drivers/staging/lustre/lnet/klnds/socklnd/socklnd_lib.c

   1 /*
   2  * GPL HEADER START
   3  *
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 only,
   8  * as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * General Public License version 2 for more details (a copy is included
  14  * in the LICENSE file that accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 2 along with this program; If not, see
  18  * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
  19  *
  20  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  21  * CA 95054 USA or visit www.sun.com if you need additional information or
  22  * have any questions.
  23  *
  24  * GPL HEADER END
  25  */
  26 /*
  27  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  28  * Use is subject to license terms.
  29  *
  30  * Copyright (c) 2011, 2012, Intel Corporation.
  31  */
  32 /*
  33  * This file is part of Lustre, http://www.lustre.org/
  34  * Lustre is a trademark of Sun Microsystems, Inc.
  35  */
  36
  37 #include "socklnd.h"
  38
  39 int
  40 ksocknal_lib_get_conn_addrs(ksock_conn_t *conn)
  41 {
  42         int rc = lnet_sock_getaddr(conn->ksnc_sock, 1, &conn->ksnc_ipaddr,
  43                                    &conn->ksnc_port);
  44
  45         /* Didn't need the {get,put}connsock dance to deref ksnc_sock... */
  46         LASSERT(!conn->ksnc_closing);
  47
  48         if (rc != 0) {
  49                 CERROR("Error %d getting sock peer IP\n", rc);
  50                 return rc;
  51         }
  52
  53         rc = lnet_sock_getaddr(conn->ksnc_sock, 0, &conn->ksnc_myipaddr, NULL);
  54         if (rc != 0) {
  55                 CERROR("Error %d getting sock local IP\n", rc);
  56                 return rc;
  57         }
  58
  59         return 0;
  60 }
  61
  62 int
  63 ksocknal_lib_zc_capable(ksock_conn_t *conn)
  64 {
  65         int caps = conn->ksnc_sock->sk->sk_route_caps;
  66
  67         if (conn->ksnc_proto == &ksocknal_protocol_v1x)
  68                 return 0;
  69
  70         /* ZC if the socket supports scatter/gather and doesn't need software
  71          * checksums */
  72         return ((caps & NETIF_F_SG) != 0 && (caps & NETIF_F_ALL_CSUM) != 0);
  73 }
  74
  75 int
  76 ksocknal_lib_send_iov(ksock_conn_t *conn, ksock_tx_t *tx)
  77 {
  78         struct socket *sock = conn->ksnc_sock;
  79         int nob;
  80         int rc;
  81
  82         if (*ksocknal_tunables.ksnd_enable_csum && /* checksum enabled */
  83             conn->ksnc_proto == &ksocknal_protocol_v2x && /* V2.x connection  */
  84             tx->tx_nob == tx->tx_resid           && /* frist sending    */
  85             tx->tx_msg.ksm_csum == 0)                /* not checksummed  */
  86                 ksocknal_lib_csum_tx(tx);
  87
  88         /* NB we can't trust socket ops to either consume our iovs
  89          * or leave them alone. */
  90
  91         {
  92 #if SOCKNAL_SINGLE_FRAG_TX
  93                 struct kvec scratch;
  94                 struct kvec *scratchiov = &scratch;
  95                 unsigned int niov = 1;
  96 #else
  97                 struct kvec *scratchiov = conn->ksnc_scheduler->kss_scratch_iov;
  98                 unsigned int niov = tx->tx_niov;
  99 #endif
 100                 struct msghdr msg = {.msg_flags = MSG_DONTWAIT};
 101                 int i;
 102
 103                 for (nob = i = 0; i < niov; i++) {
 104                         scratchiov[i] = tx->tx_iov[i];
 105                         nob += scratchiov[i].iov_len;
 106                 }
 107
 108                 if (!list_empty(&conn->ksnc_tx_queue) ||
 109                     nob < tx->tx_resid)
 110                         msg.msg_flags |= MSG_MORE;
 111
 112                 rc = kernel_sendmsg(sock, &msg, scratchiov, niov, nob);
 113         }
 114         return rc;
 115 }
 116
 117 int
 118 ksocknal_lib_send_kiov(ksock_conn_t *conn, ksock_tx_t *tx)
 119 {
 120         struct socket *sock = conn->ksnc_sock;
 121         lnet_kiov_t *kiov = tx->tx_kiov;
 122         int rc;
 123         int nob;
 124
 125         /* Not NOOP message */
 126         LASSERT(tx->tx_lnetmsg != NULL);
 127
 128         /* NB we can't trust socket ops to either consume our iovs
 129          * or leave them alone. */
 130         if (tx->tx_msg.ksm_zc_cookies[0] != 0) {
 131                 /* Zero copy is enabled */
 132                 struct sock *sk = sock->sk;
 133                 struct page *page = kiov->kiov_page;
 134                 int offset = kiov->kiov_offset;
 135                 int fragsize = kiov->kiov_len;
 136                 int msgflg = MSG_DONTWAIT;
 137
 138                 CDEBUG(D_NET, "page %p + offset %x for %d\n",
 139                                page, offset, kiov->kiov_len);
 140
 141                 if (!list_empty(&conn->ksnc_tx_queue) ||
 142                     fragsize < tx->tx_resid)
 143                         msgflg |= MSG_MORE;
 144
 145                 if (sk->sk_prot->sendpage != NULL) {
 146                         rc = sk->sk_prot->sendpage(sk, page,
 147                                                    offset, fragsize, msgflg);
 148                 } else {
 149                         rc = tcp_sendpage(sk, page, offset, fragsize, msgflg);
 150                 }
 151         } else {
 152 #if SOCKNAL_SINGLE_FRAG_TX || !SOCKNAL_RISK_KMAP_DEADLOCK
 153                 struct kvec scratch;
 154                 struct kvec *scratchiov = &scratch;
 155                 unsigned int niov = 1;
 156 #else
 157 #ifdef CONFIG_HIGHMEM
 158 #warning "XXX risk of kmap deadlock on multiple frags..."
 159 #endif
 160                 struct kvec *scratchiov = conn->ksnc_scheduler->kss_scratch_iov;
 161                 unsigned int niov = tx->tx_nkiov;
 162 #endif
 163                 struct msghdr msg = {.msg_flags = MSG_DONTWAIT};
 164                 int i;
 165
 166                 for (nob = i = 0; i < niov; i++) {
 167                         scratchiov[i].iov_base = kmap(kiov[i].kiov_page) +
 168                                                  kiov[i].kiov_offset;
 169                         nob += scratchiov[i].iov_len = kiov[i].kiov_len;
 170                 }
 171
 172                 if (!list_empty(&conn->ksnc_tx_queue) ||
 173                     nob < tx->tx_resid)
 174                         msg.msg_flags |= MSG_MORE;
 175
 176                 rc = kernel_sendmsg(sock, &msg, (struct kvec *)scratchiov, niov, nob);
 177
 178                 for (i = 0; i < niov; i++)
 179                         kunmap(kiov[i].kiov_page);
 180         }
 181         return rc;
 182 }
 183
 184 void
 185 ksocknal_lib_eager_ack(ksock_conn_t *conn)
 186 {
 187         int opt = 1;
 188         struct socket *sock = conn->ksnc_sock;
 189
 190         /* Remind the socket to ACK eagerly.  If I don't, the socket might
 191          * think I'm about to send something it could piggy-back the ACK
 192          * on, introducing delay in completing zero-copy sends in my
 193          * peer. */
 194
 195         kernel_setsockopt(sock, SOL_TCP, TCP_QUICKACK,
 196                                (char *)&opt, sizeof(opt));
 197 }
 198
 199 int
 200 ksocknal_lib_recv_iov(ksock_conn_t *conn)
 201 {
 202 #if SOCKNAL_SINGLE_FRAG_RX
 203         struct kvec scratch;
 204         struct kvec *scratchiov = &scratch;
 205         unsigned int niov = 1;
 206 #else
 207         struct kvec *scratchiov = conn->ksnc_scheduler->kss_scratch_iov;
 208         unsigned int niov = conn->ksnc_rx_niov;
 209 #endif
 210         struct kvec *iov = conn->ksnc_rx_iov;
 211         struct msghdr msg = {
 212                 .msg_flags = 0
 213         };
 214         int nob;
 215         int i;
 216         int rc;
 217         int fragnob;
 218         int sum;
 219         __u32 saved_csum;
 220
 221         /* NB we can't trust socket ops to either consume our iovs
 222          * or leave them alone. */
 223         LASSERT(niov > 0);
 224
 225         for (nob = i = 0; i < niov; i++) {
 226                 scratchiov[i] = iov[i];
 227                 nob += scratchiov[i].iov_len;
 228         }
 229         LASSERT(nob <= conn->ksnc_rx_nob_wanted);
 230
 231         rc = kernel_recvmsg(conn->ksnc_sock, &msg,
 232                 scratchiov, niov, nob, MSG_DONTWAIT);
 233
 234         saved_csum = 0;
 235         if (conn->ksnc_proto == &ksocknal_protocol_v2x) {
 236                 saved_csum = conn->ksnc_msg.ksm_csum;
 237                 conn->ksnc_msg.ksm_csum = 0;
 238         }
 239
 240         if (saved_csum != 0) {
 241                 /* accumulate checksum */
 242                 for (i = 0, sum = rc; sum > 0; i++, sum -= fragnob) {
 243                         LASSERT(i < niov);
 244
 245                         fragnob = iov[i].iov_len;
 246                         if (fragnob > sum)
 247                                 fragnob = sum;
 248
 249                         conn->ksnc_rx_csum = ksocknal_csum(conn->ksnc_rx_csum,
 250                                                            iov[i].iov_base, fragnob);
 251                 }
 252                 conn->ksnc_msg.ksm_csum = saved_csum;
 253         }
 254
 255         return rc;
 256 }
 257
 258 static void
 259 ksocknal_lib_kiov_vunmap(void *addr)
 260 {
 261         if (addr == NULL)
 262                 return;
 263
 264         vunmap(addr);
 265 }
 266
 267 static void *
 268 ksocknal_lib_kiov_vmap(lnet_kiov_t *kiov, int niov,
 269                        struct kvec *iov, struct page **pages)
 270 {
 271         void *addr;
 272         int nob;
 273         int i;
 274
 275         if (!*ksocknal_tunables.ksnd_zc_recv || pages == NULL)
 276                 return NULL;
 277
 278         LASSERT(niov <= LNET_MAX_IOV);
 279
 280         if (niov < 2 ||
 281             niov < *ksocknal_tunables.ksnd_zc_recv_min_nfrags)
 282                 return NULL;
 283
 284         for (nob = i = 0; i < niov; i++) {
 285                 if ((kiov[i].kiov_offset != 0 && i > 0) ||
 286                     (kiov[i].kiov_offset + kiov[i].kiov_len != PAGE_CACHE_SIZE && i < niov - 1))
 287                         return NULL;
 288
 289                 pages[i] = kiov[i].kiov_page;
 290                 nob += kiov[i].kiov_len;
 291         }
 292
 293         addr = vmap(pages, niov, VM_MAP, PAGE_KERNEL);
 294         if (addr == NULL)
 295                 return NULL;
 296
 297         iov->iov_base = addr + kiov[0].kiov_offset;
 298         iov->iov_len = nob;
 299
 300         return addr;
 301 }
 302
 303 int
 304 ksocknal_lib_recv_kiov(ksock_conn_t *conn)
 305 {
 306 #if SOCKNAL_SINGLE_FRAG_RX || !SOCKNAL_RISK_KMAP_DEADLOCK
 307         struct kvec scratch;
 308         struct kvec *scratchiov = &scratch;
 309         struct page **pages = NULL;
 310         unsigned int niov = 1;
 311 #else
 312 #ifdef CONFIG_HIGHMEM
 313 #warning "XXX risk of kmap deadlock on multiple frags..."
 314 #endif
 315         struct kvec *scratchiov = conn->ksnc_scheduler->kss_scratch_iov;
 316         struct page **pages = conn->ksnc_scheduler->kss_rx_scratch_pgs;
 317         unsigned int niov = conn->ksnc_rx_nkiov;
 318 #endif
 319         lnet_kiov_t   *kiov = conn->ksnc_rx_kiov;
 320         struct msghdr msg = {
 321                 .msg_flags = 0
 322         };
 323         int nob;
 324         int i;
 325         int rc;
 326         void *base;
 327         void *addr;
 328         int sum;
 329         int fragnob;
 330         int n;
 331
 332         /* NB we can't trust socket ops to either consume our iovs
 333          * or leave them alone. */
 334         addr = ksocknal_lib_kiov_vmap(kiov, niov, scratchiov, pages);
 335         if (addr != NULL) {
 336                 nob = scratchiov[0].iov_len;
 337                 n = 1;
 338
 339         } else {
 340                 for (nob = i = 0; i < niov; i++) {
 341                         nob += scratchiov[i].iov_len = kiov[i].kiov_len;
 342                         scratchiov[i].iov_base = kmap(kiov[i].kiov_page) +
 343                                                  kiov[i].kiov_offset;
 344                 }
 345                 n = niov;
 346         }
 347
 348         LASSERT(nob <= conn->ksnc_rx_nob_wanted);
 349
 350         rc = kernel_recvmsg(conn->ksnc_sock, &msg,
 351                         (struct kvec *)scratchiov, n, nob, MSG_DONTWAIT);
 352
 353         if (conn->ksnc_msg.ksm_csum != 0) {
 354                 for (i = 0, sum = rc; sum > 0; i++, sum -= fragnob) {
 355                         LASSERT(i < niov);
 356
 357                         /* Dang! have to kmap again because I have nowhere to
 358                          * stash the mapped address.  But by doing it while the
 359                          * page is still mapped, the kernel just bumps the map
 360                          * count and returns me the address it stashed. */
 361                         base = kmap(kiov[i].kiov_page) + kiov[i].kiov_offset;
 362                         fragnob = kiov[i].kiov_len;
 363                         if (fragnob > sum)
 364                                 fragnob = sum;
 365
 366                         conn->ksnc_rx_csum = ksocknal_csum(conn->ksnc_rx_csum,
 367                                                            base, fragnob);
 368
 369                         kunmap(kiov[i].kiov_page);
 370                 }
 371         }
 372
 373         if (addr != NULL) {
 374                 ksocknal_lib_kiov_vunmap(addr);
 375         } else {
 376                 for (i = 0; i < niov; i++)
 377                         kunmap(kiov[i].kiov_page);
 378         }
 379
 380         return rc;
 381 }
 382
 383 void
 384 ksocknal_lib_csum_tx(ksock_tx_t *tx)
 385 {
 386         int i;
 387         __u32 csum;
 388         void *base;
 389
 390         LASSERT(tx->tx_iov[0].iov_base == &tx->tx_msg);
 391         LASSERT(tx->tx_conn != NULL);
 392         LASSERT(tx->tx_conn->ksnc_proto == &ksocknal_protocol_v2x);
 393
 394         tx->tx_msg.ksm_csum = 0;
 395
 396         csum = ksocknal_csum(~0, tx->tx_iov[0].iov_base,
 397                              tx->tx_iov[0].iov_len);
 398
 399         if (tx->tx_kiov != NULL) {
 400                 for (i = 0; i < tx->tx_nkiov; i++) {
 401                         base = kmap(tx->tx_kiov[i].kiov_page) +
 402                                tx->tx_kiov[i].kiov_offset;
 403
 404                         csum = ksocknal_csum(csum, base, tx->tx_kiov[i].kiov_len);
 405
 406                         kunmap(tx->tx_kiov[i].kiov_page);
 407                 }
 408         } else {
 409                 for (i = 1; i < tx->tx_niov; i++)
 410                         csum = ksocknal_csum(csum, tx->tx_iov[i].iov_base,
 411                                              tx->tx_iov[i].iov_len);
 412         }
 413
 414         if (*ksocknal_tunables.ksnd_inject_csum_error) {
 415                 csum++;
 416                 *ksocknal_tunables.ksnd_inject_csum_error = 0;
 417         }
 418
 419         tx->tx_msg.ksm_csum = csum;
 420 }
 421
 422 int
 423 ksocknal_lib_get_conn_tunables(ksock_conn_t *conn, int *txmem, int *rxmem, int *nagle)
 424 {
 425         struct socket *sock = conn->ksnc_sock;
 426         int len;
 427         int rc;
 428
 429         rc = ksocknal_connsock_addref(conn);
 430         if (rc != 0) {
 431                 LASSERT(conn->ksnc_closing);
 432                 *txmem = *rxmem = *nagle = 0;
 433                 return -ESHUTDOWN;
 434         }
 435
 436         rc = lnet_sock_getbuf(sock, txmem, rxmem);
 437         if (rc == 0) {
 438                 len = sizeof(*nagle);
 439                 rc = kernel_getsockopt(sock, SOL_TCP, TCP_NODELAY,
 440                                            (char *)nagle, &len);
 441         }
 442
 443         ksocknal_connsock_decref(conn);
 444
 445         if (rc == 0)
 446                 *nagle = !*nagle;
 447         else
 448                 *txmem = *rxmem = *nagle = 0;
 449
 450         return rc;
 451 }
 452
 453 int
 454 ksocknal_lib_setup_sock(struct socket *sock)
 455 {
 456         int rc;
 457         int option;
 458         int keep_idle;
 459         int keep_intvl;
 460         int keep_count;
 461         int do_keepalive;
 462         struct linger linger;
 463
 464         sock->sk->sk_allocation = GFP_NOFS;
 465
 466         /* Ensure this socket aborts active sends immediately when we close
 467          * it. */
 468
 469         linger.l_onoff = 0;
 470         linger.l_linger = 0;
 471
 472         rc = kernel_setsockopt(sock, SOL_SOCKET, SO_LINGER,
 473                               (char *)&linger, sizeof(linger));
 474         if (rc != 0) {
 475                 CERROR("Can't set SO_LINGER: %d\n", rc);
 476                 return rc;
 477         }
 478
 479         option = -1;
 480         rc = kernel_setsockopt(sock, SOL_TCP, TCP_LINGER2,
 481                                     (char *)&option, sizeof(option));
 482         if (rc != 0) {
 483                 CERROR("Can't set SO_LINGER2: %d\n", rc);
 484                 return rc;
 485         }
 486
 487         if (!*ksocknal_tunables.ksnd_nagle) {
 488                 option = 1;
 489
 490                 rc = kernel_setsockopt(sock, SOL_TCP, TCP_NODELAY,
 491                                             (char *)&option, sizeof(option));
 492                 if (rc != 0) {
 493                         CERROR("Can't disable nagle: %d\n", rc);
 494                         return rc;
 495                 }
 496         }
 497
 498         rc = lnet_sock_setbuf(sock, *ksocknal_tunables.ksnd_tx_buffer_size,
 499                               *ksocknal_tunables.ksnd_rx_buffer_size);
 500         if (rc != 0) {
 501                 CERROR("Can't set buffer tx %d, rx %d buffers: %d\n",
 502                         *ksocknal_tunables.ksnd_tx_buffer_size,
 503                         *ksocknal_tunables.ksnd_rx_buffer_size, rc);
 504                 return rc;
 505         }
 506
 507 /* TCP_BACKOFF_* sockopt tunables unsupported in stock kernels */
 508
 509         /* snapshot tunables */
 510         keep_idle  = *ksocknal_tunables.ksnd_keepalive_idle;
 511         keep_count = *ksocknal_tunables.ksnd_keepalive_count;
 512         keep_intvl = *ksocknal_tunables.ksnd_keepalive_intvl;
 513
 514         do_keepalive = (keep_idle > 0 && keep_count > 0 && keep_intvl > 0);
 515
 516         option = (do_keepalive ? 1 : 0);
 517         rc = kernel_setsockopt(sock, SOL_SOCKET, SO_KEEPALIVE,
 518                               (char *)&option, sizeof(option));
 519         if (rc != 0) {
 520                 CERROR("Can't set SO_KEEPALIVE: %d\n", rc);
 521                 return rc;
 522         }
 523
 524         if (!do_keepalive)
 525                 return 0;
 526
 527         rc = kernel_setsockopt(sock, SOL_TCP, TCP_KEEPIDLE,
 528                                     (char *)&keep_idle, sizeof(keep_idle));
 529         if (rc != 0) {
 530                 CERROR("Can't set TCP_KEEPIDLE: %d\n", rc);
 531                 return rc;
 532         }
 533
 534         rc = kernel_setsockopt(sock, SOL_TCP, TCP_KEEPINTVL,
 535                                     (char *)&keep_intvl, sizeof(keep_intvl));
 536         if (rc != 0) {
 537                 CERROR("Can't set TCP_KEEPINTVL: %d\n", rc);
 538                 return rc;
 539         }
 540
 541         rc = kernel_setsockopt(sock, SOL_TCP, TCP_KEEPCNT,
 542                                     (char *)&keep_count, sizeof(keep_count));
 543         if (rc != 0) {
 544                 CERROR("Can't set TCP_KEEPCNT: %d\n", rc);
 545                 return rc;
 546         }
 547
 548         return 0;
 549 }
 550
 551 void
 552 ksocknal_lib_push_conn(ksock_conn_t *conn)
 553 {
 554         struct sock *sk;
 555         struct tcp_sock *tp;
 556         int nonagle;
 557         int val = 1;
 558         int rc;
 559
 560         rc = ksocknal_connsock_addref(conn);
 561         if (rc != 0)                        /* being shut down */
 562                 return;
 563
 564         sk = conn->ksnc_sock->sk;
 565         tp = tcp_sk(sk);
 566
 567         lock_sock(sk);
 568         nonagle = tp->nonagle;
 569         tp->nonagle = 1;
 570         release_sock(sk);
 571
 572         rc = kernel_setsockopt(conn->ksnc_sock, SOL_TCP, TCP_NODELAY,
 573                                       (char *)&val, sizeof(val));
 574         LASSERT(rc == 0);
 575
 576         lock_sock(sk);
 577         tp->nonagle = nonagle;
 578         release_sock(sk);
 579
 580         ksocknal_connsock_decref(conn);
 581 }
 582
 583 extern void ksocknal_read_callback(ksock_conn_t *conn);
 584 extern void ksocknal_write_callback(ksock_conn_t *conn);
 585 /*
 586  * socket call back in Linux
 587  */
 588 static void
 589 ksocknal_data_ready(struct sock *sk)
 590 {
 591         ksock_conn_t *conn;
 592
 593         /* interleave correctly with closing sockets... */
 594         LASSERT(!in_irq());
 595         read_lock(&ksocknal_data.ksnd_global_lock);
 596
 597         conn = sk->sk_user_data;
 598         if (conn == NULL) {          /* raced with ksocknal_terminate_conn */
 599                 LASSERT(sk->sk_data_ready != &ksocknal_data_ready);
 600                 sk->sk_data_ready(sk);
 601         } else
 602                 ksocknal_read_callback(conn);
 603
 604         read_unlock(&ksocknal_data.ksnd_global_lock);
 605 }
 606
 607 static void
 608 ksocknal_write_space(struct sock *sk)
 609 {
 610         ksock_conn_t *conn;
 611         int wspace;
 612         int min_wpace;
 613
 614         /* interleave correctly with closing sockets... */
 615         LASSERT(!in_irq());
 616         read_lock(&ksocknal_data.ksnd_global_lock);
 617
 618         conn = sk->sk_user_data;
 619         wspace = sk_stream_wspace(sk);
 620         min_wpace = sk_stream_min_wspace(sk);
 621
 622         CDEBUG(D_NET, "sk %p wspace %d low water %d conn %p%s%s%s\n",
 623                sk, wspace, min_wpace, conn,
 624                (conn == NULL) ? "" : (conn->ksnc_tx_ready ?
 625                                       " ready" : " blocked"),
 626                (conn == NULL) ? "" : (conn->ksnc_tx_scheduled ?
 627                                       " scheduled" : " idle"),
 628                (conn == NULL) ? "" : (list_empty(&conn->ksnc_tx_queue) ?
 629                                       " empty" : " queued"));
 630
 631         if (conn == NULL) {          /* raced with ksocknal_terminate_conn */
 632                 LASSERT(sk->sk_write_space != &ksocknal_write_space);
 633                 sk->sk_write_space(sk);
 634
 635                 read_unlock(&ksocknal_data.ksnd_global_lock);
 636                 return;
 637         }
 638
 639         if (wspace >= min_wpace) {            /* got enough space */
 640                 ksocknal_write_callback(conn);
 641
 642                 /* Clear SOCK_NOSPACE _after_ ksocknal_write_callback so the
 643                  * ENOMEM check in ksocknal_transmit is race-free (think about
 644                  * it). */
 645
 646                 clear_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
 647         }
 648
 649         read_unlock(&ksocknal_data.ksnd_global_lock);
 650 }
 651
 652 void
 653 ksocknal_lib_save_callback(struct socket *sock, ksock_conn_t *conn)
 654 {
 655         conn->ksnc_saved_data_ready = sock->sk->sk_data_ready;
 656         conn->ksnc_saved_write_space = sock->sk->sk_write_space;
 657 }
 658
 659 void
 660 ksocknal_lib_set_callback(struct socket *sock,  ksock_conn_t *conn)
 661 {
 662         sock->sk->sk_user_data = conn;
 663         sock->sk->sk_data_ready = ksocknal_data_ready;
 664         sock->sk->sk_write_space = ksocknal_write_space;
 665         return;
 666 }
 667
 668 void
 669 ksocknal_lib_reset_callback(struct socket *sock, ksock_conn_t *conn)
 670 {
 671         /* Remove conn's network callbacks.
 672          * NB I _have_ to restore the callback, rather than storing a noop,
 673          * since the socket could survive past this module being unloaded!! */
 674         sock->sk->sk_data_ready = conn->ksnc_saved_data_ready;
 675         sock->sk->sk_write_space = conn->ksnc_saved_write_space;
 676
 677         /* A callback could be in progress already; they hold a read lock
 678          * on ksnd_global_lock (to serialise with me) and NOOP if
 679          * sk_user_data is NULL. */
 680         sock->sk->sk_user_data = NULL;
 681
 682         return ;
 683 }
 684
 685 int
 686 ksocknal_lib_memory_pressure(ksock_conn_t *conn)
 687 {
 688         int rc = 0;
 689         ksock_sched_t *sched;
 690
 691         sched = conn->ksnc_scheduler;
 692         spin_lock_bh(&sched->kss_lock);
 693
 694         if (!test_bit(SOCK_NOSPACE, &conn->ksnc_sock->flags) &&
 695             !conn->ksnc_tx_ready) {
 696                 /* SOCK_NOSPACE is set when the socket fills
 697                  * and cleared in the write_space callback
 698                  * (which also sets ksnc_tx_ready).  If
 699                  * SOCK_NOSPACE and ksnc_tx_ready are BOTH
 700                  * zero, I didn't fill the socket and
 701                  * write_space won't reschedule me, so I
 702                  * return -ENOMEM to get my caller to retry
 703                  * after a timeout */
 704                 rc = -ENOMEM;
 705         }
 706
 707         spin_unlock_bh(&sched->kss_lock);
 708
 709         return rc;
 710 }