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From:   Nathan Chancellor <natechancellor@gmail.com>
To:     Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>,
        "David (ChunMing) Zhou" <David1.Zhou@amd.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Leo Li <sunpeng.li@amd.com>, Rex Zhu <rex.zhu@amd.com>,
        Evan Quan <evan.quan@amd.com>
Cc:     David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
        amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
        Nathan Chancellor <natechancellor@gmail.com>
Subject: [PATCH 4/7] drm/amd/powerplay: Zero initialize freq in smu_v11_0_get_current_clk_freq
Date:   Wed,  3 Jul 2019 22:52:15 -0700
Message-Id: <20190704055217.45860-5-natechancellor@gmail.com>
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clang warns (trimmed for brevity):

drivers/gpu/drm/amd/amdgpu/../powerplay/smu_v11_0.c:1098:10: warning:
variable 'freq' is used uninitialized whenever '?:' condition is false
[-Wsometimes-uninitialized]
                ret =  smu_get_current_clk_freq_by_table(smu, clk_id, &freq);
                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If get_current_clk_freq_by_table is ever NULL, freq will fail to be
properly initialized. Zero initialize it to avoid using uninitialized
stack values.

smu_get_current_clk_freq_by_table expands to a ternary operator
conditional on smu->funcs->get_current_clk_freq_by_table being not NULL.
When this is false, freq will be uninitialized. Zero initialize freq to
avoid using random stack values if that ever happens.

Fixes: e36182490dec ("drm/amd/powerplay: fix dpm freq unit error (10KHz -> Mhz)")
Link: https://github.com/ClangBuiltLinux/linux/issues/585
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
---
 drivers/gpu/drm/amd/powerplay/smu_v11_0.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/powerplay/smu_v11_0.c b/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
index 632a20587c8b..a6f8cd6df7f1 100644
--- a/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
+++ b/drivers/gpu/drm/amd/powerplay/smu_v11_0.c
@@ -1088,7 +1088,7 @@ static int smu_v11_0_get_current_clk_freq(struct smu_context *smu,
 					  uint32_t *value)
 {
 	int ret = 0;
-	uint32_t freq;
+	uint32_t freq = 0;
 
 	if (clk_id >= SMU_CLK_COUNT || !value)
 		return -EINVAL;
-- 
2.22.0