drm/amd/display: check top_pipe_to_program pointer

[ Upstream commit a689e8d1f80012f90384ebac9dcfac4201f9f77e ]

Clang static analysis reports this error

drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc.c:2870:7: warning:
Dereference of null pointer [clang-analyzer-core.NullDereference]
                if
(top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
                    ^

top_pipe_to_program being NULL is caught as an error
But then it is used to report the error.

So add a check before using it.

Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index c798c65d42765998971d2cda33bb03393aeec71d..1860ccc3f4f2c9d7154f89d8e2d152fd656edc26 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -2703,7 +2703,8 @@ static void commit_planes_for_stream(struct dc *dc,
 #endif
 
        if ((update_type != UPDATE_TYPE_FAST) && stream->update_flags.bits.dsc_changed)
-               if (top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
+               if (top_pipe_to_program &&
+                       top_pipe_to_program->stream_res.tg->funcs->lock_doublebuffer_enable) {
                        if (should_use_dmub_lock(stream->link)) {
                                union dmub_hw_lock_flags hw_locks = { 0 };
                                struct dmub_hw_lock_inst_flags inst_flags = { 0 };