vhost_scsi: removed deferred tasks

Removed deferred tasks and dynamic memory management in task processing
in vhost_scsi. Each vhost task will now have it's own iovec array

Change-Id: Ie51a2404e9cd3c4e03bcea5a8d5b16498dd4d093
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/363342
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>

lib/vhost/task.c

@@ -47,18 +47,11 @@
 		typeof(((type *)0)->member) *__mptr = (ptr); \
 		(type *)((char *)__mptr - offsetof(type, member)); })
 
-typedef TAILQ_HEAD(, spdk_vhost_task) need_iovecs_tailq_t;
-
 static struct rte_mempool *g_task_pool;
-static struct rte_mempool *g_iov_buffer_pool;
-
-static need_iovecs_tailq_t g_need_iovecs[RTE_MAX_LCORE];
 
 void
 spdk_vhost_task_put(struct spdk_vhost_task *task)
 {
-	assert(&task->scsi.iov == task->scsi.iovs);
-	assert(task->scsi.iovcnt == 1);
 	spdk_scsi_task_put(&task->scsi);
 }
 
@@ -91,44 +84,6 @@ spdk_vhost_task_get(struct spdk_vhost_scsi_dev *vdev)
 	return task;
 }
 
-void
-spdk_vhost_enqueue_task(struct spdk_vhost_task *task)
-{
-	need_iovecs_tailq_t *tailq = &g_need_iovecs[rte_lcore_id()];
-
-	TAILQ_INSERT_TAIL(tailq, task, iovecs_link);
-}
-
-struct spdk_vhost_task *
-spdk_vhost_dequeue_task(void)
-{
-	need_iovecs_tailq_t *tailq = &g_need_iovecs[rte_lcore_id()];
-	struct spdk_vhost_task *task;
-
-	if (TAILQ_EMPTY(tailq))
-		return NULL;
-
-	task = TAILQ_FIRST(tailq);
-	TAILQ_REMOVE(tailq, task, iovecs_link);
-
-	return task;
-}
-
-struct iovec *
-spdk_vhost_iovec_alloc(void)
-{
-	struct iovec *iov = NULL;
-
-	rte_mempool_get(g_iov_buffer_pool, (void **)&iov);
-	return iov;
-}
-
-void
-spdk_vhost_iovec_free(struct iovec *iov)
-{
-	rte_mempool_put(g_iov_buffer_pool, iov);
-}
-
 static void
 spdk_vhost_subsystem_init(void)
 {
@@ -139,23 +94,8 @@ spdk_vhost_subsystem_init(void)
 	if (!g_task_pool) {
 		SPDK_ERRLOG("create task pool failed\n");
 		rc = -1;
-		goto end;
 	}
 
-	g_iov_buffer_pool = rte_mempool_create("vhost iov buffer pool", 2048,
-					       VHOST_SCSI_IOVS_LEN * sizeof(struct iovec),
-					       128, 0, NULL, NULL, NULL, NULL, SOCKET_ID_ANY, 0);
-	if (!g_iov_buffer_pool) {
-		SPDK_ERRLOG("create iov buffer pool failed\n");
-		rc = -1;
-		goto end;
-	}
-
-	for (int i = 0; i < RTE_MAX_LCORE; i++) {
-		TAILQ_INIT(&g_need_iovecs[i]);
-	}
-
-end:
 	spdk_subsystem_init_next(rc);
 }
 

lib/vhost/task.h

@@ -43,6 +43,7 @@ struct spdk_vhost_dev;
 
 struct spdk_vhost_task {
 	struct spdk_scsi_task	scsi;
+	struct iovec iovs[VHOST_SCSI_IOVS_LEN];
 
 	union {
 		struct virtio_scsi_cmd_resp *resp;
@@ -55,20 +56,12 @@ struct spdk_vhost_task {
 	int req_idx;
 
 	struct rte_vhost_vring *vq;
-
-	TAILQ_ENTRY(spdk_vhost_task) iovecs_link;
 };
 
-void spdk_vhost_enqueue_task(struct spdk_vhost_task *task);
-struct spdk_vhost_task *spdk_vhost_dequeue_task(void);
-
 void spdk_vhost_task_put(struct spdk_vhost_task *task);
 struct spdk_vhost_task *spdk_vhost_task_get(struct spdk_vhost_scsi_dev *vdev);
 
 void spdk_vhost_dev_task_ref(struct spdk_vhost_dev *vdev);
 void spdk_vhost_dev_task_unref(struct spdk_vhost_dev *vdev);
 
-void spdk_vhost_iovec_free(struct iovec *iov);
-struct iovec *spdk_vhost_iovec_alloc(void);
-
 #endif /* SPDK_VHOST_TASK_H */

lib/vhost/vhost_scsi.c

@@ -99,46 +99,11 @@ static void invalid_request(struct spdk_vhost_task *task);
 static void
 submit_completion(struct spdk_vhost_task *task)
 {
-	struct iovec *iovs = NULL;
-	int result;
-
 	spdk_vhost_vq_used_ring_enqueue(&task->svdev->vdev, task->vq, task->req_idx,
 					task->scsi.data_transferred);
 	SPDK_TRACELOG(SPDK_TRACE_VHOST, "Finished task (%p) req_idx=%d\n", task, task->req_idx);
 
-	if (task->scsi.iovs != &task->scsi.iov) {
-		iovs = task->scsi.iovs;
-		task->scsi.iovs = &task->scsi.iov;
-		task->scsi.iovcnt = 1;
-	}
-
 	spdk_vhost_task_put(task);
-
-	if (!iovs) {
-		return;
-	}
-
-	while (1) {
-		task = spdk_vhost_dequeue_task();
-		if (!task) {
-			spdk_vhost_iovec_free(iovs);
-			break;
-		}
-
-		/* Set iovs so underlying functions will not try to alloc IOV */
-		task->scsi.iovs = iovs;
-		task->scsi.iovcnt = VHOST_SCSI_IOVS_LEN;
-
-		result = process_request(task);
-		if (result == 0) {
-			task_submit(task);
-			break;
-		} else {
-			task->scsi.iovs = &task->scsi.iov;
-			task->scsi.iovcnt = 1;
-			invalid_request(task);
-		}
-	}
 }
 
 static void
@@ -308,12 +273,10 @@ task_data_setup(struct spdk_vhost_task *task,
 	struct rte_vhost_vring *vq = task->vq;
 	struct spdk_vhost_dev *vdev = &task->svdev->vdev;
 	struct vring_desc *desc =  spdk_vhost_vq_get_desc(task->vq, task->req_idx);
-	struct iovec *iovs = task->scsi.iovs;
+	struct iovec *iovs = task->iovs;
-	uint16_t iovcnt = 0, iovcnt_max = task->scsi.iovcnt;
+	uint16_t iovcnt = 0, iovcnt_max = VHOST_SCSI_IOVS_LEN;
 	uint32_t len = 0;
 
-	assert(iovcnt_max == 1 || iovcnt_max == VHOST_SCSI_IOVS_LEN);
-
 	/* Sanity check. First descriptor must be readable and must have next one. */
 	if (unlikely(spdk_vhost_vring_desc_is_wr(desc) || !spdk_vhost_vring_desc_has_next(desc))) {
 		SPDK_WARNLOG("Invalid first (request) descriptor.\n");
@@ -326,6 +289,7 @@ task_data_setup(struct spdk_vhost_task *task,
 	desc = spdk_vhost_vring_desc_get_next(vq->desc, desc);
 	task->scsi.dxfer_dir = spdk_vhost_vring_desc_is_wr(desc) ? SPDK_SCSI_DIR_FROM_DEV :
 			       SPDK_SCSI_DIR_TO_DEV;
+	task->scsi.iovs = iovs;
 
 	if (task->scsi.dxfer_dir == SPDK_SCSI_DIR_FROM_DEV) {
 		/*
@@ -347,14 +311,6 @@ task_data_setup(struct spdk_vhost_task *task,
 		}
 
 		desc = spdk_vhost_vring_desc_get_next(vq->desc, desc);
-		if (iovcnt_max != VHOST_SCSI_IOVS_LEN && spdk_vhost_vring_desc_has_next(desc)) {
-			iovs = spdk_vhost_iovec_alloc();
-			if (iovs == NULL) {
-				return 1;
-			}
-
-			iovcnt_max = VHOST_SCSI_IOVS_LEN;
-		}
 
 		/* All remaining descriptors are data. */
 		while (iovcnt < iovcnt_max) {
@@ -379,19 +335,6 @@ task_data_setup(struct spdk_vhost_task *task,
 		 * No need to check descriptor WR flag as this is done while setting scsi.dxfer_dir.
 		 */
 
-		if (iovcnt_max != VHOST_SCSI_IOVS_LEN && spdk_vhost_vring_desc_has_next(desc)) {
-			/* If next descriptor is not for response, allocate iovs. */
-			if (!spdk_vhost_vring_desc_is_wr(spdk_vhost_vring_desc_get_next(vq->desc, desc))) {
-				iovs = spdk_vhost_iovec_alloc();
-
-				if (iovs == NULL) {
-					return 1;
-				}
-
-				iovcnt_max = VHOST_SCSI_IOVS_LEN;
-			}
-		}
-
 		/* Process descriptors up to response. */
 		while (!spdk_vhost_vring_desc_is_wr(desc) && iovcnt < iovcnt_max) {
 			spdk_vhost_vring_desc_to_iov(vdev, &iovs[iovcnt], desc);
@@ -413,22 +356,17 @@ task_data_setup(struct spdk_vhost_task *task,
 		}
 	}
 
-	if (iovcnt_max > 1 && iovcnt == iovcnt_max) {
+	if (iovcnt == iovcnt_max) {
 		SPDK_WARNLOG("Too many IO vectors in chain!\n");
 		goto abort_task;
 	}
 
-	task->scsi.iovs = iovs;
 	task->scsi.iovcnt = iovcnt;
 	task->scsi.length = len;
 	task->scsi.transfer_len = len;
 	return 0;
 
 abort_task:
-	if (iovs != task->scsi.iovs) {
-		spdk_vhost_iovec_free(iovs);
-	}
-
 	if (task->resp) {
 		task->resp->response = VIRTIO_SCSI_S_ABORTED;
 	}
@@ -496,9 +434,6 @@ process_requestq(struct spdk_vhost_scsi_dev *svdev, struct rte_vhost_vring *vq)
 			task_submit(task);
 			SPDK_TRACELOG(SPDK_TRACE_VHOST, "====== Task %p req_idx %d submitted ======\n", task,
 				      task->req_idx);
-		} else if (result > 0) {
-			spdk_vhost_enqueue_task(task);
-			SPDK_TRACELOG(SPDK_TRACE_VHOST, "====== Task %p req_idx %d deferred ======\n", task, task->req_idx);
 		} else {
 			invalid_request(task);
 			SPDK_TRACELOG(SPDK_TRACE_VHOST, "====== Task %p req_idx %d failed ======\n", task, task->req_idx);