Patch "drm/amd/display: handle nulled pipe context in DCE110's set_drr()" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    drm/amd/display: handle nulled pipe context in DCE110's set_drr()

to the 6.10-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-handle-nulled-pipe-context-in-dce110.patch
and it can be found in the queue-6.10 subdirectory.

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



commit 719a527402641c4c7a64dc60a1b3167caca18a26
Author: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
Date:   Mon Sep 16 14:54:05 2024 +0200

    drm/amd/display: handle nulled pipe context in DCE110's set_drr()
    
    [ Upstream commit e7d4e1438533abe448813bdc45691f9c230aa307 ]
    
    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")
    Acked-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Tobias Jakobi <tjakobi@xxxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

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 e9e9f80a02a77..542d669bf5e30 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
@@ -2020,13 +2020,20 @@ 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, &params);
-
-		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, &params);
+			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);
+		}
 	}
 }