linuxfoundation.org>
     
      ## Commit message ##
    -    drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    +    Patch "[PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute" has been added to the 5.4-stable tree
    +
    +    This is a note to let you know that I've just added the patch titled
    +
    +        [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    +
    +    to the 5.4-stable tree which can be found at:
    +        http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
    +
    +    The filename of the patch is:
    +         drm-amd-display-don-t-refer-to-dc_sink-in-is_dsc_need_re_compute.patch
    +    and it can be found in the queue-5.4 subdirectory.
    +
    +    If you, or anyone else, feels it should not be added to the stable tree,
    +    please let <stable@vger.kernel.org> know about it.
    +
    +    From jianqi.ren.cn@windriver.com  Thu Dec 12 13:11:21 2024
    +    From: <jianqi.ren.cn@windriver.com>
    +    Date: Wed, 11 Dec 2024 18:15:44 +0800
    +    Subject: [PATCH 6.1.y] drm/amd/display: Don't refer to dc_sink in is_dsc_need_re_compute
    +    To: <wayne.lin@amd.com>, <gregkh@linuxfoundation.org>
    +    Cc: <patches@lists.linux.dev>, <jerry.zuo@amd.com>, <zaeem.mohamed@amd.com>, <daniel.wheeler@amd.com>, <alexander.deucher@amd.com>, <stable@vger.kernel.org>, <harry.wentland@amd.com>, <sunpeng.li@amd.com>, <Rodrigo.Siqueira@amd.com>, <christian.koenig@amd.com>, <airlied@gmail.com>, <daniel@ffwll.ch>, <Jerry.Zuo@amd.com>, <amd-gfx@lists.freedesktop.org>, <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
    +    Message-ID: <20241211101544.2121147-1-jianqi.ren.cn@windriver.com>
    +
    +    From: Wayne Lin <wayne.lin@amd.com>
    +
    +    [ Upstream commit fcf6a49d79923a234844b8efe830a61f3f0584e4 ]
     
         [Why]
         When unplug one of monitors connected after mst hub, encounter null pointer dereference.
    @@ Commit message
         Signed-off-by: Wayne Lin <wayne.lin@amd.com>
         Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
         Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
    +    Signed-off-by: Jianqi Ren <jianqi.ren.cn@windriver.com>
     
      ## drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c ##
     @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: amdgpu_dm_mst_connector_early_unregister(struct drm_connector *connector)
    @@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: dm_dp_mst_detect(st
      
      		amdgpu_dm_set_mst_status(&aconnector->mst_status,
      			MST_REMOTE_EDID | MST_ALLOCATE_NEW_PAYLOAD | MST_CLEAR_ALLOCATED_PAYLOAD,
    -@@ drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c: static bool is_dsc_need_re_compute(
    - 		if (!aconnector || !aconnector->dsc_aux)
    - 			continue;
    - 
    --		/*
    --		 *	check if cached virtual MST DSC caps are available and DSC is supported
    --		 *	as per specifications in their Virtual DPCD registers.
    --		*/
    --		if (!(aconnector->dc_sink->dsc_caps.dsc_dec_caps.is_dsc_supported ||
    --			aconnector->dc_link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT))
    --			continue;
    --
    - 		stream_on_link[new_stream_on_link_num] = aconnector;
    - 		new_stream_on_link_num++;
    - 
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.1.y        |  Success    |  Success   |
| stable/linux-5.4.y        |  Failed     |  N/A       |