linux-kernel - [PATCH v2] drm/amdgpu: Remove unnecessary variable shadow in gfx_v9_0_rlcg

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Message-Id: <20200318210408.4113-1-natechancellor@gmail.com>
Date:   Wed, 18 Mar 2020 14:04:09 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Alex Deucher <alexander.deucher@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        Christian König <christian.koenig@....com>
Cc:     amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>,
        Joe Perches <joe@...ches.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: [PATCH v2] drm/amdgpu: Remove unnecessary variable shadow in gfx_v9_0_rlcg_wreg

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@...ches.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@...gle.com>
Signed-off-by: Nathan Chancellor <natechancellor@...il.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