diff options
Diffstat (limited to 'net/rds/ib_send.c')
| -rw-r--r-- | net/rds/ib_send.c | 874 |
1 files changed, 874 insertions, 0 deletions
diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c new file mode 100644 index 00000000000..cb6c52cb1c4 --- /dev/null +++ b/net/rds/ib_send.c @@ -0,0 +1,874 @@ +/* + * Copyright (c) 2006 Oracle. All rights reserved. + * + * This software is available to you under a choice of one of two + * licenses. You may choose to be licensed under the terms of the GNU + * General Public License (GPL) Version 2, available from the file + * COPYING in the main directory of this source tree, or the + * OpenIB.org BSD license below: + * + * Redistribution and use in source and binary forms, with or + * without modification, are permitted provided that the following + * conditions are met: + * + * - Redistributions of source code must retain the above + * copyright notice, this list of conditions and the following + * disclaimer. + * + * - Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following + * disclaimer in the documentation and/or other materials + * provided with the distribution. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + * + */ +#include <linux/kernel.h> +#include <linux/in.h> +#include <linux/device.h> +#include <linux/dmapool.h> + +#include "rds.h" +#include "rdma.h" +#include "ib.h" + +static void rds_ib_send_rdma_complete(struct rds_message *rm, + int wc_status) +{ + int notify_status; + + switch (wc_status) { + case IB_WC_WR_FLUSH_ERR: + return; + + case IB_WC_SUCCESS: + notify_status = RDS_RDMA_SUCCESS; + break; + + case IB_WC_REM_ACCESS_ERR: + notify_status = RDS_RDMA_REMOTE_ERROR; + break; + + default: + notify_status = RDS_RDMA_OTHER_ERROR; + break; + } + rds_rdma_send_complete(rm, notify_status); +} + +static void rds_ib_send_unmap_rdma(struct rds_ib_connection *ic, + struct rds_rdma_op *op) +{ + if (op->r_mapped) { + ib_dma_unmap_sg(ic->i_cm_id->device, + op->r_sg, op->r_nents, + op->r_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE); + op->r_mapped = 0; + } +} + +static void rds_ib_send_unmap_rm(struct rds_ib_connection *ic, + struct rds_ib_send_work *send, + int wc_status) +{ + struct rds_message *rm = send->s_rm; + + rdsdebug("ic %p send %p rm %p\n", ic, send, rm); + + ib_dma_unmap_sg(ic->i_cm_id->device, + rm->m_sg, rm->m_nents, + DMA_TO_DEVICE); + + if (rm->m_rdma_op != NULL) { + rds_ib_send_unmap_rdma(ic, rm->m_rdma_op); + + /* If the user asked for a completion notification on this + * message, we can implement three different semantics: + * 1. Notify when we received the ACK on the RDS message + * that was queued with the RDMA. This provides reliable + * notification of RDMA status at the expense of a one-way + * packet delay. + * 2. Notify when the IB stack gives us the completion event for + * the RDMA operation. + * 3. Notify when the IB stack gives us the completion event for + * the accompanying RDS messages. + * Here, we implement approach #3. To implement approach #2, + * call rds_rdma_send_complete from the cq_handler. To implement #1, + * don't call rds_rdma_send_complete at all, and fall back to the notify + * handling in the ACK processing code. + * + * Note: There's no need to explicitly sync any RDMA buffers using + * ib_dma_sync_sg_for_cpu - the completion for the RDMA + * operation itself unmapped the RDMA buffers, which takes care + * of synching. + */ + rds_ib_send_rdma_complete(rm, wc_status); + + if (rm->m_rdma_op->r_write) + rds_stats_add(s_send_rdma_bytes, rm->m_rdma_op->r_bytes); + else + rds_stats_add(s_recv_rdma_bytes, rm->m_rdma_op->r_bytes); + } + + /* If anyone waited for this message to get flushed out, wake + * them up now */ + rds_message_unmapped(rm); + + rds_message_put(rm); + send->s_rm = NULL; +} + +void rds_ib_send_init_ring(struct rds_ib_connection *ic) +{ + struct rds_ib_send_work *send; + u32 i; + + for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) { + struct ib_sge *sge; + + send->s_rm = NULL; + send->s_op = NULL; + + send->s_wr.wr_id = i; + send->s_wr.sg_list = send->s_sge; + send->s_wr.num_sge = 1; + send->s_wr.opcode = IB_WR_SEND; + send->s_wr.send_flags = 0; + send->s_wr.ex.imm_data = 0; + + sge = rds_ib_data_sge(ic, send->s_sge); + sge->lkey = ic->i_mr->lkey; + + sge = rds_ib_header_sge(ic, send->s_sge); + sge->addr = ic->i_send_hdrs_dma + (i * sizeof(struct rds_header)); + sge->length = sizeof(struct rds_header); + sge->lkey = ic->i_mr->lkey; + } +} + +void rds_ib_send_clear_ring(struct rds_ib_connection *ic) +{ + struct rds_ib_send_work *send; + u32 i; + + for (i = 0, send = ic->i_sends; i < ic->i_send_ring.w_nr; i++, send++) { + if (send->s_wr.opcode == 0xdead) + continue; + if (send->s_rm) + rds_ib_send_unmap_rm(ic, send, IB_WC_WR_FLUSH_ERR); + if (send->s_op) + rds_ib_send_unmap_rdma(ic, send->s_op); + } +} + +/* + * The _oldest/_free ring operations here race cleanly with the alloc/unalloc + * operations performed in the send path. As the sender allocs and potentially + * unallocs the next free entry in the ring it doesn't alter which is + * the next to be freed, which is what this is concerned with. + */ +void rds_ib_send_cq_comp_handler(struct ib_cq *cq, void *context) +{ + struct rds_connection *conn = context; + struct rds_ib_connection *ic = conn->c_transport_data; + struct ib_wc wc; + struct rds_ib_send_work *send; + u32 completed; + u32 oldest; + u32 i = 0; + int ret; + + rdsdebug("cq %p conn %p\n", cq, conn); + rds_ib_stats_inc(s_ib_tx_cq_call); + ret = ib_req_notify_cq(cq, IB_CQ_NEXT_COMP); + if (ret) + rdsdebug("ib_req_notify_cq send failed: %d\n", ret); + + while (ib_poll_cq(cq, 1, &wc) > 0) { + rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n", + (unsigned long long)wc.wr_id, wc.status, wc.byte_len, + be32_to_cpu(wc.ex.imm_data)); + rds_ib_stats_inc(s_ib_tx_cq_event); + + if (wc.wr_id == RDS_IB_ACK_WR_ID) { + if (ic->i_ack_queued + HZ/2 < jiffies) + rds_ib_stats_inc(s_ib_tx_stalled); + rds_ib_ack_send_complete(ic); + continue; + } + + oldest = rds_ib_ring_oldest(&ic->i_send_ring); + + completed = rds_ib_ring_completed(&ic->i_send_ring, wc.wr_id, oldest); + + for (i = 0; i < completed; i++) { + send = &ic->i_sends[oldest]; + + /* In the error case, wc.opcode sometimes contains garbage */ + switch (send->s_wr.opcode) { + case IB_WR_SEND: + if (send->s_rm) + rds_ib_send_unmap_rm(ic, send, wc.status); + break; + case IB_WR_RDMA_WRITE: + case IB_WR_RDMA_READ: + /* Nothing to be done - the SG list will be unmapped + * when the SEND completes. */ + break; + default: + if (printk_ratelimit()) + printk(KERN_NOTICE + "RDS/IB: %s: unexpected opcode 0x%x in WR!\n", + __func__, send->s_wr.opcode); + break; + } + + send->s_wr.opcode = 0xdead; + send->s_wr.num_sge = 1; + if (send->s_queued + HZ/2 < jiffies) + rds_ib_stats_inc(s_ib_tx_stalled); + + /* If a RDMA operation produced an error, signal this right + * away. If we don't, the subsequent SEND that goes with this + * RDMA will be canceled with ERR_WFLUSH, and the application + * never learn that the RDMA failed. */ + if (unlikely(wc.status == IB_WC_REM_ACCESS_ERR && send->s_op)) { + struct rds_message *rm; + + rm = rds_send_get_message(conn, send->s_op); + if (rm) + rds_ib_send_rdma_complete(rm, wc.status); + } + + oldest = (oldest + 1) % ic->i_send_ring.w_nr; + } + + rds_ib_ring_free(&ic->i_send_ring, completed); + + if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags) + || test_bit(0, &conn->c_map_queued)) + queue_delayed_work(rds_wq, &conn->c_send_w, 0); + + /* We expect errors as the qp is drained during shutdown */ + if (wc.status != IB_WC_SUCCESS && rds_conn_up(conn)) { + rds_ib_conn_error(conn, + "send completion on %pI4 " + "had status %u, disconnecting and reconnecting\n", + &conn->c_faddr, wc.status); + } + } +} + +/* + * This is the main function for allocating credits when sending + * messages. + * + * Conceptually, we have two counters: + * - send credits: this tells us how many WRs we're allowed + * to submit without overruning the reciever's queue. For + * each SEND WR we post, we decrement this by one. + * + * - posted credits: this tells us how many WRs we recently + * posted to the receive queue. This value is transferred + * to the peer as a "credit update" in a RDS header field. + * Every time we transmit credits to the peer, we subtract + * the amount of transferred credits from this counter. + * + * It is essential that we avoid situations where both sides have + * exhausted their send credits, and are unable to send new credits + * to the peer. We achieve this by requiring that we send at least + * one credit update to the peer before exhausting our credits. + * When new credits arrive, we subtract one credit that is withheld + * until we've posted new buffers and are ready to transmit these + * credits (see rds_ib_send_add_credits below). + * + * The RDS send code is essentially single-threaded; rds_send_xmit + * grabs c_send_lock to ensure exclusive access to the send ring. + * However, the ACK sending code is independent and can race with + * message SENDs. + * + * In the send path, we need to update the counters for send credits + * and the counter of posted buffers atomically - when we use the + * last available credit, we cannot allow another thread to race us + * and grab the posted credits counter. Hence, we have to use a + * spinlock to protect the credit counter, or use atomics. + * + * Spinlocks shared between the send and the receive path are bad, + * because they create unnecessary delays. An early implementation + * using a spinlock showed a 5% degradation in throughput at some + * loads. + * + * This implementation avoids spinlocks completely, putting both + * counters into a single atomic, and updating that atomic using + * atomic_add (in the receive path, when receiving fresh credits), + * and using atomic_cmpxchg when updating the two counters. + */ +int rds_ib_send_grab_credits(struct rds_ib_connection *ic, + u32 wanted, u32 *adv_credits, int need_posted) +{ + unsigned int avail, posted, got = 0, advertise; + long oldval, newval; + + *adv_credits = 0; + if (!ic->i_flowctl) + return wanted; + +try_again: + advertise = 0; + oldval = newval = atomic_read(&ic->i_credits); + posted = IB_GET_POST_CREDITS(oldval); + avail = IB_GET_SEND_CREDITS(oldval); + + rdsdebug("rds_ib_send_grab_credits(%u): credits=%u posted=%u\n", + wanted, avail, posted); + + /* The last credit must be used to send a credit update. */ + if (avail && !posted) + avail--; + + if (avail < wanted) { + struct rds_connection *conn = ic->i_cm_id->context; + + /* Oops, there aren't that many credits left! */ + set_bit(RDS_LL_SEND_FULL, &conn->c_flags); + got = avail; + } else { + /* Sometimes you get what you want, lalala. */ + got = wanted; + } + newval -= IB_SET_SEND_CREDITS(got); + + /* + * If need_posted is non-zero, then the caller wants + * the posted regardless of whether any send credits are + * available. + */ + if (posted && (got || need_posted)) { + advertise = min_t(unsigned int, posted, RDS_MAX_ADV_CREDIT); + newval -= IB_SET_POST_CREDITS(advertise); + } + + /* Finally bill everything */ + if (atomic_cmpxchg(&ic->i_credits, oldval, newval) != oldval) + goto try_again; + + *adv_credits = advertise; + return got; +} + +void rds_ib_send_add_credits(struct rds_connection *conn, unsigned int credits) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + + if (credits == 0) + return; + + rdsdebug("rds_ib_send_add_credits(%u): current=%u%s\n", + credits, + IB_GET_SEND_CREDITS(atomic_read(&ic->i_credits)), + test_bit(RDS_LL_SEND_FULL, &conn->c_flags) ? ", ll_send_full" : ""); + + atomic_add(IB_SET_SEND_CREDITS(credits), &ic->i_credits); + if (test_and_clear_bit(RDS_LL_SEND_FULL, &conn->c_flags)) + queue_delayed_work(rds_wq, &conn->c_send_w, 0); + + WARN_ON(IB_GET_SEND_CREDITS(credits) >= 16384); + + rds_ib_stats_inc(s_ib_rx_credit_updates); +} + +void rds_ib_advertise_credits(struct rds_connection *conn, unsigned int posted) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + + if (posted == 0) + return; + + atomic_add(IB_SET_POST_CREDITS(posted), &ic->i_credits); + + /* Decide whether to send an update to the peer now. + * If we would send a credit update for every single buffer we + * post, we would end up with an ACK storm (ACK arrives, + * consumes buffer, we refill the ring, send ACK to remote + * advertising the newly posted buffer... ad inf) + * + * Performance pretty much depends on how often we send + * credit updates - too frequent updates mean lots of ACKs. + * Too infrequent updates, and the peer will run out of + * credits and has to throttle. + * For the time being, 16 seems to be a good compromise. + */ + if (IB_GET_POST_CREDITS(atomic_read(&ic->i_credits)) >= 16) + set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); +} + +static inline void +rds_ib_xmit_populate_wr(struct rds_ib_connection *ic, + struct rds_ib_send_work *send, unsigned int pos, + unsigned long buffer, unsigned int length, + int send_flags) +{ + struct ib_sge *sge; + + WARN_ON(pos != send - ic->i_sends); + + send->s_wr.send_flags = send_flags; + send->s_wr.opcode = IB_WR_SEND; + send->s_wr.num_sge = 2; + send->s_wr.next = NULL; + send->s_queued = jiffies; + send->s_op = NULL; + + if (length != 0) { + sge = rds_ib_data_sge(ic, send->s_sge); + sge->addr = buffer; + sge->length = length; + sge->lkey = ic->i_mr->lkey; + + sge = rds_ib_header_sge(ic, send->s_sge); + } else { + /* We're sending a packet with no payload. There is only + * one SGE */ + send->s_wr.num_sge = 1; + sge = &send->s_sge[0]; + } + + sge->addr = ic->i_send_hdrs_dma + (pos * sizeof(struct rds_header)); + sge->length = sizeof(struct rds_header); + sge->lkey = ic->i_mr->lkey; +} + +/* + * This can be called multiple times for a given message. The first time + * we see a message we map its scatterlist into the IB device so that + * we can provide that mapped address to the IB scatter gather entries + * in the IB work requests. We translate the scatterlist into a series + * of work requests that fragment the message. These work requests complete + * in order so we pass ownership of the message to the completion handler + * once we send the final fragment. + * + * The RDS core uses the c_send_lock to only enter this function once + * per connection. This makes sure that the tx ring alloc/unalloc pairs + * don't get out of sync and confuse the ring. + */ +int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm, + unsigned int hdr_off, unsigned int sg, unsigned int off) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + struct ib_device *dev = ic->i_cm_id->device; + struct rds_ib_send_work *send = NULL; + struct rds_ib_send_work *first; + struct rds_ib_send_work *prev; + struct ib_send_wr *failed_wr; + struct scatterlist *scat; + u32 pos; + u32 i; + u32 work_alloc; + u32 credit_alloc; + u32 posted; + u32 adv_credits = 0; + int send_flags = 0; + int sent; + int ret; + int flow_controlled = 0; + + BUG_ON(off % RDS_FRAG_SIZE); + BUG_ON(hdr_off != 0 && hdr_off != sizeof(struct rds_header)); + + /* FIXME we may overallocate here */ + if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) + i = 1; + else + i = ceil(be32_to_cpu(rm->m_inc.i_hdr.h_len), RDS_FRAG_SIZE); + + work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); + if (work_alloc == 0) { + set_bit(RDS_LL_SEND_FULL, &conn->c_flags); + rds_ib_stats_inc(s_ib_tx_ring_full); + ret = -ENOMEM; + goto out; + } + + credit_alloc = work_alloc; + if (ic->i_flowctl) { + credit_alloc = rds_ib_send_grab_credits(ic, work_alloc, &posted, 0); + adv_credits += posted; + if (credit_alloc < work_alloc) { + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - credit_alloc); + work_alloc = credit_alloc; + flow_controlled++; + } + if (work_alloc == 0) { + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); + rds_ib_stats_inc(s_ib_tx_throttle); + ret = -ENOMEM; + goto out; + } + } + + /* map the message the first time we see it */ + if (ic->i_rm == NULL) { + /* + printk(KERN_NOTICE "rds_ib_xmit prep msg dport=%u flags=0x%x len=%d\n", + be16_to_cpu(rm->m_inc.i_hdr.h_dport), + rm->m_inc.i_hdr.h_flags, + be32_to_cpu(rm->m_inc.i_hdr.h_len)); + */ + if (rm->m_nents) { + rm->m_count = ib_dma_map_sg(dev, + rm->m_sg, rm->m_nents, DMA_TO_DEVICE); + rdsdebug("ic %p mapping rm %p: %d\n", ic, rm, rm->m_count); + if (rm->m_count == 0) { + rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); + ret = -ENOMEM; /* XXX ? */ + goto out; + } + } else { + rm->m_count = 0; + } + + ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; + ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes; + rds_message_addref(rm); + ic->i_rm = rm; + + /* Finalize the header */ + if (test_bit(RDS_MSG_ACK_REQUIRED, &rm->m_flags)) + rm->m_inc.i_hdr.h_flags |= RDS_FLAG_ACK_REQUIRED; + if (test_bit(RDS_MSG_RETRANSMITTED, &rm->m_flags)) + rm->m_inc.i_hdr.h_flags |= RDS_FLAG_RETRANSMITTED; + + /* If it has a RDMA op, tell the peer we did it. This is + * used by the peer to release use-once RDMA MRs. */ + if (rm->m_rdma_op) { + struct rds_ext_header_rdma ext_hdr; + + ext_hdr.h_rdma_rkey = cpu_to_be32(rm->m_rdma_op->r_key); + rds_message_add_extension(&rm->m_inc.i_hdr, + RDS_EXTHDR_RDMA, &ext_hdr, sizeof(ext_hdr)); + } + if (rm->m_rdma_cookie) { + rds_message_add_rdma_dest_extension(&rm->m_inc.i_hdr, + rds_rdma_cookie_key(rm->m_rdma_cookie), + rds_rdma_cookie_offset(rm->m_rdma_cookie)); + } + + /* Note - rds_ib_piggyb_ack clears the ACK_REQUIRED bit, so + * we should not do this unless we have a chance of at least + * sticking the header into the send ring. Which is why we + * should call rds_ib_ring_alloc first. */ + rm->m_inc.i_hdr.h_ack = cpu_to_be64(rds_ib_piggyb_ack(ic)); + rds_message_make_checksum(&rm->m_inc.i_hdr); + + /* + * Update adv_credits since we reset the ACK_REQUIRED bit. + */ + rds_ib_send_grab_credits(ic, 0, &posted, 1); + adv_credits += posted; + BUG_ON(adv_credits > 255); + } else if (ic->i_rm != rm) + BUG(); + + send = &ic->i_sends[pos]; + first = send; + prev = NULL; + scat = &rm->m_sg[sg]; + sent = 0; + i = 0; + + /* Sometimes you want to put a fence between an RDMA + * READ and the following SEND. + * We could either do this all the time + * or when requested by the user. Right now, we let + * the application choose. + */ + if (rm->m_rdma_op && rm->m_rdma_op->r_fence) + send_flags = IB_SEND_FENCE; + + /* + * We could be copying the header into the unused tail of the page. + * That would need to be changed in the future when those pages might + * be mapped userspace pages or page cache pages. So instead we always + * use a second sge and our long-lived ring of mapped headers. We send + * the header after the data so that the data payload can be aligned on + * the receiver. + */ + + /* handle a 0-len message */ + if (be32_to_cpu(rm->m_inc.i_hdr.h_len) == 0) { + rds_ib_xmit_populate_wr(ic, send, pos, 0, 0, send_flags); + goto add_header; + } + + /* if there's data reference it with a chain of work reqs */ + for (; i < work_alloc && scat != &rm->m_sg[rm->m_count]; i++) { + unsigned int len; + + send = &ic->i_sends[pos]; + + len = min(RDS_FRAG_SIZE, ib_sg_dma_len(dev, scat) - off); + rds_ib_xmit_populate_wr(ic, send, pos, + ib_sg_dma_address(dev, scat) + off, len, + send_flags); + + /* + * We want to delay signaling completions just enough to get + * the batching benefits but not so much that we create dead time + * on the wire. + */ + if (ic->i_unsignaled_wrs-- == 0) { + ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; + send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; + } + + ic->i_unsignaled_bytes -= len; + if (ic->i_unsignaled_bytes <= 0) { + ic->i_unsignaled_bytes = rds_ib_sysctl_max_unsig_bytes; + send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; + } + + /* + * Always signal the last one if we're stopping due to flow control. + */ + if (flow_controlled && i == (work_alloc-1)) + send->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; + + rdsdebug("send %p wr %p num_sge %u next %p\n", send, + &send->s_wr, send->s_wr.num_sge, send->s_wr.next); + + sent += len; + off += len; + if (off == ib_sg_dma_len(dev, scat)) { + scat++; + off = 0; + } + +add_header: + /* Tack on the header after the data. The header SGE should already + * have been set up to point to the right header buffer. */ + memcpy(&ic->i_send_hdrs[pos], &rm->m_inc.i_hdr, sizeof(struct rds_header)); + + if (0) { + struct rds_header *hdr = &ic->i_send_hdrs[pos]; + + printk(KERN_NOTICE "send WR dport=%u flags=0x%x len=%d\n", + be16_to_cpu(hdr->h_dport), + hdr->h_flags, + be32_to_cpu(hdr->h_len)); + } + if (adv_credits) { + struct rds_header *hdr = &ic->i_send_hdrs[pos]; + + /* add credit and redo the header checksum */ + hdr->h_credit = adv_credits; + rds_message_make_checksum(hdr); + adv_credits = 0; + rds_ib_stats_inc(s_ib_tx_credit_updates); + } + + if (prev) + prev->s_wr.next = &send->s_wr; + prev = send; + + pos = (pos + 1) % ic->i_send_ring.w_nr; + } + + /* Account the RDS header in the number of bytes we sent, but just once. + * The caller has no concept of fragmentation. */ + if (hdr_off == 0) + sent += sizeof(struct rds_header); + + /* if we finished the message then send completion owns it */ + if (scat == &rm->m_sg[rm->m_count]) { + prev->s_rm = ic->i_rm; + prev->s_wr.send_flags |= IB_SEND_SIGNALED | IB_SEND_SOLICITED; + ic->i_rm = NULL; + } + + if (i < work_alloc) { + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); + work_alloc = i; + } + if (ic->i_flowctl && i < credit_alloc) + rds_ib_send_add_credits(conn, credit_alloc - i); + + /* XXX need to worry about failed_wr and partial sends. */ + failed_wr = &first->s_wr; + ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); + rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, + first, &first->s_wr, ret, failed_wr); + BUG_ON(failed_wr != &first->s_wr); + if (ret) { + printk(KERN_WARNING "RDS/IB: ib_post_send to %pI4 " + "returned %d\n", &conn->c_faddr, ret); + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); + if (prev->s_rm) { + ic->i_rm = prev->s_rm; + prev->s_rm = NULL; + } + /* Finesse this later */ + BUG(); + goto out; + } + + ret = sent; +out: + BUG_ON(adv_credits); + return ret; +} + +int rds_ib_xmit_rdma(struct rds_connection *conn, struct rds_rdma_op *op) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + struct rds_ib_send_work *send = NULL; + struct rds_ib_send_work *first; + struct rds_ib_send_work *prev; + struct ib_send_wr *failed_wr; + struct rds_ib_device *rds_ibdev; + struct scatterlist *scat; + unsigned long len; + u64 remote_addr = op->r_remote_addr; + u32 pos; + u32 work_alloc; + u32 i; + u32 j; + int sent; + int ret; + int num_sge; + + rds_ibdev = ib_get_client_data(ic->i_cm_id->device, &rds_ib_client); + + /* map the message the first time we see it */ + if (!op->r_mapped) { + op->r_count = ib_dma_map_sg(ic->i_cm_id->device, + op->r_sg, op->r_nents, (op->r_write) ? + DMA_TO_DEVICE : DMA_FROM_DEVICE); + rdsdebug("ic %p mapping op %p: %d\n", ic, op, op->r_count); + if (op->r_count == 0) { + rds_ib_stats_inc(s_ib_tx_sg_mapping_failure); + ret = -ENOMEM; /* XXX ? */ + goto out; + } + + op->r_mapped = 1; + } + + /* + * Instead of knowing how to return a partial rdma read/write we insist that there + * be enough work requests to send the entire message. + */ + i = ceil(op->r_count, rds_ibdev->max_sge); + + work_alloc = rds_ib_ring_alloc(&ic->i_send_ring, i, &pos); + if (work_alloc != i) { + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); + rds_ib_stats_inc(s_ib_tx_ring_full); + ret = -ENOMEM; + goto out; + } + + send = &ic->i_sends[pos]; + first = send; + prev = NULL; + scat = &op->r_sg[0]; + sent = 0; + num_sge = op->r_count; + + for (i = 0; i < work_alloc && scat != &op->r_sg[op->r_count]; i++) { + send->s_wr.send_flags = 0; + send->s_queued = jiffies; + /* + * We want to delay signaling completions just enough to get + * the batching benefits but not so much that we create dead time on the wire. + */ + if (ic->i_unsignaled_wrs-- == 0) { + ic->i_unsignaled_wrs = rds_ib_sysctl_max_unsig_wrs; + send->s_wr.send_flags = IB_SEND_SIGNALED; + } + + send->s_wr.opcode = op->r_write ? IB_WR_RDMA_WRITE : IB_WR_RDMA_READ; + send->s_wr.wr.rdma.remote_addr = remote_addr; + send->s_wr.wr.rdma.rkey = op->r_key; + send->s_op = op; + + if (num_sge > rds_ibdev->max_sge) { + send->s_wr.num_sge = rds_ibdev->max_sge; + num_sge -= rds_ibdev->max_sge; + } else { + send->s_wr.num_sge = num_sge; + } + + send->s_wr.next = NULL; + + if (prev) + prev->s_wr.next = &send->s_wr; + + for (j = 0; j < send->s_wr.num_sge && scat != &op->r_sg[op->r_count]; j++) { + len = ib_sg_dma_len(ic->i_cm_id->device, scat); + send->s_sge[j].addr = + ib_sg_dma_address(ic->i_cm_id->device, scat); + send->s_sge[j].length = len; + send->s_sge[j].lkey = ic->i_mr->lkey; + + sent += len; + rdsdebug("ic %p sent %d remote_addr %llu\n", ic, sent, remote_addr); + + remote_addr += len; + scat++; + } + + rdsdebug("send %p wr %p num_sge %u next %p\n", send, + &send->s_wr, send->s_wr.num_sge, send->s_wr.next); + + prev = send; + if (++send == &ic->i_sends[ic->i_send_ring.w_nr]) + send = ic->i_sends; + } + + /* if we finished the message then send completion owns it */ + if (scat == &op->r_sg[op->r_count]) + prev->s_wr.send_flags = IB_SEND_SIGNALED; + + if (i < work_alloc) { + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc - i); + work_alloc = i; + } + + failed_wr = &first->s_wr; + ret = ib_post_send(ic->i_cm_id->qp, &first->s_wr, &failed_wr); + rdsdebug("ic %p first %p (wr %p) ret %d wr %p\n", ic, + first, &first->s_wr, ret, failed_wr); + BUG_ON(failed_wr != &first->s_wr); + if (ret) { + printk(KERN_WARNING "RDS/IB: rdma ib_post_send to %pI4 " + "returned %d\n", &conn->c_faddr, ret); + rds_ib_ring_unalloc(&ic->i_send_ring, work_alloc); + goto out; + } + + if (unlikely(failed_wr != &first->s_wr)) { + printk(KERN_WARNING "RDS/IB: ib_post_send() rc=%d, but failed_wqe updated!\n", ret); + BUG_ON(failed_wr != &first->s_wr); + } + + +out: + return ret; +} + +void rds_ib_xmit_complete(struct rds_connection *conn) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + + /* We may have a pending ACK or window update we were unable + * to send previously (due to flow control). Try again. */ + rds_ib_attempt_ack(ic); +} |