From the comments of drm_for_each_connector_iter(), we know

that "connector is only valid within the list body, if you want to use connector after calling drm_connector_list_iter_end() then you need to grab your own reference first using drm_connector_get()". So fix the wrong use of connector according to the comments and then call drm_connector_put() after using connector finishes.

Signed-off-by: He Ying heying24@huawei.com ---

V2: Use proper subject prefix

drivers/gpu/drm/sun4i/sun4i_tcon.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 9f06dec0fc61..24fa6784ee5f 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -47,12 +47,12 @@ static struct drm_connector *sun4i_tcon_get_connector(const struct drm_encoder * drm_connector_list_iter_begin(encoder->dev, &iter); drm_for_each_connector_iter(connector, &iter) if (connector->encoder == encoder) { - drm_connector_list_iter_end(&iter); - return connector; + drm_connector_get(connector); + break; } drm_connector_list_iter_end(&iter);

- return NULL; + return connector; }

static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder) @@ -65,6 +65,7 @@ static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder) return -EINVAL;

info = &connector->display_info; + drm_connector_put(connector); if (info->num_bus_formats != 1) return -EINVAL;

@@ -361,6 +362,7 @@ static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon *tcon, /* TODO support normal CPU interface modes */ struct sun6i_dsi *dsi = encoder_to_sun6i_dsi(encoder); struct mipi_dsi_device *device = dsi->device; + struct drm_connector *connector; u8 bpp = mipi_dsi_pixel_format_to_bpp(device->format); u8 lanes = device->lanes; u32 block_space, start_delay; @@ -372,7 +374,9 @@ static void sun4i_tcon0_mode_set_cpu(struct sun4i_tcon *tcon, sun4i_tcon0_mode_set_common(tcon, mode);

/* Set dithering if needed */ - sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder)); + connector = sun4i_tcon_get_connector(encoder); + sun4i_tcon0_mode_set_dithering(tcon, connector); + drm_connector_put(connector);

regmap_update_bits(tcon->regs, SUN4I_TCON0_CTL_REG, SUN4I_TCON0_CTL_IF_MASK, @@ -430,6 +434,7 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon, const struct drm_display_mode *mode) { unsigned int bp; + struct drm_connector *connector; u8 clk_delay; u32 reg, val = 0;

@@ -440,7 +445,9 @@ static void sun4i_tcon0_mode_set_lvds(struct sun4i_tcon *tcon, sun4i_tcon0_mode_set_common(tcon, mode);

/* Set dithering if needed */ - sun4i_tcon0_mode_set_dithering(tcon, sun4i_tcon_get_connector(encoder)); + connector = sun4i_tcon_get_connector(encoder); + sun4i_tcon0_mode_set_dithering(tcon, connector); + drm_connector_put(connector);

/* Adjust clock delay */ clk_delay = sun4i_tcon_get_clk_delay(mode, 0); @@ -518,6 +525,7 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,

/* Set dithering if needed */ sun4i_tcon0_mode_set_dithering(tcon, connector); + drm_connector_put(connector);

/* Adjust clock delay */ clk_delay = sun4i_tcon_get_clk_delay(mode, 0);

在 2021/11/2 23:03, Maxime Ripard 写道:

Hi,

On Tue, Nov 02, 2021 at 04:46:28AM -0400, He Ying wrote:

...

From the comments of drm_for_each_connector_iter(), we know that "connector is only valid within the list body, if you want to use connector after calling drm_connector_list_iter_end() then you need to grab your own reference first using drm_connector_get()". So fix the wrong use of connector according to the comments and then call drm_connector_put() after using connector finishes.

Signed-off-by: He Ying heying24@huawei.com

V2: Use proper subject prefix

drivers/gpu/drm/sun4i/sun4i_tcon.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c index 9f06dec0fc61..24fa6784ee5f 100644 --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c @@ -47,12 +47,12 @@ static struct drm_connector *sun4i_tcon_get_connector(const struct drm_encoder * drm_connector_list_iter_begin(encoder->dev, &iter); drm_for_each_connector_iter(connector, &iter) if (connector->encoder == encoder) {

• 	drm_connector_list_iter_end(&iter);
  

• 	return connector;
  

• 	drm_connector_get(connector);
  

• 	break;
  

  } drm_connector_list_iter_end(&iter);

• return NULL;

• return connector;

Connector might be uninitialized if we don't find one here

Connector should be NULL if we don't find one. The code is

#define drm_for_each_connector_iter(connector, iter) \    while ((connector = drm_connector_list_iter_next(iter)))

So, when we don't break from the while body, connector

can only be NULL.

...

}

static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder) @@ -65,6 +65,7 @@ static int sun4i_tcon_get_pixel_depth(const struct drm_encoder *encoder) return -EINVAL;

info = &connector->display_info;

• drm_connector_put(connector); if (info->num_bus_formats != 1)

We're still accessing connector->display_info here, but it might have been freed already.

Agree. I'll place it after using 'info' finishes in v3.

Maxime