v4.19.13 snapshot.
diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
new file mode 100644
index 0000000..2f16146
--- /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);
+}