[PATCH V6 13/18] amdkfd: introduce new helper kfd_lookup_process_by_id

[Zhu Lingshan <lingshan.zhu@amd.com>]

This commit introduces a new helper function
kfd_lookup_process_by_id which can find a
kfd process that identified by its context id from
the kfd process table

Signed-off-by: Zhu Lingshan <lingshan.zhu@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
---
 drivers/gpu/drm/amd/amdkfd/kfd_priv.h    |  1 +
 drivers/gpu/drm/amd/amdkfd/kfd_process.c | 21 +++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
index b6ad546c400c..44ecdaf02657 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h
@@ -1062,6 +1062,7 @@ int kfd_create_process_sysfs(struct kfd_process *process);
 struct kfd_process *kfd_lookup_process_by_pasid(u32 pasid,
 						 struct kfd_process_device **pdd);
 struct kfd_process *kfd_lookup_process_by_mm(const struct mm_struct *mm);
+struct kfd_process *kfd_lookup_process_by_id(const struct mm_struct *mm, u16 id);
 
 int kfd_process_gpuidx_from_gpuid(struct kfd_process *p, uint32_t gpu_id);
 int kfd_process_gpuid_from_node(struct kfd_process *p, struct kfd_node *node,
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
index 6b39d6314a0d..4350552e9648 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
@@ -1955,6 +1955,27 @@ struct kfd_process *kfd_lookup_process_by_mm(const struct mm_struct *mm)
 	return p;
 }
 
+/* This increments the process->ref counter. */
+struct kfd_process *kfd_lookup_process_by_id(const struct mm_struct *mm, u16 id)
+{
+	struct kfd_process *p, *ret_p = NULL;
+	unsigned int temp;
+
+	int idx = srcu_read_lock(&kfd_processes_srcu);
+
+	hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
+		if (p->mm == mm && p->context_id == id) {
+			kref_get(&p->ref);
+			ret_p = p;
+			break;
+		}
+	}
+
+	srcu_read_unlock(&kfd_processes_srcu, idx);
+
+	return ret_p;
+}
+
 /* kfd_process_evict_queues - Evict all user queues of a process
  *
  * Eviction is reference-counted per process-device. This means multiple
-- 
2.51.0