[PATCH 5.16 016/164] drm/amd/display: Fix stream->link_enc unassigned during stream removal

Greg Kroah-Hartman
2022-02-28T18:01:05Z

From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

commit 3743e7f6fcb938b7d8b7967e6a9442805e269b3d upstream.

[Why]
Found when running igt@kms_atomic.

Userspace attempts to do a TEST_COMMIT when 0 streams which calls
dc_remove_stream_from_ctx. This in turn calls link_enc_unassign
which ends up modifying stream->link = NULL directly, causing the
global link_enc to be removed preventing further link activity
and future link validation from passing.

[How]
We take care of link_enc unassignment at the start of
link_enc_cfg_link_encs_assign so this call is no longer necessary.

Fixes global state from being modified while unlocked.

Reviewed-by: Jimmy Kizito <Jimmy.Kizito@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@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>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 4 ----
1 file changed, 4 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -1876,10 +1876,6 @@ enum dc_status dc_remove_stream_from_ctx
dc->res_pool,
del_pipe->stream_res.stream_enc,
false);
- /* Release link encoder from stream in new dc_state. */
- if (dc->res_pool->funcs->link_enc_unassign)
- dc->res_pool->funcs->link_enc_unassign(new_ctx, del_pipe->stream);
-
#if defined(CONFIG_DRM_AMD_DC_DCN)
if (is_dp_128b_132b_signal(del_pipe)) {
update_hpo_dp_stream_engine_usage(