2019-09-30 20:41:48

by Rodrigo Siqueira Jordao

[permalink] [raw]
Subject: [PATCH] drm/amdgpu: Initialize variable before use

The 'debug_data' variable gets printed in debug statements without a
prior initialization in the function
hubbub1_verify_allow_pstate_change_high, as reported when building with
gcc 9.1.0:

warning: ‘debug_data’ may be used uninitialized in this function [-Wmaybe-uninitialized]
290 | printk##once(KERN_##level "[" DRM_NAME "] " fmt, ##__VA_ARGS__)
| ^~~~~~
dc/dcn10/dcn10_hubbub.c:134:15: note: ‘debug_data’ was declared here
134 | unsigned int debug_data;

Note that initialize debug_data with 0, in this case, is safe because we
have a loop in a few lines below that will initialize this variable with
the proper value.

Signed-off-by: Rodrigo Siqueira <[email protected]>
---
drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
index a780057e2dbc..b6967a7e6c7b 100644
--- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
+++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
@@ -133,7 +133,7 @@ bool hubbub1_verify_allow_pstate_change_high(
static unsigned int max_sampled_pstate_wait_us; /* data collection */
static bool forced_pstate_allow; /* help with revert wa */

- unsigned int debug_data;
+ unsigned int debug_data = 0;
unsigned int i;

if (forced_pstate_allow) {
--
2.23.0


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2019-10-02 13:48:17

by Alex Deucher

[permalink] [raw]
Subject: Re: [PATCH] drm/amdgpu: Initialize variable before use

On Mon, Sep 30, 2019 at 4:09 PM Siqueira, Rodrigo
<[email protected]> wrote:
>
> The 'debug_data' variable gets printed in debug statements without a
> prior initialization in the function
> hubbub1_verify_allow_pstate_change_high, as reported when building with
> gcc 9.1.0:
>
> warning: ‘debug_data’ may be used uninitialized in this function [-Wmaybe-uninitialized]
> 290 | printk##once(KERN_##level "[" DRM_NAME "] " fmt, ##__VA_ARGS__)
> | ^~~~~~
> dc/dcn10/dcn10_hubbub.c:134:15: note: ‘debug_data’ was declared here
> 134 | unsigned int debug_data;
>
> Note that initialize debug_data with 0, in this case, is safe because we
> have a loop in a few lines below that will initialize this variable with
> the proper value.
>
> Signed-off-by: Rodrigo Siqueira <[email protected]>

Reviewed-by: Alex Deucher <[email protected]>

> ---
> drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
> index a780057e2dbc..b6967a7e6c7b 100644
> --- a/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
> +++ b/drivers/gpu/drm/amd/display/dc/dcn10/dcn10_hubbub.c
> @@ -133,7 +133,7 @@ bool hubbub1_verify_allow_pstate_change_high(
> static unsigned int max_sampled_pstate_wait_us; /* data collection */
> static bool forced_pstate_allow; /* help with revert wa */
>
> - unsigned int debug_data;
> + unsigned int debug_data = 0;
> unsigned int i;
>
> if (forced_pstate_allow) {
> --
> 2.23.0
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