drivers/net/sfc/tx.c

   1 /****************************************************************************
   2  * Driver for Solarflare Solarstorm network controllers and boards
   3  * Copyright 2005-2006 Fen Systems Ltd.
   4  * Copyright 2005-2008 Solarflare Communications Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published
   8  * by the Free Software Foundation, incorporated herein by reference.
   9  */
  10
  11 #include <linux/pci.h>
  12 #include <linux/tcp.h>
  13 #include <linux/ip.h>
  14 #include <linux/in.h>
  15 #include <linux/if_ether.h>
  16 #include <linux/highmem.h>
  17 #include "net_driver.h"
  18 #include "tx.h"
  19 #include "efx.h"
  20 #include "falcon.h"
  21 #include "workarounds.h"
  22
  23 /*
  24  * TX descriptor ring full threshold
  25  *
  26  * The tx_queue descriptor ring fill-level must fall below this value
  27  * before we restart the netif queue
  28  */
  29 #define EFX_NETDEV_TX_THRESHOLD(_tx_queue)      \
  30         (_tx_queue->efx->type->txd_ring_mask / 2u)
  31
  32 /* We want to be able to nest calls to netif_stop_queue(), since each
  33  * channel can have an individual stop on the queue.
  34  */
  35 void efx_stop_queue(struct efx_nic *efx)
  36 {
  37         spin_lock_bh(&efx->netif_stop_lock);
  38         EFX_TRACE(efx, "stop TX queue\n");
  39
  40         atomic_inc(&efx->netif_stop_count);
  41         netif_stop_queue(efx->net_dev);
  42
  43         spin_unlock_bh(&efx->netif_stop_lock);
  44 }
  45
  46 /* Wake netif's TX queue
  47  * We want to be able to nest calls to netif_stop_queue(), since each
  48  * channel can have an individual stop on the queue.
  49  */
  50 void efx_wake_queue(struct efx_nic *efx)
  51 {
  52         local_bh_disable();
  53         if (atomic_dec_and_lock(&efx->netif_stop_count,
  54                                 &efx->netif_stop_lock)) {
  55                 EFX_TRACE(efx, "waking TX queue\n");
  56                 netif_wake_queue(efx->net_dev);
  57                 spin_unlock(&efx->netif_stop_lock);
  58         }
  59         local_bh_enable();
  60 }
  61
  62 static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
  63                                struct efx_tx_buffer *buffer)
  64 {
  65         if (buffer->unmap_len) {
  66                 struct pci_dev *pci_dev = tx_queue->efx->pci_dev;
  67                 dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
  68                                          buffer->unmap_len);
  69                 if (buffer->unmap_single)
  70                         pci_unmap_single(pci_dev, unmap_addr, buffer->unmap_len,
  71                                          PCI_DMA_TODEVICE);
  72                 else
  73                         pci_unmap_page(pci_dev, unmap_addr, buffer->unmap_len,
  74                                        PCI_DMA_TODEVICE);
  75                 buffer->unmap_len = 0;
  76                 buffer->unmap_single = false;
  77         }
  78
  79         if (buffer->skb) {
  80                 dev_kfree_skb_any((struct sk_buff *) buffer->skb);
  81                 buffer->skb = NULL;
  82                 EFX_TRACE(tx_queue->efx, "TX queue %d transmission id %x "
  83                           "complete\n", tx_queue->queue, read_ptr);
  84         }
  85 }
  86
  87 /**
  88  * struct efx_tso_header - a DMA mapped buffer for packet headers
  89  * @next: Linked list of free ones.
  90  *      The list is protected by the TX queue lock.
  91  * @dma_unmap_len: Length to unmap for an oversize buffer, or 0.
  92  * @dma_addr: The DMA address of the header below.
  93  *
  94  * This controls the memory used for a TSO header.  Use TSOH_DATA()
  95  * to find the packet header data.  Use TSOH_SIZE() to calculate the
  96  * total size required for a given packet header length.  TSO headers
  97  * in the free list are exactly %TSOH_STD_SIZE bytes in size.
  98  */
  99 struct efx_tso_header {
 100         union {
 101                 struct efx_tso_header *next;
 102                 size_t unmap_len;
 103         };
 104         dma_addr_t dma_addr;
 105 };
 106
 107 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
 108                                struct sk_buff *skb);
 109 static void efx_fini_tso(struct efx_tx_queue *tx_queue);
 110 static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue,
 111                                struct efx_tso_header *tsoh);
 112
 113 static void efx_tsoh_free(struct efx_tx_queue *tx_queue,
 114                           struct efx_tx_buffer *buffer)
 115 {
 116         if (buffer->tsoh) {
 117                 if (likely(!buffer->tsoh->unmap_len)) {
 118                         buffer->tsoh->next = tx_queue->tso_headers_free;
 119                         tx_queue->tso_headers_free = buffer->tsoh;
 120                 } else {
 121                         efx_tsoh_heap_free(tx_queue, buffer->tsoh);
 122                 }
 123                 buffer->tsoh = NULL;
 124         }
 125 }
 126
 127
 128 /*
 129  * Add a socket buffer to a TX queue
 130  *
 131  * This maps all fragments of a socket buffer for DMA and adds them to
 132  * the TX queue.  The queue's insert pointer will be incremented by
 133  * the number of fragments in the socket buffer.
 134  *
 135  * If any DMA mapping fails, any mapped fragments will be unmapped,
 136  * the queue's insert pointer will be restored to its original value.
 137  *
 138  * Returns NETDEV_TX_OK or NETDEV_TX_BUSY
 139  * You must hold netif_tx_lock() to call this function.
 140  */
 141 static int efx_enqueue_skb(struct efx_tx_queue *tx_queue,
 142                            struct sk_buff *skb)
 143 {
 144         struct efx_nic *efx = tx_queue->efx;
 145         struct pci_dev *pci_dev = efx->pci_dev;
 146         struct efx_tx_buffer *buffer;
 147         skb_frag_t *fragment;
 148         struct page *page;
 149         int page_offset;
 150         unsigned int len, unmap_len = 0, fill_level, insert_ptr, misalign;
 151         dma_addr_t dma_addr, unmap_addr = 0;
 152         unsigned int dma_len;
 153         bool unmap_single;
 154         int q_space, i = 0;
 155         int rc = NETDEV_TX_OK;
 156
 157         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
 158
 159         if (skb_shinfo((struct sk_buff *)skb)->gso_size)
 160                 return efx_enqueue_skb_tso(tx_queue, skb);
 161
 162         /* Get size of the initial fragment */
 163         len = skb_headlen(skb);
 164
 165         /* Pad if necessary */
 166         if (EFX_WORKAROUND_15592(efx) && skb->len <= 32) {
 167                 EFX_BUG_ON_PARANOID(skb->data_len);
 168                 len = 32 + 1;
 169                 if (skb_pad(skb, len - skb->len))
 170                         return NETDEV_TX_OK;
 171         }
 172
 173         fill_level = tx_queue->insert_count - tx_queue->old_read_count;
 174         q_space = efx->type->txd_ring_mask - 1 - fill_level;
 175
 176         /* Map for DMA.  Use pci_map_single rather than pci_map_page
 177          * since this is more efficient on machines with sparse
 178          * memory.
 179          */
 180         unmap_single = true;
 181         dma_addr = pci_map_single(pci_dev, skb->data, len, PCI_DMA_TODEVICE);
 182
 183         /* Process all fragments */
 184         while (1) {
 185                 if (unlikely(pci_dma_mapping_error(pci_dev, dma_addr)))
 186                         goto pci_err;
 187
 188                 /* Store fields for marking in the per-fragment final
 189                  * descriptor */
 190                 unmap_len = len;
 191                 unmap_addr = dma_addr;
 192
 193                 /* Add to TX queue, splitting across DMA boundaries */
 194                 do {
 195                         if (unlikely(q_space-- <= 0)) {
 196                                 /* It might be that completions have
 197                                  * happened since the xmit path last
 198                                  * checked.  Update the xmit path's
 199                                  * copy of read_count.
 200                                  */
 201                                 ++tx_queue->stopped;
 202                                 /* This memory barrier protects the
 203                                  * change of stopped from the access
 204                                  * of read_count. */
 205                                 smp_mb();
 206                                 tx_queue->old_read_count =
 207                                         *(volatile unsigned *)
 208                                         &tx_queue->read_count;
 209                                 fill_level = (tx_queue->insert_count
 210                                               - tx_queue->old_read_count);
 211                                 q_space = (efx->type->txd_ring_mask - 1 -
 212                                            fill_level);
 213                                 if (unlikely(q_space-- <= 0))
 214                                         goto stop;
 215                                 smp_mb();
 216                                 --tx_queue->stopped;
 217                         }
 218
 219                         insert_ptr = (tx_queue->insert_count &
 220                                       efx->type->txd_ring_mask);
 221                         buffer = &tx_queue->buffer[insert_ptr];
 222                         efx_tsoh_free(tx_queue, buffer);
 223                         EFX_BUG_ON_PARANOID(buffer->tsoh);
 224                         EFX_BUG_ON_PARANOID(buffer->skb);
 225                         EFX_BUG_ON_PARANOID(buffer->len);
 226                         EFX_BUG_ON_PARANOID(!buffer->continuation);
 227                         EFX_BUG_ON_PARANOID(buffer->unmap_len);
 228
 229                         dma_len = (((~dma_addr) & efx->type->tx_dma_mask) + 1);
 230                         if (likely(dma_len > len))
 231                                 dma_len = len;
 232
 233                         misalign = (unsigned)dma_addr & efx->type->bug5391_mask;
 234                         if (misalign && dma_len + misalign > 512)
 235                                 dma_len = 512 - misalign;
 236
 237                         /* Fill out per descriptor fields */
 238                         buffer->len = dma_len;
 239                         buffer->dma_addr = dma_addr;
 240                         len -= dma_len;
 241                         dma_addr += dma_len;
 242                         ++tx_queue->insert_count;
 243                 } while (len);
 244
 245                 /* Transfer ownership of the unmapping to the final buffer */
 246                 buffer->unmap_single = unmap_single;
 247                 buffer->unmap_len = unmap_len;
 248                 unmap_len = 0;
 249
 250                 /* Get address and size of next fragment */
 251                 if (i >= skb_shinfo(skb)->nr_frags)
 252                         break;
 253                 fragment = &skb_shinfo(skb)->frags[i];
 254                 len = fragment->size;
 255                 page = fragment->page;
 256                 page_offset = fragment->page_offset;
 257                 i++;
 258                 /* Map for DMA */
 259                 unmap_single = false;
 260                 dma_addr = pci_map_page(pci_dev, page, page_offset, len,
 261                                         PCI_DMA_TODEVICE);
 262         }
 263
 264         /* Transfer ownership of the skb to the final buffer */
 265         buffer->skb = skb;
 266         buffer->continuation = false;
 267
 268         /* Pass off to hardware */
 269         falcon_push_buffers(tx_queue);
 270
 271         return NETDEV_TX_OK;
 272
 273  pci_err:
 274         EFX_ERR_RL(efx, " TX queue %d could not map skb with %d bytes %d "
 275                    "fragments for DMA\n", tx_queue->queue, skb->len,
 276                    skb_shinfo(skb)->nr_frags + 1);
 277
 278         /* Mark the packet as transmitted, and free the SKB ourselves */
 279         dev_kfree_skb_any((struct sk_buff *)skb);
 280         goto unwind;
 281
 282  stop:
 283         rc = NETDEV_TX_BUSY;
 284
 285         if (tx_queue->stopped == 1)
 286                 efx_stop_queue(efx);
 287
 288  unwind:
 289         /* Work backwards until we hit the original insert pointer value */
 290         while (tx_queue->insert_count != tx_queue->write_count) {
 291                 --tx_queue->insert_count;
 292                 insert_ptr = tx_queue->insert_count & efx->type->txd_ring_mask;
 293                 buffer = &tx_queue->buffer[insert_ptr];
 294                 efx_dequeue_buffer(tx_queue, buffer);
 295                 buffer->len = 0;
 296         }
 297
 298         /* Free the fragment we were mid-way through pushing */
 299         if (unmap_len) {
 300                 if (unmap_single)
 301                         pci_unmap_single(pci_dev, unmap_addr, unmap_len,
 302                                          PCI_DMA_TODEVICE);
 303                 else
 304                         pci_unmap_page(pci_dev, unmap_addr, unmap_len,
 305                                        PCI_DMA_TODEVICE);
 306         }
 307
 308         return rc;
 309 }
 310
 311 /* Remove packets from the TX queue
 312  *
 313  * This removes packets from the TX queue, up to and including the
 314  * specified index.
 315  */
 316 static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
 317                                 unsigned int index)
 318 {
 319         struct efx_nic *efx = tx_queue->efx;
 320         unsigned int stop_index, read_ptr;
 321         unsigned int mask = tx_queue->efx->type->txd_ring_mask;
 322
 323         stop_index = (index + 1) & mask;
 324         read_ptr = tx_queue->read_count & mask;
 325
 326         while (read_ptr != stop_index) {
 327                 struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr];
 328                 if (unlikely(buffer->len == 0)) {
 329                         EFX_ERR(tx_queue->efx, "TX queue %d spurious TX "
 330                                 "completion id %x\n", tx_queue->queue,
 331                                 read_ptr);
 332                         efx_schedule_reset(efx, RESET_TYPE_TX_SKIP);
 333                         return;
 334                 }
 335
 336                 efx_dequeue_buffer(tx_queue, buffer);
 337                 buffer->continuation = true;
 338                 buffer->len = 0;
 339
 340                 ++tx_queue->read_count;
 341                 read_ptr = tx_queue->read_count & mask;
 342         }
 343 }
 344
 345 /* Initiate a packet transmission on the specified TX queue.
 346  * Note that returning anything other than NETDEV_TX_OK will cause the
 347  * OS to free the skb.
 348  *
 349  * This function is split out from efx_hard_start_xmit to allow the
 350  * loopback test to direct packets via specific TX queues.  It is
 351  * therefore a non-static inline, so as not to penalise performance
 352  * for non-loopback transmissions.
 353  *
 354  * Context: netif_tx_lock held
 355  */
 356 inline int efx_xmit(struct efx_nic *efx,
 357                     struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 358 {
 359         int rc;
 360
 361         /* Map fragments for DMA and add to TX queue */
 362         rc = efx_enqueue_skb(tx_queue, skb);
 363         if (unlikely(rc != NETDEV_TX_OK))
 364                 goto out;
 365
 366         /* Update last TX timer */
 367         efx->net_dev->trans_start = jiffies;
 368
 369  out:
 370         return rc;
 371 }
 372
 373 /* Initiate a packet transmission.  We use one channel per CPU
 374  * (sharing when we have more CPUs than channels).  On Falcon, the TX
 375  * completion events will be directed back to the CPU that transmitted
 376  * the packet, which should be cache-efficient.
 377  *
 378  * Context: non-blocking.
 379  * Note that returning anything other than NETDEV_TX_OK will cause the
 380  * OS to free the skb.
 381  */
 382 int efx_hard_start_xmit(struct sk_buff *skb, struct net_device *net_dev)
 383 {
 384         struct efx_nic *efx = netdev_priv(net_dev);
 385         struct efx_tx_queue *tx_queue;
 386
 387         if (unlikely(efx->port_inhibited))
 388                 return NETDEV_TX_BUSY;
 389
 390         if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
 391                 tx_queue = &efx->tx_queue[EFX_TX_QUEUE_OFFLOAD_CSUM];
 392         else
 393                 tx_queue = &efx->tx_queue[EFX_TX_QUEUE_NO_CSUM];
 394
 395         return efx_xmit(efx, tx_queue, skb);
 396 }
 397
 398 void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index)
 399 {
 400         unsigned fill_level;
 401         struct efx_nic *efx = tx_queue->efx;
 402
 403         EFX_BUG_ON_PARANOID(index > efx->type->txd_ring_mask);
 404
 405         efx_dequeue_buffers(tx_queue, index);
 406
 407         /* See if we need to restart the netif queue.  This barrier
 408          * separates the update of read_count from the test of
 409          * stopped. */
 410         smp_mb();
 411         if (unlikely(tx_queue->stopped) && likely(efx->port_enabled)) {
 412                 fill_level = tx_queue->insert_count - tx_queue->read_count;
 413                 if (fill_level < EFX_NETDEV_TX_THRESHOLD(tx_queue)) {
 414                         EFX_BUG_ON_PARANOID(!efx_dev_registered(efx));
 415
 416                         /* Do this under netif_tx_lock(), to avoid racing
 417                          * with efx_xmit(). */
 418                         netif_tx_lock(efx->net_dev);
 419                         if (tx_queue->stopped) {
 420                                 tx_queue->stopped = 0;
 421                                 efx_wake_queue(efx);
 422                         }
 423                         netif_tx_unlock(efx->net_dev);
 424                 }
 425         }
 426 }
 427
 428 int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
 429 {
 430         struct efx_nic *efx = tx_queue->efx;
 431         unsigned int txq_size;
 432         int i, rc;
 433
 434         EFX_LOG(efx, "creating TX queue %d\n", tx_queue->queue);
 435
 436         /* Allocate software ring */
 437         txq_size = (efx->type->txd_ring_mask + 1) * sizeof(*tx_queue->buffer);
 438         tx_queue->buffer = kzalloc(txq_size, GFP_KERNEL);
 439         if (!tx_queue->buffer)
 440                 return -ENOMEM;
 441         for (i = 0; i <= efx->type->txd_ring_mask; ++i)
 442                 tx_queue->buffer[i].continuation = true;
 443
 444         /* Allocate hardware ring */
 445         rc = falcon_probe_tx(tx_queue);
 446         if (rc)
 447                 goto fail;
 448
 449         return 0;
 450
 451  fail:
 452         kfree(tx_queue->buffer);
 453         tx_queue->buffer = NULL;
 454         return rc;
 455 }
 456
 457 void efx_init_tx_queue(struct efx_tx_queue *tx_queue)
 458 {
 459         EFX_LOG(tx_queue->efx, "initialising TX queue %d\n", tx_queue->queue);
 460
 461         tx_queue->insert_count = 0;
 462         tx_queue->write_count = 0;
 463         tx_queue->read_count = 0;
 464         tx_queue->old_read_count = 0;
 465         BUG_ON(tx_queue->stopped);
 466
 467         /* Set up TX descriptor ring */
 468         falcon_init_tx(tx_queue);
 469 }
 470
 471 void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
 472 {
 473         struct efx_tx_buffer *buffer;
 474
 475         if (!tx_queue->buffer)
 476                 return;
 477
 478         /* Free any buffers left in the ring */
 479         while (tx_queue->read_count != tx_queue->write_count) {
 480                 buffer = &tx_queue->buffer[tx_queue->read_count &
 481                                            tx_queue->efx->type->txd_ring_mask];
 482                 efx_dequeue_buffer(tx_queue, buffer);
 483                 buffer->continuation = true;
 484                 buffer->len = 0;
 485
 486                 ++tx_queue->read_count;
 487         }
 488 }
 489
 490 void efx_fini_tx_queue(struct efx_tx_queue *tx_queue)
 491 {
 492         EFX_LOG(tx_queue->efx, "shutting down TX queue %d\n", tx_queue->queue);
 493
 494         /* Flush TX queue, remove descriptor ring */
 495         falcon_fini_tx(tx_queue);
 496
 497         efx_release_tx_buffers(tx_queue);
 498
 499         /* Free up TSO header cache */
 500         efx_fini_tso(tx_queue);
 501
 502         /* Release queue's stop on port, if any */
 503         if (tx_queue->stopped) {
 504                 tx_queue->stopped = 0;
 505                 efx_wake_queue(tx_queue->efx);
 506         }
 507 }
 508
 509 void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
 510 {
 511         EFX_LOG(tx_queue->efx, "destroying TX queue %d\n", tx_queue->queue);
 512         falcon_remove_tx(tx_queue);
 513
 514         kfree(tx_queue->buffer);
 515         tx_queue->buffer = NULL;
 516 }
 517
 518
 519 /* Efx TCP segmentation acceleration.
 520  *
 521  * Why?  Because by doing it here in the driver we can go significantly
 522  * faster than the GSO.
 523  *
 524  * Requires TX checksum offload support.
 525  */
 526
 527 /* Number of bytes inserted at the start of a TSO header buffer,
 528  * similar to NET_IP_ALIGN.
 529  */
 530 #ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 531 #define TSOH_OFFSET     0
 532 #else
 533 #define TSOH_OFFSET     NET_IP_ALIGN
 534 #endif
 535
 536 #define TSOH_BUFFER(tsoh)       ((u8 *)(tsoh + 1) + TSOH_OFFSET)
 537
 538 /* Total size of struct efx_tso_header, buffer and padding */
 539 #define TSOH_SIZE(hdr_len)                                      \
 540         (sizeof(struct efx_tso_header) + TSOH_OFFSET + hdr_len)
 541
 542 /* Size of blocks on free list.  Larger blocks must be allocated from
 543  * the heap.
 544  */
 545 #define TSOH_STD_SIZE           128
 546
 547 #define PTR_DIFF(p1, p2)  ((u8 *)(p1) - (u8 *)(p2))
 548 #define ETH_HDR_LEN(skb)  (skb_network_header(skb) - (skb)->data)
 549 #define SKB_TCP_OFF(skb)  PTR_DIFF(tcp_hdr(skb), (skb)->data)
 550 #define SKB_IPV4_OFF(skb) PTR_DIFF(ip_hdr(skb), (skb)->data)
 551
 552 /**
 553  * struct tso_state - TSO state for an SKB
 554  * @out_len: Remaining length in current segment
 555  * @seqnum: Current sequence number
 556  * @ipv4_id: Current IPv4 ID, host endian
 557  * @packet_space: Remaining space in current packet
 558  * @dma_addr: DMA address of current position
 559  * @in_len: Remaining length in current SKB fragment
 560  * @unmap_len: Length of SKB fragment
 561  * @unmap_addr: DMA address of SKB fragment
 562  * @unmap_single: DMA single vs page mapping flag
 563  * @header_len: Number of bytes of header
 564  * @full_packet_size: Number of bytes to put in each outgoing segment
 565  *
 566  * The state used during segmentation.  It is put into this data structure
 567  * just to make it easy to pass into inline functions.
 568  */
 569 struct tso_state {
 570         /* Output position */
 571         unsigned out_len;
 572         unsigned seqnum;
 573         unsigned ipv4_id;
 574         unsigned packet_space;
 575
 576         /* Input position */
 577         dma_addr_t dma_addr;
 578         unsigned in_len;
 579         unsigned unmap_len;
 580         dma_addr_t unmap_addr;
 581         bool unmap_single;
 582
 583         unsigned header_len;
 584         int full_packet_size;
 585 };
 586
 587
 588 /*
 589  * Verify that our various assumptions about sk_buffs and the conditions
 590  * under which TSO will be attempted hold true.
 591  */
 592 static void efx_tso_check_safe(struct sk_buff *skb)
 593 {
 594         __be16 protocol = skb->protocol;
 595
 596         EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto !=
 597                             protocol);
 598         if (protocol == htons(ETH_P_8021Q)) {
 599                 /* Find the encapsulated protocol; reset network header
 600                  * and transport header based on that. */
 601                 struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data;
 602                 protocol = veh->h_vlan_encapsulated_proto;
 603                 skb_set_network_header(skb, sizeof(*veh));
 604                 if (protocol == htons(ETH_P_IP))
 605                         skb_set_transport_header(skb, sizeof(*veh) +
 606                                                  4 * ip_hdr(skb)->ihl);
 607         }
 608
 609         EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IP));
 610         EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP);
 611         EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data)
 612                              + (tcp_hdr(skb)->doff << 2u)) >
 613                             skb_headlen(skb));
 614 }
 615
 616
 617 /*
 618  * Allocate a page worth of efx_tso_header structures, and string them
 619  * into the tx_queue->tso_headers_free linked list. Return 0 or -ENOMEM.
 620  */
 621 static int efx_tsoh_block_alloc(struct efx_tx_queue *tx_queue)
 622 {
 623
 624         struct pci_dev *pci_dev = tx_queue->efx->pci_dev;
 625         struct efx_tso_header *tsoh;
 626         dma_addr_t dma_addr;
 627         u8 *base_kva, *kva;
 628
 629         base_kva = pci_alloc_consistent(pci_dev, PAGE_SIZE, &dma_addr);
 630         if (base_kva == NULL) {
 631                 EFX_ERR(tx_queue->efx, "Unable to allocate page for TSO"
 632                         " headers\n");
 633                 return -ENOMEM;
 634         }
 635
 636         /* pci_alloc_consistent() allocates pages. */
 637         EFX_BUG_ON_PARANOID(dma_addr & (PAGE_SIZE - 1u));
 638
 639         for (kva = base_kva; kva < base_kva + PAGE_SIZE; kva += TSOH_STD_SIZE) {
 640                 tsoh = (struct efx_tso_header *)kva;
 641                 tsoh->dma_addr = dma_addr + (TSOH_BUFFER(tsoh) - base_kva);
 642                 tsoh->next = tx_queue->tso_headers_free;
 643                 tx_queue->tso_headers_free = tsoh;
 644         }
 645
 646         return 0;
 647 }
 648
 649
 650 /* Free up a TSO header, and all others in the same page. */
 651 static void efx_tsoh_block_free(struct efx_tx_queue *tx_queue,
 652                                 struct efx_tso_header *tsoh,
 653                                 struct pci_dev *pci_dev)
 654 {
 655         struct efx_tso_header **p;
 656         unsigned long base_kva;
 657         dma_addr_t base_dma;
 658
 659         base_kva = (unsigned long)tsoh & PAGE_MASK;
 660         base_dma = tsoh->dma_addr & PAGE_MASK;
 661
 662         p = &tx_queue->tso_headers_free;
 663         while (*p != NULL) {
 664                 if (((unsigned long)*p & PAGE_MASK) == base_kva)
 665                         *p = (*p)->next;
 666                 else
 667                         p = &(*p)->next;
 668         }
 669
 670         pci_free_consistent(pci_dev, PAGE_SIZE, (void *)base_kva, base_dma);
 671 }
 672
 673 static struct efx_tso_header *
 674 efx_tsoh_heap_alloc(struct efx_tx_queue *tx_queue, size_t header_len)
 675 {
 676         struct efx_tso_header *tsoh;
 677
 678         tsoh = kmalloc(TSOH_SIZE(header_len), GFP_ATOMIC | GFP_DMA);
 679         if (unlikely(!tsoh))
 680                 return NULL;
 681
 682         tsoh->dma_addr = pci_map_single(tx_queue->efx->pci_dev,
 683                                         TSOH_BUFFER(tsoh), header_len,
 684                                         PCI_DMA_TODEVICE);
 685         if (unlikely(pci_dma_mapping_error(tx_queue->efx->pci_dev,
 686                                            tsoh->dma_addr))) {
 687                 kfree(tsoh);
 688                 return NULL;
 689         }
 690
 691         tsoh->unmap_len = header_len;
 692         return tsoh;
 693 }
 694
 695 static void
 696 efx_tsoh_heap_free(struct efx_tx_queue *tx_queue, struct efx_tso_header *tsoh)
 697 {
 698         pci_unmap_single(tx_queue->efx->pci_dev,
 699                          tsoh->dma_addr, tsoh->unmap_len,
 700                          PCI_DMA_TODEVICE);
 701         kfree(tsoh);
 702 }
 703
 704 /**
 705  * efx_tx_queue_insert - push descriptors onto the TX queue
 706  * @tx_queue:           Efx TX queue
 707  * @dma_addr:           DMA address of fragment
 708  * @len:                Length of fragment
 709  * @final_buffer:       The final buffer inserted into the queue
 710  *
 711  * Push descriptors onto the TX queue.  Return 0 on success or 1 if
 712  * @tx_queue full.
 713  */
 714 static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
 715                                dma_addr_t dma_addr, unsigned len,
 716                                struct efx_tx_buffer **final_buffer)
 717 {
 718         struct efx_tx_buffer *buffer;
 719         struct efx_nic *efx = tx_queue->efx;
 720         unsigned dma_len, fill_level, insert_ptr, misalign;
 721         int q_space;
 722
 723         EFX_BUG_ON_PARANOID(len <= 0);
 724
 725         fill_level = tx_queue->insert_count - tx_queue->old_read_count;
 726         /* -1 as there is no way to represent all descriptors used */
 727         q_space = efx->type->txd_ring_mask - 1 - fill_level;
 728
 729         while (1) {
 730                 if (unlikely(q_space-- <= 0)) {
 731                         /* It might be that completions have happened
 732                          * since the xmit path last checked.  Update
 733                          * the xmit path's copy of read_count.
 734                          */
 735                         ++tx_queue->stopped;
 736                         /* This memory barrier protects the change of
 737                          * stopped from the access of read_count. */
 738                         smp_mb();
 739                         tx_queue->old_read_count =
 740                                 *(volatile unsigned *)&tx_queue->read_count;
 741                         fill_level = (tx_queue->insert_count
 742                                       - tx_queue->old_read_count);
 743                         q_space = efx->type->txd_ring_mask - 1 - fill_level;
 744                         if (unlikely(q_space-- <= 0)) {
 745                                 *final_buffer = NULL;
 746                                 return 1;
 747                         }
 748                         smp_mb();
 749                         --tx_queue->stopped;
 750                 }
 751
 752                 insert_ptr = tx_queue->insert_count & efx->type->txd_ring_mask;
 753                 buffer = &tx_queue->buffer[insert_ptr];
 754                 ++tx_queue->insert_count;
 755
 756                 EFX_BUG_ON_PARANOID(tx_queue->insert_count -
 757                                     tx_queue->read_count >
 758                                     efx->type->txd_ring_mask);
 759
 760                 efx_tsoh_free(tx_queue, buffer);
 761                 EFX_BUG_ON_PARANOID(buffer->len);
 762                 EFX_BUG_ON_PARANOID(buffer->unmap_len);
 763                 EFX_BUG_ON_PARANOID(buffer->skb);
 764                 EFX_BUG_ON_PARANOID(!buffer->continuation);
 765                 EFX_BUG_ON_PARANOID(buffer->tsoh);
 766
 767                 buffer->dma_addr = dma_addr;
 768
 769                 /* Ensure we do not cross a boundary unsupported by H/W */
 770                 dma_len = (~dma_addr & efx->type->tx_dma_mask) + 1;
 771
 772                 misalign = (unsigned)dma_addr & efx->type->bug5391_mask;
 773                 if (misalign && dma_len + misalign > 512)
 774                         dma_len = 512 - misalign;
 775
 776                 /* If there is enough space to send then do so */
 777                 if (dma_len >= len)
 778                         break;
 779
 780                 buffer->len = dma_len; /* Don't set the other members */
 781                 dma_addr += dma_len;
 782                 len -= dma_len;
 783         }
 784
 785         EFX_BUG_ON_PARANOID(!len);
 786         buffer->len = len;
 787         *final_buffer = buffer;
 788         return 0;
 789 }
 790
 791
 792 /*
 793  * Put a TSO header into the TX queue.
 794  *
 795  * This is special-cased because we know that it is small enough to fit in
 796  * a single fragment, and we know it doesn't cross a page boundary.  It
 797  * also allows us to not worry about end-of-packet etc.
 798  */
 799 static void efx_tso_put_header(struct efx_tx_queue *tx_queue,
 800                                struct efx_tso_header *tsoh, unsigned len)
 801 {
 802         struct efx_tx_buffer *buffer;
 803
 804         buffer = &tx_queue->buffer[tx_queue->insert_count &
 805                                    tx_queue->efx->type->txd_ring_mask];
 806         efx_tsoh_free(tx_queue, buffer);
 807         EFX_BUG_ON_PARANOID(buffer->len);
 808         EFX_BUG_ON_PARANOID(buffer->unmap_len);
 809         EFX_BUG_ON_PARANOID(buffer->skb);
 810         EFX_BUG_ON_PARANOID(!buffer->continuation);
 811         EFX_BUG_ON_PARANOID(buffer->tsoh);
 812         buffer->len = len;
 813         buffer->dma_addr = tsoh->dma_addr;
 814         buffer->tsoh = tsoh;
 815
 816         ++tx_queue->insert_count;
 817 }
 818
 819
 820 /* Remove descriptors put into a tx_queue. */
 821 static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
 822 {
 823         struct efx_tx_buffer *buffer;
 824         dma_addr_t unmap_addr;
 825
 826         /* Work backwards until we hit the original insert pointer value */
 827         while (tx_queue->insert_count != tx_queue->write_count) {
 828                 --tx_queue->insert_count;
 829                 buffer = &tx_queue->buffer[tx_queue->insert_count &
 830                                            tx_queue->efx->type->txd_ring_mask];
 831                 efx_tsoh_free(tx_queue, buffer);
 832                 EFX_BUG_ON_PARANOID(buffer->skb);
 833                 buffer->len = 0;
 834                 buffer->continuation = true;
 835                 if (buffer->unmap_len) {
 836                         unmap_addr = (buffer->dma_addr + buffer->len -
 837                                       buffer->unmap_len);
 838                         if (buffer->unmap_single)
 839                                 pci_unmap_single(tx_queue->efx->pci_dev,
 840                                                  unmap_addr, buffer->unmap_len,
 841                                                  PCI_DMA_TODEVICE);
 842                         else
 843                                 pci_unmap_page(tx_queue->efx->pci_dev,
 844                                                unmap_addr, buffer->unmap_len,
 845                                                PCI_DMA_TODEVICE);
 846                         buffer->unmap_len = 0;
 847                 }
 848         }
 849 }
 850
 851
 852 /* Parse the SKB header and initialise state. */
 853 static void tso_start(struct tso_state *st, const struct sk_buff *skb)
 854 {
 855         /* All ethernet/IP/TCP headers combined size is TCP header size
 856          * plus offset of TCP header relative to start of packet.
 857          */
 858         st->header_len = ((tcp_hdr(skb)->doff << 2u)
 859                           + PTR_DIFF(tcp_hdr(skb), skb->data));
 860         st->full_packet_size = st->header_len + skb_shinfo(skb)->gso_size;
 861
 862         st->ipv4_id = ntohs(ip_hdr(skb)->id);
 863         st->seqnum = ntohl(tcp_hdr(skb)->seq);
 864
 865         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg);
 866         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn);
 867         EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst);
 868
 869         st->packet_space = st->full_packet_size;
 870         st->out_len = skb->len - st->header_len;
 871         st->unmap_len = 0;
 872         st->unmap_single = false;
 873 }
 874
 875 static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
 876                             skb_frag_t *frag)
 877 {
 878         st->unmap_addr = pci_map_page(efx->pci_dev, frag->page,
 879                                       frag->page_offset, frag->size,
 880                                       PCI_DMA_TODEVICE);
 881         if (likely(!pci_dma_mapping_error(efx->pci_dev, st->unmap_addr))) {
 882                 st->unmap_single = false;
 883                 st->unmap_len = frag->size;
 884                 st->in_len = frag->size;
 885                 st->dma_addr = st->unmap_addr;
 886                 return 0;
 887         }
 888         return -ENOMEM;
 889 }
 890
 891 static int tso_get_head_fragment(struct tso_state *st, struct efx_nic *efx,
 892                                  const struct sk_buff *skb)
 893 {
 894         int hl = st->header_len;
 895         int len = skb_headlen(skb) - hl;
 896
 897         st->unmap_addr = pci_map_single(efx->pci_dev, skb->data + hl,
 898                                         len, PCI_DMA_TODEVICE);
 899         if (likely(!pci_dma_mapping_error(efx->pci_dev, st->unmap_addr))) {
 900                 st->unmap_single = true;
 901                 st->unmap_len = len;
 902                 st->in_len = len;
 903                 st->dma_addr = st->unmap_addr;
 904                 return 0;
 905         }
 906         return -ENOMEM;
 907 }
 908
 909
 910 /**
 911  * tso_fill_packet_with_fragment - form descriptors for the current fragment
 912  * @tx_queue:           Efx TX queue
 913  * @skb:                Socket buffer
 914  * @st:                 TSO state
 915  *
 916  * Form descriptors for the current fragment, until we reach the end
 917  * of fragment or end-of-packet.  Return 0 on success, 1 if not enough
 918  * space in @tx_queue.
 919  */
 920 static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
 921                                          const struct sk_buff *skb,
 922                                          struct tso_state *st)
 923 {
 924         struct efx_tx_buffer *buffer;
 925         int n, end_of_packet, rc;
 926
 927         if (st->in_len == 0)
 928                 return 0;
 929         if (st->packet_space == 0)
 930                 return 0;
 931
 932         EFX_BUG_ON_PARANOID(st->in_len <= 0);
 933         EFX_BUG_ON_PARANOID(st->packet_space <= 0);
 934
 935         n = min(st->in_len, st->packet_space);
 936
 937         st->packet_space -= n;
 938         st->out_len -= n;
 939         st->in_len -= n;
 940
 941         rc = efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
 942         if (likely(rc == 0)) {
 943                 if (st->out_len == 0)
 944                         /* Transfer ownership of the skb */
 945                         buffer->skb = skb;
 946
 947                 end_of_packet = st->out_len == 0 || st->packet_space == 0;
 948                 buffer->continuation = !end_of_packet;
 949
 950                 if (st->in_len == 0) {
 951                         /* Transfer ownership of the pci mapping */
 952                         buffer->unmap_len = st->unmap_len;
 953                         buffer->unmap_single = st->unmap_single;
 954                         st->unmap_len = 0;
 955                 }
 956         }
 957
 958         st->dma_addr += n;
 959         return rc;
 960 }
 961
 962
 963 /**
 964  * tso_start_new_packet - generate a new header and prepare for the new packet
 965  * @tx_queue:           Efx TX queue
 966  * @skb:                Socket buffer
 967  * @st:                 TSO state
 968  *
 969  * Generate a new header and prepare for the new packet.  Return 0 on
 970  * success, or -1 if failed to alloc header.
 971  */
 972 static int tso_start_new_packet(struct efx_tx_queue *tx_queue,
 973                                 const struct sk_buff *skb,
 974                                 struct tso_state *st)
 975 {
 976         struct efx_tso_header *tsoh;
 977         struct iphdr *tsoh_iph;
 978         struct tcphdr *tsoh_th;
 979         unsigned ip_length;
 980         u8 *header;
 981
 982         /* Allocate a DMA-mapped header buffer. */
 983         if (likely(TSOH_SIZE(st->header_len) <= TSOH_STD_SIZE)) {
 984                 if (tx_queue->tso_headers_free == NULL) {
 985                         if (efx_tsoh_block_alloc(tx_queue))
 986                                 return -1;
 987                 }
 988                 EFX_BUG_ON_PARANOID(!tx_queue->tso_headers_free);
 989                 tsoh = tx_queue->tso_headers_free;
 990                 tx_queue->tso_headers_free = tsoh->next;
 991                 tsoh->unmap_len = 0;
 992         } else {
 993                 tx_queue->tso_long_headers++;
 994                 tsoh = efx_tsoh_heap_alloc(tx_queue, st->header_len);
 995                 if (unlikely(!tsoh))
 996                         return -1;
 997         }
 998
 999         header = TSOH_BUFFER(tsoh);
1000         tsoh_th = (struct tcphdr *)(header + SKB_TCP_OFF(skb));
1001         tsoh_iph = (struct iphdr *)(header + SKB_IPV4_OFF(skb));
1002
1003         /* Copy and update the headers. */
1004         memcpy(header, skb->data, st->header_len);
1005
1006         tsoh_th->seq = htonl(st->seqnum);
1007         st->seqnum += skb_shinfo(skb)->gso_size;
1008         if (st->out_len > skb_shinfo(skb)->gso_size) {
1009                 /* This packet will not finish the TSO burst. */
1010                 ip_length = st->full_packet_size - ETH_HDR_LEN(skb);
1011                 tsoh_th->fin = 0;
1012                 tsoh_th->psh = 0;
1013         } else {
1014                 /* This packet will be the last in the TSO burst. */
1015                 ip_length = st->header_len - ETH_HDR_LEN(skb) + st->out_len;
1016                 tsoh_th->fin = tcp_hdr(skb)->fin;
1017                 tsoh_th->psh = tcp_hdr(skb)->psh;
1018         }
1019         tsoh_iph->tot_len = htons(ip_length);
1020
1021         /* Linux leaves suitable gaps in the IP ID space for us to fill. */
1022         tsoh_iph->id = htons(st->ipv4_id);
1023         st->ipv4_id++;
1024
1025         st->packet_space = skb_shinfo(skb)->gso_size;
1026         ++tx_queue->tso_packets;
1027
1028         /* Form a descriptor for this header. */
1029         efx_tso_put_header(tx_queue, tsoh, st->header_len);
1030
1031         return 0;
1032 }
1033
1034
1035 /**
1036  * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer
1037  * @tx_queue:           Efx TX queue
1038  * @skb:                Socket buffer
1039  *
1040  * Context: You must hold netif_tx_lock() to call this function.
1041  *
1042  * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if
1043  * @skb was not enqueued.  In all cases @skb is consumed.  Return
1044  * %NETDEV_TX_OK or %NETDEV_TX_BUSY.
1045  */
1046 static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
1047                                struct sk_buff *skb)
1048 {
1049         struct efx_nic *efx = tx_queue->efx;
1050         int frag_i, rc, rc2 = NETDEV_TX_OK;
1051         struct tso_state state;
1052
1053         /* Verify TSO is safe - these checks should never fail. */
1054         efx_tso_check_safe(skb);
1055
1056         EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count);
1057
1058         tso_start(&state, skb);
1059
1060         /* Assume that skb header area contains exactly the headers, and
1061          * all payload is in the frag list.
1062          */
1063         if (skb_headlen(skb) == state.header_len) {
1064                 /* Grab the first payload fragment. */
1065                 EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1);
1066                 frag_i = 0;
1067                 rc = tso_get_fragment(&state, efx,
1068                                       skb_shinfo(skb)->frags + frag_i);
1069                 if (rc)
1070                         goto mem_err;
1071         } else {
1072                 rc = tso_get_head_fragment(&state, efx, skb);
1073                 if (rc)
1074                         goto mem_err;
1075                 frag_i = -1;
1076         }
1077
1078         if (tso_start_new_packet(tx_queue, skb, &state) < 0)
1079                 goto mem_err;
1080
1081         while (1) {
1082                 rc = tso_fill_packet_with_fragment(tx_queue, skb, &state);
1083                 if (unlikely(rc))
1084                         goto stop;
1085
1086                 /* Move onto the next fragment? */
1087                 if (state.in_len == 0) {
1088                         if (++frag_i >= skb_shinfo(skb)->nr_frags)
1089                                 /* End of payload reached. */
1090                                 break;
1091                         rc = tso_get_fragment(&state, efx,
1092                                               skb_shinfo(skb)->frags + frag_i);
1093                         if (rc)
1094                                 goto mem_err;
1095                 }
1096
1097                 /* Start at new packet? */
1098                 if (state.packet_space == 0 &&
1099                     tso_start_new_packet(tx_queue, skb, &state) < 0)
1100                         goto mem_err;
1101         }
1102
1103         /* Pass off to hardware */
1104         falcon_push_buffers(tx_queue);
1105
1106         tx_queue->tso_bursts++;
1107         return NETDEV_TX_OK;
1108
1109  mem_err:
1110         EFX_ERR(efx, "Out of memory for TSO headers, or PCI mapping error\n");
1111         dev_kfree_skb_any((struct sk_buff *)skb);
1112         goto unwind;
1113
1114  stop:
1115         rc2 = NETDEV_TX_BUSY;
1116
1117         /* Stop the queue if it wasn't stopped before. */
1118         if (tx_queue->stopped == 1)
1119                 efx_stop_queue(efx);
1120
1121  unwind:
1122         /* Free the DMA mapping we were in the process of writing out */
1123         if (state.unmap_len) {
1124                 if (state.unmap_single)
1125                         pci_unmap_single(efx->pci_dev, state.unmap_addr,
1126                                          state.unmap_len, PCI_DMA_TODEVICE);
1127                 else
1128                         pci_unmap_page(efx->pci_dev, state.unmap_addr,
1129                                        state.unmap_len, PCI_DMA_TODEVICE);
1130         }
1131
1132         efx_enqueue_unwind(tx_queue);
1133         return rc2;
1134 }
1135
1136
1137 /*
1138  * Free up all TSO datastructures associated with tx_queue. This
1139  * routine should be called only once the tx_queue is both empty and
1140  * will no longer be used.
1141  */
1142 static void efx_fini_tso(struct efx_tx_queue *tx_queue)
1143 {
1144         unsigned i;
1145
1146         if (tx_queue->buffer) {
1147                 for (i = 0; i <= tx_queue->efx->type->txd_ring_mask; ++i)
1148                         efx_tsoh_free(tx_queue, &tx_queue->buffer[i]);
1149         }
1150
1151         while (tx_queue->tso_headers_free != NULL)
1152                 efx_tsoh_block_free(tx_queue, tx_queue->tso_headers_free,
1153                                     tx_queue->efx->pci_dev);
1154 }