drm/msm: Fix error return checking

BugLink: https://bugs.launchpad.net/bugs/1837257
[ Upstream commit 098336deb946f37a70afc0979af388b615c378bf ]

The error checks on ret for a negative error return always fails because
the return value of iommu_map_sg() is unsigned and can never be negative.

Detected with Coccinelle:
drivers/gpu/drm/msm/msm_iommu.c:69:9-12: WARNING: Unsigned expression
compared with zero: ret < 0

Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
CC: Rob Clark <robdclark@gmail.com>
CC: David Airlie <airlied@linux.ie>
CC: Julia Lawall <julia.lawall@lip6.fr>
CC: linux-arm-msm@vger.kernel.org
CC: dri-devel@lists.freedesktop.org
CC: freedreno@lists.freedesktop.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/gpu/drm/msm/msm_iommu.c b/drivers/gpu/drm/msm/msm_iommu.c
index b359f7b9d19bdfe61406980192425b4910afbfef..a1fc8e39d56eb7653ee2d9a4722d766aa68c2c4c 100644 (file)
--- a/drivers/gpu/drm/msm/msm_iommu.c
+++ b/drivers/gpu/drm/msm/msm_iommu.c
@@ -66,7 +66,7 @@ static int msm_iommu_map(struct msm_mmu *mmu, uint64_t iova,
        pm_runtime_get_sync(mmu->dev);
        ret = iommu_map_sg(iommu->domain, iova, sgt->sgl, sgt->nents, prot);
 //     pm_runtime_put_sync(mmu->dev);
-       WARN_ON(ret < 0);
+       WARN_ON(!ret);
 
        return (ret == len) ? 0 : -EINVAL;
 }