[PATCH 6/6] drm/amdkfd: Fix sdma queue allocate race condition

[Zeng, Oak]

SDMA queue allocation requires the dqm lock as it modify
the global dqm members. Introduce functions to allocate/deallocate
in locked/unlocked circumstance.

Change-Id: Id3084524c5f65d9629b12cf6b4862a7516945cb1
Signed-off-by: Oak Zeng <Oak.Zeng at amd.com>
---
 .../gpu/drm/amd/amdkfd/kfd_device_queue_manager.c  | 34 ++++++++++++++++------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
index 2cd47e3..8c66abd 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device_queue_manager.c
@@ -53,6 +53,8 @@ static int map_queues_cpsch(struct device_queue_manager *dqm);
 
 static void deallocate_sdma_queue(struct device_queue_manager *dqm,
 				struct queue *q);
+static void deallocate_sdma_queue_locked(struct device_queue_manager *dqm,
+				struct queue *q);
 
 static inline void deallocate_hqd(struct device_queue_manager *dqm,
 				struct queue *q);
@@ -436,10 +438,10 @@ static int destroy_queue_nocpsch_locked(struct device_queue_manager *dqm,
 		deallocate_hqd(dqm, q);
 	} else if (q->properties.type == KFD_QUEUE_TYPE_SDMA) {
 		dqm->sdma_queue_count--;
-		deallocate_sdma_queue(dqm, q);
+		deallocate_sdma_queue_locked(dqm, q);
 	} else if (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI) {
 		dqm->xgmi_sdma_queue_count--;
-		deallocate_sdma_queue(dqm, q);
+		deallocate_sdma_queue_locked(dqm, q);
 	} else {
 		pr_debug("q->properties.type %d is invalid\n",
 				q->properties.type);
@@ -909,9 +911,12 @@ static int allocate_sdma_queue(struct device_queue_manager *dqm,
 {
 	int bit;
 
+	dqm_lock(dqm);
 	if (q->properties.type == KFD_QUEUE_TYPE_SDMA) {
-		if (dqm->sdma_bitmap == 0)
+		if (dqm->sdma_bitmap == 0) {
+			dqm_unlock(dqm);
 			return -ENOMEM;
+		}
 		bit = __ffs64(dqm->sdma_bitmap);
 		dqm->sdma_bitmap &= ~(1ULL << bit);
 		q->sdma_id = bit;
@@ -920,8 +925,10 @@ static int allocate_sdma_queue(struct device_queue_manager *dqm,
 		q->properties.sdma_queue_id = q->sdma_id /
 				get_num_sdma_engines(dqm);
 	} else if (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI) {
-		if (dqm->xgmi_sdma_bitmap == 0)
+		if (dqm->xgmi_sdma_bitmap == 0) {
+			dqm_unlock(dqm);
 			return -ENOMEM;
+		}
 		bit = __ffs64(dqm->xgmi_sdma_bitmap);
 		dqm->xgmi_sdma_bitmap &= ~(1ULL << bit);
 		q->sdma_id = bit;
@@ -937,13 +944,14 @@ static int allocate_sdma_queue(struct device_queue_manager *dqm,
 				get_num_xgmi_sdma_engines(dqm);
 	}
 
+	dqm_unlock(dqm);
 	pr_debug("SDMA engine id: %d\n", q->properties.sdma_engine_id);
 	pr_debug("SDMA queue id: %d\n", q->properties.sdma_queue_id);
 
 	return 0;
 }
 
-static void deallocate_sdma_queue(struct device_queue_manager *dqm,
+static void deallocate_sdma_queue_locked(struct device_queue_manager *dqm,
 				struct queue *q)
 {
 	if (q->properties.type == KFD_QUEUE_TYPE_SDMA) {
@@ -957,6 +965,14 @@ static void deallocate_sdma_queue(struct device_queue_manager *dqm,
 	}
 }
 
+static void deallocate_sdma_queue(struct device_queue_manager *dqm,
+				struct queue *q)
+{
+	dqm_lock(dqm);
+	deallocate_sdma_queue_locked(dqm, q);
+	dqm_unlock(dqm);
+}
+
 /*
  * Device Queue Manager implementation for cp scheduler
  */
@@ -1353,10 +1369,10 @@ static int destroy_queue_cpsch(struct device_queue_manager *dqm,
 
 	if (q->properties.type == KFD_QUEUE_TYPE_SDMA) {
 		dqm->sdma_queue_count--;
-		deallocate_sdma_queue(dqm, q);
+		deallocate_sdma_queue_locked(dqm, q);
 	} else if (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI) {
 		dqm->xgmi_sdma_queue_count--;
-		deallocate_sdma_queue(dqm, q);
+		deallocate_sdma_queue_locked(dqm, q);
 	}
 
 	list_del(&q->list);
@@ -1582,10 +1598,10 @@ static int process_termination_cpsch(struct device_queue_manager *dqm,
 	list_for_each_entry(q, &qpd->queues_list, list) {
 		if (q->properties.type == KFD_QUEUE_TYPE_SDMA) {
 			dqm->sdma_queue_count--;
-			deallocate_sdma_queue(dqm, q);
+			deallocate_sdma_queue_locked(dqm, q);
 		} else if (q->properties.type == KFD_QUEUE_TYPE_SDMA_XGMI) {
 			dqm->xgmi_sdma_queue_count--;
-			deallocate_sdma_queue(dqm, q);
+			deallocate_sdma_queue_locked(dqm, q);
 		}
 
 		if (q->properties.is_active)
-- 
2.7.4