[PATCH] drm/amdgpu: Initialize shadow to false in gfx_v9_0_rlcg_wreg

[PATCH] drm/amdgpu: Initialize shadow to false in gfx_v9_0_rlcg_wreg

[Nathan Chancellor]

clang warns:

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
is used uninitialized whenever 'if' condition is
false [-Wsometimes-uninitialized]
        if (offset == grbm_cntl || offset == grbm_idx)
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
occurs here
        if (shadow) {
            ^~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:2: note: remove the 'if' if
its condition is always true
        if (offset == grbm_cntl || offset == grbm_idx)
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:738:13: note: initialize the
variable 'shadow' to silence this warning
        bool shadow;
                   ^
                    = 0
1 warning generated.

It is not wrong so initialize shadow to false to ensure shadow is always
used initialized.

Fixes: 2e0cc4d48b91 ("drm/amdgpu: revise RLCG access path")
Link: https://github.com/ClangBuiltLinux/linux/issues/936
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 7bc2486167e7..affbff76758c 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -735,7 +735,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
 	static void *spare_int;
 	static uint32_t grbm_cntl;
 	static uint32_t grbm_idx;
-	bool shadow;
+	bool shadow = false;
 
 	scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
 	scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
-- 
2.26.0.rc1

Re: [PATCH] drm/amdgpu: Initialize shadow to false in gfx_v9_0_rlcg_wreg

[Nick Desaulniers]

On Tue, Mar 17, 2020 at 5:25 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> clang warns:
>
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
> is used uninitialized whenever 'if' condition is
> false [-Wsometimes-uninitialized]
>         if (offset == grbm_cntl || offset == grbm_idx)
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
> occurs here
>         if (shadow) {
>             ^~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:2: note: remove the 'if' if
> its condition is always true
>         if (offset == grbm_cntl || offset == grbm_idx)
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:738:13: note: initialize the
> variable 'shadow' to silence this warning
>         bool shadow;
>                    ^
>                     = 0
> 1 warning generated.
>
> It is not wrong so initialize shadow to false to ensure shadow is always
> used initialized.

Yep, thanks for the patch.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

>
> Fixes: 2e0cc4d48b91 ("drm/amdgpu: revise RLCG access path")
> Link: https://github.com/ClangBuiltLinux/linux/issues/936
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 7bc2486167e7..affbff76758c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -735,7 +735,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
>         static void *spare_int;
>         static uint32_t grbm_cntl;
>         static uint32_t grbm_idx;
> -       bool shadow;
> +       bool shadow = false;
>
>         scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
>         scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
> --
> 2.26.0.rc1
>
> --
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> To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
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-- 
Thanks,
~Nick Desaulniers

Re: [PATCH] drm/amdgpu: Initialize shadow to false in gfx_v9_0_rlcg_wreg

[Joe Perches]

On Tue, 2020-03-17 at 17:25 -0700, Nathan Chancellor wrote:
> clang warns:
> 
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
> is used uninitialized whenever 'if' condition is
> false [-Wsometimes-uninitialized]
>         if (offset == grbm_cntl || offset == grbm_idx)
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
> occurs here
>         if (shadow) {
>             ^~~~~~

Wouldn't it be better to get rid of the shadow variable completely?
---
 drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 7bc248..496b9e 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -735,7 +735,6 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
 	static void *spare_int;
 	static uint32_t grbm_cntl;
 	static uint32_t grbm_idx;
-	bool shadow;
 
 	scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
 	scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
@@ -751,10 +750,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
 		return;
 	}
 
-	if (offset == grbm_cntl || offset == grbm_idx)
-		shadow = true;
-
-	if (shadow) {
+	if (offset == grbm_cntl || offset == grbm_idx) {
 		if (offset  == grbm_cntl)
 			writel(v, scratch_reg2);
 		else if (offset == grbm_idx)

Re: [PATCH] drm/amdgpu: Initialize shadow to false in gfx_v9_0_rlcg_wreg

[Nick Desaulniers]

On Wed, Mar 18, 2020 at 1:28 PM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2020-03-17 at 17:25 -0700, Nathan Chancellor wrote:
> > clang warns:
> >
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
> > is used uninitialized whenever 'if' condition is
> > false [-Wsometimes-uninitialized]
> >         if (offset == grbm_cntl || offset == grbm_idx)
> >             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
> > occurs here
> >         if (shadow) {
> >             ^~~~~~
>
> Wouldn't it be better to get rid of the shadow variable completely?

Yes, much better indeed. Seems it only has one use.

> ---
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 7bc248..496b9e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -735,7 +735,6 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
>         static void *spare_int;
>         static uint32_t grbm_cntl;
>         static uint32_t grbm_idx;
> -       bool shadow;
>
>         scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
>         scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
> @@ -751,10 +750,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
>                 return;
>         }
>
> -       if (offset == grbm_cntl || offset == grbm_idx)
> -               shadow = true;
> -
> -       if (shadow) {
> +       if (offset == grbm_cntl || offset == grbm_idx) {
>                 if (offset  == grbm_cntl)
>                         writel(v, scratch_reg2);
>                 else if (offset == grbm_idx)
>
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
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-- 
Thanks,
~Nick Desaulniers

[PATCH v2] drm/amdgpu: Remove unnecessary variable shadow in gfx_v9_0_rlcg_wreg

[Nathan Chancellor]

clang warns:

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
is used uninitialized whenever 'if' condition is
false [-Wsometimes-uninitialized]
        if (offset == grbm_cntl || offset == grbm_idx)
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
occurs here
        if (shadow) {
            ^~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:2: note: remove the 'if' if
its condition is always true
        if (offset == grbm_cntl || offset == grbm_idx)
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:738:13: note: initialize the
variable 'shadow' to silence this warning
        bool shadow;
                   ^
                    = 0
1 warning generated.

shadow is only assigned in one condition and used as the condition for
another if statement; combine the two if statements and remove shadow
to make the code cleaner and resolve this warning.

Fixes: 2e0cc4d48b91 ("drm/amdgpu: revise RLCG access path")
Link: https://github.com/ClangBuiltLinux/linux/issues/936
Suggested-by: Joe Perches <joe@perches.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---

v1 -> v2:

* Remove shadow altogether, as suggested by Joe Perches.
* Add Nick's Reviewed-by, as I assume it still stands.

 drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
index 7bc2486167e7..496b9edca3c3 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
@@ -735,7 +735,6 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
 	static void *spare_int;
 	static uint32_t grbm_cntl;
 	static uint32_t grbm_idx;
-	bool shadow;
 
 	scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
 	scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
@@ -751,10 +750,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
 		return;
 	}
 
-	if (offset == grbm_cntl || offset == grbm_idx)
-		shadow = true;
-
-	if (shadow) {
+	if (offset == grbm_cntl || offset == grbm_idx) {
 		if (offset  == grbm_cntl)
 			writel(v, scratch_reg2);
 		else if (offset == grbm_idx)
-- 
2.26.0.rc1

Re: [PATCH v2] drm/amdgpu: Remove unnecessary variable shadow in gfx_v9_0_rlcg_wreg

[Nick Desaulniers]

On Wed, Mar 18, 2020 at 2:05 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> clang warns:
>
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
> is used uninitialized whenever 'if' condition is
> false [-Wsometimes-uninitialized]
>         if (offset == grbm_cntl || offset == grbm_idx)
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
> occurs here
>         if (shadow) {
>             ^~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:2: note: remove the 'if' if
> its condition is always true
>         if (offset == grbm_cntl || offset == grbm_idx)
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:738:13: note: initialize the
> variable 'shadow' to silence this warning
>         bool shadow;
>                    ^
>                     = 0
> 1 warning generated.
>
> shadow is only assigned in one condition and used as the condition for
> another if statement; combine the two if statements and remove shadow
> to make the code cleaner and resolve this warning.
>
> Fixes: 2e0cc4d48b91 ("drm/amdgpu: revise RLCG access path")
> Link: https://github.com/ClangBuiltLinux/linux/issues/936
> Suggested-by: Joe Perches <joe@perches.com>
> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
> ---
>
> v1 -> v2:
>
> * Remove shadow altogether, as suggested by Joe Perches.
> * Add Nick's Reviewed-by, as I assume it still stands.

yep, thanks

>
>  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> index 7bc2486167e7..496b9edca3c3 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> @@ -735,7 +735,6 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
>         static void *spare_int;
>         static uint32_t grbm_cntl;
>         static uint32_t grbm_idx;
> -       bool shadow;
>
>         scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
>         scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
> @@ -751,10 +750,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
>                 return;
>         }
>
> -       if (offset == grbm_cntl || offset == grbm_idx)
> -               shadow = true;
> -
> -       if (shadow) {
> +       if (offset == grbm_cntl || offset == grbm_idx) {
>                 if (offset  == grbm_cntl)
>                         writel(v, scratch_reg2);
>                 else if (offset == grbm_idx)
> --
> 2.26.0.rc1
>


-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] drm/amdgpu: Remove unnecessary variable shadow in gfx_v9_0_rlcg_wreg

[Alex Deucher]

On Wed, Mar 18, 2020 at 5:08 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> On Wed, Mar 18, 2020 at 2:05 PM Nathan Chancellor
> <natechancellor@gmail.com> wrote:
> >
> > clang warns:
> >
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:6: warning: variable 'shadow'
> > is used uninitialized whenever 'if' condition is
> > false [-Wsometimes-uninitialized]
> >         if (offset == grbm_cntl || offset == grbm_idx)
> >             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:757:6: note: uninitialized use
> > occurs here
> >         if (shadow) {
> >             ^~~~~~
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:754:2: note: remove the 'if' if
> > its condition is always true
> >         if (offset == grbm_cntl || offset == grbm_idx)
> >         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c:738:13: note: initialize the
> > variable 'shadow' to silence this warning
> >         bool shadow;
> >                    ^
> >                     = 0
> > 1 warning generated.
> >
> > shadow is only assigned in one condition and used as the condition for
> > another if statement; combine the two if statements and remove shadow
> > to make the code cleaner and resolve this warning.
> >
> > Fixes: 2e0cc4d48b91 ("drm/amdgpu: revise RLCG access path")
> > Link: https://github.com/ClangBuiltLinux/linux/issues/936
> > Suggested-by: Joe Perches <joe@perches.com>
> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Applied.  thanks!

Alex

> > ---
> >
> > v1 -> v2:
> >
> > * Remove shadow altogether, as suggested by Joe Perches.
> > * Add Nick's Reviewed-by, as I assume it still stands.
>
> yep, thanks
>
> >
> >  drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c | 6 +-----
> >  1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> > index 7bc2486167e7..496b9edca3c3 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c
> > @@ -735,7 +735,6 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
> >         static void *spare_int;
> >         static uint32_t grbm_cntl;
> >         static uint32_t grbm_idx;
> > -       bool shadow;
> >
> >         scratch_reg0 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG0_BASE_IDX] + mmSCRATCH_REG0)*4;
> >         scratch_reg1 = adev->rmmio + (adev->reg_offset[GC_HWIP][0][mmSCRATCH_REG1_BASE_IDX] + mmSCRATCH_REG1)*4;
> > @@ -751,10 +750,7 @@ void gfx_v9_0_rlcg_wreg(struct amdgpu_device *adev, u32 offset, u32 v)
> >                 return;
> >         }
> >
> > -       if (offset == grbm_cntl || offset == grbm_idx)
> > -               shadow = true;
> > -
> > -       if (shadow) {
> > +       if (offset == grbm_cntl || offset == grbm_idx) {
> >                 if (offset  == grbm_cntl)
> >                         writel(v, scratch_reg2);
> >                 else if (offset == grbm_idx)
> > --
> > 2.26.0.rc1
> >
>
>
> --
> Thanks,
> ~Nick Desaulniers
> _______________________________________________
> amd-gfx mailing list
> amd-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/amd-gfx