Hi Ville,
Thank you for the patch.
On Fri, Feb 18, 2022 at 12:03:47PM +0200, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@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.
@is_mode_copy@ @@ drm_mode_copy(...) { ... }
@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@intel.com Cc: Neil Armstrong narmstrong@baylibre.com Cc: Robert Foss robert.foss@linaro.org Cc: Laurent Pinchart Laurent.pinchart@ideasonboard.com Cc: Jonas Karlman jonas@kwiboo.se Cc: Jernej Skrabec jernej.skrabec@gmail.com Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Laurent Pinchart laurent.pinchart@ideasonboard.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); drm_mode_debug_printmodeline(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, mutex_lock(&hdmi->mutex);
/* 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);
mutex_unlock(&hdmi->mutex);
} 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,