IB/srp: allow lockless work posting
Only one CPU at a time will own an RX IU, so using the address of the IU as the work request cookie allows us to avoid taking a lock. We can similarly prepare the TX path for lockless posting by moving the free TX IUs to a list. This also removes the requirement that the queue sizes be a power of 2. Signed-off-by: Bart Van Assche <bvanassche@acm.org> [ broken out, small cleanups, and modified to avoid needing an extra field in the IU by David Dillow] Signed-off-by: David Dillow <dillowda@ornl.gov>
This commit is contained in:
Bart Van Assche
David Dillow
Родитель
9709f0e05b
Коммит
dcb4cb85f4
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@ -568,7 +568,7 @@ static int srp_reconnect_target(struct srp_target_port *target)
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struct ib_qp_attr qp_attr;
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struct srp_request *req, *tmp;
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struct ib_wc wc;
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int ret;
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int i, ret;
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if (!srp_change_state(target, SRP_TARGET_LIVE, SRP_TARGET_CONNECTING))
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return -EAGAIN;
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@ -601,9 +601,9 @@ static int srp_reconnect_target(struct srp_target_port *target)
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srp_reset_req(target, req);
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spin_unlock_irq(target->scsi_host->host_lock);
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target->rx_head = 0;
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target->tx_head = 0;
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target->tx_tail = 0;
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list_del_init(&target->free_tx);
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for (i = 0; i < SRP_SQ_SIZE; ++i)
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list_move(&target->tx_ring[i]->list, &target->free_tx);
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target->qp_in_error = 0;
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ret = srp_connect_target(target);
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@ -817,7 +817,7 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target,
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/*
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* Must be called with target->scsi_host->host_lock held to protect
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* req_lim and tx_head. Lock cannot be dropped between call here and
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* req_lim and free_tx. Lock cannot be dropped between call here and
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* call to __srp_post_send().
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*
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* Note:
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@ -837,7 +837,7 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
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srp_send_completion(target->send_cq, target);
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if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE)
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if (list_empty(&target->free_tx))
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return NULL;
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/* Initiator responses to target requests do not consume credits */
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@ -846,14 +846,14 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target,
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return NULL;
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}
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iu = target->tx_ring[target->tx_head & SRP_SQ_MASK];
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iu = list_first_entry(&target->free_tx, struct srp_iu, list);
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iu->type = iu_type;
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return iu;
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}
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/*
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* Must be called with target->scsi_host->host_lock held to protect
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* req_lim and tx_head.
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* req_lim and free_tx.
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*/
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static int __srp_post_send(struct srp_target_port *target,
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struct srp_iu *iu, int len)
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@ -867,7 +867,7 @@ static int __srp_post_send(struct srp_target_port *target,
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list.lkey = target->srp_host->srp_dev->mr->lkey;
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wr.next = NULL;
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wr.wr_id = target->tx_head & SRP_SQ_MASK;
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wr.wr_id = (uintptr_t) iu;
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wr.sg_list = &list;
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wr.num_sge = 1;
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wr.opcode = IB_WR_SEND;
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@ -876,7 +876,7 @@ static int __srp_post_send(struct srp_target_port *target,
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ret = ib_post_send(target->qp, &wr, &bad_wr);
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if (!ret) {
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++target->tx_head;
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list_del(&iu->list);
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if (iu->type != SRP_IU_RSP)
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--target->req_lim;
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}
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@ -884,36 +884,21 @@ static int __srp_post_send(struct srp_target_port *target,
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return ret;
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}
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static int srp_post_recv(struct srp_target_port *target)
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static int srp_post_recv(struct srp_target_port *target, struct srp_iu *iu)
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{
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unsigned long flags;
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struct srp_iu *iu;
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struct ib_sge list;
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struct ib_recv_wr wr, *bad_wr;
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unsigned int next;
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int ret;
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spin_lock_irqsave(target->scsi_host->host_lock, flags);
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next = target->rx_head & SRP_RQ_MASK;
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wr.wr_id = next;
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iu = target->rx_ring[next];
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struct ib_sge list;
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list.addr = iu->dma;
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list.length = iu->size;
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list.lkey = target->srp_host->srp_dev->mr->lkey;
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wr.next = NULL;
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wr.wr_id = (uintptr_t) iu;
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wr.sg_list = &list;
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wr.num_sge = 1;
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ret = ib_post_recv(target->qp, &wr, &bad_wr);
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if (!ret)
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++target->rx_head;
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spin_unlock_irqrestore(target->scsi_host->host_lock, flags);
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return ret;
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return ib_post_recv(target->qp, &wr, &bad_wr);
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}
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static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp)
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@ -1030,14 +1015,11 @@ static void srp_process_aer_req(struct srp_target_port *target,
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static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
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{
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struct ib_device *dev;
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struct srp_iu *iu;
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struct ib_device *dev = target->srp_host->srp_dev->dev;
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struct srp_iu *iu = (struct srp_iu *) wc->wr_id;
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int res;
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u8 opcode;
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iu = target->rx_ring[wc->wr_id];
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dev = target->srp_host->srp_dev->dev;
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ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_ti_iu_len,
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DMA_FROM_DEVICE);
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@ -1078,7 +1060,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc)
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ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len,
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DMA_FROM_DEVICE);
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res = srp_post_recv(target);
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res = srp_post_recv(target, iu);
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if (res != 0)
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shost_printk(KERN_ERR, target->scsi_host,
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PFX "Recv failed with error code %d\n", res);
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@ -1107,6 +1089,7 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
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{
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struct srp_target_port *target = target_ptr;
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struct ib_wc wc;
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struct srp_iu *iu;
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while (ib_poll_cq(cq, 1, &wc) > 0) {
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if (wc.status) {
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@ -1117,7 +1100,8 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr)
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break;
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}
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++target->tx_tail;
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iu = (struct srp_iu *) wc.wr_id;
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list_add(&iu->list, &target->free_tx);
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}
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}
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@ -1212,6 +1196,8 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target)
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GFP_KERNEL, DMA_TO_DEVICE);
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if (!target->tx_ring[i])
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goto err;
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list_add(&target->tx_ring[i]->list, &target->free_tx);
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}
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return 0;
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@ -1373,7 +1359,8 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event)
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break;
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for (i = 0; i < SRP_RQ_SIZE; i++) {
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target->status = srp_post_recv(target);
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struct srp_iu *iu = target->rx_ring[i];
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target->status = srp_post_recv(target, iu);
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if (target->status)
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break;
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}
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@ -1965,6 +1952,7 @@ static ssize_t srp_create_target(struct device *dev,
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target->scsi_host = target_host;
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target->srp_host = host;
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INIT_LIST_HEAD(&target->free_tx);
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INIT_LIST_HEAD(&target->free_reqs);
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INIT_LIST_HEAD(&target->req_queue);
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for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) {
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@ -2235,8 +2223,7 @@ static int __init srp_init_module(void)
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{
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int ret;
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BUILD_BUG_ON_NOT_POWER_OF_2(SRP_SQ_SIZE);
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BUILD_BUG_ON_NOT_POWER_OF_2(SRP_RQ_SIZE);
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BUILD_BUG_ON(FIELD_SIZEOF(struct ib_wc, wr_id) < sizeof(void *));
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if (srp_sg_tablesize > 255) {
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printk(KERN_WARNING PFX "Clamping srp_sg_tablesize to 255\n");
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@ -59,10 +59,8 @@ enum {
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SRP_RQ_SHIFT = 6,
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SRP_RQ_SIZE = 1 << SRP_RQ_SHIFT,
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SRP_RQ_MASK = SRP_RQ_SIZE - 1,
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SRP_SQ_SIZE = SRP_RQ_SIZE,
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SRP_SQ_MASK = SRP_SQ_SIZE - 1,
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SRP_RSP_SQ_SIZE = 1,
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SRP_REQ_SQ_SIZE = SRP_SQ_SIZE - SRP_RSP_SQ_SIZE,
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SRP_TSK_MGMT_SQ_SIZE = 1,
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@ -144,11 +142,9 @@ struct srp_target_port {
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int zero_req_lim;
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unsigned rx_head;
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struct srp_iu *rx_ring[SRP_RQ_SIZE];
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unsigned tx_head;
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unsigned tx_tail;
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struct list_head free_tx;
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struct srp_iu *tx_ring[SRP_SQ_SIZE];
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struct list_head free_reqs;
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@ -168,6 +164,7 @@ struct srp_target_port {
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};
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struct srp_iu {
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struct list_head list;
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u64 dma;
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void *buf;
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size_t size;
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