drm/amdgpu: use post-decrement in error handling

We need to use post-decrement to get the pci_map_page undone also for
i==0, and to avoid some very unpleasant behaviour if pci_map_page
failed already at i==0.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 6442a06..1cbb16e 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -712,7 +712,7 @@ static int amdgpu_ttm_tt_populate(struct ttm_tt *ttm)
                                                       0, PAGE_SIZE,
                                                       PCI_DMA_BIDIRECTIONAL);
                if (pci_dma_mapping_error(adev->pdev, gtt->ttm.dma_address[i])) {
-                       while (--i) {
+                       while (i--) {
                                pci_unmap_page(adev->pdev, gtt->ttm.dma_address[i],
                                               PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
                                gtt->ttm.dma_address[i] = 0;