drm/amdkfd: Check if there are kfd porcesses using adev by kfd_processes_count

During gpu hot-unplug need check if there are kfd porcesses still using the
being removed gpu before clean resources of the device. Current driver checks
if kfd_processes_table is empty. kfd processes are not terminated after
removed from kfd_processes_table immediately. They are still alive and may
access the device until kfd_process_wq work queue got ran.

Check kfd->kfd_processes_count value that is updated after kfd process got
uninitialized when its ref becomes zero.

Fixes: 6cca686dfce7 ("drm/amdkfd: kfd driver supports hot unplug/replug amdgpu devices")
Signed-off-by: Xiaogang Chen <xiaogang.chen@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit d12d05c4bc4c15585130af43e897923ff292df7b)

1 files changed, 1 insertions, 32 deletions

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 8ff97bf7d95a..b7f8f7ff8198 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -1737,37 +1737,6 @@ bool kgd2kfd_vmfault_fast_path(struct amdgpu_device *adev, struct amdgpu_iv_entr
 	return false;
 }
 
-/* check if there is kfd process still uses adev */
-static bool kgd2kfd_check_device_idle(struct amdgpu_device *adev)
-{
-	struct kfd_process *p;
-	struct hlist_node *p_temp;
-	unsigned int temp;
-	struct kfd_node *dev;
-
-	mutex_lock(&kfd_processes_mutex);
-
-	if (hash_empty(kfd_processes_table)) {
-		mutex_unlock(&kfd_processes_mutex);
-		return true;
-	}
-
-	/* check if there is device still use adev */
-	hash_for_each_safe(kfd_processes_table, temp, p_temp, p, kfd_processes) {
-		for (int i = 0; i < p->n_pdds; i++) {
-			dev = p->pdds[i]->dev;
-			if (dev->adev == adev) {
-				mutex_unlock(&kfd_processes_mutex);
-				return false;
-			}
-		}
-	}
-
-	mutex_unlock(&kfd_processes_mutex);
-
-	return true;
-}
-
 /** kgd2kfd_teardown_processes - gracefully tear down existing
  *  kfd processes that use adev
  *
@@ -1800,7 +1769,7 @@ void kgd2kfd_teardown_processes(struct amdgpu_device *adev)
 	mutex_unlock(&kfd_processes_mutex);
 
 	/* wait all kfd processes use adev terminate */
-	while (!kgd2kfd_check_device_idle(adev))
+	while (!!atomic_read(&adev->kfd.dev->kfd_processes_count))
 		cond_resched();
 }