linux-kernel - [PATCH 4.2.y-ckt 167/273] drm/amdgpu: use post-decrement in error handling

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Message-Id: <1457391064-6660-168-git-send-email-kamal@canonical.com>
Date:	Mon,  7 Mar 2016 14:49:18 -0800
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Alex Deucher <alexander.deucher@....com>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 4.2.y-ckt 167/273] drm/amdgpu: use post-decrement in error handling

4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Rasmus Villemoes <linux@...musvillemoes.dk>

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@....com>
Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index e3f73b7..0345298 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -708,7 +708,7 @@ 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;
-- 
2.7.0