[PATCH] drm/amdgpu: SRIOV flr_work should use down_write

[Victor Skvortsov]

Host initiated VF FLR may fail if someone else
is already holding a read_lock. Change from
down_write_trylock to down_write to guarantee
the reset goes through.

Signed-off-by: Victor Skvortsov <victor.skvortsov at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c | 5 +++--
 drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
index cd2719bc0139..e4365c97adaa 100644
--- a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
+++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
@@ -252,11 +252,12 @@ static void xgpu_ai_mailbox_flr_work(struct work_struct *work)
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
 	 */
-	if (!down_write_trylock(&adev->reset_sem))
+	if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0)
 		return;
 
+	down_write(&adev->reset_sem);
+
 	amdgpu_virt_fini_vf2pf_work_item(adev);
-	atomic_set(&adev->in_gpu_reset, 1);
 
 	xgpu_ai_mailbox_trans_msg(adev, IDH_READY_TO_RESET, 0, 0, 0);
 
diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
index 2bc93808469a..1cde70c72e54 100644
--- a/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
+++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_nv.c
@@ -281,11 +281,12 @@ static void xgpu_nv_mailbox_flr_work(struct work_struct *work)
 	 * otherwise the mailbox msg will be ruined/reseted by
 	 * the VF FLR.
 	 */
-	if (!down_write_trylock(&adev->reset_sem))
+	if (atomic_cmpxchg(&adev->in_gpu_reset, 0, 1) != 0)
 		return;
 
+	down_write(&adev->reset_sem);
+
 	amdgpu_virt_fini_vf2pf_work_item(adev);
-	atomic_set(&adev->in_gpu_reset, 1);
 
 	xgpu_nv_mailbox_trans_msg(adev, IDH_READY_TO_RESET, 0, 0, 0);
 
-- 
2.25.1