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Diffstat (limited to '')
| -rw-r--r-- | net/rds/ib_recv.c | 1066 |
1 files changed, 1066 insertions, 0 deletions
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c new file mode 100644 index 000000000..2f16146e4 --- /dev/null +++ b/net/rds/ib_recv.c @@ -0,0 +1,1066 @@ +/* + * Copyright (c) 2006, 2017 Oracle and/or its affiliates. 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/slab.h> +#include <linux/pci.h> +#include <linux/dma-mapping.h> +#include <rdma/rdma_cm.h> + +#include "rds_single_path.h" +#include "rds.h" +#include "ib.h" + +static struct kmem_cache *rds_ib_incoming_slab; +static struct kmem_cache *rds_ib_frag_slab; +static atomic_t rds_ib_allocation = ATOMIC_INIT(0); + +void rds_ib_recv_init_ring(struct rds_ib_connection *ic) +{ + struct rds_ib_recv_work *recv; + u32 i; + + for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) { + struct ib_sge *sge; + + recv->r_ibinc = NULL; + recv->r_frag = NULL; + + recv->r_wr.next = NULL; + recv->r_wr.wr_id = i; + recv->r_wr.sg_list = recv->r_sge; + recv->r_wr.num_sge = RDS_IB_RECV_SGE; + + sge = &recv->r_sge[0]; + sge->addr = ic->i_recv_hdrs_dma + (i * sizeof(struct rds_header)); + sge->length = sizeof(struct rds_header); + sge->lkey = ic->i_pd->local_dma_lkey; + + sge = &recv->r_sge[1]; + sge->addr = 0; + sge->length = RDS_FRAG_SIZE; + sge->lkey = ic->i_pd->local_dma_lkey; + } +} + +/* + * The entire 'from' list, including the from element itself, is put on + * to the tail of the 'to' list. + */ +static void list_splice_entire_tail(struct list_head *from, + struct list_head *to) +{ + struct list_head *from_last = from->prev; + + list_splice_tail(from_last, to); + list_add_tail(from_last, to); +} + +static void rds_ib_cache_xfer_to_ready(struct rds_ib_refill_cache *cache) +{ + struct list_head *tmp; + + tmp = xchg(&cache->xfer, NULL); + if (tmp) { + if (cache->ready) + list_splice_entire_tail(tmp, cache->ready); + else + cache->ready = tmp; + } +} + +static int rds_ib_recv_alloc_cache(struct rds_ib_refill_cache *cache, gfp_t gfp) +{ + struct rds_ib_cache_head *head; + int cpu; + + cache->percpu = alloc_percpu_gfp(struct rds_ib_cache_head, gfp); + if (!cache->percpu) + return -ENOMEM; + + for_each_possible_cpu(cpu) { + head = per_cpu_ptr(cache->percpu, cpu); + head->first = NULL; + head->count = 0; + } + cache->xfer = NULL; + cache->ready = NULL; + + return 0; +} + +int rds_ib_recv_alloc_caches(struct rds_ib_connection *ic, gfp_t gfp) +{ + int ret; + + ret = rds_ib_recv_alloc_cache(&ic->i_cache_incs, gfp); + if (!ret) { + ret = rds_ib_recv_alloc_cache(&ic->i_cache_frags, gfp); + if (ret) + free_percpu(ic->i_cache_incs.percpu); + } + + return ret; +} + +static void rds_ib_cache_splice_all_lists(struct rds_ib_refill_cache *cache, + struct list_head *caller_list) +{ + struct rds_ib_cache_head *head; + int cpu; + + for_each_possible_cpu(cpu) { + head = per_cpu_ptr(cache->percpu, cpu); + if (head->first) { + list_splice_entire_tail(head->first, caller_list); + head->first = NULL; + } + } + + if (cache->ready) { + list_splice_entire_tail(cache->ready, caller_list); + cache->ready = NULL; + } +} + +void rds_ib_recv_free_caches(struct rds_ib_connection *ic) +{ + struct rds_ib_incoming *inc; + struct rds_ib_incoming *inc_tmp; + struct rds_page_frag *frag; + struct rds_page_frag *frag_tmp; + LIST_HEAD(list); + + rds_ib_cache_xfer_to_ready(&ic->i_cache_incs); + rds_ib_cache_splice_all_lists(&ic->i_cache_incs, &list); + free_percpu(ic->i_cache_incs.percpu); + + list_for_each_entry_safe(inc, inc_tmp, &list, ii_cache_entry) { + list_del(&inc->ii_cache_entry); + WARN_ON(!list_empty(&inc->ii_frags)); + kmem_cache_free(rds_ib_incoming_slab, inc); + } + + rds_ib_cache_xfer_to_ready(&ic->i_cache_frags); + rds_ib_cache_splice_all_lists(&ic->i_cache_frags, &list); + free_percpu(ic->i_cache_frags.percpu); + + list_for_each_entry_safe(frag, frag_tmp, &list, f_cache_entry) { + list_del(&frag->f_cache_entry); + WARN_ON(!list_empty(&frag->f_item)); + kmem_cache_free(rds_ib_frag_slab, frag); + } +} + +/* fwd decl */ +static void rds_ib_recv_cache_put(struct list_head *new_item, + struct rds_ib_refill_cache *cache); +static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache); + + +/* Recycle frag and attached recv buffer f_sg */ +static void rds_ib_frag_free(struct rds_ib_connection *ic, + struct rds_page_frag *frag) +{ + rdsdebug("frag %p page %p\n", frag, sg_page(&frag->f_sg)); + + rds_ib_recv_cache_put(&frag->f_cache_entry, &ic->i_cache_frags); + atomic_add(RDS_FRAG_SIZE / SZ_1K, &ic->i_cache_allocs); + rds_ib_stats_add(s_ib_recv_added_to_cache, RDS_FRAG_SIZE); +} + +/* Recycle inc after freeing attached frags */ +void rds_ib_inc_free(struct rds_incoming *inc) +{ + struct rds_ib_incoming *ibinc; + struct rds_page_frag *frag; + struct rds_page_frag *pos; + struct rds_ib_connection *ic = inc->i_conn->c_transport_data; + + ibinc = container_of(inc, struct rds_ib_incoming, ii_inc); + + /* Free attached frags */ + list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) { + list_del_init(&frag->f_item); + rds_ib_frag_free(ic, frag); + } + BUG_ON(!list_empty(&ibinc->ii_frags)); + + rdsdebug("freeing ibinc %p inc %p\n", ibinc, inc); + rds_ib_recv_cache_put(&ibinc->ii_cache_entry, &ic->i_cache_incs); +} + +static void rds_ib_recv_clear_one(struct rds_ib_connection *ic, + struct rds_ib_recv_work *recv) +{ + if (recv->r_ibinc) { + rds_inc_put(&recv->r_ibinc->ii_inc); + recv->r_ibinc = NULL; + } + if (recv->r_frag) { + ib_dma_unmap_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, 1, DMA_FROM_DEVICE); + rds_ib_frag_free(ic, recv->r_frag); + recv->r_frag = NULL; + } +} + +void rds_ib_recv_clear_ring(struct rds_ib_connection *ic) +{ + u32 i; + + for (i = 0; i < ic->i_recv_ring.w_nr; i++) + rds_ib_recv_clear_one(ic, &ic->i_recvs[i]); +} + +static struct rds_ib_incoming *rds_ib_refill_one_inc(struct rds_ib_connection *ic, + gfp_t slab_mask) +{ + struct rds_ib_incoming *ibinc; + struct list_head *cache_item; + int avail_allocs; + + cache_item = rds_ib_recv_cache_get(&ic->i_cache_incs); + if (cache_item) { + ibinc = container_of(cache_item, struct rds_ib_incoming, ii_cache_entry); + } else { + avail_allocs = atomic_add_unless(&rds_ib_allocation, + 1, rds_ib_sysctl_max_recv_allocation); + if (!avail_allocs) { + rds_ib_stats_inc(s_ib_rx_alloc_limit); + return NULL; + } + ibinc = kmem_cache_alloc(rds_ib_incoming_slab, slab_mask); + if (!ibinc) { + atomic_dec(&rds_ib_allocation); + return NULL; + } + rds_ib_stats_inc(s_ib_rx_total_incs); + } + INIT_LIST_HEAD(&ibinc->ii_frags); + rds_inc_init(&ibinc->ii_inc, ic->conn, &ic->conn->c_faddr); + + return ibinc; +} + +static struct rds_page_frag *rds_ib_refill_one_frag(struct rds_ib_connection *ic, + gfp_t slab_mask, gfp_t page_mask) +{ + struct rds_page_frag *frag; + struct list_head *cache_item; + int ret; + + cache_item = rds_ib_recv_cache_get(&ic->i_cache_frags); + if (cache_item) { + frag = container_of(cache_item, struct rds_page_frag, f_cache_entry); + atomic_sub(RDS_FRAG_SIZE / SZ_1K, &ic->i_cache_allocs); + rds_ib_stats_add(s_ib_recv_added_to_cache, RDS_FRAG_SIZE); + } else { + frag = kmem_cache_alloc(rds_ib_frag_slab, slab_mask); + if (!frag) + return NULL; + + sg_init_table(&frag->f_sg, 1); + ret = rds_page_remainder_alloc(&frag->f_sg, + RDS_FRAG_SIZE, page_mask); + if (ret) { + kmem_cache_free(rds_ib_frag_slab, frag); + return NULL; + } + rds_ib_stats_inc(s_ib_rx_total_frags); + } + + INIT_LIST_HEAD(&frag->f_item); + + return frag; +} + +static int rds_ib_recv_refill_one(struct rds_connection *conn, + struct rds_ib_recv_work *recv, gfp_t gfp) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + struct ib_sge *sge; + int ret = -ENOMEM; + gfp_t slab_mask = GFP_NOWAIT; + gfp_t page_mask = GFP_NOWAIT; + + if (gfp & __GFP_DIRECT_RECLAIM) { + slab_mask = GFP_KERNEL; + page_mask = GFP_HIGHUSER; + } + + if (!ic->i_cache_incs.ready) + rds_ib_cache_xfer_to_ready(&ic->i_cache_incs); + if (!ic->i_cache_frags.ready) + rds_ib_cache_xfer_to_ready(&ic->i_cache_frags); + + /* + * ibinc was taken from recv if recv contained the start of a message. + * recvs that were continuations will still have this allocated. + */ + if (!recv->r_ibinc) { + recv->r_ibinc = rds_ib_refill_one_inc(ic, slab_mask); + if (!recv->r_ibinc) + goto out; + } + + WARN_ON(recv->r_frag); /* leak! */ + recv->r_frag = rds_ib_refill_one_frag(ic, slab_mask, page_mask); + if (!recv->r_frag) + goto out; + + ret = ib_dma_map_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, + 1, DMA_FROM_DEVICE); + WARN_ON(ret != 1); + + sge = &recv->r_sge[0]; + sge->addr = ic->i_recv_hdrs_dma + (recv - ic->i_recvs) * sizeof(struct rds_header); + sge->length = sizeof(struct rds_header); + + sge = &recv->r_sge[1]; + sge->addr = ib_sg_dma_address(ic->i_cm_id->device, &recv->r_frag->f_sg); + sge->length = ib_sg_dma_len(ic->i_cm_id->device, &recv->r_frag->f_sg); + + ret = 0; +out: + return ret; +} + +static int acquire_refill(struct rds_connection *conn) +{ + return test_and_set_bit(RDS_RECV_REFILL, &conn->c_flags) == 0; +} + +static void release_refill(struct rds_connection *conn) +{ + clear_bit(RDS_RECV_REFILL, &conn->c_flags); + + /* We don't use wait_on_bit()/wake_up_bit() because our waking is in a + * hot path and finding waiters is very rare. We don't want to walk + * the system-wide hashed waitqueue buckets in the fast path only to + * almost never find waiters. + */ + if (waitqueue_active(&conn->c_waitq)) + wake_up_all(&conn->c_waitq); +} + +/* + * This tries to allocate and post unused work requests after making sure that + * they have all the allocations they need to queue received fragments into + * sockets. + */ +void rds_ib_recv_refill(struct rds_connection *conn, int prefill, gfp_t gfp) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + struct rds_ib_recv_work *recv; + unsigned int posted = 0; + int ret = 0; + bool can_wait = !!(gfp & __GFP_DIRECT_RECLAIM); + u32 pos; + + /* the goal here is to just make sure that someone, somewhere + * is posting buffers. If we can't get the refill lock, + * let them do their thing + */ + if (!acquire_refill(conn)) + return; + + while ((prefill || rds_conn_up(conn)) && + rds_ib_ring_alloc(&ic->i_recv_ring, 1, &pos)) { + if (pos >= ic->i_recv_ring.w_nr) { + printk(KERN_NOTICE "Argh - ring alloc returned pos=%u\n", + pos); + break; + } + + recv = &ic->i_recvs[pos]; + ret = rds_ib_recv_refill_one(conn, recv, gfp); + if (ret) { + break; + } + + rdsdebug("recv %p ibinc %p page %p addr %lu\n", recv, + recv->r_ibinc, sg_page(&recv->r_frag->f_sg), + (long) ib_sg_dma_address( + ic->i_cm_id->device, + &recv->r_frag->f_sg)); + + /* XXX when can this fail? */ + ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, NULL); + if (ret) { + rds_ib_conn_error(conn, "recv post on " + "%pI6c returned %d, disconnecting and " + "reconnecting\n", &conn->c_faddr, + ret); + break; + } + + posted++; + } + + /* We're doing flow control - update the window. */ + if (ic->i_flowctl && posted) + rds_ib_advertise_credits(conn, posted); + + if (ret) + rds_ib_ring_unalloc(&ic->i_recv_ring, 1); + + release_refill(conn); + + /* if we're called from the softirq handler, we'll be GFP_NOWAIT. + * in this case the ring being low is going to lead to more interrupts + * and we can safely let the softirq code take care of it unless the + * ring is completely empty. + * + * if we're called from krdsd, we'll be GFP_KERNEL. In this case + * we might have raced with the softirq code while we had the refill + * lock held. Use rds_ib_ring_low() instead of ring_empty to decide + * if we should requeue. + */ + if (rds_conn_up(conn) && + ((can_wait && rds_ib_ring_low(&ic->i_recv_ring)) || + rds_ib_ring_empty(&ic->i_recv_ring))) { + queue_delayed_work(rds_wq, &conn->c_recv_w, 1); + } +} + +/* + * We want to recycle several types of recv allocations, like incs and frags. + * To use this, the *_free() function passes in the ptr to a list_head within + * the recyclee, as well as the cache to put it on. + * + * First, we put the memory on a percpu list. When this reaches a certain size, + * We move it to an intermediate non-percpu list in a lockless manner, with some + * xchg/compxchg wizardry. + * + * N.B. Instead of a list_head as the anchor, we use a single pointer, which can + * be NULL and xchg'd. The list is actually empty when the pointer is NULL, and + * list_empty() will return true with one element is actually present. + */ +static void rds_ib_recv_cache_put(struct list_head *new_item, + struct rds_ib_refill_cache *cache) +{ + unsigned long flags; + struct list_head *old, *chpfirst; + + local_irq_save(flags); + + chpfirst = __this_cpu_read(cache->percpu->first); + if (!chpfirst) + INIT_LIST_HEAD(new_item); + else /* put on front */ + list_add_tail(new_item, chpfirst); + + __this_cpu_write(cache->percpu->first, new_item); + __this_cpu_inc(cache->percpu->count); + + if (__this_cpu_read(cache->percpu->count) < RDS_IB_RECYCLE_BATCH_COUNT) + goto end; + + /* + * Return our per-cpu first list to the cache's xfer by atomically + * grabbing the current xfer list, appending it to our per-cpu list, + * and then atomically returning that entire list back to the + * cache's xfer list as long as it's still empty. + */ + do { + old = xchg(&cache->xfer, NULL); + if (old) + list_splice_entire_tail(old, chpfirst); + old = cmpxchg(&cache->xfer, NULL, chpfirst); + } while (old); + + + __this_cpu_write(cache->percpu->first, NULL); + __this_cpu_write(cache->percpu->count, 0); +end: + local_irq_restore(flags); +} + +static struct list_head *rds_ib_recv_cache_get(struct rds_ib_refill_cache *cache) +{ + struct list_head *head = cache->ready; + + if (head) { + if (!list_empty(head)) { + cache->ready = head->next; + list_del_init(head); + } else + cache->ready = NULL; + } + + return head; +} + +int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iov_iter *to) +{ + struct rds_ib_incoming *ibinc; + struct rds_page_frag *frag; + unsigned long to_copy; + unsigned long frag_off = 0; + int copied = 0; + int ret; + u32 len; + + ibinc = container_of(inc, struct rds_ib_incoming, ii_inc); + frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item); + len = be32_to_cpu(inc->i_hdr.h_len); + + while (iov_iter_count(to) && copied < len) { + if (frag_off == RDS_FRAG_SIZE) { + frag = list_entry(frag->f_item.next, + struct rds_page_frag, f_item); + frag_off = 0; + } + to_copy = min_t(unsigned long, iov_iter_count(to), + RDS_FRAG_SIZE - frag_off); + to_copy = min_t(unsigned long, to_copy, len - copied); + + /* XXX needs + offset for multiple recvs per page */ + rds_stats_add(s_copy_to_user, to_copy); + ret = copy_page_to_iter(sg_page(&frag->f_sg), + frag->f_sg.offset + frag_off, + to_copy, + to); + if (ret != to_copy) + return -EFAULT; + + frag_off += to_copy; + copied += to_copy; + } + + return copied; +} + +/* ic starts out kzalloc()ed */ +void rds_ib_recv_init_ack(struct rds_ib_connection *ic) +{ + struct ib_send_wr *wr = &ic->i_ack_wr; + struct ib_sge *sge = &ic->i_ack_sge; + + sge->addr = ic->i_ack_dma; + sge->length = sizeof(struct rds_header); + sge->lkey = ic->i_pd->local_dma_lkey; + + wr->sg_list = sge; + wr->num_sge = 1; + wr->opcode = IB_WR_SEND; + wr->wr_id = RDS_IB_ACK_WR_ID; + wr->send_flags = IB_SEND_SIGNALED | IB_SEND_SOLICITED; +} + +/* + * You'd think that with reliable IB connections you wouldn't need to ack + * messages that have been received. The problem is that IB hardware generates + * an ack message before it has DMAed the message into memory. This creates a + * potential message loss if the HCA is disabled for any reason between when it + * sends the ack and before the message is DMAed and processed. This is only a + * potential issue if another HCA is available for fail-over. + * + * When the remote host receives our ack they'll free the sent message from + * their send queue. To decrease the latency of this we always send an ack + * immediately after we've received messages. + * + * For simplicity, we only have one ack in flight at a time. This puts + * pressure on senders to have deep enough send queues to absorb the latency of + * a single ack frame being in flight. This might not be good enough. + * + * This is implemented by have a long-lived send_wr and sge which point to a + * statically allocated ack frame. This ack wr does not fall under the ring + * accounting that the tx and rx wrs do. The QP attribute specifically makes + * room for it beyond the ring size. Send completion notices its special + * wr_id and avoids working with the ring in that case. + */ +#ifndef KERNEL_HAS_ATOMIC64 +void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq, int ack_required) +{ + unsigned long flags; + + spin_lock_irqsave(&ic->i_ack_lock, flags); + ic->i_ack_next = seq; + if (ack_required) + set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + spin_unlock_irqrestore(&ic->i_ack_lock, flags); +} + +static u64 rds_ib_get_ack(struct rds_ib_connection *ic) +{ + unsigned long flags; + u64 seq; + + clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + + spin_lock_irqsave(&ic->i_ack_lock, flags); + seq = ic->i_ack_next; + spin_unlock_irqrestore(&ic->i_ack_lock, flags); + + return seq; +} +#else +void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq, int ack_required) +{ + atomic64_set(&ic->i_ack_next, seq); + if (ack_required) { + smp_mb__before_atomic(); + set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + } +} + +static u64 rds_ib_get_ack(struct rds_ib_connection *ic) +{ + clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + smp_mb__after_atomic(); + + return atomic64_read(&ic->i_ack_next); +} +#endif + + +static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credits) +{ + struct rds_header *hdr = ic->i_ack; + u64 seq; + int ret; + + seq = rds_ib_get_ack(ic); + + rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq); + rds_message_populate_header(hdr, 0, 0, 0); + hdr->h_ack = cpu_to_be64(seq); + hdr->h_credit = adv_credits; + rds_message_make_checksum(hdr); + ic->i_ack_queued = jiffies; + + ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, NULL); + if (unlikely(ret)) { + /* Failed to send. Release the WR, and + * force another ACK. + */ + clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags); + set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + + rds_ib_stats_inc(s_ib_ack_send_failure); + + rds_ib_conn_error(ic->conn, "sending ack failed\n"); + } else + rds_ib_stats_inc(s_ib_ack_sent); +} + +/* + * There are 3 ways of getting acknowledgements to the peer: + * 1. We call rds_ib_attempt_ack from the recv completion handler + * to send an ACK-only frame. + * However, there can be only one such frame in the send queue + * at any time, so we may have to postpone it. + * 2. When another (data) packet is transmitted while there's + * an ACK in the queue, we piggyback the ACK sequence number + * on the data packet. + * 3. If the ACK WR is done sending, we get called from the + * send queue completion handler, and check whether there's + * another ACK pending (postponed because the WR was on the + * queue). If so, we transmit it. + * + * We maintain 2 variables: + * - i_ack_flags, which keeps track of whether the ACK WR + * is currently in the send queue or not (IB_ACK_IN_FLIGHT) + * - i_ack_next, which is the last sequence number we received + * + * Potentially, send queue and receive queue handlers can run concurrently. + * It would be nice to not have to use a spinlock to synchronize things, + * but the one problem that rules this out is that 64bit updates are + * not atomic on all platforms. Things would be a lot simpler if + * we had atomic64 or maybe cmpxchg64 everywhere. + * + * Reconnecting complicates this picture just slightly. When we + * reconnect, we may be seeing duplicate packets. The peer + * is retransmitting them, because it hasn't seen an ACK for + * them. It is important that we ACK these. + * + * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with + * this flag set *MUST* be acknowledged immediately. + */ + +/* + * When we get here, we're called from the recv queue handler. + * Check whether we ought to transmit an ACK. + */ +void rds_ib_attempt_ack(struct rds_ib_connection *ic) +{ + unsigned int adv_credits; + + if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags)) + return; + + if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) { + rds_ib_stats_inc(s_ib_ack_send_delayed); + return; + } + + /* Can we get a send credit? */ + if (!rds_ib_send_grab_credits(ic, 1, &adv_credits, 0, RDS_MAX_ADV_CREDIT)) { + rds_ib_stats_inc(s_ib_tx_throttle); + clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags); + return; + } + + clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags); + rds_ib_send_ack(ic, adv_credits); +} + +/* + * We get here from the send completion handler, when the + * adapter tells us the ACK frame was sent. + */ +void rds_ib_ack_send_complete(struct rds_ib_connection *ic) +{ + clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags); + rds_ib_attempt_ack(ic); +} + +/* + * This is called by the regular xmit code when it wants to piggyback + * an ACK on an outgoing frame. + */ +u64 rds_ib_piggyb_ack(struct rds_ib_connection *ic) +{ + if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags)) + rds_ib_stats_inc(s_ib_ack_send_piggybacked); + return rds_ib_get_ack(ic); +} + +/* + * It's kind of lame that we're copying from the posted receive pages into + * long-lived bitmaps. We could have posted the bitmaps and rdma written into + * them. But receiving new congestion bitmaps should be a *rare* event, so + * hopefully we won't need to invest that complexity in making it more + * efficient. By copying we can share a simpler core with TCP which has to + * copy. + */ +static void rds_ib_cong_recv(struct rds_connection *conn, + struct rds_ib_incoming *ibinc) +{ + struct rds_cong_map *map; + unsigned int map_off; + unsigned int map_page; + struct rds_page_frag *frag; + unsigned long frag_off; + unsigned long to_copy; + unsigned long copied; + uint64_t uncongested = 0; + void *addr; + + /* catch completely corrupt packets */ + if (be32_to_cpu(ibinc->ii_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES) + return; + + map = conn->c_fcong; + map_page = 0; + map_off = 0; + + frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item); + frag_off = 0; + + copied = 0; + + while (copied < RDS_CONG_MAP_BYTES) { + uint64_t *src, *dst; + unsigned int k; + + to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off); + BUG_ON(to_copy & 7); /* Must be 64bit aligned. */ + + addr = kmap_atomic(sg_page(&frag->f_sg)); + + src = addr + frag->f_sg.offset + frag_off; + dst = (void *)map->m_page_addrs[map_page] + map_off; + for (k = 0; k < to_copy; k += 8) { + /* Record ports that became uncongested, ie + * bits that changed from 0 to 1. */ + uncongested |= ~(*src) & *dst; + *dst++ = *src++; + } + kunmap_atomic(addr); + + copied += to_copy; + + map_off += to_copy; + if (map_off == PAGE_SIZE) { + map_off = 0; + map_page++; + } + + frag_off += to_copy; + if (frag_off == RDS_FRAG_SIZE) { + frag = list_entry(frag->f_item.next, + struct rds_page_frag, f_item); + frag_off = 0; + } + } + + /* the congestion map is in little endian order */ + uncongested = le64_to_cpu(uncongested); + + rds_cong_map_updated(map, uncongested); +} + +static void rds_ib_process_recv(struct rds_connection *conn, + struct rds_ib_recv_work *recv, u32 data_len, + struct rds_ib_ack_state *state) +{ + struct rds_ib_connection *ic = conn->c_transport_data; + struct rds_ib_incoming *ibinc = ic->i_ibinc; + struct rds_header *ihdr, *hdr; + + /* XXX shut down the connection if port 0,0 are seen? */ + + rdsdebug("ic %p ibinc %p recv %p byte len %u\n", ic, ibinc, recv, + data_len); + + if (data_len < sizeof(struct rds_header)) { + rds_ib_conn_error(conn, "incoming message " + "from %pI6c didn't include a " + "header, disconnecting and " + "reconnecting\n", + &conn->c_faddr); + return; + } + data_len -= sizeof(struct rds_header); + + ihdr = &ic->i_recv_hdrs[recv - ic->i_recvs]; + + /* Validate the checksum. */ + if (!rds_message_verify_checksum(ihdr)) { + rds_ib_conn_error(conn, "incoming message " + "from %pI6c has corrupted header - " + "forcing a reconnect\n", + &conn->c_faddr); + rds_stats_inc(s_recv_drop_bad_checksum); + return; + } + + /* Process the ACK sequence which comes with every packet */ + state->ack_recv = be64_to_cpu(ihdr->h_ack); + state->ack_recv_valid = 1; + + /* Process the credits update if there was one */ + if (ihdr->h_credit) + rds_ib_send_add_credits(conn, ihdr->h_credit); + + if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && data_len == 0) { + /* This is an ACK-only packet. The fact that it gets + * special treatment here is that historically, ACKs + * were rather special beasts. + */ + rds_ib_stats_inc(s_ib_ack_received); + + /* + * Usually the frags make their way on to incs and are then freed as + * the inc is freed. We don't go that route, so we have to drop the + * page ref ourselves. We can't just leave the page on the recv + * because that confuses the dma mapping of pages and each recv's use + * of a partial page. + * + * FIXME: Fold this into the code path below. + */ + rds_ib_frag_free(ic, recv->r_frag); + recv->r_frag = NULL; + return; + } + + /* + * If we don't already have an inc on the connection then this + * fragment has a header and starts a message.. copy its header + * into the inc and save the inc so we can hang upcoming fragments + * off its list. + */ + if (!ibinc) { + ibinc = recv->r_ibinc; + recv->r_ibinc = NULL; + ic->i_ibinc = ibinc; + + hdr = &ibinc->ii_inc.i_hdr; + ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_HDR] = + local_clock(); + memcpy(hdr, ihdr, sizeof(*hdr)); + ic->i_recv_data_rem = be32_to_cpu(hdr->h_len); + ibinc->ii_inc.i_rx_lat_trace[RDS_MSG_RX_START] = + local_clock(); + + rdsdebug("ic %p ibinc %p rem %u flag 0x%x\n", ic, ibinc, + ic->i_recv_data_rem, hdr->h_flags); + } else { + hdr = &ibinc->ii_inc.i_hdr; + /* We can't just use memcmp here; fragments of a + * single message may carry different ACKs */ + if (hdr->h_sequence != ihdr->h_sequence || + hdr->h_len != ihdr->h_len || + hdr->h_sport != ihdr->h_sport || + hdr->h_dport != ihdr->h_dport) { + rds_ib_conn_error(conn, + "fragment header mismatch; forcing reconnect\n"); + return; + } + } + + list_add_tail(&recv->r_frag->f_item, &ibinc->ii_frags); + recv->r_frag = NULL; + + if (ic->i_recv_data_rem > RDS_FRAG_SIZE) + ic->i_recv_data_rem -= RDS_FRAG_SIZE; + else { + ic->i_recv_data_rem = 0; + ic->i_ibinc = NULL; + + if (ibinc->ii_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP) { + rds_ib_cong_recv(conn, ibinc); + } else { + rds_recv_incoming(conn, &conn->c_faddr, &conn->c_laddr, + &ibinc->ii_inc, GFP_ATOMIC); + state->ack_next = be64_to_cpu(hdr->h_sequence); + state->ack_next_valid = 1; + } + + /* Evaluate the ACK_REQUIRED flag *after* we received + * the complete frame, and after bumping the next_rx + * sequence. */ + if (hdr->h_flags & RDS_FLAG_ACK_REQUIRED) { + rds_stats_inc(s_recv_ack_required); + state->ack_required = 1; + } + + rds_inc_put(&ibinc->ii_inc); + } +} + +void rds_ib_recv_cqe_handler(struct rds_ib_connection *ic, + struct ib_wc *wc, + struct rds_ib_ack_state *state) +{ + struct rds_connection *conn = ic->conn; + struct rds_ib_recv_work *recv; + + rdsdebug("wc wr_id 0x%llx status %u (%s) byte_len %u imm_data %u\n", + (unsigned long long)wc->wr_id, wc->status, + ib_wc_status_msg(wc->status), wc->byte_len, + be32_to_cpu(wc->ex.imm_data)); + + rds_ib_stats_inc(s_ib_rx_cq_event); + recv = &ic->i_recvs[rds_ib_ring_oldest(&ic->i_recv_ring)]; + ib_dma_unmap_sg(ic->i_cm_id->device, &recv->r_frag->f_sg, 1, + DMA_FROM_DEVICE); + + /* Also process recvs in connecting state because it is possible + * to get a recv completion _before_ the rdmacm ESTABLISHED + * event is processed. + */ + if (wc->status == IB_WC_SUCCESS) { + rds_ib_process_recv(conn, recv, wc->byte_len, state); + } else { + /* We expect errors as the qp is drained during shutdown */ + if (rds_conn_up(conn) || rds_conn_connecting(conn)) + rds_ib_conn_error(conn, "recv completion on <%pI6c,%pI6c> had status %u (%s), disconnecting and reconnecting\n", + &conn->c_laddr, &conn->c_faddr, + wc->status, + ib_wc_status_msg(wc->status)); + } + + /* rds_ib_process_recv() doesn't always consume the frag, and + * we might not have called it at all if the wc didn't indicate + * success. We already unmapped the frag's pages, though, and + * the following rds_ib_ring_free() call tells the refill path + * that it will not find an allocated frag here. Make sure we + * keep that promise by freeing a frag that's still on the ring. + */ + if (recv->r_frag) { + rds_ib_frag_free(ic, recv->r_frag); + recv->r_frag = NULL; + } + rds_ib_ring_free(&ic->i_recv_ring, 1); + + /* If we ever end up with a really empty receive ring, we're + * in deep trouble, as the sender will definitely see RNR + * timeouts. */ + if (rds_ib_ring_empty(&ic->i_recv_ring)) + rds_ib_stats_inc(s_ib_rx_ring_empty); + + if (rds_ib_ring_low(&ic->i_recv_ring)) { + rds_ib_recv_refill(conn, 0, GFP_NOWAIT); + rds_ib_stats_inc(s_ib_rx_refill_from_cq); + } +} + +int rds_ib_recv_path(struct rds_conn_path *cp) +{ + struct rds_connection *conn = cp->cp_conn; + struct rds_ib_connection *ic = conn->c_transport_data; + + rdsdebug("conn %p\n", conn); + if (rds_conn_up(conn)) { + rds_ib_attempt_ack(ic); + rds_ib_recv_refill(conn, 0, GFP_KERNEL); + rds_ib_stats_inc(s_ib_rx_refill_from_thread); + } + + return 0; +} + +int rds_ib_recv_init(void) +{ + struct sysinfo si; + int ret = -ENOMEM; + + /* Default to 30% of all available RAM for recv memory */ + si_meminfo(&si); + rds_ib_sysctl_max_recv_allocation = si.totalram / 3 * PAGE_SIZE / RDS_FRAG_SIZE; + + rds_ib_incoming_slab = kmem_cache_create("rds_ib_incoming", + sizeof(struct rds_ib_incoming), + 0, SLAB_HWCACHE_ALIGN, NULL); + if (!rds_ib_incoming_slab) + goto out; + + rds_ib_frag_slab = kmem_cache_create("rds_ib_frag", + sizeof(struct rds_page_frag), + 0, SLAB_HWCACHE_ALIGN, NULL); + if (!rds_ib_frag_slab) { + kmem_cache_destroy(rds_ib_incoming_slab); + rds_ib_incoming_slab = NULL; + } else + ret = 0; +out: + return ret; +} + +void rds_ib_recv_exit(void) +{ + kmem_cache_destroy(rds_ib_incoming_slab); + kmem_cache_destroy(rds_ib_frag_slab); +} |