Commit 2dbcdf33 authored by Nicholas Bellinger's avatar Nicholas Bellinger
Browse files

xen-scsiback: Convert to percpu_ida tag allocation 



This patch converts xen-scsiback to use percpu_ida tag
pre-allocation for struct vscsibk_pend descriptor, in
order to avoid fast-path struct vscsibk_pend memory
allocations.

Note by default this is currently hardcoded to 128.

(Add wrapper for handling pending_req tag failure - Juergen)
(Drop left-over se_cmd memset in scsiback_cmd_exec - Juergen)

Acked-by: default avatarJuergen Gross <jgross@suse.com>
Tested-by: default avatarJuergen Gross <jgross@suse.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: default avatarNicholas Bellinger <nab@linux-iscsi.org>
parent cff834c1

drivers/xen/xen-scsiback.c

+89 −78
Original line number Diff line number Diff line
@@ -141,6 +141,8 @@ struct scsiback_tmr { 
	wait_queue_head_t tmr_wait;

};



#define VSCSI_DEFAULT_SESSION_TAGS	128



struct scsiback_nexus {

	/* Pointer to TCM session for I_T Nexus */

	struct se_session *tvn_se_sess;
@@ -190,7 +192,6 @@ module_param_named(max_buffer_pages, scsiback_max_buffer_pages, int, 0644); 
MODULE_PARM_DESC(max_buffer_pages,

"Maximum number of free pages to keep in backend buffer");



static struct kmem_cache *scsiback_cachep;

static DEFINE_SPINLOCK(free_pages_lock);

static int free_pages_num;

static LIST_HEAD(scsiback_free_pages);
@@ -321,11 +322,11 @@ static void scsiback_free_translation_entry(struct kref *kref) 
	kfree(entry);

}



static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,

			uint32_t resid, struct vscsibk_pend *pending_req)

static void scsiback_send_response(struct vscsibk_info *info,

			char *sense_buffer, int32_t result, uint32_t resid,

			uint16_t rqid)

{

	struct vscsiif_response *ring_res;

	struct vscsibk_info *info = pending_req->info;

	int notify;

	struct scsi_sense_hdr sshdr;

	unsigned long flags;
@@ -337,7 +338,7 @@ static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result, 
	info->ring.rsp_prod_pvt++;



	ring_res->rslt   = result;

	ring_res->rqid   = pending_req->rqid;

	ring_res->rqid   = rqid;



	if (sense_buffer != NULL &&

	    scsi_normalize_sense(sense_buffer, VSCSIIF_SENSE_BUFFERSIZE,
@@ -357,6 +358,13 @@ static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result, 


	if (notify)

		notify_remote_via_irq(info->irq);

}



static void scsiback_do_resp_with_sense(char *sense_buffer, int32_t result,

			uint32_t resid, struct vscsibk_pend *pending_req)

{

	scsiback_send_response(pending_req->info, sense_buffer, result,

			       resid, pending_req->rqid);



	if (pending_req->v2p)

		kref_put(&pending_req->v2p->kref,
@@ -388,10 +396,6 @@ static void scsiback_cmd_exec(struct vscsibk_pend *pending_req) 
	struct se_session *sess = pending_req->v2p->tpg->tpg_nexus->tvn_se_sess;

	int rc;



	memset(pending_req->sense_buffer, 0, VSCSIIF_SENSE_BUFFERSIZE);



	memset(se_cmd, 0, sizeof(*se_cmd));



	scsiback_get(pending_req->info);

	se_cmd->tag = pending_req->rqid;

	rc = target_submit_cmd_map_sgls(se_cmd, sess, pending_req->cmnd,
@@ -616,15 +620,13 @@ static void scsiback_device_action(struct vscsibk_pend *pending_req, 
	err = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?

		SUCCESS : FAILED;



out:

	if (tmr) {

	scsiback_do_resp_with_sense(NULL, err, 0, pending_req);

	transport_generic_free_cmd(&pending_req->se_cmd, 1);

	return;

out:

	if (tmr)

		kfree(tmr);

	}



	scsiback_do_resp_with_sense(NULL, err, 0, pending_req);



	kmem_cache_free(scsiback_cachep, pending_req);

}



/*
@@ -653,15 +655,53 @@ out: 
	return entry;

}



static int prepare_pending_reqs(struct vscsibk_info *info,

				struct vscsiif_request *ring_req,

				struct vscsibk_pend *pending_req)

static struct vscsibk_pend *scsiback_get_pend_req(struct vscsiif_back_ring *ring,

				struct v2p_entry *v2p)

{

	struct scsiback_tpg *tpg = v2p->tpg;

	struct scsiback_nexus *nexus = tpg->tpg_nexus;

	struct se_session *se_sess = nexus->tvn_se_sess;

	struct vscsibk_pend *req;

	int tag, i;



	tag = percpu_ida_alloc(&se_sess->sess_tag_pool, TASK_RUNNING);

	if (tag < 0) {

		pr_err("Unable to obtain tag for vscsiif_request\n");

		return ERR_PTR(-ENOMEM);

	}



	req = &((struct vscsibk_pend *)se_sess->sess_cmd_map)[tag];

	memset(req, 0, sizeof(*req));

	req->se_cmd.map_tag = tag;



	for (i = 0; i < VSCSI_MAX_GRANTS; i++)

		req->grant_handles[i] = SCSIBACK_INVALID_HANDLE;



	return req;

}



static struct vscsibk_pend *prepare_pending_reqs(struct vscsibk_info *info,

				struct vscsiif_back_ring *ring,

				struct vscsiif_request *ring_req)

{

	struct vscsibk_pend *pending_req;

	struct v2p_entry *v2p;

	struct ids_tuple vir;



	pending_req->rqid       = ring_req->rqid;

	pending_req->info       = info;

	/* request range check from frontend */

	if ((ring_req->sc_data_direction != DMA_BIDIRECTIONAL) &&

		(ring_req->sc_data_direction != DMA_TO_DEVICE) &&

		(ring_req->sc_data_direction != DMA_FROM_DEVICE) &&

		(ring_req->sc_data_direction != DMA_NONE)) {

		pr_debug("invalid parameter data_dir = %d\n",

			ring_req->sc_data_direction);

		return ERR_PTR(-EINVAL);

	}

	if (ring_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {

		pr_debug("invalid parameter cmd_len = %d\n",

			ring_req->cmd_len);

		return ERR_PTR(-EINVAL);

	}



	vir.chn = ring_req->channel;

	vir.tgt = ring_req->id;
@@ -669,33 +709,24 @@ static int prepare_pending_reqs(struct vscsibk_info *info, 


	v2p = scsiback_do_translation(info, &vir);

	if (!v2p) {

		pending_req->v2p = NULL;

		pr_debug("the v2p of (chn:%d, tgt:%d, lun:%d) doesn't exist.\n",

			 vir.chn, vir.tgt, vir.lun);

		return -ENODEV;

		return ERR_PTR(-ENODEV);

	}

	pending_req->v2p = v2p;



	/* request range check from frontend */

	pending_req->sc_data_direction = ring_req->sc_data_direction;

	if ((pending_req->sc_data_direction != DMA_BIDIRECTIONAL) &&

		(pending_req->sc_data_direction != DMA_TO_DEVICE) &&

		(pending_req->sc_data_direction != DMA_FROM_DEVICE) &&

		(pending_req->sc_data_direction != DMA_NONE)) {

		pr_debug("invalid parameter data_dir = %d\n",

			pending_req->sc_data_direction);

		return -EINVAL;

	pending_req = scsiback_get_pend_req(ring, v2p);

	if (IS_ERR(pending_req)) {

		kref_put(&v2p->kref, scsiback_free_translation_entry);

		return ERR_PTR(-ENOMEM);

	}



	pending_req->rqid = ring_req->rqid;

	pending_req->info = info;

	pending_req->v2p = v2p;

	pending_req->sc_data_direction = ring_req->sc_data_direction;

	pending_req->cmd_len = ring_req->cmd_len;

	if (pending_req->cmd_len > VSCSIIF_MAX_COMMAND_SIZE) {

		pr_debug("invalid parameter cmd_len = %d\n",

			pending_req->cmd_len);

		return -EINVAL;

	}

	memcpy(pending_req->cmnd, ring_req->cmnd, pending_req->cmd_len);



	return 0;

	return pending_req;

}



static int scsiback_do_cmd_fn(struct vscsibk_info *info)
@@ -704,7 +735,7 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) 
	struct vscsiif_request ring_req;

	struct vscsibk_pend *pending_req;

	RING_IDX rc, rp;

	int err, more_to_do;

	int more_to_do;

	uint32_t result;



	rc = ring->req_cons;
@@ -722,16 +753,13 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) 
	while ((rc != rp)) {

		if (RING_REQUEST_CONS_OVERFLOW(ring, rc))

			break;

		pending_req = kmem_cache_alloc(scsiback_cachep, GFP_KERNEL);

		if (!pending_req)

			return 1;



		RING_COPY_REQUEST(ring, rc, &ring_req);

		ring->req_cons = ++rc;



		err = prepare_pending_reqs(info, &ring_req, pending_req);

		if (err) {

			switch (err) {

		pending_req = prepare_pending_reqs(info, ring, &ring_req);

		if (IS_ERR(pending_req)) {

			switch (PTR_ERR(pending_req)) {

			case -ENODEV:

				result = DID_NO_CONNECT;

				break;
@@ -739,9 +767,8 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) 
				result = DRIVER_ERROR;

				break;

			}

			scsiback_do_resp_with_sense(NULL, result << 24, 0,

						    pending_req);

			kmem_cache_free(scsiback_cachep, pending_req);

			scsiback_send_response(info, NULL, result << 24, 0,

					       ring_req.rqid);

			return 1;

		}
@@ -751,7 +778,7 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) 
				scsiback_fast_flush_area(pending_req);

				scsiback_do_resp_with_sense(NULL,

						DRIVER_ERROR << 24, 0, pending_req);

				kmem_cache_free(scsiback_cachep, pending_req);

				transport_generic_free_cmd(&pending_req->se_cmd, 0);

			} else {

				scsiback_cmd_exec(pending_req);

			}
@@ -765,9 +792,9 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) 
			break;

		default:

			pr_err_ratelimited("invalid request\n");

			scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24,

						    0, pending_req);

			kmem_cache_free(scsiback_cachep, pending_req);

			scsiback_do_resp_with_sense(NULL, DRIVER_ERROR << 24, 0,

						    pending_req);

			transport_generic_free_cmd(&pending_req->se_cmd, 0);

			break;

		}
@@ -1355,10 +1382,9 @@ static int scsiback_check_stop_free(struct se_cmd *se_cmd) 


static void scsiback_release_cmd(struct se_cmd *se_cmd)

{

	struct vscsibk_pend *pending_req = container_of(se_cmd,

				struct vscsibk_pend, se_cmd);

	struct se_session *se_sess = se_cmd->se_sess;



	kmem_cache_free(scsiback_cachep, pending_req);

	percpu_ida_free(&se_sess->sess_tag_pool, se_cmd->map_tag);

}



static int scsiback_shutdown_session(struct se_session *se_sess)
@@ -1511,7 +1537,9 @@ static int scsiback_make_nexus(struct scsiback_tpg *tpg, 
		goto out_unlock;

	}



	tv_nexus->tvn_se_sess = target_alloc_session(&tpg->se_tpg, 0, 0,

	tv_nexus->tvn_se_sess = target_alloc_session(&tpg->se_tpg,

						     VSCSI_DEFAULT_SESSION_TAGS,

						     sizeof(struct vscsibk_pend),

						     TARGET_PROT_NORMAL, name,

						     tv_nexus, scsiback_alloc_sess_cb);

	if (IS_ERR(tv_nexus->tvn_se_sess)) {
@@ -1840,16 +1868,6 @@ static struct xenbus_driver scsiback_driver = { 
	.otherend_changed	= scsiback_frontend_changed

};



static void scsiback_init_pend(void *p)

{

	struct vscsibk_pend *pend = p;

	int i;



	memset(pend, 0, sizeof(*pend));

	for (i = 0; i < VSCSI_MAX_GRANTS; i++)

		pend->grant_handles[i] = SCSIBACK_INVALID_HANDLE;

}



static int __init scsiback_init(void)

{

	int ret;
@@ -1860,14 +1878,9 @@ static int __init scsiback_init(void) 
	pr_debug("xen-pvscsi: fabric module %s on %s/%s on "UTS_RELEASE"\n",

		 VSCSI_VERSION, utsname()->sysname, utsname()->machine);



	scsiback_cachep = kmem_cache_create("vscsiif_cache",

		sizeof(struct vscsibk_pend), 0, 0, scsiback_init_pend);

	if (!scsiback_cachep)

		return -ENOMEM;



	ret = xenbus_register_backend(&scsiback_driver);

	if (ret)

		goto out_cache_destroy;

		goto out;



	ret = target_register_template(&scsiback_ops);

	if (ret)
@@ -1877,8 +1890,7 @@ static int __init scsiback_init(void) 


out_unregister_xenbus:

	xenbus_unregister_driver(&scsiback_driver);

out_cache_destroy:

	kmem_cache_destroy(scsiback_cachep);

out:

	pr_err("%s: error %d\n", __func__, ret);

	return ret;

}
@@ -1894,7 +1906,6 @@ static void __exit scsiback_exit(void) 
	}

	target_unregister_template(&scsiback_ops);

	xenbus_unregister_driver(&scsiback_driver);

	kmem_cache_destroy(scsiback_cachep);

}



module_init(scsiback_init);

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