drm/amdgpu: use post-decrement in error handling

commit 09ccbb74b6718ad4d1290de3f5669212c0ac7d4b upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 6442a06d6fdc1ce9115d280cc916b4e55923f2fa..1cbb16e153079e7463a0ac070d1a19461deb588e 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;