drm/amdgpu/gfx10: fix race condition for kiq

During preemption test for gfx10, it uses kiq to trigger
gfx preemption, which would result in race condition
with flushing TLB for kiq.

Signed-off-by: Jack Xiao <Jack.Xiao@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
index a6170a3..ddf6d81 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfx_v10_0.c
@@ -7836,12 +7836,17 @@ static int gfx_v10_0_ring_preempt_ib(struct amdgpu_ring *ring)
        struct amdgpu_device *adev = ring->adev;
        struct amdgpu_kiq *kiq = &adev->gfx.kiq;
        struct amdgpu_ring *kiq_ring = &kiq->ring;
+       unsigned long flags;
 
        if (!kiq->pmf || !kiq->pmf->kiq_unmap_queues)
                return -EINVAL;
 
-       if (amdgpu_ring_alloc(kiq_ring, kiq->pmf->unmap_queues_size))
+       spin_lock_irqsave(&kiq->ring_lock, flags);
+
+       if (amdgpu_ring_alloc(kiq_ring, kiq->pmf->unmap_queues_size)) {
+               spin_unlock_irqrestore(&kiq->ring_lock, flags);
                return -ENOMEM;
+       }
 
        /* assert preemption condition */
        amdgpu_ring_set_preempt_cond_exec(ring, false);
@@ -7852,6 +7857,8 @@ static int gfx_v10_0_ring_preempt_ib(struct amdgpu_ring *ring)
                                   ++ring->trail_seq);
        amdgpu_ring_commit(kiq_ring);
 
+       spin_unlock_irqrestore(&kiq->ring_lock, flags);
+
        /* poll the trailing fence */
        for (i = 0; i < adev->usec_timeout; i++) {
                if (ring->trail_seq ==