Pileus Git - ~andy/linux/blob - drivers/net/xen-netback/netback.c

   1 /*
   2  * Back-end of the driver for virtual network devices. This portion of the
   3  * driver exports a 'unified' network-device interface that can be accessed
   4  * by any operating system that implements a compatible front end. A
   5  * reference front-end implementation can be found in:
   6  *  drivers/net/xen-netfront.c
   7  *
   8  * Copyright (c) 2002-2005, K A Fraser
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License version 2
  12  * as published by the Free Software Foundation; or, when distributed
  13  * separately from the Linux kernel or incorporated into other
  14  * software packages, subject to the following license:
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a copy
  17  * of this source file (the "Software"), to deal in the Software without
  18  * restriction, including without limitation the rights to use, copy, modify,
  19  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  20  * and to permit persons to whom the Software is furnished to do so, subject to
  21  * the following conditions:
  22  *
  23  * The above copyright notice and this permission notice shall be included in
  24  * all copies or substantial portions of the Software.
  25  *
  26  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  27  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  28  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  29  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  30  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  31  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  32  * IN THE SOFTWARE.
  33  */
  34
  35 #include "common.h"
  36
  37 #include <linux/kthread.h>
  38 #include <linux/if_vlan.h>
  39 #include <linux/udp.h>
  40
  41 #include <net/tcp.h>
  42
  43 #include <xen/xen.h>
  44 #include <xen/events.h>
  45 #include <xen/interface/memory.h>
  46
  47 #include <asm/xen/hypercall.h>
  48 #include <asm/xen/page.h>
  49
  50 /*
  51  * This is the maximum slots a skb can have. If a guest sends a skb
  52  * which exceeds this limit it is considered malicious.
  53  */
  54 #define MAX_SKB_SLOTS_DEFAULT 20
  55 static unsigned int max_skb_slots = MAX_SKB_SLOTS_DEFAULT;
  56 module_param(max_skb_slots, uint, 0444);
  57
  58 typedef unsigned int pending_ring_idx_t;
  59 #define INVALID_PENDING_RING_IDX (~0U)
  60
  61 struct pending_tx_info {
  62         struct xen_netif_tx_request req; /* coalesced tx request */
  63         struct xenvif *vif;
  64         pending_ring_idx_t head; /* head != INVALID_PENDING_RING_IDX
  65                                   * if it is head of one or more tx
  66                                   * reqs
  67                                   */
  68 };
  69
  70 struct netbk_rx_meta {
  71         int id;
  72         int size;
  73         int gso_size;
  74 };
  75
  76 #define MAX_PENDING_REQS 256
  77
  78 /* Discriminate from any valid pending_idx value. */
  79 #define INVALID_PENDING_IDX 0xFFFF
  80
  81 #define MAX_BUFFER_OFFSET PAGE_SIZE
  82
  83 /* extra field used in struct page */
  84 union page_ext {
  85         struct {
  86 #if BITS_PER_LONG < 64
  87 #define IDX_WIDTH   8
  88 #define GROUP_WIDTH (BITS_PER_LONG - IDX_WIDTH)
  89                 unsigned int group:GROUP_WIDTH;
  90                 unsigned int idx:IDX_WIDTH;
  91 #else
  92                 unsigned int group, idx;
  93 #endif
  94         } e;
  95         void *mapping;
  96 };
  97
  98 struct xen_netbk {
  99         wait_queue_head_t wq;
 100         struct task_struct *task;
 101
 102         struct sk_buff_head rx_queue;
 103         struct sk_buff_head tx_queue;
 104
 105         struct timer_list net_timer;
 106
 107         struct page *mmap_pages[MAX_PENDING_REQS];
 108
 109         pending_ring_idx_t pending_prod;
 110         pending_ring_idx_t pending_cons;
 111         struct list_head net_schedule_list;
 112
 113         /* Protect the net_schedule_list in netif. */
 114         spinlock_t net_schedule_list_lock;
 115
 116         atomic_t netfront_count;
 117
 118         struct pending_tx_info pending_tx_info[MAX_PENDING_REQS];
 119         /* Coalescing tx requests before copying makes number of grant
 120          * copy ops greater or equal to number of slots required. In
 121          * worst case a tx request consumes 2 gnttab_copy.
 122          */
 123         struct gnttab_copy tx_copy_ops[2*MAX_PENDING_REQS];
 124
 125         u16 pending_ring[MAX_PENDING_REQS];
 126
 127         /*
 128          * Given MAX_BUFFER_OFFSET of 4096 the worst case is that each
 129          * head/fragment page uses 2 copy operations because it
 130          * straddles two buffers in the frontend.
 131          */
 132         struct gnttab_copy grant_copy_op[2*XEN_NETIF_RX_RING_SIZE];
 133         struct netbk_rx_meta meta[2*XEN_NETIF_RX_RING_SIZE];
 134 };
 135
 136 static struct xen_netbk *xen_netbk;
 137 static int xen_netbk_group_nr;
 138
 139 /*
 140  * If head != INVALID_PENDING_RING_IDX, it means this tx request is head of
 141  * one or more merged tx requests, otherwise it is the continuation of
 142  * previous tx request.
 143  */
 144 static inline int pending_tx_is_head(struct xen_netbk *netbk, RING_IDX idx)
 145 {
 146         return netbk->pending_tx_info[idx].head != INVALID_PENDING_RING_IDX;
 147 }
 148
 149 void xen_netbk_add_xenvif(struct xenvif *vif)
 150 {
 151         int i;
 152         int min_netfront_count;
 153         int min_group = 0;
 154         struct xen_netbk *netbk;
 155
 156         min_netfront_count = atomic_read(&xen_netbk[0].netfront_count);
 157         for (i = 0; i < xen_netbk_group_nr; i++) {
 158                 int netfront_count = atomic_read(&xen_netbk[i].netfront_count);
 159                 if (netfront_count < min_netfront_count) {
 160                         min_group = i;
 161                         min_netfront_count = netfront_count;
 162                 }
 163         }
 164
 165         netbk = &xen_netbk[min_group];
 166
 167         vif->netbk = netbk;
 168         atomic_inc(&netbk->netfront_count);
 169 }
 170
 171 void xen_netbk_remove_xenvif(struct xenvif *vif)
 172 {
 173         struct xen_netbk *netbk = vif->netbk;
 174         vif->netbk = NULL;
 175         atomic_dec(&netbk->netfront_count);
 176 }
 177
 178 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
 179                                   u8 status);
 180 static void make_tx_response(struct xenvif *vif,
 181                              struct xen_netif_tx_request *txp,
 182                              s8       st);
 183 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
 184                                              u16      id,
 185                                              s8       st,
 186                                              u16      offset,
 187                                              u16      size,
 188                                              u16      flags);
 189
 190 static inline unsigned long idx_to_pfn(struct xen_netbk *netbk,
 191                                        u16 idx)
 192 {
 193         return page_to_pfn(netbk->mmap_pages[idx]);
 194 }
 195
 196 static inline unsigned long idx_to_kaddr(struct xen_netbk *netbk,
 197                                          u16 idx)
 198 {
 199         return (unsigned long)pfn_to_kaddr(idx_to_pfn(netbk, idx));
 200 }
 201
 202 /* extra field used in struct page */
 203 static inline void set_page_ext(struct page *pg, struct xen_netbk *netbk,
 204                                 unsigned int idx)
 205 {
 206         unsigned int group = netbk - xen_netbk;
 207         union page_ext ext = { .e = { .group = group + 1, .idx = idx } };
 208
 209         BUILD_BUG_ON(sizeof(ext) > sizeof(ext.mapping));
 210         pg->mapping = ext.mapping;
 211 }
 212
 213 static int get_page_ext(struct page *pg,
 214                         unsigned int *pgroup, unsigned int *pidx)
 215 {
 216         union page_ext ext = { .mapping = pg->mapping };
 217         struct xen_netbk *netbk;
 218         unsigned int group, idx;
 219
 220         group = ext.e.group - 1;
 221
 222         if (group < 0 || group >= xen_netbk_group_nr)
 223                 return 0;
 224
 225         netbk = &xen_netbk[group];
 226
 227         idx = ext.e.idx;
 228
 229         if ((idx < 0) || (idx >= MAX_PENDING_REQS))
 230                 return 0;
 231
 232         if (netbk->mmap_pages[idx] != pg)
 233                 return 0;
 234
 235         *pgroup = group;
 236         *pidx = idx;
 237
 238         return 1;
 239 }
 240
 241 /*
 242  * This is the amount of packet we copy rather than map, so that the
 243  * guest can't fiddle with the contents of the headers while we do
 244  * packet processing on them (netfilter, routing, etc).
 245  */
 246 #define PKT_PROT_LEN    (ETH_HLEN + \
 247                          VLAN_HLEN + \
 248                          sizeof(struct iphdr) + MAX_IPOPTLEN + \
 249                          sizeof(struct tcphdr) + MAX_TCP_OPTION_SPACE)
 250
 251 static u16 frag_get_pending_idx(skb_frag_t *frag)
 252 {
 253         return (u16)frag->page_offset;
 254 }
 255
 256 static void frag_set_pending_idx(skb_frag_t *frag, u16 pending_idx)
 257 {
 258         frag->page_offset = pending_idx;
 259 }
 260
 261 static inline pending_ring_idx_t pending_index(unsigned i)
 262 {
 263         return i & (MAX_PENDING_REQS-1);
 264 }
 265
 266 static inline pending_ring_idx_t nr_pending_reqs(struct xen_netbk *netbk)
 267 {
 268         return MAX_PENDING_REQS -
 269                 netbk->pending_prod + netbk->pending_cons;
 270 }
 271
 272 static void xen_netbk_kick_thread(struct xen_netbk *netbk)
 273 {
 274         wake_up(&netbk->wq);
 275 }
 276
 277 static int max_required_rx_slots(struct xenvif *vif)
 278 {
 279         int max = DIV_ROUND_UP(vif->dev->mtu, PAGE_SIZE);
 280
 281         /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 282         if (vif->can_sg || vif->gso || vif->gso_prefix)
 283                 max += MAX_SKB_FRAGS + 1; /* extra_info + frags */
 284
 285         return max;
 286 }
 287
 288 int xen_netbk_rx_ring_full(struct xenvif *vif)
 289 {
 290         RING_IDX peek   = vif->rx_req_cons_peek;
 291         RING_IDX needed = max_required_rx_slots(vif);
 292
 293         return ((vif->rx.sring->req_prod - peek) < needed) ||
 294                ((vif->rx.rsp_prod_pvt + XEN_NETIF_RX_RING_SIZE - peek) < needed);
 295 }
 296
 297 int xen_netbk_must_stop_queue(struct xenvif *vif)
 298 {
 299         if (!xen_netbk_rx_ring_full(vif))
 300                 return 0;
 301
 302         vif->rx.sring->req_event = vif->rx_req_cons_peek +
 303                 max_required_rx_slots(vif);
 304         mb(); /* request notification /then/ check the queue */
 305
 306         return xen_netbk_rx_ring_full(vif);
 307 }
 308
 309 /*
 310  * Returns true if we should start a new receive buffer instead of
 311  * adding 'size' bytes to a buffer which currently contains 'offset'
 312  * bytes.
 313  */
 314 static bool start_new_rx_buffer(int offset, unsigned long size, int head)
 315 {
 316         /* simple case: we have completely filled the current buffer. */
 317         if (offset == MAX_BUFFER_OFFSET)
 318                 return true;
 319
 320         /*
 321          * complex case: start a fresh buffer if the current frag
 322          * would overflow the current buffer but only if:
 323          *     (i)   this frag would fit completely in the next buffer
 324          * and (ii)  there is already some data in the current buffer
 325          * and (iii) this is not the head buffer.
 326          *
 327          * Where:
 328          * - (i) stops us splitting a frag into two copies
 329          *   unless the frag is too large for a single buffer.
 330          * - (ii) stops us from leaving a buffer pointlessly empty.
 331          * - (iii) stops us leaving the first buffer
 332          *   empty. Strictly speaking this is already covered
 333          *   by (ii) but is explicitly checked because
 334          *   netfront relies on the first buffer being
 335          *   non-empty and can crash otherwise.
 336          *
 337          * This means we will effectively linearise small
 338          * frags but do not needlessly split large buffers
 339          * into multiple copies tend to give large frags their
 340          * own buffers as before.
 341          */
 342         if ((offset + size > MAX_BUFFER_OFFSET) &&
 343             (size <= MAX_BUFFER_OFFSET) && offset && !head)
 344                 return true;
 345
 346         return false;
 347 }
 348
 349 /*
 350  * Figure out how many ring slots we're going to need to send @skb to
 351  * the guest. This function is essentially a dry run of
 352  * netbk_gop_frag_copy.
 353  */
 354 unsigned int xen_netbk_count_skb_slots(struct xenvif *vif, struct sk_buff *skb)
 355 {
 356         unsigned int count;
 357         int i, copy_off;
 358
 359         count = DIV_ROUND_UP(skb_headlen(skb), PAGE_SIZE);
 360
 361         copy_off = skb_headlen(skb) % PAGE_SIZE;
 362
 363         if (skb_shinfo(skb)->gso_size)
 364                 count++;
 365
 366         for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
 367                 unsigned long size = skb_frag_size(&skb_shinfo(skb)->frags[i]);
 368                 unsigned long offset = skb_shinfo(skb)->frags[i].page_offset;
 369                 unsigned long bytes;
 370
 371                 offset &= ~PAGE_MASK;
 372
 373                 while (size > 0) {
 374                         BUG_ON(offset >= PAGE_SIZE);
 375                         BUG_ON(copy_off > MAX_BUFFER_OFFSET);
 376
 377                         bytes = PAGE_SIZE - offset;
 378
 379                         if (bytes > size)
 380                                 bytes = size;
 381
 382                         if (start_new_rx_buffer(copy_off, bytes, 0)) {
 383                                 count++;
 384                                 copy_off = 0;
 385                         }
 386
 387                         if (copy_off + bytes > MAX_BUFFER_OFFSET)
 388                                 bytes = MAX_BUFFER_OFFSET - copy_off;
 389
 390                         copy_off += bytes;
 391
 392                         offset += bytes;
 393                         size -= bytes;
 394
 395                         if (offset == PAGE_SIZE)
 396                                 offset = 0;
 397                 }
 398         }
 399         return count;
 400 }
 401
 402 struct netrx_pending_operations {
 403         unsigned copy_prod, copy_cons;
 404         unsigned meta_prod, meta_cons;
 405         struct gnttab_copy *copy;
 406         struct netbk_rx_meta *meta;
 407         int copy_off;
 408         grant_ref_t copy_gref;
 409 };
 410
 411 static struct netbk_rx_meta *get_next_rx_buffer(struct xenvif *vif,
 412                                                 struct netrx_pending_operations *npo)
 413 {
 414         struct netbk_rx_meta *meta;
 415         struct xen_netif_rx_request *req;
 416
 417         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 418
 419         meta = npo->meta + npo->meta_prod++;
 420         meta->gso_size = 0;
 421         meta->size = 0;
 422         meta->id = req->id;
 423
 424         npo->copy_off = 0;
 425         npo->copy_gref = req->gref;
 426
 427         return meta;
 428 }
 429
 430 /*
 431  * Set up the grant operations for this fragment. If it's a flipping
 432  * interface, we also set up the unmap request from here.
 433  */
 434 static void netbk_gop_frag_copy(struct xenvif *vif, struct sk_buff *skb,
 435                                 struct netrx_pending_operations *npo,
 436                                 struct page *page, unsigned long size,
 437                                 unsigned long offset, int *head)
 438 {
 439         struct gnttab_copy *copy_gop;
 440         struct netbk_rx_meta *meta;
 441         /*
 442          * These variables are used iff get_page_ext returns true,
 443          * in which case they are guaranteed to be initialized.
 444          */
 445         unsigned int uninitialized_var(group), uninitialized_var(idx);
 446         int foreign = get_page_ext(page, &group, &idx);
 447         unsigned long bytes;
 448
 449         /* Data must not cross a page boundary. */
 450         BUG_ON(size + offset > PAGE_SIZE<<compound_order(page));
 451
 452         meta = npo->meta + npo->meta_prod - 1;
 453
 454         /* Skip unused frames from start of page */
 455         page += offset >> PAGE_SHIFT;
 456         offset &= ~PAGE_MASK;
 457
 458         while (size > 0) {
 459                 BUG_ON(offset >= PAGE_SIZE);
 460                 BUG_ON(npo->copy_off > MAX_BUFFER_OFFSET);
 461
 462                 bytes = PAGE_SIZE - offset;
 463
 464                 if (bytes > size)
 465                         bytes = size;
 466
 467                 if (start_new_rx_buffer(npo->copy_off, bytes, *head)) {
 468                         /*
 469                          * Netfront requires there to be some data in the head
 470                          * buffer.
 471                          */
 472                         BUG_ON(*head);
 473
 474                         meta = get_next_rx_buffer(vif, npo);
 475                 }
 476
 477                 if (npo->copy_off + bytes > MAX_BUFFER_OFFSET)
 478                         bytes = MAX_BUFFER_OFFSET - npo->copy_off;
 479
 480                 copy_gop = npo->copy + npo->copy_prod++;
 481                 copy_gop->flags = GNTCOPY_dest_gref;
 482                 if (foreign) {
 483                         struct xen_netbk *netbk = &xen_netbk[group];
 484                         struct pending_tx_info *src_pend;
 485
 486                         src_pend = &netbk->pending_tx_info[idx];
 487
 488                         copy_gop->source.domid = src_pend->vif->domid;
 489                         copy_gop->source.u.ref = src_pend->req.gref;
 490                         copy_gop->flags |= GNTCOPY_source_gref;
 491                 } else {
 492                         void *vaddr = page_address(page);
 493                         copy_gop->source.domid = DOMID_SELF;
 494                         copy_gop->source.u.gmfn = virt_to_mfn(vaddr);
 495                 }
 496                 copy_gop->source.offset = offset;
 497                 copy_gop->dest.domid = vif->domid;
 498
 499                 copy_gop->dest.offset = npo->copy_off;
 500                 copy_gop->dest.u.ref = npo->copy_gref;
 501                 copy_gop->len = bytes;
 502
 503                 npo->copy_off += bytes;
 504                 meta->size += bytes;
 505
 506                 offset += bytes;
 507                 size -= bytes;
 508
 509                 /* Next frame */
 510                 if (offset == PAGE_SIZE && size) {
 511                         BUG_ON(!PageCompound(page));
 512                         page++;
 513                         offset = 0;
 514                 }
 515
 516                 /* Leave a gap for the GSO descriptor. */
 517                 if (*head && skb_shinfo(skb)->gso_size && !vif->gso_prefix)
 518                         vif->rx.req_cons++;
 519
 520                 *head = 0; /* There must be something in this buffer now. */
 521
 522         }
 523 }
 524
 525 /*
 526  * Prepare an SKB to be transmitted to the frontend.
 527  *
 528  * This function is responsible for allocating grant operations, meta
 529  * structures, etc.
 530  *
 531  * It returns the number of meta structures consumed. The number of
 532  * ring slots used is always equal to the number of meta slots used
 533  * plus the number of GSO descriptors used. Currently, we use either
 534  * zero GSO descriptors (for non-GSO packets) or one descriptor (for
 535  * frontend-side LRO).
 536  */
 537 static int netbk_gop_skb(struct sk_buff *skb,
 538                          struct netrx_pending_operations *npo)
 539 {
 540         struct xenvif *vif = netdev_priv(skb->dev);
 541         int nr_frags = skb_shinfo(skb)->nr_frags;
 542         int i;
 543         struct xen_netif_rx_request *req;
 544         struct netbk_rx_meta *meta;
 545         unsigned char *data;
 546         int head = 1;
 547         int old_meta_prod;
 548
 549         old_meta_prod = npo->meta_prod;
 550
 551         /* Set up a GSO prefix descriptor, if necessary */
 552         if (skb_shinfo(skb)->gso_size && vif->gso_prefix) {
 553                 req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 554                 meta = npo->meta + npo->meta_prod++;
 555                 meta->gso_size = skb_shinfo(skb)->gso_size;
 556                 meta->size = 0;
 557                 meta->id = req->id;
 558         }
 559
 560         req = RING_GET_REQUEST(&vif->rx, vif->rx.req_cons++);
 561         meta = npo->meta + npo->meta_prod++;
 562
 563         if (!vif->gso_prefix)
 564                 meta->gso_size = skb_shinfo(skb)->gso_size;
 565         else
 566                 meta->gso_size = 0;
 567
 568         meta->size = 0;
 569         meta->id = req->id;
 570         npo->copy_off = 0;
 571         npo->copy_gref = req->gref;
 572
 573         data = skb->data;
 574         while (data < skb_tail_pointer(skb)) {
 575                 unsigned int offset = offset_in_page(data);
 576                 unsigned int len = PAGE_SIZE - offset;
 577
 578                 if (data + len > skb_tail_pointer(skb))
 579                         len = skb_tail_pointer(skb) - data;
 580
 581                 netbk_gop_frag_copy(vif, skb, npo,
 582                                     virt_to_page(data), len, offset, &head);
 583                 data += len;
 584         }
 585
 586         for (i = 0; i < nr_frags; i++) {
 587                 netbk_gop_frag_copy(vif, skb, npo,
 588                                     skb_frag_page(&skb_shinfo(skb)->frags[i]),
 589                                     skb_frag_size(&skb_shinfo(skb)->frags[i]),
 590                                     skb_shinfo(skb)->frags[i].page_offset,
 591                                     &head);
 592         }
 593
 594         return npo->meta_prod - old_meta_prod;
 595 }
 596
 597 /*
 598  * This is a twin to netbk_gop_skb.  Assume that netbk_gop_skb was
 599  * used to set up the operations on the top of
 600  * netrx_pending_operations, which have since been done.  Check that
 601  * they didn't give any errors and advance over them.
 602  */
 603 static int netbk_check_gop(struct xenvif *vif, int nr_meta_slots,
 604                            struct netrx_pending_operations *npo)
 605 {
 606         struct gnttab_copy     *copy_op;
 607         int status = XEN_NETIF_RSP_OKAY;
 608         int i;
 609
 610         for (i = 0; i < nr_meta_slots; i++) {
 611                 copy_op = npo->copy + npo->copy_cons++;
 612                 if (copy_op->status != GNTST_okay) {
 613                         netdev_dbg(vif->dev,
 614                                    "Bad status %d from copy to DOM%d.\n",
 615                                    copy_op->status, vif->domid);
 616                         status = XEN_NETIF_RSP_ERROR;
 617                 }
 618         }
 619
 620         return status;
 621 }
 622
 623 static void netbk_add_frag_responses(struct xenvif *vif, int status,
 624                                      struct netbk_rx_meta *meta,
 625                                      int nr_meta_slots)
 626 {
 627         int i;
 628         unsigned long offset;
 629
 630         /* No fragments used */
 631         if (nr_meta_slots <= 1)
 632                 return;
 633
 634         nr_meta_slots--;
 635
 636         for (i = 0; i < nr_meta_slots; i++) {
 637                 int flags;
 638                 if (i == nr_meta_slots - 1)
 639                         flags = 0;
 640                 else
 641                         flags = XEN_NETRXF_more_data;
 642
 643                 offset = 0;
 644                 make_rx_response(vif, meta[i].id, status, offset,
 645                                  meta[i].size, flags);
 646         }
 647 }
 648
 649 struct skb_cb_overlay {
 650         int meta_slots_used;
 651 };
 652
 653 static void xen_netbk_rx_action(struct xen_netbk *netbk)
 654 {
 655         struct xenvif *vif = NULL, *tmp;
 656         s8 status;
 657         u16 irq, flags;
 658         struct xen_netif_rx_response *resp;
 659         struct sk_buff_head rxq;
 660         struct sk_buff *skb;
 661         LIST_HEAD(notify);
 662         int ret;
 663         int nr_frags;
 664         int count;
 665         unsigned long offset;
 666         struct skb_cb_overlay *sco;
 667
 668         struct netrx_pending_operations npo = {
 669                 .copy  = netbk->grant_copy_op,
 670                 .meta  = netbk->meta,
 671         };
 672
 673         skb_queue_head_init(&rxq);
 674
 675         count = 0;
 676
 677         while ((skb = skb_dequeue(&netbk->rx_queue)) != NULL) {
 678                 vif = netdev_priv(skb->dev);
 679                 nr_frags = skb_shinfo(skb)->nr_frags;
 680
 681                 sco = (struct skb_cb_overlay *)skb->cb;
 682                 sco->meta_slots_used = netbk_gop_skb(skb, &npo);
 683
 684                 count += nr_frags + 1;
 685
 686                 __skb_queue_tail(&rxq, skb);
 687
 688                 /* Filled the batch queue? */
 689                 /* XXX FIXME: RX path dependent on MAX_SKB_FRAGS */
 690                 if (count + MAX_SKB_FRAGS >= XEN_NETIF_RX_RING_SIZE)
 691                         break;
 692         }
 693
 694         BUG_ON(npo.meta_prod > ARRAY_SIZE(netbk->meta));
 695
 696         if (!npo.copy_prod)
 697                 return;
 698
 699         BUG_ON(npo.copy_prod > ARRAY_SIZE(netbk->grant_copy_op));
 700         gnttab_batch_copy(netbk->grant_copy_op, npo.copy_prod);
 701
 702         while ((skb = __skb_dequeue(&rxq)) != NULL) {
 703                 sco = (struct skb_cb_overlay *)skb->cb;
 704
 705                 vif = netdev_priv(skb->dev);
 706
 707                 if (netbk->meta[npo.meta_cons].gso_size && vif->gso_prefix) {
 708                         resp = RING_GET_RESPONSE(&vif->rx,
 709                                                 vif->rx.rsp_prod_pvt++);
 710
 711                         resp->flags = XEN_NETRXF_gso_prefix | XEN_NETRXF_more_data;
 712
 713                         resp->offset = netbk->meta[npo.meta_cons].gso_size;
 714                         resp->id = netbk->meta[npo.meta_cons].id;
 715                         resp->status = sco->meta_slots_used;
 716
 717                         npo.meta_cons++;
 718                         sco->meta_slots_used--;
 719                 }
 720
 721
 722                 vif->dev->stats.tx_bytes += skb->len;
 723                 vif->dev->stats.tx_packets++;
 724
 725                 status = netbk_check_gop(vif, sco->meta_slots_used, &npo);
 726
 727                 if (sco->meta_slots_used == 1)
 728                         flags = 0;
 729                 else
 730                         flags = XEN_NETRXF_more_data;
 731
 732                 if (skb->ip_summed == CHECKSUM_PARTIAL) /* local packet? */
 733                         flags |= XEN_NETRXF_csum_blank | XEN_NETRXF_data_validated;
 734                 else if (skb->ip_summed == CHECKSUM_UNNECESSARY)
 735                         /* remote but checksummed. */
 736                         flags |= XEN_NETRXF_data_validated;
 737
 738                 offset = 0;
 739                 resp = make_rx_response(vif, netbk->meta[npo.meta_cons].id,
 740                                         status, offset,
 741                                         netbk->meta[npo.meta_cons].size,
 742                                         flags);
 743
 744                 if (netbk->meta[npo.meta_cons].gso_size && !vif->gso_prefix) {
 745                         struct xen_netif_extra_info *gso =
 746                                 (struct xen_netif_extra_info *)
 747                                 RING_GET_RESPONSE(&vif->rx,
 748                                                   vif->rx.rsp_prod_pvt++);
 749
 750                         resp->flags |= XEN_NETRXF_extra_info;
 751
 752                         gso->u.gso.size = netbk->meta[npo.meta_cons].gso_size;
 753                         gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
 754                         gso->u.gso.pad = 0;
 755                         gso->u.gso.features = 0;
 756
 757                         gso->type = XEN_NETIF_EXTRA_TYPE_GSO;
 758                         gso->flags = 0;
 759                 }
 760
 761                 netbk_add_frag_responses(vif, status,
 762                                          netbk->meta + npo.meta_cons + 1,
 763                                          sco->meta_slots_used);
 764
 765                 RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->rx, ret);
 766                 irq = vif->irq;
 767                 if (ret && list_empty(&vif->notify_list))
 768                         list_add_tail(&vif->notify_list, &notify);
 769
 770                 xenvif_notify_tx_completion(vif);
 771
 772                 xenvif_put(vif);
 773                 npo.meta_cons += sco->meta_slots_used;
 774                 dev_kfree_skb(skb);
 775         }
 776
 777         list_for_each_entry_safe(vif, tmp, &notify, notify_list) {
 778                 notify_remote_via_irq(vif->irq);
 779                 list_del_init(&vif->notify_list);
 780         }
 781
 782         /* More work to do? */
 783         if (!skb_queue_empty(&netbk->rx_queue) &&
 784                         !timer_pending(&netbk->net_timer))
 785                 xen_netbk_kick_thread(netbk);
 786 }
 787
 788 void xen_netbk_queue_tx_skb(struct xenvif *vif, struct sk_buff *skb)
 789 {
 790         struct xen_netbk *netbk = vif->netbk;
 791
 792         skb_queue_tail(&netbk->rx_queue, skb);
 793
 794         xen_netbk_kick_thread(netbk);
 795 }
 796
 797 static void xen_netbk_alarm(unsigned long data)
 798 {
 799         struct xen_netbk *netbk = (struct xen_netbk *)data;
 800         xen_netbk_kick_thread(netbk);
 801 }
 802
 803 static int __on_net_schedule_list(struct xenvif *vif)
 804 {
 805         return !list_empty(&vif->schedule_list);
 806 }
 807
 808 /* Must be called with net_schedule_list_lock held */
 809 static void remove_from_net_schedule_list(struct xenvif *vif)
 810 {
 811         if (likely(__on_net_schedule_list(vif))) {
 812                 list_del_init(&vif->schedule_list);
 813                 xenvif_put(vif);
 814         }
 815 }
 816
 817 static struct xenvif *poll_net_schedule_list(struct xen_netbk *netbk)
 818 {
 819         struct xenvif *vif = NULL;
 820
 821         spin_lock_irq(&netbk->net_schedule_list_lock);
 822         if (list_empty(&netbk->net_schedule_list))
 823                 goto out;
 824
 825         vif = list_first_entry(&netbk->net_schedule_list,
 826                                struct xenvif, schedule_list);
 827         if (!vif)
 828                 goto out;
 829
 830         xenvif_get(vif);
 831
 832         remove_from_net_schedule_list(vif);
 833 out:
 834         spin_unlock_irq(&netbk->net_schedule_list_lock);
 835         return vif;
 836 }
 837
 838 void xen_netbk_schedule_xenvif(struct xenvif *vif)
 839 {
 840         unsigned long flags;
 841         struct xen_netbk *netbk = vif->netbk;
 842
 843         if (__on_net_schedule_list(vif))
 844                 goto kick;
 845
 846         spin_lock_irqsave(&netbk->net_schedule_list_lock, flags);
 847         if (!__on_net_schedule_list(vif) &&
 848             likely(xenvif_schedulable(vif))) {
 849                 list_add_tail(&vif->schedule_list, &netbk->net_schedule_list);
 850                 xenvif_get(vif);
 851         }
 852         spin_unlock_irqrestore(&netbk->net_schedule_list_lock, flags);
 853
 854 kick:
 855         smp_mb();
 856         if ((nr_pending_reqs(netbk) < (MAX_PENDING_REQS/2)) &&
 857             !list_empty(&netbk->net_schedule_list))
 858                 xen_netbk_kick_thread(netbk);
 859 }
 860
 861 void xen_netbk_deschedule_xenvif(struct xenvif *vif)
 862 {
 863         struct xen_netbk *netbk = vif->netbk;
 864         spin_lock_irq(&netbk->net_schedule_list_lock);
 865         remove_from_net_schedule_list(vif);
 866         spin_unlock_irq(&netbk->net_schedule_list_lock);
 867 }
 868
 869 void xen_netbk_check_rx_xenvif(struct xenvif *vif)
 870 {
 871         int more_to_do;
 872
 873         RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, more_to_do);
 874
 875         if (more_to_do)
 876                 xen_netbk_schedule_xenvif(vif);
 877 }
 878
 879 static void tx_add_credit(struct xenvif *vif)
 880 {
 881         unsigned long max_burst, max_credit;
 882
 883         /*
 884          * Allow a burst big enough to transmit a jumbo packet of up to 128kB.
 885          * Otherwise the interface can seize up due to insufficient credit.
 886          */
 887         max_burst = RING_GET_REQUEST(&vif->tx, vif->tx.req_cons)->size;
 888         max_burst = min(max_burst, 131072UL);
 889         max_burst = max(max_burst, vif->credit_bytes);
 890
 891         /* Take care that adding a new chunk of credit doesn't wrap to zero. */
 892         max_credit = vif->remaining_credit + vif->credit_bytes;
 893         if (max_credit < vif->remaining_credit)
 894                 max_credit = ULONG_MAX; /* wrapped: clamp to ULONG_MAX */
 895
 896         vif->remaining_credit = min(max_credit, max_burst);
 897 }
 898
 899 static void tx_credit_callback(unsigned long data)
 900 {
 901         struct xenvif *vif = (struct xenvif *)data;
 902         tx_add_credit(vif);
 903         xen_netbk_check_rx_xenvif(vif);
 904 }
 905
 906 static void netbk_tx_err(struct xenvif *vif,
 907                          struct xen_netif_tx_request *txp, RING_IDX end)
 908 {
 909         RING_IDX cons = vif->tx.req_cons;
 910
 911         do {
 912                 make_tx_response(vif, txp, XEN_NETIF_RSP_ERROR);
 913                 if (cons == end)
 914                         break;
 915                 txp = RING_GET_REQUEST(&vif->tx, cons++);
 916         } while (1);
 917         vif->tx.req_cons = cons;
 918         xen_netbk_check_rx_xenvif(vif);
 919         xenvif_put(vif);
 920 }
 921
 922 static void netbk_fatal_tx_err(struct xenvif *vif)
 923 {
 924         netdev_err(vif->dev, "fatal error; disabling device\n");
 925         xenvif_carrier_off(vif);
 926         xenvif_put(vif);
 927 }
 928
 929 static int netbk_count_requests(struct xenvif *vif,
 930                                 struct xen_netif_tx_request *first,
 931                                 RING_IDX first_idx,
 932                                 struct xen_netif_tx_request *txp,
 933                                 int work_to_do)
 934 {
 935         RING_IDX cons = vif->tx.req_cons;
 936         int slots = 0;
 937         int drop_err = 0;
 938
 939         if (!(first->flags & XEN_NETTXF_more_data))
 940                 return 0;
 941
 942         do {
 943                 if (slots >= work_to_do) {
 944                         netdev_err(vif->dev,
 945                                    "Asked for %d slots but exceeds this limit\n",
 946                                    work_to_do);
 947                         netbk_fatal_tx_err(vif);
 948                         return -ENODATA;
 949                 }
 950
 951                 /* This guest is really using too many slots and
 952                  * considered malicious.
 953                  */
 954                 if (unlikely(slots >= max_skb_slots)) {
 955                         netdev_err(vif->dev,
 956                                    "Malicious frontend using %d slots, threshold %u\n",
 957                                    slots, max_skb_slots);
 958                         netbk_fatal_tx_err(vif);
 959                         return -E2BIG;
 960                 }
 961
 962                 /* Xen network protocol had implicit dependency on
 963                  * MAX_SKB_FRAGS. XEN_NETIF_NR_SLOTS_MIN is set to the
 964                  * historical MAX_SKB_FRAGS value 18 to honor the same
 965                  * behavior as before. Any packet using more than 18
 966                  * slots but less than max_skb_slots slots is dropped
 967                  */
 968                 if (!drop_err && slots >= XEN_NETIF_NR_SLOTS_MIN) {
 969                         if (net_ratelimit())
 970                                 netdev_dbg(vif->dev,
 971                                            "Too many slots (%d) exceeding limit (%d), dropping packet\n",
 972                                            slots, XEN_NETIF_NR_SLOTS_MIN);
 973                         drop_err = -E2BIG;
 974                 }
 975
 976                 memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + slots),
 977                        sizeof(*txp));
 978
 979                 /* If the guest submitted a frame >= 64 KiB then
 980                  * first->size overflowed and following slots will
 981                  * appear to be larger than the frame.
 982                  *
 983                  * This cannot be fatal error as there are buggy
 984                  * frontends that do this.
 985                  *
 986                  * Consume all slots and drop the packet.
 987                  */
 988                 if (!drop_err && txp->size > first->size) {
 989                         if (net_ratelimit())
 990                                 netdev_dbg(vif->dev,
 991                                            "Invalid tx request, slot size %u > remaining size %u\n",
 992                                            txp->size, first->size);
 993                         drop_err = -EIO;
 994                 }
 995
 996                 first->size -= txp->size;
 997                 slots++;
 998
 999                 if (unlikely((txp->offset + txp->size) > PAGE_SIZE)) {
1000                         netdev_err(vif->dev, "Cross page boundary, txp->offset: %x, size: %u\n",
1001                                  txp->offset, txp->size);
1002                         netbk_fatal_tx_err(vif);
1003                         return -EINVAL;
1004                 }
1005         } while ((txp++)->flags & XEN_NETTXF_more_data);
1006
1007         if (drop_err) {
1008                 netbk_tx_err(vif, first, first_idx + slots);
1009                 return drop_err;
1010         }
1011
1012         return slots;
1013 }
1014
1015 static struct page *xen_netbk_alloc_page(struct xen_netbk *netbk,
1016                                          u16 pending_idx)
1017 {
1018         struct page *page;
1019         page = alloc_page(GFP_KERNEL|__GFP_COLD);
1020         if (!page)
1021                 return NULL;
1022         set_page_ext(page, netbk, pending_idx);
1023         netbk->mmap_pages[pending_idx] = page;
1024         return page;
1025 }
1026
1027 static struct gnttab_copy *xen_netbk_get_requests(struct xen_netbk *netbk,
1028                                                   struct xenvif *vif,
1029                                                   struct sk_buff *skb,
1030                                                   struct xen_netif_tx_request *txp,
1031                                                   struct gnttab_copy *gop)
1032 {
1033         struct skb_shared_info *shinfo = skb_shinfo(skb);
1034         skb_frag_t *frags = shinfo->frags;
1035         u16 pending_idx = *((u16 *)skb->data);
1036         u16 head_idx = 0;
1037         int slot, start;
1038         struct page *page;
1039         pending_ring_idx_t index, start_idx = 0;
1040         uint16_t dst_offset;
1041         unsigned int nr_slots;
1042         struct pending_tx_info *first = NULL;
1043
1044         /* At this point shinfo->nr_frags is in fact the number of
1045          * slots, which can be as large as XEN_NETIF_NR_SLOTS_MIN.
1046          */
1047         nr_slots = shinfo->nr_frags;
1048
1049         /* Skip first skb fragment if it is on same page as header fragment. */
1050         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1051
1052         /* Coalesce tx requests, at this point the packet passed in
1053          * should be <= 64K. Any packets larger than 64K have been
1054          * handled in netbk_count_requests().
1055          */
1056         for (shinfo->nr_frags = slot = start; slot < nr_slots;
1057              shinfo->nr_frags++) {
1058                 struct pending_tx_info *pending_tx_info =
1059                         netbk->pending_tx_info;
1060
1061                 page = alloc_page(GFP_KERNEL|__GFP_COLD);
1062                 if (!page)
1063                         goto err;
1064
1065                 dst_offset = 0;
1066                 first = NULL;
1067                 while (dst_offset < PAGE_SIZE && slot < nr_slots) {
1068                         gop->flags = GNTCOPY_source_gref;
1069
1070                         gop->source.u.ref = txp->gref;
1071                         gop->source.domid = vif->domid;
1072                         gop->source.offset = txp->offset;
1073
1074                         gop->dest.domid = DOMID_SELF;
1075
1076                         gop->dest.offset = dst_offset;
1077                         gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1078
1079                         if (dst_offset + txp->size > PAGE_SIZE) {
1080                                 /* This page can only merge a portion
1081                                  * of tx request. Do not increment any
1082                                  * pointer / counter here. The txp
1083                                  * will be dealt with in future
1084                                  * rounds, eventually hitting the
1085                                  * `else` branch.
1086                                  */
1087                                 gop->len = PAGE_SIZE - dst_offset;
1088                                 txp->offset += gop->len;
1089                                 txp->size -= gop->len;
1090                                 dst_offset += gop->len; /* quit loop */
1091                         } else {
1092                                 /* This tx request can be merged in the page */
1093                                 gop->len = txp->size;
1094                                 dst_offset += gop->len;
1095
1096                                 index = pending_index(netbk->pending_cons++);
1097
1098                                 pending_idx = netbk->pending_ring[index];
1099
1100                                 memcpy(&pending_tx_info[pending_idx].req, txp,
1101                                        sizeof(*txp));
1102                                 xenvif_get(vif);
1103
1104                                 pending_tx_info[pending_idx].vif = vif;
1105
1106                                 /* Poison these fields, corresponding
1107                                  * fields for head tx req will be set
1108                                  * to correct values after the loop.
1109                                  */
1110                                 netbk->mmap_pages[pending_idx] = (void *)(~0UL);
1111                                 pending_tx_info[pending_idx].head =
1112                                         INVALID_PENDING_RING_IDX;
1113
1114                                 if (!first) {
1115                                         first = &pending_tx_info[pending_idx];
1116                                         start_idx = index;
1117                                         head_idx = pending_idx;
1118                                 }
1119
1120                                 txp++;
1121                                 slot++;
1122                         }
1123
1124                         gop++;
1125                 }
1126
1127                 first->req.offset = 0;
1128                 first->req.size = dst_offset;
1129                 first->head = start_idx;
1130                 set_page_ext(page, netbk, head_idx);
1131                 netbk->mmap_pages[head_idx] = page;
1132                 frag_set_pending_idx(&frags[shinfo->nr_frags], head_idx);
1133         }
1134
1135         BUG_ON(shinfo->nr_frags > MAX_SKB_FRAGS);
1136
1137         return gop;
1138 err:
1139         /* Unwind, freeing all pages and sending error responses. */
1140         while (shinfo->nr_frags-- > start) {
1141                 xen_netbk_idx_release(netbk,
1142                                 frag_get_pending_idx(&frags[shinfo->nr_frags]),
1143                                 XEN_NETIF_RSP_ERROR);
1144         }
1145         /* The head too, if necessary. */
1146         if (start)
1147                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1148
1149         return NULL;
1150 }
1151
1152 static int xen_netbk_tx_check_gop(struct xen_netbk *netbk,
1153                                   struct sk_buff *skb,
1154                                   struct gnttab_copy **gopp)
1155 {
1156         struct gnttab_copy *gop = *gopp;
1157         u16 pending_idx = *((u16 *)skb->data);
1158         struct skb_shared_info *shinfo = skb_shinfo(skb);
1159         struct pending_tx_info *tx_info;
1160         int nr_frags = shinfo->nr_frags;
1161         int i, err, start;
1162         u16 peek; /* peek into next tx request */
1163
1164         /* Check status of header. */
1165         err = gop->status;
1166         if (unlikely(err))
1167                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1168
1169         /* Skip first skb fragment if it is on same page as header fragment. */
1170         start = (frag_get_pending_idx(&shinfo->frags[0]) == pending_idx);
1171
1172         for (i = start; i < nr_frags; i++) {
1173                 int j, newerr;
1174                 pending_ring_idx_t head;
1175
1176                 pending_idx = frag_get_pending_idx(&shinfo->frags[i]);
1177                 tx_info = &netbk->pending_tx_info[pending_idx];
1178                 head = tx_info->head;
1179
1180                 /* Check error status: if okay then remember grant handle. */
1181                 do {
1182                         newerr = (++gop)->status;
1183                         if (newerr)
1184                                 break;
1185                         peek = netbk->pending_ring[pending_index(++head)];
1186                 } while (!pending_tx_is_head(netbk, peek));
1187
1188                 if (likely(!newerr)) {
1189                         /* Had a previous error? Invalidate this fragment. */
1190                         if (unlikely(err))
1191                                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1192                         continue;
1193                 }
1194
1195                 /* Error on this fragment: respond to client with an error. */
1196                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_ERROR);
1197
1198                 /* Not the first error? Preceding frags already invalidated. */
1199                 if (err)
1200                         continue;
1201
1202                 /* First error: invalidate header and preceding fragments. */
1203                 pending_idx = *((u16 *)skb->data);
1204                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1205                 for (j = start; j < i; j++) {
1206                         pending_idx = frag_get_pending_idx(&shinfo->frags[j]);
1207                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1208                 }
1209
1210                 /* Remember the error: invalidate all subsequent fragments. */
1211                 err = newerr;
1212         }
1213
1214         *gopp = gop + 1;
1215         return err;
1216 }
1217
1218 static void xen_netbk_fill_frags(struct xen_netbk *netbk, struct sk_buff *skb)
1219 {
1220         struct skb_shared_info *shinfo = skb_shinfo(skb);
1221         int nr_frags = shinfo->nr_frags;
1222         int i;
1223
1224         for (i = 0; i < nr_frags; i++) {
1225                 skb_frag_t *frag = shinfo->frags + i;
1226                 struct xen_netif_tx_request *txp;
1227                 struct page *page;
1228                 u16 pending_idx;
1229
1230                 pending_idx = frag_get_pending_idx(frag);
1231
1232                 txp = &netbk->pending_tx_info[pending_idx].req;
1233                 page = virt_to_page(idx_to_kaddr(netbk, pending_idx));
1234                 __skb_fill_page_desc(skb, i, page, txp->offset, txp->size);
1235                 skb->len += txp->size;
1236                 skb->data_len += txp->size;
1237                 skb->truesize += txp->size;
1238
1239                 /* Take an extra reference to offset xen_netbk_idx_release */
1240                 get_page(netbk->mmap_pages[pending_idx]);
1241                 xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1242         }
1243 }
1244
1245 static int xen_netbk_get_extras(struct xenvif *vif,
1246                                 struct xen_netif_extra_info *extras,
1247                                 int work_to_do)
1248 {
1249         struct xen_netif_extra_info extra;
1250         RING_IDX cons = vif->tx.req_cons;
1251
1252         do {
1253                 if (unlikely(work_to_do-- <= 0)) {
1254                         netdev_err(vif->dev, "Missing extra info\n");
1255                         netbk_fatal_tx_err(vif);
1256                         return -EBADR;
1257                 }
1258
1259                 memcpy(&extra, RING_GET_REQUEST(&vif->tx, cons),
1260                        sizeof(extra));
1261                 if (unlikely(!extra.type ||
1262                              extra.type >= XEN_NETIF_EXTRA_TYPE_MAX)) {
1263                         vif->tx.req_cons = ++cons;
1264                         netdev_err(vif->dev,
1265                                    "Invalid extra type: %d\n", extra.type);
1266                         netbk_fatal_tx_err(vif);
1267                         return -EINVAL;
1268                 }
1269
1270                 memcpy(&extras[extra.type - 1], &extra, sizeof(extra));
1271                 vif->tx.req_cons = ++cons;
1272         } while (extra.flags & XEN_NETIF_EXTRA_FLAG_MORE);
1273
1274         return work_to_do;
1275 }
1276
1277 static int netbk_set_skb_gso(struct xenvif *vif,
1278                              struct sk_buff *skb,
1279                              struct xen_netif_extra_info *gso)
1280 {
1281         if (!gso->u.gso.size) {
1282                 netdev_err(vif->dev, "GSO size must not be zero.\n");
1283                 netbk_fatal_tx_err(vif);
1284                 return -EINVAL;
1285         }
1286
1287         /* Currently only TCPv4 S.O. is supported. */
1288         if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
1289                 netdev_err(vif->dev, "Bad GSO type %d.\n", gso->u.gso.type);
1290                 netbk_fatal_tx_err(vif);
1291                 return -EINVAL;
1292         }
1293
1294         skb_shinfo(skb)->gso_size = gso->u.gso.size;
1295         skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
1296
1297         /* Header must be checked, and gso_segs computed. */
1298         skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
1299         skb_shinfo(skb)->gso_segs = 0;
1300
1301         return 0;
1302 }
1303
1304 static int checksum_setup(struct xenvif *vif, struct sk_buff *skb)
1305 {
1306         struct iphdr *iph;
1307         int err = -EPROTO;
1308         int recalculate_partial_csum = 0;
1309
1310         /*
1311          * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
1312          * peers can fail to set NETRXF_csum_blank when sending a GSO
1313          * frame. In this case force the SKB to CHECKSUM_PARTIAL and
1314          * recalculate the partial checksum.
1315          */
1316         if (skb->ip_summed != CHECKSUM_PARTIAL && skb_is_gso(skb)) {
1317                 vif->rx_gso_checksum_fixup++;
1318                 skb->ip_summed = CHECKSUM_PARTIAL;
1319                 recalculate_partial_csum = 1;
1320         }
1321
1322         /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
1323         if (skb->ip_summed != CHECKSUM_PARTIAL)
1324                 return 0;
1325
1326         if (skb->protocol != htons(ETH_P_IP))
1327                 goto out;
1328
1329         iph = (void *)skb->data;
1330         switch (iph->protocol) {
1331         case IPPROTO_TCP:
1332                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1333                                           offsetof(struct tcphdr, check)))
1334                         goto out;
1335
1336                 if (recalculate_partial_csum) {
1337                         struct tcphdr *tcph = tcp_hdr(skb);
1338                         tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1339                                                          skb->len - iph->ihl*4,
1340                                                          IPPROTO_TCP, 0);
1341                 }
1342                 break;
1343         case IPPROTO_UDP:
1344                 if (!skb_partial_csum_set(skb, 4 * iph->ihl,
1345                                           offsetof(struct udphdr, check)))
1346                         goto out;
1347
1348                 if (recalculate_partial_csum) {
1349                         struct udphdr *udph = udp_hdr(skb);
1350                         udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
1351                                                          skb->len - iph->ihl*4,
1352                                                          IPPROTO_UDP, 0);
1353                 }
1354                 break;
1355         default:
1356                 if (net_ratelimit())
1357                         netdev_err(vif->dev,
1358                                    "Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
1359                                    iph->protocol);
1360                 goto out;
1361         }
1362
1363         err = 0;
1364
1365 out:
1366         return err;
1367 }
1368
1369 static bool tx_credit_exceeded(struct xenvif *vif, unsigned size)
1370 {
1371         unsigned long now = jiffies;
1372         unsigned long next_credit =
1373                 vif->credit_timeout.expires +
1374                 msecs_to_jiffies(vif->credit_usec / 1000);
1375
1376         /* Timer could already be pending in rare cases. */
1377         if (timer_pending(&vif->credit_timeout))
1378                 return true;
1379
1380         /* Passed the point where we can replenish credit? */
1381         if (time_after_eq(now, next_credit)) {
1382                 vif->credit_timeout.expires = now;
1383                 tx_add_credit(vif);
1384         }
1385
1386         /* Still too big to send right now? Set a callback. */
1387         if (size > vif->remaining_credit) {
1388                 vif->credit_timeout.data     =
1389                         (unsigned long)vif;
1390                 vif->credit_timeout.function =
1391                         tx_credit_callback;
1392                 mod_timer(&vif->credit_timeout,
1393                           next_credit);
1394
1395                 return true;
1396         }
1397
1398         return false;
1399 }
1400
1401 static unsigned xen_netbk_tx_build_gops(struct xen_netbk *netbk)
1402 {
1403         struct gnttab_copy *gop = netbk->tx_copy_ops, *request_gop;
1404         struct sk_buff *skb;
1405         int ret;
1406
1407         while ((nr_pending_reqs(netbk) + XEN_NETIF_NR_SLOTS_MIN
1408                 < MAX_PENDING_REQS) &&
1409                 !list_empty(&netbk->net_schedule_list)) {
1410                 struct xenvif *vif;
1411                 struct xen_netif_tx_request txreq;
1412                 struct xen_netif_tx_request txfrags[max_skb_slots];
1413                 struct page *page;
1414                 struct xen_netif_extra_info extras[XEN_NETIF_EXTRA_TYPE_MAX-1];
1415                 u16 pending_idx;
1416                 RING_IDX idx;
1417                 int work_to_do;
1418                 unsigned int data_len;
1419                 pending_ring_idx_t index;
1420
1421                 /* Get a netif from the list with work to do. */
1422                 vif = poll_net_schedule_list(netbk);
1423                 /* This can sometimes happen because the test of
1424                  * list_empty(net_schedule_list) at the top of the
1425                  * loop is unlocked.  Just go back and have another
1426                  * look.
1427                  */
1428                 if (!vif)
1429                         continue;
1430
1431                 if (vif->tx.sring->req_prod - vif->tx.req_cons >
1432                     XEN_NETIF_TX_RING_SIZE) {
1433                         netdev_err(vif->dev,
1434                                    "Impossible number of requests. "
1435                                    "req_prod %d, req_cons %d, size %ld\n",
1436                                    vif->tx.sring->req_prod, vif->tx.req_cons,
1437                                    XEN_NETIF_TX_RING_SIZE);
1438                         netbk_fatal_tx_err(vif);
1439                         continue;
1440                 }
1441
1442                 RING_FINAL_CHECK_FOR_REQUESTS(&vif->tx, work_to_do);
1443                 if (!work_to_do) {
1444                         xenvif_put(vif);
1445                         continue;
1446                 }
1447
1448                 idx = vif->tx.req_cons;
1449                 rmb(); /* Ensure that we see the request before we copy it. */
1450                 memcpy(&txreq, RING_GET_REQUEST(&vif->tx, idx), sizeof(txreq));
1451
1452                 /* Credit-based scheduling. */
1453                 if (txreq.size > vif->remaining_credit &&
1454                     tx_credit_exceeded(vif, txreq.size)) {
1455                         xenvif_put(vif);
1456                         continue;
1457                 }
1458
1459                 vif->remaining_credit -= txreq.size;
1460
1461                 work_to_do--;
1462                 vif->tx.req_cons = ++idx;
1463
1464                 memset(extras, 0, sizeof(extras));
1465                 if (txreq.flags & XEN_NETTXF_extra_info) {
1466                         work_to_do = xen_netbk_get_extras(vif, extras,
1467                                                           work_to_do);
1468                         idx = vif->tx.req_cons;
1469                         if (unlikely(work_to_do < 0))
1470                                 continue;
1471                 }
1472
1473                 ret = netbk_count_requests(vif, &txreq, idx,
1474                                            txfrags, work_to_do);
1475                 if (unlikely(ret < 0))
1476                         continue;
1477
1478                 idx += ret;
1479
1480                 if (unlikely(txreq.size < ETH_HLEN)) {
1481                         netdev_dbg(vif->dev,
1482                                    "Bad packet size: %d\n", txreq.size);
1483                         netbk_tx_err(vif, &txreq, idx);
1484                         continue;
1485                 }
1486
1487                 /* No crossing a page as the payload mustn't fragment. */
1488                 if (unlikely((txreq.offset + txreq.size) > PAGE_SIZE)) {
1489                         netdev_err(vif->dev,
1490                                    "txreq.offset: %x, size: %u, end: %lu\n",
1491                                    txreq.offset, txreq.size,
1492                                    (txreq.offset&~PAGE_MASK) + txreq.size);
1493                         netbk_fatal_tx_err(vif);
1494                         continue;
1495                 }
1496
1497                 index = pending_index(netbk->pending_cons);
1498                 pending_idx = netbk->pending_ring[index];
1499
1500                 data_len = (txreq.size > PKT_PROT_LEN &&
1501                             ret < XEN_NETIF_NR_SLOTS_MIN) ?
1502                         PKT_PROT_LEN : txreq.size;
1503
1504                 skb = alloc_skb(data_len + NET_SKB_PAD + NET_IP_ALIGN,
1505                                 GFP_ATOMIC | __GFP_NOWARN);
1506                 if (unlikely(skb == NULL)) {
1507                         netdev_dbg(vif->dev,
1508                                    "Can't allocate a skb in start_xmit.\n");
1509                         netbk_tx_err(vif, &txreq, idx);
1510                         break;
1511                 }
1512
1513                 /* Packets passed to netif_rx() must have some headroom. */
1514                 skb_reserve(skb, NET_SKB_PAD + NET_IP_ALIGN);
1515
1516                 if (extras[XEN_NETIF_EXTRA_TYPE_GSO - 1].type) {
1517                         struct xen_netif_extra_info *gso;
1518                         gso = &extras[XEN_NETIF_EXTRA_TYPE_GSO - 1];
1519
1520                         if (netbk_set_skb_gso(vif, skb, gso)) {
1521                                 /* Failure in netbk_set_skb_gso is fatal. */
1522                                 kfree_skb(skb);
1523                                 continue;
1524                         }
1525                 }
1526
1527                 /* XXX could copy straight to head */
1528                 page = xen_netbk_alloc_page(netbk, pending_idx);
1529                 if (!page) {
1530                         kfree_skb(skb);
1531                         netbk_tx_err(vif, &txreq, idx);
1532                         continue;
1533                 }
1534
1535                 gop->source.u.ref = txreq.gref;
1536                 gop->source.domid = vif->domid;
1537                 gop->source.offset = txreq.offset;
1538
1539                 gop->dest.u.gmfn = virt_to_mfn(page_address(page));
1540                 gop->dest.domid = DOMID_SELF;
1541                 gop->dest.offset = txreq.offset;
1542
1543                 gop->len = txreq.size;
1544                 gop->flags = GNTCOPY_source_gref;
1545
1546                 gop++;
1547
1548                 memcpy(&netbk->pending_tx_info[pending_idx].req,
1549                        &txreq, sizeof(txreq));
1550                 netbk->pending_tx_info[pending_idx].vif = vif;
1551                 netbk->pending_tx_info[pending_idx].head = index;
1552                 *((u16 *)skb->data) = pending_idx;
1553
1554                 __skb_put(skb, data_len);
1555
1556                 skb_shinfo(skb)->nr_frags = ret;
1557                 if (data_len < txreq.size) {
1558                         skb_shinfo(skb)->nr_frags++;
1559                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1560                                              pending_idx);
1561                 } else {
1562                         frag_set_pending_idx(&skb_shinfo(skb)->frags[0],
1563                                              INVALID_PENDING_IDX);
1564                 }
1565
1566                 netbk->pending_cons++;
1567
1568                 request_gop = xen_netbk_get_requests(netbk, vif,
1569                                                      skb, txfrags, gop);
1570                 if (request_gop == NULL) {
1571                         kfree_skb(skb);
1572                         netbk_tx_err(vif, &txreq, idx);
1573                         continue;
1574                 }
1575                 gop = request_gop;
1576
1577                 __skb_queue_tail(&netbk->tx_queue, skb);
1578
1579                 vif->tx.req_cons = idx;
1580                 xen_netbk_check_rx_xenvif(vif);
1581
1582                 if ((gop-netbk->tx_copy_ops) >= ARRAY_SIZE(netbk->tx_copy_ops))
1583                         break;
1584         }
1585
1586         return gop - netbk->tx_copy_ops;
1587 }
1588
1589 static void xen_netbk_tx_submit(struct xen_netbk *netbk)
1590 {
1591         struct gnttab_copy *gop = netbk->tx_copy_ops;
1592         struct sk_buff *skb;
1593
1594         while ((skb = __skb_dequeue(&netbk->tx_queue)) != NULL) {
1595                 struct xen_netif_tx_request *txp;
1596                 struct xenvif *vif;
1597                 u16 pending_idx;
1598                 unsigned data_len;
1599
1600                 pending_idx = *((u16 *)skb->data);
1601                 vif = netbk->pending_tx_info[pending_idx].vif;
1602                 txp = &netbk->pending_tx_info[pending_idx].req;
1603
1604                 /* Check the remap error code. */
1605                 if (unlikely(xen_netbk_tx_check_gop(netbk, skb, &gop))) {
1606                         netdev_dbg(vif->dev, "netback grant failed.\n");
1607                         skb_shinfo(skb)->nr_frags = 0;
1608                         kfree_skb(skb);
1609                         continue;
1610                 }
1611
1612                 data_len = skb->len;
1613                 memcpy(skb->data,
1614                        (void *)(idx_to_kaddr(netbk, pending_idx)|txp->offset),
1615                        data_len);
1616                 if (data_len < txp->size) {
1617                         /* Append the packet payload as a fragment. */
1618                         txp->offset += data_len;
1619                         txp->size -= data_len;
1620                 } else {
1621                         /* Schedule a response immediately. */
1622                         xen_netbk_idx_release(netbk, pending_idx, XEN_NETIF_RSP_OKAY);
1623                 }
1624
1625                 if (txp->flags & XEN_NETTXF_csum_blank)
1626                         skb->ip_summed = CHECKSUM_PARTIAL;
1627                 else if (txp->flags & XEN_NETTXF_data_validated)
1628                         skb->ip_summed = CHECKSUM_UNNECESSARY;
1629
1630                 xen_netbk_fill_frags(netbk, skb);
1631
1632                 /*
1633                  * If the initial fragment was < PKT_PROT_LEN then
1634                  * pull through some bytes from the other fragments to
1635                  * increase the linear region to PKT_PROT_LEN bytes.
1636                  */
1637                 if (skb_headlen(skb) < PKT_PROT_LEN && skb_is_nonlinear(skb)) {
1638                         int target = min_t(int, skb->len, PKT_PROT_LEN);
1639                         __pskb_pull_tail(skb, target - skb_headlen(skb));
1640                 }
1641
1642                 skb->dev      = vif->dev;
1643                 skb->protocol = eth_type_trans(skb, skb->dev);
1644                 skb_reset_network_header(skb);
1645
1646                 if (checksum_setup(vif, skb)) {
1647                         netdev_dbg(vif->dev,
1648                                    "Can't setup checksum in net_tx_action\n");
1649                         kfree_skb(skb);
1650                         continue;
1651                 }
1652
1653                 skb_probe_transport_header(skb, 0);
1654
1655                 vif->dev->stats.rx_bytes += skb->len;
1656                 vif->dev->stats.rx_packets++;
1657
1658                 xenvif_receive_skb(vif, skb);
1659         }
1660 }
1661
1662 /* Called after netfront has transmitted */
1663 static void xen_netbk_tx_action(struct xen_netbk *netbk)
1664 {
1665         unsigned nr_gops;
1666
1667         nr_gops = xen_netbk_tx_build_gops(netbk);
1668
1669         if (nr_gops == 0)
1670                 return;
1671
1672         gnttab_batch_copy(netbk->tx_copy_ops, nr_gops);
1673
1674         xen_netbk_tx_submit(netbk);
1675 }
1676
1677 static void xen_netbk_idx_release(struct xen_netbk *netbk, u16 pending_idx,
1678                                   u8 status)
1679 {
1680         struct xenvif *vif;
1681         struct pending_tx_info *pending_tx_info;
1682         pending_ring_idx_t head;
1683         u16 peek; /* peek into next tx request */
1684
1685         BUG_ON(netbk->mmap_pages[pending_idx] == (void *)(~0UL));
1686
1687         /* Already complete? */
1688         if (netbk->mmap_pages[pending_idx] == NULL)
1689                 return;
1690
1691         pending_tx_info = &netbk->pending_tx_info[pending_idx];
1692
1693         vif = pending_tx_info->vif;
1694         head = pending_tx_info->head;
1695
1696         BUG_ON(!pending_tx_is_head(netbk, head));
1697         BUG_ON(netbk->pending_ring[pending_index(head)] != pending_idx);
1698
1699         do {
1700                 pending_ring_idx_t index;
1701                 pending_ring_idx_t idx = pending_index(head);
1702                 u16 info_idx = netbk->pending_ring[idx];
1703
1704                 pending_tx_info = &netbk->pending_tx_info[info_idx];
1705                 make_tx_response(vif, &pending_tx_info->req, status);
1706
1707                 /* Setting any number other than
1708                  * INVALID_PENDING_RING_IDX indicates this slot is
1709                  * starting a new packet / ending a previous packet.
1710                  */
1711                 pending_tx_info->head = 0;
1712
1713                 index = pending_index(netbk->pending_prod++);
1714                 netbk->pending_ring[index] = netbk->pending_ring[info_idx];
1715
1716                 xenvif_put(vif);
1717
1718                 peek = netbk->pending_ring[pending_index(++head)];
1719
1720         } while (!pending_tx_is_head(netbk, peek));
1721
1722         netbk->mmap_pages[pending_idx]->mapping = 0;
1723         put_page(netbk->mmap_pages[pending_idx]);
1724         netbk->mmap_pages[pending_idx] = NULL;
1725 }
1726
1727
1728 static void make_tx_response(struct xenvif *vif,
1729                              struct xen_netif_tx_request *txp,
1730                              s8       st)
1731 {
1732         RING_IDX i = vif->tx.rsp_prod_pvt;
1733         struct xen_netif_tx_response *resp;
1734         int notify;
1735
1736         resp = RING_GET_RESPONSE(&vif->tx, i);
1737         resp->id     = txp->id;
1738         resp->status = st;
1739
1740         if (txp->flags & XEN_NETTXF_extra_info)
1741                 RING_GET_RESPONSE(&vif->tx, ++i)->status = XEN_NETIF_RSP_NULL;
1742
1743         vif->tx.rsp_prod_pvt = ++i;
1744         RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(&vif->tx, notify);
1745         if (notify)
1746                 notify_remote_via_irq(vif->irq);
1747 }
1748
1749 static struct xen_netif_rx_response *make_rx_response(struct xenvif *vif,
1750                                              u16      id,
1751                                              s8       st,
1752                                              u16      offset,
1753                                              u16      size,
1754                                              u16      flags)
1755 {
1756         RING_IDX i = vif->rx.rsp_prod_pvt;
1757         struct xen_netif_rx_response *resp;
1758
1759         resp = RING_GET_RESPONSE(&vif->rx, i);
1760         resp->offset     = offset;
1761         resp->flags      = flags;
1762         resp->id         = id;
1763         resp->status     = (s16)size;
1764         if (st < 0)
1765                 resp->status = (s16)st;
1766
1767         vif->rx.rsp_prod_pvt = ++i;
1768
1769         return resp;
1770 }
1771
1772 static inline int rx_work_todo(struct xen_netbk *netbk)
1773 {
1774         return !skb_queue_empty(&netbk->rx_queue);
1775 }
1776
1777 static inline int tx_work_todo(struct xen_netbk *netbk)
1778 {
1779
1780         if ((nr_pending_reqs(netbk) + XEN_NETIF_NR_SLOTS_MIN
1781              < MAX_PENDING_REQS) &&
1782              !list_empty(&netbk->net_schedule_list))
1783                 return 1;
1784
1785         return 0;
1786 }
1787
1788 static int xen_netbk_kthread(void *data)
1789 {
1790         struct xen_netbk *netbk = data;
1791         while (!kthread_should_stop()) {
1792                 wait_event_interruptible(netbk->wq,
1793                                 rx_work_todo(netbk) ||
1794                                 tx_work_todo(netbk) ||
1795                                 kthread_should_stop());
1796                 cond_resched();
1797
1798                 if (kthread_should_stop())
1799                         break;
1800
1801                 if (rx_work_todo(netbk))
1802                         xen_netbk_rx_action(netbk);
1803
1804                 if (tx_work_todo(netbk))
1805                         xen_netbk_tx_action(netbk);
1806         }
1807
1808         return 0;
1809 }
1810
1811 void xen_netbk_unmap_frontend_rings(struct xenvif *vif)
1812 {
1813         if (vif->tx.sring)
1814                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1815                                         vif->tx.sring);
1816         if (vif->rx.sring)
1817                 xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
1818                                         vif->rx.sring);
1819 }
1820
1821 int xen_netbk_map_frontend_rings(struct xenvif *vif,
1822                                  grant_ref_t tx_ring_ref,
1823                                  grant_ref_t rx_ring_ref)
1824 {
1825         void *addr;
1826         struct xen_netif_tx_sring *txs;
1827         struct xen_netif_rx_sring *rxs;
1828
1829         int err = -ENOMEM;
1830
1831         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1832                                      tx_ring_ref, &addr);
1833         if (err)
1834                 goto err;
1835
1836         txs = (struct xen_netif_tx_sring *)addr;
1837         BACK_RING_INIT(&vif->tx, txs, PAGE_SIZE);
1838
1839         err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
1840                                      rx_ring_ref, &addr);
1841         if (err)
1842                 goto err;
1843
1844         rxs = (struct xen_netif_rx_sring *)addr;
1845         BACK_RING_INIT(&vif->rx, rxs, PAGE_SIZE);
1846
1847         vif->rx_req_cons_peek = 0;
1848
1849         return 0;
1850
1851 err:
1852         xen_netbk_unmap_frontend_rings(vif);
1853         return err;
1854 }
1855
1856 static int __init netback_init(void)
1857 {
1858         int i;
1859         int rc = 0;
1860         int group;
1861
1862         if (!xen_domain())
1863                 return -ENODEV;
1864
1865         if (max_skb_slots < XEN_NETIF_NR_SLOTS_MIN) {
1866                 printk(KERN_INFO
1867                        "xen-netback: max_skb_slots too small (%d), bump it to XEN_NETIF_NR_SLOTS_MIN (%d)\n",
1868                        max_skb_slots, XEN_NETIF_NR_SLOTS_MIN);
1869                 max_skb_slots = XEN_NETIF_NR_SLOTS_MIN;
1870         }
1871
1872         xen_netbk_group_nr = num_online_cpus();
1873         xen_netbk = vzalloc(sizeof(struct xen_netbk) * xen_netbk_group_nr);
1874         if (!xen_netbk)
1875                 return -ENOMEM;
1876
1877         for (group = 0; group < xen_netbk_group_nr; group++) {
1878                 struct xen_netbk *netbk = &xen_netbk[group];
1879                 skb_queue_head_init(&netbk->rx_queue);
1880                 skb_queue_head_init(&netbk->tx_queue);
1881
1882                 init_timer(&netbk->net_timer);
1883                 netbk->net_timer.data = (unsigned long)netbk;
1884                 netbk->net_timer.function = xen_netbk_alarm;
1885
1886                 netbk->pending_cons = 0;
1887                 netbk->pending_prod = MAX_PENDING_REQS;
1888                 for (i = 0; i < MAX_PENDING_REQS; i++)
1889                         netbk->pending_ring[i] = i;
1890
1891                 init_waitqueue_head(&netbk->wq);
1892                 netbk->task = kthread_create(xen_netbk_kthread,
1893                                              (void *)netbk,
1894                                              "netback/%u", group);
1895
1896                 if (IS_ERR(netbk->task)) {
1897                         printk(KERN_ALERT "kthread_create() fails at netback\n");
1898                         del_timer(&netbk->net_timer);
1899                         rc = PTR_ERR(netbk->task);
1900                         goto failed_init;
1901                 }
1902
1903                 kthread_bind(netbk->task, group);
1904
1905                 INIT_LIST_HEAD(&netbk->net_schedule_list);
1906
1907                 spin_lock_init(&netbk->net_schedule_list_lock);
1908
1909                 atomic_set(&netbk->netfront_count, 0);
1910
1911                 wake_up_process(netbk->task);
1912         }
1913
1914         rc = xenvif_xenbus_init();
1915         if (rc)
1916                 goto failed_init;
1917
1918         return 0;
1919
1920 failed_init:
1921         while (--group >= 0) {
1922                 struct xen_netbk *netbk = &xen_netbk[group];
1923                 for (i = 0; i < MAX_PENDING_REQS; i++) {
1924                         if (netbk->mmap_pages[i])
1925                                 __free_page(netbk->mmap_pages[i]);
1926                 }
1927                 del_timer(&netbk->net_timer);
1928                 kthread_stop(netbk->task);
1929         }
1930         vfree(xen_netbk);
1931         return rc;
1932
1933 }
1934
1935 module_init(netback_init);
1936
1937 MODULE_LICENSE("Dual BSD/GPL");
1938 MODULE_ALIAS("xen-backend:vif");