From: Bart Van Assche <bvanassche@xxxxxxx> 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@xxxxxxx> [ broken out, small cleanups, and modified to avoid needing an extra field in the IU by David Dillow] Signed-off-by: David Dillow <dillowda@xxxxxxxx> --- drivers/infiniband/ulp/srp/ib_srp.c | 65 ++++++++++++++--------------------- drivers/infiniband/ulp/srp/ib_srp.h | 7 +--- 2 files changed, 28 insertions(+), 44 deletions(-) diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c index def9e6b..aa78d26 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.c +++ b/drivers/infiniband/ulp/srp/ib_srp.c @@ -568,7 +568,7 @@ static int srp_reconnect_target(struct srp_target_port *target) struct ib_qp_attr qp_attr; struct srp_request *req, *tmp; struct ib_wc wc; - int ret; + int i, ret; if (!srp_change_state(target, SRP_TARGET_LIVE, SRP_TARGET_CONNECTING)) return -EAGAIN; @@ -601,9 +601,9 @@ static int srp_reconnect_target(struct srp_target_port *target) srp_reset_req(target, req); spin_unlock_irq(target->scsi_host->host_lock); - target->rx_head = 0; - target->tx_head = 0; - target->tx_tail = 0; + list_del_init(&target->free_tx); + for (i = 0; i < SRP_SQ_SIZE; ++i) + list_move(&target->tx_ring[i]->list, &target->free_tx); target->qp_in_error = 0; ret = srp_connect_target(target); @@ -817,7 +817,7 @@ static int srp_map_data(struct scsi_cmnd *scmnd, struct srp_target_port *target, /* * Must be called with target->scsi_host->host_lock held to protect - * req_lim and tx_head. Lock cannot be dropped between call here and + * req_lim and free_tx. Lock cannot be dropped between call here and * call to __srp_post_send(). * * Note: @@ -837,7 +837,7 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target, srp_send_completion(target->send_cq, target); - if (target->tx_head - target->tx_tail >= SRP_SQ_SIZE) + if (list_empty(&target->free_tx)) return NULL; /* Initiator responses to target requests do not consume credits */ @@ -846,14 +846,14 @@ static struct srp_iu *__srp_get_tx_iu(struct srp_target_port *target, return NULL; } - iu = target->tx_ring[target->tx_head & SRP_SQ_MASK]; + iu = list_first_entry(&target->free_tx, struct srp_iu, list); iu->type = iu_type; return iu; } /* * Must be called with target->scsi_host->host_lock held to protect - * req_lim and tx_head. + * req_lim and free_tx. */ static int __srp_post_send(struct srp_target_port *target, struct srp_iu *iu, int len) @@ -867,7 +867,7 @@ static int __srp_post_send(struct srp_target_port *target, list.lkey = target->srp_host->srp_dev->mr->lkey; wr.next = NULL; - wr.wr_id = target->tx_head & SRP_SQ_MASK; + wr.wr_id = (uintptr_t) iu; wr.sg_list = &list; wr.num_sge = 1; wr.opcode = IB_WR_SEND; @@ -876,7 +876,7 @@ static int __srp_post_send(struct srp_target_port *target, ret = ib_post_send(target->qp, &wr, &bad_wr); if (!ret) { - ++target->tx_head; + list_del(&iu->list); if (iu->type != SRP_IU_RSP) --target->req_lim; } @@ -884,36 +884,21 @@ static int __srp_post_send(struct srp_target_port *target, return ret; } -static int srp_post_recv(struct srp_target_port *target) +static int srp_post_recv(struct srp_target_port *target, struct srp_iu *iu) { - unsigned long flags; - struct srp_iu *iu; - struct ib_sge list; struct ib_recv_wr wr, *bad_wr; - unsigned int next; - int ret; - - spin_lock_irqsave(target->scsi_host->host_lock, flags); - - next = target->rx_head & SRP_RQ_MASK; - wr.wr_id = next; - iu = target->rx_ring[next]; + struct ib_sge list; list.addr = iu->dma; list.length = iu->size; list.lkey = target->srp_host->srp_dev->mr->lkey; wr.next = NULL; + wr.wr_id = (uintptr_t) iu; wr.sg_list = &list; wr.num_sge = 1; - ret = ib_post_recv(target->qp, &wr, &bad_wr); - if (!ret) - ++target->rx_head; - - spin_unlock_irqrestore(target->scsi_host->host_lock, flags); - - return ret; + return ib_post_recv(target->qp, &wr, &bad_wr); } static void srp_process_rsp(struct srp_target_port *target, struct srp_rsp *rsp) @@ -1030,14 +1015,11 @@ static void srp_process_aer_req(struct srp_target_port *target, static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) { - struct ib_device *dev; - struct srp_iu *iu; + struct ib_device *dev = target->srp_host->srp_dev->dev; + struct srp_iu *iu = (struct srp_iu *) wc->wr_id; int res; u8 opcode; - iu = target->rx_ring[wc->wr_id]; - - dev = target->srp_host->srp_dev->dev; ib_dma_sync_single_for_cpu(dev, iu->dma, target->max_ti_iu_len, DMA_FROM_DEVICE); @@ -1078,7 +1060,7 @@ static void srp_handle_recv(struct srp_target_port *target, struct ib_wc *wc) ib_dma_sync_single_for_device(dev, iu->dma, target->max_ti_iu_len, DMA_FROM_DEVICE); - res = srp_post_recv(target); + res = srp_post_recv(target, iu); if (res != 0) shost_printk(KERN_ERR, target->scsi_host, PFX "Recv failed with error code %d\n", res); @@ -1107,6 +1089,7 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr) { struct srp_target_port *target = target_ptr; struct ib_wc wc; + struct srp_iu *iu; while (ib_poll_cq(cq, 1, &wc) > 0) { if (wc.status) { @@ -1117,7 +1100,8 @@ static void srp_send_completion(struct ib_cq *cq, void *target_ptr) break; } - ++target->tx_tail; + iu = (struct srp_iu *) wc.wr_id; + list_add(&iu->list, &target->free_tx); } } @@ -1212,6 +1196,8 @@ static int srp_alloc_iu_bufs(struct srp_target_port *target) GFP_KERNEL, DMA_TO_DEVICE); if (!target->tx_ring[i]) goto err; + + list_add(&target->tx_ring[i]->list, &target->free_tx); } return 0; @@ -1373,7 +1359,8 @@ static int srp_cm_handler(struct ib_cm_id *cm_id, struct ib_cm_event *event) break; for (i = 0; i < SRP_RQ_SIZE; i++) { - target->status = srp_post_recv(target); + struct srp_iu *iu = target->rx_ring[i]; + target->status = srp_post_recv(target, iu); if (target->status) break; } @@ -1965,6 +1952,7 @@ static ssize_t srp_create_target(struct device *dev, target->scsi_host = target_host; target->srp_host = host; + INIT_LIST_HEAD(&target->free_tx); INIT_LIST_HEAD(&target->free_reqs); INIT_LIST_HEAD(&target->req_queue); for (i = 0; i < SRP_CMD_SQ_SIZE; ++i) { @@ -2235,8 +2223,7 @@ static int __init srp_init_module(void) { int ret; - BUILD_BUG_ON_NOT_POWER_OF_2(SRP_SQ_SIZE); - BUILD_BUG_ON_NOT_POWER_OF_2(SRP_RQ_SIZE); + BUILD_BUG_ON(FIELD_SIZEOF(struct ib_wc, wr_id) < sizeof(void *)); if (srp_sg_tablesize > 255) { printk(KERN_WARNING PFX "Clamping srp_sg_tablesize to 255\n"); diff --git a/drivers/infiniband/ulp/srp/ib_srp.h b/drivers/infiniband/ulp/srp/ib_srp.h index f8b689a..41ecb46 100644 --- a/drivers/infiniband/ulp/srp/ib_srp.h +++ b/drivers/infiniband/ulp/srp/ib_srp.h @@ -59,10 +59,8 @@ enum { SRP_RQ_SHIFT = 6, SRP_RQ_SIZE = 1 << SRP_RQ_SHIFT, - SRP_RQ_MASK = SRP_RQ_SIZE - 1, SRP_SQ_SIZE = SRP_RQ_SIZE, - SRP_SQ_MASK = SRP_SQ_SIZE - 1, SRP_RSP_SQ_SIZE = 1, SRP_REQ_SQ_SIZE = SRP_SQ_SIZE - SRP_RSP_SQ_SIZE, SRP_TSK_MGMT_SQ_SIZE = 1, @@ -144,11 +142,9 @@ struct srp_target_port { int zero_req_lim; - unsigned rx_head; struct srp_iu *rx_ring[SRP_RQ_SIZE]; - unsigned tx_head; - unsigned tx_tail; + struct list_head free_tx; struct srp_iu *tx_ring[SRP_SQ_SIZE]; struct list_head free_reqs; @@ -168,6 +164,7 @@ struct srp_target_port { }; struct srp_iu { + struct list_head list; u64 dma; void *buf; size_t size; -- 1.7.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html