drm/amd/display: Fix variable dereferenced before check

[PATCH] drm/amd/display: Fix variable dereferenced before check

Posted by sunliming 3 years, 7 months ago

Fixes the following smatch warning:

drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:311 dc_dmub_srv_p_state_delegate()
warn: variable dereferenced before check 'dc' (see line 309)

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: sunliming <sunliming@kylinos.cn>
---
 drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
index 09b304507bad..ebf99e8f93e0 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
+++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
@@ -323,11 +323,13 @@ bool dc_dmub_srv_p_state_delegate(struct dc *dc, bool should_manage_pstate, stru
 	struct dmub_cmd_fw_assisted_mclk_switch_config *config_data = &cmd.fw_assisted_mclk_switch.config_data;
 	int i = 0;
 	int ramp_up_num_steps = 1; // TODO: Ramp is currently disabled. Reenable it.
-	uint8_t visual_confirm_enabled = dc->debug.visual_confirm == VISUAL_CONFIRM_FAMS;
+	uint8_t visual_confirm_enabled;
 
 	if (dc == NULL)
 		return false;
 
+	visual_confirm_enabled = dc->debug.visual_confirm == VISUAL_CONFIRM_FAMS;
+
 	// Format command.
 	cmd.fw_assisted_mclk_switch.header.type = DMUB_CMD__FW_ASSISTED_MCLK_SWITCH;
 	cmd.fw_assisted_mclk_switch.header.sub_type = DMUB_CMD__FAMS_SETUP_FW_CTRL;
-- 
2.25.1

Re: [PATCH] drm/amd/display: Fix variable dereferenced before check

Posted by Alex Deucher 3 years, 7 months ago

Applied.  Thanks!

Alex

On Fri, Aug 26, 2022 at 4:41 AM sunliming <sunliming@kylinos.cn> wrote:
>
> Fixes the following smatch warning:
>
> drivers/gpu/drm/amd/amdgpu/../display/dc/dc_dmub_srv.c:311 dc_dmub_srv_p_state_delegate()
> warn: variable dereferenced before check 'dc' (see line 309)
>
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: sunliming <sunliming@kylinos.cn>
> ---
>  drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> index 09b304507bad..ebf99e8f93e0 100644
> --- a/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> +++ b/drivers/gpu/drm/amd/display/dc/dc_dmub_srv.c
> @@ -323,11 +323,13 @@ bool dc_dmub_srv_p_state_delegate(struct dc *dc, bool should_manage_pstate, stru
>         struct dmub_cmd_fw_assisted_mclk_switch_config *config_data = &cmd.fw_assisted_mclk_switch.config_data;
>         int i = 0;
>         int ramp_up_num_steps = 1; // TODO: Ramp is currently disabled. Reenable it.
> -       uint8_t visual_confirm_enabled = dc->debug.visual_confirm == VISUAL_CONFIRM_FAMS;
> +       uint8_t visual_confirm_enabled;
>
>         if (dc == NULL)
>                 return false;
>
> +       visual_confirm_enabled = dc->debug.visual_confirm == VISUAL_CONFIRM_FAMS;
> +
>         // Format command.
>         cmd.fw_assisted_mclk_switch.header.type = DMUB_CMD__FW_ASSISTED_MCLK_SWITCH;
>         cmd.fw_assisted_mclk_switch.header.sub_type = DMUB_CMD__FAMS_SETUP_FW_CTRL;
> --
> 2.25.1
>