From 2dbcdf33dbf61f44b29adb52338282c3d7840d0e Mon Sep 17 00:00:00 2001 From: Nicholas Bellinger Date: Sun, 24 Jan 2016 22:41:50 -0800 Subject: [PATCH] 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: Juergen Gross Tested-by: Juergen Gross Cc: Hannes Reinecke Cc: David Vrabel Signed-off-by: Nicholas Bellinger --- drivers/xen/xen-scsiback.c | 167 ++++++++++++++++++++----------------- 1 file changed, 89 insertions(+), 78 deletions(-) diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c index 077993fcc203..3f379f79cfb9 100644 --- a/drivers/xen/xen-scsiback.c +++ b/drivers/xen/xen-scsiback.c @@ -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; + scsiback_do_resp_with_sense(NULL, err, 0, pending_req); + transport_generic_free_cmd(&pending_req->se_cmd, 1); + return; out: - if (tmr) { - transport_generic_free_cmd(&pending_req->se_cmd, 1); + 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; + vir.chn, vir.tgt, vir.lun); + 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; } @@ -750,8 +777,8 @@ static int scsiback_do_cmd_fn(struct vscsibk_info *info) if (scsiback_gnttab_data_map(&ring_req, pending_req)) { 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); + DRIVER_ERROR << 24, 0, 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); -- 2.20.1