linux-kernel - [PATCH AUTOSEL 6.1 13/61] drm/amd/display: Spinlock before reading event

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Message-ID: <20240801002803.3935985-13-sashal@kernel.org>
Date: Wed, 31 Jul 2024 20:25:31 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Alex Hung <alex.hung@....com>,
	Harry Wentland <harry.wentland@....com>,
	Tom Chung <chiahsuan.chung@....com>,
	Daniel Wheeler <daniel.wheeler@....com>,
	Alex Deucher <alexander.deucher@....com>,
	Sasha Levin <sashal@...nel.org>,
	sunpeng.li@....com,
	Rodrigo.Siqueira@....com,
	christian.koenig@....com,
	Xinhui.Pan@....com,
	airlied@...il.com,
	daniel@...ll.ch,
	hamza.mahfooz@....com,
	roman.li@....com,
	mario.limonciello@....com,
	Wayne.Lin@....com,
	amd-gfx@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 6.1 13/61] drm/amd/display: Spinlock before reading event

From: Alex Hung <alex.hung@....com>

[ Upstream commit ae13c8a5cff92015b9a3eb7cee65ebc75859487f ]

[WHY & HOW]
A read of acrtc_attach->base.state->event was not locked so moving it
inside the spinlock.

This fixes a LOCK_EVASION issue reported by Coverity.

Reviewed-by: Harry Wentland <harry.wentland@....com>
Acked-by: Tom Chung <chiahsuan.chung@....com>
Signed-off-by: Alex Hung <alex.hung@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 160811ac1fb97..2c6caddf1de34 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8052,15 +8052,13 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
 				bundle->stream_update.vrr_infopacket =
 					&acrtc_state->stream->vrr_infopacket;
 		}
-	} else if (cursor_update && acrtc_state->active_planes > 0 &&
-		   acrtc_attach->base.state->event) {
-		drm_crtc_vblank_get(pcrtc);
-
+	} else if (cursor_update && acrtc_state->active_planes > 0) {
 		spin_lock_irqsave(&pcrtc->dev->event_lock, flags);
-
-		acrtc_attach->event = acrtc_attach->base.state->event;
-		acrtc_attach->base.state->event = NULL;
-
+		if (acrtc_attach->base.state->event) {
+			drm_crtc_vblank_get(pcrtc);
+			acrtc_attach->event = acrtc_attach->base.state->event;
+			acrtc_attach->base.state->event = NULL;
+		}
 		spin_unlock_irqrestore(&pcrtc->dev->event_lock, flags);
 	}
 
-- 
2.43.0