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drm/amd/display: Fix double free during GPU reset on DC streams

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[Why]
The issue only occurs during the GPU reset code path.

We first backup the current state prior to commiting 0 streams
internally from DM to DC. This state backup contains valid link
encoder assignments.

DC will clear the link encoder assignments as part of current state
(but not the backup, since it was a copied before the commit) and
free the extra stream reference it held.

DC requires that the link encoder assignments remain cleared/invalid
prior to commiting. Since the backup still has valid assignments we
call the interface post reset to clear them. This routine also
releases the extra reference that the link encoder interface held -
resulting in a double free (and eventually a NULL pointer dereference).

[How]
We'll have to do a full DC commit anyway after GPU reset because
the stream count previously went to 0.

We don't need to retain the assignment that we had backed up, so
just copy off of the now clean current state assignment after the
reset has occcurred with the new link_enc_cfg_copy() interface.

Fixes: 6d63fcc2a3 ("drm/amd/display: Reset link encoder assignments for GPU reset")

Reviewed-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Nicholas Kazlauskas 2022-02-28 10:48:56 -05:00 committed by Alex Deucher
parent 84ce38c7bf
commit 32685b32d8
3 changed files with 18 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
View File

@ -2633,10 +2633,13 @@ static int dm_resume(void *handle)
* before the 0 streams commit. * before the 0 streams commit.
* *
* DC expects that link encoder assignments are *not* valid * DC expects that link encoder assignments are *not* valid
* when committing a state, so as a workaround it needs to be * when committing a state, so as a workaround we can copy
* cleared here. * off of the current state.
*
* We lose the previous assignments, but we had already
* commit 0 streams anyway.
*/ */
link_enc_cfg_init(dm->dc, dc_state); link_enc_cfg_copy(adev->dm.dc->current_state, dc_state);
if (dc_enable_dmub_notifications(adev->dm.dc)) if (dc_enable_dmub_notifications(adev->dm.dc))
amdgpu_dm_outbox_init(adev); amdgpu_dm_outbox_init(adev);

7
drivers/gpu/drm/amd/display/dc/core/dc_link_enc_cfg.c
View File

@ -272,6 +272,13 @@ void link_enc_cfg_init(
state->res_ctx.link_enc_cfg_ctx.mode = LINK_ENC_CFG_STEADY; state->res_ctx.link_enc_cfg_ctx.mode = LINK_ENC_CFG_STEADY;
} }
void link_enc_cfg_copy(const struct dc_state *src_ctx, struct dc_state *dst_ctx)
{
memcpy(&dst_ctx->res_ctx.link_enc_cfg_ctx,
&src_ctx->res_ctx.link_enc_cfg_ctx,
sizeof(dst_ctx->res_ctx.link_enc_cfg_ctx));
}
void link_enc_cfg_link_encs_assign( void link_enc_cfg_link_encs_assign(
struct dc *dc, struct dc *dc,
struct dc_state *state, struct dc_state *state,

5
drivers/gpu/drm/amd/display/dc/inc/link_enc_cfg.h
View File

@ -39,6 +39,11 @@ void link_enc_cfg_init(
const struct dc *dc, const struct dc *dc,
struct dc_state *state); struct dc_state *state);
/*
* Copies a link encoder assignment from another state.
*/
void link_enc_cfg_copy(const struct dc_state *src_ctx, struct dc_state *dst_ctx);
/* /*
* Algorithm for assigning available DIG link encoders to streams. * Algorithm for assigning available DIG link encoders to streams.
* *