[Intel-gfx] [PATCH 06/22] drm/bridge: Use drm_mode_copy()

Ville Syrjala ville.syrjala at linux.intel.com
Fri Feb 18 10:03:47 UTC 2022

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

struct drm_display_mode embeds a list head, so overwriting
the full struct with another one will corrupt the list
(if the destination mode is on a list). Use drm_mode_copy()
instead which explicitly preserves the list head of
the destination mode.

Even if we know the destination mode is not on any list
using drm_mode_copy() seems decent as it sets a good
example. Bad examples of not using it might eventually
get copied into code where preserving the list head
actually matters.

Obviously one case not covered here is when the mode
itself is embedded in a larger structure and the whole
structure is copied. But if we are careful when copying
into modes embedded in structures I think we can be a
little more reassured that bogus list heads haven't been
propagated in.


@depends on !is_mode_copy@
struct drm_display_mode *mode;
expression E, S;
- *mode = E
+ drm_mode_copy(mode, &E)
- memcpy(mode, E, S)
+ drm_mode_copy(mode, E)

@depends on !is_mode_copy@
struct drm_display_mode mode;
expression E;
- mode = E
+ drm_mode_copy(&mode, &E)
- memcpy(&mode, E, S)
+ drm_mode_copy(&mode, E)

struct drm_display_mode *mode;
- &*mode
+ mode

Cc: Andrzej Hajda <andrzej.hajda at intel.com>
Cc: Neil Armstrong <narmstrong at baylibre.com>
Cc: Robert Foss <robert.foss at linaro.org>
Cc: Laurent Pinchart <Laurent.pinchart at ideasonboard.com>
Cc: Jonas Karlman <jonas at kwiboo.se>
Cc: Jernej Skrabec <jernej.skrabec at gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
 drivers/gpu/drm/bridge/nwl-dsi.c          | 2 +-
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 2 +-
 drivers/gpu/drm/bridge/tc358767.c         | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/nwl-dsi.c b/drivers/gpu/drm/bridge/nwl-dsi.c
index 963a6794735f..881cf338d5cf 100644
--- a/drivers/gpu/drm/bridge/nwl-dsi.c
+++ b/drivers/gpu/drm/bridge/nwl-dsi.c
@@ -857,7 +857,7 @@ nwl_dsi_bridge_mode_set(struct drm_bridge *bridge,
 	/* Save the new desired phy config */
 	memcpy(&dsi->phy_cfg, &new_cfg, sizeof(new_cfg));
-	memcpy(&dsi->mode, adjusted_mode, sizeof(dsi->mode));
+	drm_mode_copy(&dsi->mode, adjusted_mode);
 	if (pm_runtime_resume_and_get(dev) < 0)
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 4befc104d220..a563460f8d20 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2830,7 +2830,7 @@ static void dw_hdmi_bridge_mode_set(struct drm_bridge *bridge,
 	/* Store the display mode for plugin/DKMS poweron events */
-	memcpy(&hdmi->previous_mode, mode, sizeof(hdmi->previous_mode));
+	drm_mode_copy(&hdmi->previous_mode, mode);
diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index c23e0abc65e8..7f9574b17caa 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1312,7 +1312,7 @@ static void tc_bridge_mode_set(struct drm_bridge *bridge,
 	struct tc_data *tc = bridge_to_tc(bridge);
-	tc->mode = *mode;
+	drm_mode_copy(&tc->mode, mode);
 static struct edid *tc_get_edid(struct drm_bridge *bridge,

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