[PATCH 5.16 152/285] drm/amdgpu: fix off by one in amdgpu_gfx_kiq_acquire()

Greg Kroah-Hartman
2022-04-12T08:37:58Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit 1647b54ed55d4d48c7199d439f8834626576cbe9 ]

This post-op should be a pre-op so that we do not pass -1 as the bit
number to test_bit(). The current code will loop downwards from 63 to
-1. After changing to a pre-op, it loops from 63 to 0.

Fixes: 71c37505e7ea ("drm/amdgpu/gfx: move more common KIQ code to amdgpu_gfx.c")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
index 1916ec84dd71..e7845df6cad2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gfx.c
@@ -266,7 +266,7 @@ static int amdgpu_gfx_kiq_acquire(struct amdgpu_device *adev,
* adev->gfx.mec.num_pipe_per_mec
* adev->gfx.mec.num_queue_per_pipe;

- while (queue_bit-- >= 0) {
+ while (--queue_bit >= 0) {
if (test_bit(queue_bit, adev->gfx.mec.queue_bitmap))
continue;

--
2.35.1