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bh=17aeOdEACV6GCmSBNGeLhdL7I8VMOLywDStXvLbpbKk=; b=ojuVvFEXn/gGW0SP5NdZUQROnTkTUOAZyp/wSw4/fBO+b3CQyaMLNiif9gCN9jM+oE aasCaNpANZfoO7QNk3wa89P2qP5kusmMypwnQ42ekaycdLHklA1MkVpm/bQ0QYoCxSZT bQvnvLQIBPCGy7e1AaWtm7J5u14DZbWRd41O8D3gjEqDWHilPJKdWJ++i8d3bq/7V8Si cRib9CAGShbKUl7mLoN6C3xlBG6nb2yw5HAfA/9uwdzsLlZtXWYOMlwP049Z6nrn1h8x s7qwn4fPODgGfblhMkIxy5FhDqk2hoxVCp0qURLhZ3go43EccSHRdylrgjPnLuKrj/E6 jiWg== X-Gm-Message-State: APjAAAWwVwnkz8CLPjJ7G/dizzkhwxH2BUmeHBkY6IsyJYYkpS3Le439 AABMgLl7bENHPHmW5o/BJjtiFBLte8p6rlUIU6Y= X-Google-Smtp-Source: APXvYqyJqzPNBd01KuJnFGkGbR9BT5A13oFsJBoVd9HZiHyyG7q0VSD1WrYZcsuWBBJork2bw1Gm9MyvPiwdDVL8C2A= X-Received: by 2002:a7b:cb89:: with SMTP id m9mr29337295wmi.141.1574693718199; Mon, 25 Nov 2019 06:55:18 -0800 (PST) MIME-Version: 1.0 References: <20191123192336.11678-1-natechancellor@gmail.com> In-Reply-To: <20191123192336.11678-1-natechancellor@gmail.com> From: Alex Deucher Date: Mon, 25 Nov 2019 09:55:06 -0500 Message-ID: Subject: Re: [PATCH] drm/amdgpu: Ensure ret is always initialized when using SOC15_WAIT_ON_RREG To: Nathan Chancellor Cc: Alex Deucher , =?UTF-8?Q?Christian_K=C3=B6nig?= , "David (ChunMing) Zhou" , LKML , Maling list - DRI developers , clang-built-linux , amd-gfx list , Leo Liu Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 25, 2019 at 3:07 AM Nathan Chancellor wrote: > > Commit b0f3cd3191cd ("drm/amdgpu: remove unnecessary JPEG2.0 code from > VCN2.0") introduced a new clang warning in the vcn_v2_0_stop function: > > ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1082:2: warning: variable 'r' > is used uninitialized whenever 'while' loop exits because its condition > is false [-Wsometimes-uninitialized] > SOC15_WAIT_ON_RREG(VCN, 0, mmUVD_STATUS, UVD_STATUS__IDLE, 0x7, r); > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../drivers/gpu/drm/amd/amdgpu/../amdgpu/soc15_common.h:55:10: note: > expanded from macro 'SOC15_WAIT_ON_RREG' > while ((tmp_ & (mask)) != (expected_value)) { \ > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1083:6: note: uninitialized use > occurs here > if (r) > ^ > ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1082:2: note: remove the > condition if it is always true > SOC15_WAIT_ON_RREG(VCN, 0, mmUVD_STATUS, UVD_STATUS__IDLE, 0x7, r); > ^ > ../drivers/gpu/drm/amd/amdgpu/../amdgpu/soc15_common.h:55:10: note: > expanded from macro 'SOC15_WAIT_ON_RREG' > while ((tmp_ & (mask)) != (expected_value)) { \ > ^ > ../drivers/gpu/drm/amd/amdgpu/vcn_v2_0.c:1072:7: note: initialize the > variable 'r' to silence this warning > int r; > ^ > = 0 > 1 warning generated. > > To prevent warnings like this from happening in the future, make the > SOC15_WAIT_ON_RREG macro initialize its ret variable before the while > loop that can time out. This macro's return value is always checked so > it should set ret in both the success and fail path. > > Link: https://github.com/ClangBuiltLinux/linux/issues/776 > Signed-off-by: Nathan Chancellor Applied. Thanks! Alex > --- > drivers/gpu/drm/amd/amdgpu/soc15_common.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/gpu/drm/amd/amdgpu/soc15_common.h b/drivers/gpu/drm/amd/amdgpu/soc15_common.h > index 839f186e1182..19e870c79896 100644 > --- a/drivers/gpu/drm/amd/amdgpu/soc15_common.h > +++ b/drivers/gpu/drm/amd/amdgpu/soc15_common.h > @@ -52,6 +52,7 @@ > uint32_t old_ = 0; \ > uint32_t tmp_ = RREG32(adev->reg_offset[ip##_HWIP][inst][reg##_BASE_IDX] + reg); \ > uint32_t loop = adev->usec_timeout; \ > + ret = 0; \ > while ((tmp_ & (mask)) != (expected_value)) { \ > if (old_ != tmp_) { \ > loop = adev->usec_timeout; \ > -- > 2.24.0 > > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel