linux-kernel - [PATCH 2/2] drm/amd/powerplay: vega20: fix uninitialized variable use

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Date:   Mon,  8 Jul 2019 16:07:59 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Rex Zhu <rex.zhu@....com>, Evan Quan <evan.quan@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     Arnd Bergmann <arnd@...db.de>, Huang Rui <ray.huang@....com>,
        Kevin Wang <kevin1.wang@....com>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Likun Gao <Likun.Gao@....com>,
        Chengming Gui <Jack.Gui@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] drm/amd/powerplay: vega20: fix uninitialized variable use

If smu_get_current_rpm() fails, we can't use the output,
as that may be uninitialized:

drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:3023:8: error: variable 'current_rpm' is used uninitialized whenever '?:' condition is false [-Werror,-Wsometimes-uninitialized]
        ret = smu_get_current_rpm(smu, &current_rpm);
              ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:735:3: note: expanded from macro 'smu_get_current_rpm'
        ((smu)->funcs->get_current_rpm ? (smu)->funcs->get_current_rpm((smu), (speed)) : 0)
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:3024:12: note: uninitialized use occurs here
        percent = current_rpm * 100 / pptable->FanMaximumRpm;
                  ^~~~~~~~~~~
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:3023:8: note: remove the '?:' if its condition is always true
        ret = smu_get_current_rpm(smu, &current_rpm);
              ^
drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:735:3: note: expanded from macro 'smu_get_current_rpm'
        ((smu)->funcs->get_current_rpm ? (smu)->funcs->get_current_rpm((smu), (speed)) : 0)
         ^
drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:3020:22: note: initialize the variable 'current_rpm' to silence this warning
        uint32_t current_rpm;

Propagate the error code in that case.

Fixes: ee0db82027ee ("drm/amd/powerplay: move PPTable_t uses into asic level")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 drivers/gpu/drm/amd/powerplay/vega20_ppt.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/powerplay/vega20_ppt.c b/drivers/gpu/drm/amd/powerplay/vega20_ppt.c
index 9ce3f1c8ae0f..20d477f8dc84 100644
--- a/drivers/gpu/drm/amd/powerplay/vega20_ppt.c
+++ b/drivers/gpu/drm/amd/powerplay/vega20_ppt.c
@@ -3021,10 +3021,13 @@ static int vega20_get_fan_speed_percent(struct smu_context *smu,
 	PPTable_t *pptable = smu->smu_table.driver_pptable;
 
 	ret = smu_get_current_rpm(smu, &current_rpm);
+	if (ret)
+		return ret;
+
 	percent = current_rpm * 100 / pptable->FanMaximumRpm;
 	*speed = percent > 100 ? 100 : percent;
 
-	return ret;
+	return 0;
 }
 
 static int vega20_get_gpu_power(struct smu_context *smu, uint32_t *value)
-- 
2.20.0