[PATCH 1/1] drm/amd/display: handle nulled pipe context in DCE110's set_drr()
tjakobi at math.uni-bielefeld.de
tjakobi at math.uni-bielefeld.de
Mon Sep 16 12:54:05 UTC 2024
From: Tobias Jakobi <tjakobi at math.uni-bielefeld.de>
As set_drr() is called from IRQ context, it can happen that the
pipe context has been nulled by dc_state_destruct().
Apply the same protection here that is already present for
dcn35_set_drr() and dcn10_set_drr(). I.e. fetch the tg pointer
first (to avoid a race with dc_state_destruct()), and then
check the local copy before using it.
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3142
Fixes: 06ad7e164256 ("drm/amd/display: Destroy DC context while keeping DML and DML2")
Signed-off-by: Tobias Jakobi <tjakobi at math.uni-bielefeld.de>
---
.../amd/display/dc/hwss/dce110/dce110_hwseq.c | 21 ++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c b/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
index 0d3ea291eeee..666dfc6d192e 100644
--- a/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
+++ b/drivers/gpu/drm/amd/display/dc/hwss/dce110/dce110_hwseq.c
@@ -1970,13 +1970,20 @@ static void set_drr(struct pipe_ctx **pipe_ctx,
* as well.
*/
for (i = 0; i < num_pipes; i++) {
- pipe_ctx[i]->stream_res.tg->funcs->set_drr(
- pipe_ctx[i]->stream_res.tg, ¶ms);
-
- if (adjust.v_total_max != 0 && adjust.v_total_min != 0)
- pipe_ctx[i]->stream_res.tg->funcs->set_static_screen_control(
- pipe_ctx[i]->stream_res.tg,
- event_triggers, num_frames);
+ /* dc_state_destruct() might null the stream resources, so fetch tg
+ * here first to avoid a race condition. The lifetime of the pointee
+ * itself (the timing_generator object) is not a problem here.
+ */
+ struct timing_generator *tg = pipe_ctx[i]->stream_res.tg;
+
+ if ((tg != NULL) && tg->funcs) {
+ if (tg->funcs->set_drr)
+ tg->funcs->set_drr(tg, ¶ms);
+ if (adjust.v_total_max != 0 && adjust.v_total_min != 0)
+ if (tg->funcs->set_static_screen_control)
+ tg->funcs->set_static_screen_control(
+ tg, event_triggers, num_frames);
+ }
}
}
--
2.44.2
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