Root/net/rds/ib_recv.c

1/*
2 * Copyright (c) 2006 Oracle. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses. You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 * Redistribution and use in source and binary forms, with or
11 * without modification, are permitted provided that the following
12 * conditions are met:
13 *
14 * - Redistributions of source code must retain the above
15 * copyright notice, this list of conditions and the following
16 * disclaimer.
17 *
18 * - Redistributions in binary form must reproduce the above
19 * copyright notice, this list of conditions and the following
20 * disclaimer in the documentation and/or other materials
21 * provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 *
32 */
33#include <linux/kernel.h>
34#include <linux/slab.h>
35#include <linux/pci.h>
36#include <linux/dma-mapping.h>
37#include <rdma/rdma_cm.h>
38
39#include "rds.h"
40#include "ib.h"
41
42static struct kmem_cache *rds_ib_incoming_slab;
43static struct kmem_cache *rds_ib_frag_slab;
44static atomic_t rds_ib_allocation = ATOMIC_INIT(0);
45
46static void rds_ib_frag_drop_page(struct rds_page_frag *frag)
47{
48    rdsdebug("frag %p page %p\n", frag, frag->f_page);
49    __free_page(frag->f_page);
50    frag->f_page = NULL;
51}
52
53static void rds_ib_frag_free(struct rds_page_frag *frag)
54{
55    rdsdebug("frag %p page %p\n", frag, frag->f_page);
56    BUG_ON(frag->f_page != NULL);
57    kmem_cache_free(rds_ib_frag_slab, frag);
58}
59
60/*
61 * We map a page at a time. Its fragments are posted in order. This
62 * is called in fragment order as the fragments get send completion events.
63 * Only the last frag in the page performs the unmapping.
64 *
65 * It's OK for ring cleanup to call this in whatever order it likes because
66 * DMA is not in flight and so we can unmap while other ring entries still
67 * hold page references in their frags.
68 */
69static void rds_ib_recv_unmap_page(struct rds_ib_connection *ic,
70                   struct rds_ib_recv_work *recv)
71{
72    struct rds_page_frag *frag = recv->r_frag;
73
74    rdsdebug("recv %p frag %p page %p\n", recv, frag, frag->f_page);
75    if (frag->f_mapped)
76        ib_dma_unmap_page(ic->i_cm_id->device,
77                   frag->f_mapped,
78                   RDS_FRAG_SIZE, DMA_FROM_DEVICE);
79    frag->f_mapped = 0;
80}
81
82void rds_ib_recv_init_ring(struct rds_ib_connection *ic)
83{
84    struct rds_ib_recv_work *recv;
85    u32 i;
86
87    for (i = 0, recv = ic->i_recvs; i < ic->i_recv_ring.w_nr; i++, recv++) {
88        struct ib_sge *sge;
89
90        recv->r_ibinc = NULL;
91        recv->r_frag = NULL;
92
93        recv->r_wr.next = NULL;
94        recv->r_wr.wr_id = i;
95        recv->r_wr.sg_list = recv->r_sge;
96        recv->r_wr.num_sge = RDS_IB_RECV_SGE;
97
98        sge = rds_ib_data_sge(ic, recv->r_sge);
99        sge->addr = 0;
100        sge->length = RDS_FRAG_SIZE;
101        sge->lkey = ic->i_mr->lkey;
102
103        sge = rds_ib_header_sge(ic, recv->r_sge);
104        sge->addr = ic->i_recv_hdrs_dma + (i * sizeof(struct rds_header));
105        sge->length = sizeof(struct rds_header);
106        sge->lkey = ic->i_mr->lkey;
107    }
108}
109
110static void rds_ib_recv_clear_one(struct rds_ib_connection *ic,
111                  struct rds_ib_recv_work *recv)
112{
113    if (recv->r_ibinc) {
114        rds_inc_put(&recv->r_ibinc->ii_inc);
115        recv->r_ibinc = NULL;
116    }
117    if (recv->r_frag) {
118        rds_ib_recv_unmap_page(ic, recv);
119        if (recv->r_frag->f_page)
120            rds_ib_frag_drop_page(recv->r_frag);
121        rds_ib_frag_free(recv->r_frag);
122        recv->r_frag = NULL;
123    }
124}
125
126void rds_ib_recv_clear_ring(struct rds_ib_connection *ic)
127{
128    u32 i;
129
130    for (i = 0; i < ic->i_recv_ring.w_nr; i++)
131        rds_ib_recv_clear_one(ic, &ic->i_recvs[i]);
132
133    if (ic->i_frag.f_page)
134        rds_ib_frag_drop_page(&ic->i_frag);
135}
136
137static int rds_ib_recv_refill_one(struct rds_connection *conn,
138                  struct rds_ib_recv_work *recv,
139                  gfp_t kptr_gfp, gfp_t page_gfp)
140{
141    struct rds_ib_connection *ic = conn->c_transport_data;
142    dma_addr_t dma_addr;
143    struct ib_sge *sge;
144    int ret = -ENOMEM;
145
146    if (recv->r_ibinc == NULL) {
147        if (!atomic_add_unless(&rds_ib_allocation, 1, rds_ib_sysctl_max_recv_allocation)) {
148            rds_ib_stats_inc(s_ib_rx_alloc_limit);
149            goto out;
150        }
151        recv->r_ibinc = kmem_cache_alloc(rds_ib_incoming_slab,
152                         kptr_gfp);
153        if (recv->r_ibinc == NULL) {
154            atomic_dec(&rds_ib_allocation);
155            goto out;
156        }
157        INIT_LIST_HEAD(&recv->r_ibinc->ii_frags);
158        rds_inc_init(&recv->r_ibinc->ii_inc, conn, conn->c_faddr);
159    }
160
161    if (recv->r_frag == NULL) {
162        recv->r_frag = kmem_cache_alloc(rds_ib_frag_slab, kptr_gfp);
163        if (recv->r_frag == NULL)
164            goto out;
165        INIT_LIST_HEAD(&recv->r_frag->f_item);
166        recv->r_frag->f_page = NULL;
167    }
168
169    if (ic->i_frag.f_page == NULL) {
170        ic->i_frag.f_page = alloc_page(page_gfp);
171        if (ic->i_frag.f_page == NULL)
172            goto out;
173        ic->i_frag.f_offset = 0;
174    }
175
176    dma_addr = ib_dma_map_page(ic->i_cm_id->device,
177                  ic->i_frag.f_page,
178                  ic->i_frag.f_offset,
179                  RDS_FRAG_SIZE,
180                  DMA_FROM_DEVICE);
181    if (ib_dma_mapping_error(ic->i_cm_id->device, dma_addr))
182        goto out;
183
184    /*
185     * Once we get the RDS_PAGE_LAST_OFF frag then rds_ib_frag_unmap()
186     * must be called on this recv. This happens as completions hit
187     * in order or on connection shutdown.
188     */
189    recv->r_frag->f_page = ic->i_frag.f_page;
190    recv->r_frag->f_offset = ic->i_frag.f_offset;
191    recv->r_frag->f_mapped = dma_addr;
192
193    sge = rds_ib_data_sge(ic, recv->r_sge);
194    sge->addr = dma_addr;
195    sge->length = RDS_FRAG_SIZE;
196
197    sge = rds_ib_header_sge(ic, recv->r_sge);
198    sge->addr = ic->i_recv_hdrs_dma + (recv - ic->i_recvs) * sizeof(struct rds_header);
199    sge->length = sizeof(struct rds_header);
200
201    get_page(recv->r_frag->f_page);
202
203    if (ic->i_frag.f_offset < RDS_PAGE_LAST_OFF) {
204        ic->i_frag.f_offset += RDS_FRAG_SIZE;
205    } else {
206        put_page(ic->i_frag.f_page);
207        ic->i_frag.f_page = NULL;
208        ic->i_frag.f_offset = 0;
209    }
210
211    ret = 0;
212out:
213    return ret;
214}
215
216/*
217 * This tries to allocate and post unused work requests after making sure that
218 * they have all the allocations they need to queue received fragments into
219 * sockets. The i_recv_mutex is held here so that ring_alloc and _unalloc
220 * pairs don't go unmatched.
221 *
222 * -1 is returned if posting fails due to temporary resource exhaustion.
223 */
224int rds_ib_recv_refill(struct rds_connection *conn, gfp_t kptr_gfp,
225               gfp_t page_gfp, int prefill)
226{
227    struct rds_ib_connection *ic = conn->c_transport_data;
228    struct rds_ib_recv_work *recv;
229    struct ib_recv_wr *failed_wr;
230    unsigned int posted = 0;
231    int ret = 0;
232    u32 pos;
233
234    while ((prefill || rds_conn_up(conn)) &&
235           rds_ib_ring_alloc(&ic->i_recv_ring, 1, &pos)) {
236        if (pos >= ic->i_recv_ring.w_nr) {
237            printk(KERN_NOTICE "Argh - ring alloc returned pos=%u\n",
238                    pos);
239            ret = -EINVAL;
240            break;
241        }
242
243        recv = &ic->i_recvs[pos];
244        ret = rds_ib_recv_refill_one(conn, recv, kptr_gfp, page_gfp);
245        if (ret) {
246            ret = -1;
247            break;
248        }
249
250        /* XXX when can this fail? */
251        ret = ib_post_recv(ic->i_cm_id->qp, &recv->r_wr, &failed_wr);
252        rdsdebug("recv %p ibinc %p page %p addr %lu ret %d\n", recv,
253             recv->r_ibinc, recv->r_frag->f_page,
254             (long) recv->r_frag->f_mapped, ret);
255        if (ret) {
256            rds_ib_conn_error(conn, "recv post on "
257                   "%pI4 returned %d, disconnecting and "
258                   "reconnecting\n", &conn->c_faddr,
259                   ret);
260            ret = -1;
261            break;
262        }
263
264        posted++;
265    }
266
267    /* We're doing flow control - update the window. */
268    if (ic->i_flowctl && posted)
269        rds_ib_advertise_credits(conn, posted);
270
271    if (ret)
272        rds_ib_ring_unalloc(&ic->i_recv_ring, 1);
273    return ret;
274}
275
276void rds_ib_inc_purge(struct rds_incoming *inc)
277{
278    struct rds_ib_incoming *ibinc;
279    struct rds_page_frag *frag;
280    struct rds_page_frag *pos;
281
282    ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
283    rdsdebug("purging ibinc %p inc %p\n", ibinc, inc);
284
285    list_for_each_entry_safe(frag, pos, &ibinc->ii_frags, f_item) {
286        list_del_init(&frag->f_item);
287        rds_ib_frag_drop_page(frag);
288        rds_ib_frag_free(frag);
289    }
290}
291
292void rds_ib_inc_free(struct rds_incoming *inc)
293{
294    struct rds_ib_incoming *ibinc;
295
296    ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
297
298    rds_ib_inc_purge(inc);
299    rdsdebug("freeing ibinc %p inc %p\n", ibinc, inc);
300    BUG_ON(!list_empty(&ibinc->ii_frags));
301    kmem_cache_free(rds_ib_incoming_slab, ibinc);
302    atomic_dec(&rds_ib_allocation);
303    BUG_ON(atomic_read(&rds_ib_allocation) < 0);
304}
305
306int rds_ib_inc_copy_to_user(struct rds_incoming *inc, struct iovec *first_iov,
307                size_t size)
308{
309    struct rds_ib_incoming *ibinc;
310    struct rds_page_frag *frag;
311    struct iovec *iov = first_iov;
312    unsigned long to_copy;
313    unsigned long frag_off = 0;
314    unsigned long iov_off = 0;
315    int copied = 0;
316    int ret;
317    u32 len;
318
319    ibinc = container_of(inc, struct rds_ib_incoming, ii_inc);
320    frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item);
321    len = be32_to_cpu(inc->i_hdr.h_len);
322
323    while (copied < size && copied < len) {
324        if (frag_off == RDS_FRAG_SIZE) {
325            frag = list_entry(frag->f_item.next,
326                      struct rds_page_frag, f_item);
327            frag_off = 0;
328        }
329        while (iov_off == iov->iov_len) {
330            iov_off = 0;
331            iov++;
332        }
333
334        to_copy = min(iov->iov_len - iov_off, RDS_FRAG_SIZE - frag_off);
335        to_copy = min_t(size_t, to_copy, size - copied);
336        to_copy = min_t(unsigned long, to_copy, len - copied);
337
338        rdsdebug("%lu bytes to user [%p, %zu] + %lu from frag "
339             "[%p, %lu] + %lu\n",
340             to_copy, iov->iov_base, iov->iov_len, iov_off,
341             frag->f_page, frag->f_offset, frag_off);
342
343        /* XXX needs + offset for multiple recvs per page */
344        ret = rds_page_copy_to_user(frag->f_page,
345                        frag->f_offset + frag_off,
346                        iov->iov_base + iov_off,
347                        to_copy);
348        if (ret) {
349            copied = ret;
350            break;
351        }
352
353        iov_off += to_copy;
354        frag_off += to_copy;
355        copied += to_copy;
356    }
357
358    return copied;
359}
360
361/* ic starts out kzalloc()ed */
362void rds_ib_recv_init_ack(struct rds_ib_connection *ic)
363{
364    struct ib_send_wr *wr = &ic->i_ack_wr;
365    struct ib_sge *sge = &ic->i_ack_sge;
366
367    sge->addr = ic->i_ack_dma;
368    sge->length = sizeof(struct rds_header);
369    sge->lkey = ic->i_mr->lkey;
370
371    wr->sg_list = sge;
372    wr->num_sge = 1;
373    wr->opcode = IB_WR_SEND;
374    wr->wr_id = RDS_IB_ACK_WR_ID;
375    wr->send_flags = IB_SEND_SIGNALED | IB_SEND_SOLICITED;
376}
377
378/*
379 * You'd think that with reliable IB connections you wouldn't need to ack
380 * messages that have been received. The problem is that IB hardware generates
381 * an ack message before it has DMAed the message into memory. This creates a
382 * potential message loss if the HCA is disabled for any reason between when it
383 * sends the ack and before the message is DMAed and processed. This is only a
384 * potential issue if another HCA is available for fail-over.
385 *
386 * When the remote host receives our ack they'll free the sent message from
387 * their send queue. To decrease the latency of this we always send an ack
388 * immediately after we've received messages.
389 *
390 * For simplicity, we only have one ack in flight at a time. This puts
391 * pressure on senders to have deep enough send queues to absorb the latency of
392 * a single ack frame being in flight. This might not be good enough.
393 *
394 * This is implemented by have a long-lived send_wr and sge which point to a
395 * statically allocated ack frame. This ack wr does not fall under the ring
396 * accounting that the tx and rx wrs do. The QP attribute specifically makes
397 * room for it beyond the ring size. Send completion notices its special
398 * wr_id and avoids working with the ring in that case.
399 */
400#ifndef KERNEL_HAS_ATOMIC64
401static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,
402                int ack_required)
403{
404    unsigned long flags;
405
406    spin_lock_irqsave(&ic->i_ack_lock, flags);
407    ic->i_ack_next = seq;
408    if (ack_required)
409        set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
410    spin_unlock_irqrestore(&ic->i_ack_lock, flags);
411}
412
413static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
414{
415    unsigned long flags;
416    u64 seq;
417
418    clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
419
420    spin_lock_irqsave(&ic->i_ack_lock, flags);
421    seq = ic->i_ack_next;
422    spin_unlock_irqrestore(&ic->i_ack_lock, flags);
423
424    return seq;
425}
426#else
427static void rds_ib_set_ack(struct rds_ib_connection *ic, u64 seq,
428                int ack_required)
429{
430    atomic64_set(&ic->i_ack_next, seq);
431    if (ack_required) {
432        smp_mb__before_clear_bit();
433        set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
434    }
435}
436
437static u64 rds_ib_get_ack(struct rds_ib_connection *ic)
438{
439    clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
440    smp_mb__after_clear_bit();
441
442    return atomic64_read(&ic->i_ack_next);
443}
444#endif
445
446
447static void rds_ib_send_ack(struct rds_ib_connection *ic, unsigned int adv_credits)
448{
449    struct rds_header *hdr = ic->i_ack;
450    struct ib_send_wr *failed_wr;
451    u64 seq;
452    int ret;
453
454    seq = rds_ib_get_ack(ic);
455
456    rdsdebug("send_ack: ic %p ack %llu\n", ic, (unsigned long long) seq);
457    rds_message_populate_header(hdr, 0, 0, 0);
458    hdr->h_ack = cpu_to_be64(seq);
459    hdr->h_credit = adv_credits;
460    rds_message_make_checksum(hdr);
461    ic->i_ack_queued = jiffies;
462
463    ret = ib_post_send(ic->i_cm_id->qp, &ic->i_ack_wr, &failed_wr);
464    if (unlikely(ret)) {
465        /* Failed to send. Release the WR, and
466         * force another ACK.
467         */
468        clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
469        set_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
470
471        rds_ib_stats_inc(s_ib_ack_send_failure);
472        /* Need to finesse this later. */
473        BUG();
474    } else
475        rds_ib_stats_inc(s_ib_ack_sent);
476}
477
478/*
479 * There are 3 ways of getting acknowledgements to the peer:
480 * 1. We call rds_ib_attempt_ack from the recv completion handler
481 * to send an ACK-only frame.
482 * However, there can be only one such frame in the send queue
483 * at any time, so we may have to postpone it.
484 * 2. When another (data) packet is transmitted while there's
485 * an ACK in the queue, we piggyback the ACK sequence number
486 * on the data packet.
487 * 3. If the ACK WR is done sending, we get called from the
488 * send queue completion handler, and check whether there's
489 * another ACK pending (postponed because the WR was on the
490 * queue). If so, we transmit it.
491 *
492 * We maintain 2 variables:
493 * - i_ack_flags, which keeps track of whether the ACK WR
494 * is currently in the send queue or not (IB_ACK_IN_FLIGHT)
495 * - i_ack_next, which is the last sequence number we received
496 *
497 * Potentially, send queue and receive queue handlers can run concurrently.
498 * It would be nice to not have to use a spinlock to synchronize things,
499 * but the one problem that rules this out is that 64bit updates are
500 * not atomic on all platforms. Things would be a lot simpler if
501 * we had atomic64 or maybe cmpxchg64 everywhere.
502 *
503 * Reconnecting complicates this picture just slightly. When we
504 * reconnect, we may be seeing duplicate packets. The peer
505 * is retransmitting them, because it hasn't seen an ACK for
506 * them. It is important that we ACK these.
507 *
508 * ACK mitigation adds a header flag "ACK_REQUIRED"; any packet with
509 * this flag set *MUST* be acknowledged immediately.
510 */
511
512/*
513 * When we get here, we're called from the recv queue handler.
514 * Check whether we ought to transmit an ACK.
515 */
516void rds_ib_attempt_ack(struct rds_ib_connection *ic)
517{
518    unsigned int adv_credits;
519
520    if (!test_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
521        return;
522
523    if (test_and_set_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags)) {
524        rds_ib_stats_inc(s_ib_ack_send_delayed);
525        return;
526    }
527
528    /* Can we get a send credit? */
529    if (!rds_ib_send_grab_credits(ic, 1, &adv_credits, 0, RDS_MAX_ADV_CREDIT)) {
530        rds_ib_stats_inc(s_ib_tx_throttle);
531        clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
532        return;
533    }
534
535    clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags);
536    rds_ib_send_ack(ic, adv_credits);
537}
538
539/*
540 * We get here from the send completion handler, when the
541 * adapter tells us the ACK frame was sent.
542 */
543void rds_ib_ack_send_complete(struct rds_ib_connection *ic)
544{
545    clear_bit(IB_ACK_IN_FLIGHT, &ic->i_ack_flags);
546    rds_ib_attempt_ack(ic);
547}
548
549/*
550 * This is called by the regular xmit code when it wants to piggyback
551 * an ACK on an outgoing frame.
552 */
553u64 rds_ib_piggyb_ack(struct rds_ib_connection *ic)
554{
555    if (test_and_clear_bit(IB_ACK_REQUESTED, &ic->i_ack_flags))
556        rds_ib_stats_inc(s_ib_ack_send_piggybacked);
557    return rds_ib_get_ack(ic);
558}
559
560static struct rds_header *rds_ib_get_header(struct rds_connection *conn,
561                        struct rds_ib_recv_work *recv,
562                        u32 data_len)
563{
564    struct rds_ib_connection *ic = conn->c_transport_data;
565    void *hdr_buff = &ic->i_recv_hdrs[recv - ic->i_recvs];
566    void *addr;
567    u32 misplaced_hdr_bytes;
568
569    /*
570     * Support header at the front (RDS 3.1+) as well as header-at-end.
571     *
572     * Cases:
573     * 1) header all in header buff (great!)
574     * 2) header all in data page (copy all to header buff)
575     * 3) header split across hdr buf + data page
576     * (move bit in hdr buff to end before copying other bit from data page)
577     */
578    if (conn->c_version > RDS_PROTOCOL_3_0 || data_len == RDS_FRAG_SIZE)
579            return hdr_buff;
580
581    if (data_len <= (RDS_FRAG_SIZE - sizeof(struct rds_header))) {
582        addr = kmap_atomic(recv->r_frag->f_page, KM_SOFTIRQ0);
583        memcpy(hdr_buff,
584               addr + recv->r_frag->f_offset + data_len,
585               sizeof(struct rds_header));
586        kunmap_atomic(addr, KM_SOFTIRQ0);
587        return hdr_buff;
588    }
589
590    misplaced_hdr_bytes = (sizeof(struct rds_header) - (RDS_FRAG_SIZE - data_len));
591
592    memmove(hdr_buff + misplaced_hdr_bytes, hdr_buff, misplaced_hdr_bytes);
593
594    addr = kmap_atomic(recv->r_frag->f_page, KM_SOFTIRQ0);
595    memcpy(hdr_buff, addr + recv->r_frag->f_offset + data_len,
596           sizeof(struct rds_header) - misplaced_hdr_bytes);
597    kunmap_atomic(addr, KM_SOFTIRQ0);
598    return hdr_buff;
599}
600
601/*
602 * It's kind of lame that we're copying from the posted receive pages into
603 * long-lived bitmaps. We could have posted the bitmaps and rdma written into
604 * them. But receiving new congestion bitmaps should be a *rare* event, so
605 * hopefully we won't need to invest that complexity in making it more
606 * efficient. By copying we can share a simpler core with TCP which has to
607 * copy.
608 */
609static void rds_ib_cong_recv(struct rds_connection *conn,
610                  struct rds_ib_incoming *ibinc)
611{
612    struct rds_cong_map *map;
613    unsigned int map_off;
614    unsigned int map_page;
615    struct rds_page_frag *frag;
616    unsigned long frag_off;
617    unsigned long to_copy;
618    unsigned long copied;
619    uint64_t uncongested = 0;
620    void *addr;
621
622    /* catch completely corrupt packets */
623    if (be32_to_cpu(ibinc->ii_inc.i_hdr.h_len) != RDS_CONG_MAP_BYTES)
624        return;
625
626    map = conn->c_fcong;
627    map_page = 0;
628    map_off = 0;
629
630    frag = list_entry(ibinc->ii_frags.next, struct rds_page_frag, f_item);
631    frag_off = 0;
632
633    copied = 0;
634
635    while (copied < RDS_CONG_MAP_BYTES) {
636        uint64_t *src, *dst;
637        unsigned int k;
638
639        to_copy = min(RDS_FRAG_SIZE - frag_off, PAGE_SIZE - map_off);
640        BUG_ON(to_copy & 7); /* Must be 64bit aligned. */
641
642        addr = kmap_atomic(frag->f_page, KM_SOFTIRQ0);
643
644        src = addr + frag_off;
645        dst = (void *)map->m_page_addrs[map_page] + map_off;
646        for (k = 0; k < to_copy; k += 8) {
647            /* Record ports that became uncongested, ie
648             * bits that changed from 0 to 1. */
649            uncongested |= ~(*src) & *dst;
650            *dst++ = *src++;
651        }
652        kunmap_atomic(addr, KM_SOFTIRQ0);
653
654        copied += to_copy;
655
656        map_off += to_copy;
657        if (map_off == PAGE_SIZE) {
658            map_off = 0;
659            map_page++;
660        }
661
662        frag_off += to_copy;
663        if (frag_off == RDS_FRAG_SIZE) {
664            frag = list_entry(frag->f_item.next,
665                      struct rds_page_frag, f_item);
666            frag_off = 0;
667        }
668    }
669
670    /* the congestion map is in little endian order */
671    uncongested = le64_to_cpu(uncongested);
672
673    rds_cong_map_updated(map, uncongested);
674}
675
676/*
677 * Rings are posted with all the allocations they'll need to queue the
678 * incoming message to the receiving socket so this can't fail.
679 * All fragments start with a header, so we can make sure we're not receiving
680 * garbage, and we can tell a small 8 byte fragment from an ACK frame.
681 */
682struct rds_ib_ack_state {
683    u64 ack_next;
684    u64 ack_recv;
685    unsigned int ack_required:1;
686    unsigned int ack_next_valid:1;
687    unsigned int ack_recv_valid:1;
688};
689
690static void rds_ib_process_recv(struct rds_connection *conn,
691                struct rds_ib_recv_work *recv, u32 data_len,
692                struct rds_ib_ack_state *state)
693{
694    struct rds_ib_connection *ic = conn->c_transport_data;
695    struct rds_ib_incoming *ibinc = ic->i_ibinc;
696    struct rds_header *ihdr, *hdr;
697
698    /* XXX shut down the connection if port 0,0 are seen? */
699
700    rdsdebug("ic %p ibinc %p recv %p byte len %u\n", ic, ibinc, recv,
701         data_len);
702
703    if (data_len < sizeof(struct rds_header)) {
704        rds_ib_conn_error(conn, "incoming message "
705               "from %pI4 didn't inclue a "
706               "header, disconnecting and "
707               "reconnecting\n",
708               &conn->c_faddr);
709        return;
710    }
711    data_len -= sizeof(struct rds_header);
712
713    ihdr = rds_ib_get_header(conn, recv, data_len);
714
715    /* Validate the checksum. */
716    if (!rds_message_verify_checksum(ihdr)) {
717        rds_ib_conn_error(conn, "incoming message "
718               "from %pI4 has corrupted header - "
719               "forcing a reconnect\n",
720               &conn->c_faddr);
721        rds_stats_inc(s_recv_drop_bad_checksum);
722        return;
723    }
724
725    /* Process the ACK sequence which comes with every packet */
726    state->ack_recv = be64_to_cpu(ihdr->h_ack);
727    state->ack_recv_valid = 1;
728
729    /* Process the credits update if there was one */
730    if (ihdr->h_credit)
731        rds_ib_send_add_credits(conn, ihdr->h_credit);
732
733    if (ihdr->h_sport == 0 && ihdr->h_dport == 0 && data_len == 0) {
734        /* This is an ACK-only packet. The fact that it gets
735         * special treatment here is that historically, ACKs
736         * were rather special beasts.
737         */
738        rds_ib_stats_inc(s_ib_ack_received);
739
740        /*
741         * Usually the frags make their way on to incs and are then freed as
742         * the inc is freed. We don't go that route, so we have to drop the
743         * page ref ourselves. We can't just leave the page on the recv
744         * because that confuses the dma mapping of pages and each recv's use
745         * of a partial page. We can leave the frag, though, it will be
746         * reused.
747         *
748         * FIXME: Fold this into the code path below.
749         */
750        rds_ib_frag_drop_page(recv->r_frag);
751        return;
752    }
753
754    /*
755     * If we don't already have an inc on the connection then this
756     * fragment has a header and starts a message.. copy its header
757     * into the inc and save the inc so we can hang upcoming fragments
758     * off its list.
759     */
760    if (ibinc == NULL) {
761        ibinc = recv->r_ibinc;
762        recv->r_ibinc = NULL;
763        ic->i_ibinc = ibinc;
764
765        hdr = &ibinc->ii_inc.i_hdr;
766        memcpy(hdr, ihdr, sizeof(*hdr));
767        ic->i_recv_data_rem = be32_to_cpu(hdr->h_len);
768
769        rdsdebug("ic %p ibinc %p rem %u flag 0x%x\n", ic, ibinc,
770             ic->i_recv_data_rem, hdr->h_flags);
771    } else {
772        hdr = &ibinc->ii_inc.i_hdr;
773        /* We can't just use memcmp here; fragments of a
774         * single message may carry different ACKs */
775        if (hdr->h_sequence != ihdr->h_sequence ||
776            hdr->h_len != ihdr->h_len ||
777            hdr->h_sport != ihdr->h_sport ||
778            hdr->h_dport != ihdr->h_dport) {
779            rds_ib_conn_error(conn,
780                "fragment header mismatch; forcing reconnect\n");
781            return;
782        }
783    }
784
785    list_add_tail(&recv->r_frag->f_item, &ibinc->ii_frags);
786    recv->r_frag = NULL;
787
788    if (ic->i_recv_data_rem > RDS_FRAG_SIZE)
789        ic->i_recv_data_rem -= RDS_FRAG_SIZE;
790    else {
791        ic->i_recv_data_rem = 0;
792        ic->i_ibinc = NULL;
793
794        if (ibinc->ii_inc.i_hdr.h_flags == RDS_FLAG_CONG_BITMAP)
795            rds_ib_cong_recv(conn, ibinc);
796        else {
797            rds_recv_incoming(conn, conn->c_faddr, conn->c_laddr,
798                      &ibinc->ii_inc, GFP_ATOMIC,
799                      KM_SOFTIRQ0);
800            state->ack_next = be64_to_cpu(hdr->h_sequence);
801            state->ack_next_valid = 1;
802        }
803
804        /* Evaluate the ACK_REQUIRED flag *after* we received
805         * the complete frame, and after bumping the next_rx
806         * sequence. */
807        if (hdr->h_flags & RDS_FLAG_ACK_REQUIRED) {
808            rds_stats_inc(s_recv_ack_required);
809            state->ack_required = 1;
810        }
811
812        rds_inc_put(&ibinc->ii_inc);
813    }
814}
815
816/*
817 * Plucking the oldest entry from the ring can be done concurrently with
818 * the thread refilling the ring. Each ring operation is protected by
819 * spinlocks and the transient state of refilling doesn't change the
820 * recording of which entry is oldest.
821 *
822 * This relies on IB only calling one cq comp_handler for each cq so that
823 * there will only be one caller of rds_recv_incoming() per RDS connection.
824 */
825void rds_ib_recv_cq_comp_handler(struct ib_cq *cq, void *context)
826{
827    struct rds_connection *conn = context;
828    struct rds_ib_connection *ic = conn->c_transport_data;
829
830    rdsdebug("conn %p cq %p\n", conn, cq);
831
832    rds_ib_stats_inc(s_ib_rx_cq_call);
833
834    tasklet_schedule(&ic->i_recv_tasklet);
835}
836
837static inline void rds_poll_cq(struct rds_ib_connection *ic,
838                   struct rds_ib_ack_state *state)
839{
840    struct rds_connection *conn = ic->conn;
841    struct ib_wc wc;
842    struct rds_ib_recv_work *recv;
843
844    while (ib_poll_cq(ic->i_recv_cq, 1, &wc) > 0) {
845        rdsdebug("wc wr_id 0x%llx status %u byte_len %u imm_data %u\n",
846             (unsigned long long)wc.wr_id, wc.status, wc.byte_len,
847             be32_to_cpu(wc.ex.imm_data));
848        rds_ib_stats_inc(s_ib_rx_cq_event);
849
850        recv = &ic->i_recvs[rds_ib_ring_oldest(&ic->i_recv_ring)];
851
852        rds_ib_recv_unmap_page(ic, recv);
853
854        /*
855         * Also process recvs in connecting state because it is possible
856         * to get a recv completion _before_ the rdmacm ESTABLISHED
857         * event is processed.
858         */
859        if (rds_conn_up(conn) || rds_conn_connecting(conn)) {
860            /* We expect errors as the qp is drained during shutdown */
861            if (wc.status == IB_WC_SUCCESS) {
862                rds_ib_process_recv(conn, recv, wc.byte_len, state);
863            } else {
864                rds_ib_conn_error(conn, "recv completion on "
865                       "%pI4 had status %u, disconnecting and "
866                       "reconnecting\n", &conn->c_faddr,
867                       wc.status);
868            }
869        }
870
871        rds_ib_ring_free(&ic->i_recv_ring, 1);
872    }
873}
874
875void rds_ib_recv_tasklet_fn(unsigned long data)
876{
877    struct rds_ib_connection *ic = (struct rds_ib_connection *) data;
878    struct rds_connection *conn = ic->conn;
879    struct rds_ib_ack_state state = { 0, };
880
881    rds_poll_cq(ic, &state);
882    ib_req_notify_cq(ic->i_recv_cq, IB_CQ_SOLICITED);
883    rds_poll_cq(ic, &state);
884
885    if (state.ack_next_valid)
886        rds_ib_set_ack(ic, state.ack_next, state.ack_required);
887    if (state.ack_recv_valid && state.ack_recv > ic->i_ack_recv) {
888        rds_send_drop_acked(conn, state.ack_recv, NULL);
889        ic->i_ack_recv = state.ack_recv;
890    }
891    if (rds_conn_up(conn))
892        rds_ib_attempt_ack(ic);
893
894    /* If we ever end up with a really empty receive ring, we're
895     * in deep trouble, as the sender will definitely see RNR
896     * timeouts. */
897    if (rds_ib_ring_empty(&ic->i_recv_ring))
898        rds_ib_stats_inc(s_ib_rx_ring_empty);
899
900    /*
901     * If the ring is running low, then schedule the thread to refill.
902     */
903    if (rds_ib_ring_low(&ic->i_recv_ring))
904        queue_delayed_work(rds_wq, &conn->c_recv_w, 0);
905}
906
907int rds_ib_recv(struct rds_connection *conn)
908{
909    struct rds_ib_connection *ic = conn->c_transport_data;
910    int ret = 0;
911
912    rdsdebug("conn %p\n", conn);
913
914    /*
915     * If we get a temporary posting failure in this context then
916     * we're really low and we want the caller to back off for a bit.
917     */
918    mutex_lock(&ic->i_recv_mutex);
919    if (rds_ib_recv_refill(conn, GFP_KERNEL, GFP_HIGHUSER, 0))
920        ret = -ENOMEM;
921    else
922        rds_ib_stats_inc(s_ib_rx_refill_from_thread);
923    mutex_unlock(&ic->i_recv_mutex);
924
925    if (rds_conn_up(conn))
926        rds_ib_attempt_ack(ic);
927
928    return ret;
929}
930
931int __init rds_ib_recv_init(void)
932{
933    struct sysinfo si;
934    int ret = -ENOMEM;
935
936    /* Default to 30% of all available RAM for recv memory */
937    si_meminfo(&si);
938    rds_ib_sysctl_max_recv_allocation = si.totalram / 3 * PAGE_SIZE / RDS_FRAG_SIZE;
939
940    rds_ib_incoming_slab = kmem_cache_create("rds_ib_incoming",
941                    sizeof(struct rds_ib_incoming),
942                    0, 0, NULL);
943    if (rds_ib_incoming_slab == NULL)
944        goto out;
945
946    rds_ib_frag_slab = kmem_cache_create("rds_ib_frag",
947                    sizeof(struct rds_page_frag),
948                    0, 0, NULL);
949    if (rds_ib_frag_slab == NULL)
950        kmem_cache_destroy(rds_ib_incoming_slab);
951    else
952        ret = 0;
953out:
954    return ret;
955}
956
957void rds_ib_recv_exit(void)
958{
959    kmem_cache_destroy(rds_ib_incoming_slab);
960    kmem_cache_destroy(rds_ib_frag_slab);
961}
962

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