diff options
Diffstat (limited to 'drivers/net/ethernet/sfc/tx.c')
| -rw-r--r-- | drivers/net/ethernet/sfc/tx.c | 1207 |
1 files changed, 1207 insertions, 0 deletions
diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c new file mode 100644 index 000000000000..df88c5430f95 --- /dev/null +++ b/drivers/net/ethernet/sfc/tx.c @@ -0,0 +1,1207 @@ +/**************************************************************************** + * Driver for Solarflare Solarstorm network controllers and boards + * Copyright 2005-2006 Fen Systems Ltd. + * Copyright 2005-2010 Solarflare Communications Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 as published + * by the Free Software Foundation, incorporated herein by reference. + */ + +#include <linux/pci.h> +#include <linux/tcp.h> +#include <linux/ip.h> +#include <linux/in.h> +#include <linux/ipv6.h> +#include <linux/slab.h> +#include <net/ipv6.h> +#include <linux/if_ether.h> +#include <linux/highmem.h> +#include "net_driver.h" +#include "efx.h" +#include "nic.h" +#include "workarounds.h" + +/* + * TX descriptor ring full threshold + * + * The tx_queue descriptor ring fill-level must fall below this value + * before we restart the netif queue + */ +#define EFX_TXQ_THRESHOLD(_efx) ((_efx)->txq_entries / 2u) + +static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue, + struct efx_tx_buffer *buffer) +{ + if (buffer->unmap_len) { + struct pci_dev *pci_dev = tx_queue->efx->pci_dev; + dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len - + buffer->unmap_len); + if (buffer->unmap_single) + pci_unmap_single(pci_dev, unmap_addr, buffer->unmap_len, + PCI_DMA_TODEVICE); + else + pci_unmap_page(pci_dev, unmap_addr, buffer->unmap_len, + PCI_DMA_TODEVICE); + buffer->unmap_len = 0; + buffer->unmap_single = false; + } + + if (buffer->skb) { + dev_kfree_skb_any((struct sk_buff *) buffer->skb); + buffer->skb = NULL; + netif_vdbg(tx_queue->efx, tx_done, tx_queue->efx->net_dev, + "TX queue %d transmission id %x complete\n", + tx_queue->queue, tx_queue->read_count); + } +} + +/** + * struct efx_tso_header - a DMA mapped buffer for packet headers + * @next: Linked list of free ones. + * The list is protected by the TX queue lock. + * @dma_unmap_len: Length to unmap for an oversize buffer, or 0. + * @dma_addr: The DMA address of the header below. + * + * This controls the memory used for a TSO header. Use TSOH_DATA() + * to find the packet header data. Use TSOH_SIZE() to calculate the + * total size required for a given packet header length. TSO headers + * in the free list are exactly %TSOH_STD_SIZE bytes in size. + */ +struct efx_tso_header { + union { + struct efx_tso_header *next; + size_t unmap_len; + }; + dma_addr_t dma_addr; +}; + +static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, + struct sk_buff *skb); +static void efx_fini_tso(struct efx_tx_queue *tx_queue); +static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue, + struct efx_tso_header *tsoh); + +static void efx_tsoh_free(struct efx_tx_queue *tx_queue, + struct efx_tx_buffer *buffer) +{ + if (buffer->tsoh) { + if (likely(!buffer->tsoh->unmap_len)) { + buffer->tsoh->next = tx_queue->tso_headers_free; + tx_queue->tso_headers_free = buffer->tsoh; + } else { + efx_tsoh_heap_free(tx_queue, buffer->tsoh); + } + buffer->tsoh = NULL; + } +} + + +static inline unsigned +efx_max_tx_len(struct efx_nic *efx, dma_addr_t dma_addr) +{ + /* Depending on the NIC revision, we can use descriptor + * lengths up to 8K or 8K-1. However, since PCI Express + * devices must split read requests at 4K boundaries, there is + * little benefit from using descriptors that cross those + * boundaries and we keep things simple by not doing so. + */ + unsigned len = (~dma_addr & 0xfff) + 1; + + /* Work around hardware bug for unaligned buffers. */ + if (EFX_WORKAROUND_5391(efx) && (dma_addr & 0xf)) + len = min_t(unsigned, len, 512 - (dma_addr & 0xf)); + + return len; +} + +/* + * Add a socket buffer to a TX queue + * + * This maps all fragments of a socket buffer for DMA and adds them to + * the TX queue. The queue's insert pointer will be incremented by + * the number of fragments in the socket buffer. + * + * If any DMA mapping fails, any mapped fragments will be unmapped, + * the queue's insert pointer will be restored to its original value. + * + * This function is split out from efx_hard_start_xmit to allow the + * loopback test to direct packets via specific TX queues. + * + * Returns NETDEV_TX_OK or NETDEV_TX_BUSY + * You must hold netif_tx_lock() to call this function. + */ +netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb) +{ + struct efx_nic *efx = tx_queue->efx; + struct pci_dev *pci_dev = efx->pci_dev; + struct efx_tx_buffer *buffer; + skb_frag_t *fragment; + unsigned int len, unmap_len = 0, fill_level, insert_ptr; + dma_addr_t dma_addr, unmap_addr = 0; + unsigned int dma_len; + bool unmap_single; + int q_space, i = 0; + netdev_tx_t rc = NETDEV_TX_OK; + + EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count); + + if (skb_shinfo(skb)->gso_size) + return efx_enqueue_skb_tso(tx_queue, skb); + + /* Get size of the initial fragment */ + len = skb_headlen(skb); + + /* Pad if necessary */ + if (EFX_WORKAROUND_15592(efx) && skb->len <= 32) { + EFX_BUG_ON_PARANOID(skb->data_len); + len = 32 + 1; + if (skb_pad(skb, len - skb->len)) + return NETDEV_TX_OK; + } + + fill_level = tx_queue->insert_count - tx_queue->old_read_count; + q_space = efx->txq_entries - 1 - fill_level; + + /* Map for DMA. Use pci_map_single rather than pci_map_page + * since this is more efficient on machines with sparse + * memory. + */ + unmap_single = true; + dma_addr = pci_map_single(pci_dev, skb->data, len, PCI_DMA_TODEVICE); + + /* Process all fragments */ + while (1) { + if (unlikely(pci_dma_mapping_error(pci_dev, dma_addr))) + goto pci_err; + + /* Store fields for marking in the per-fragment final + * descriptor */ + unmap_len = len; + unmap_addr = dma_addr; + + /* Add to TX queue, splitting across DMA boundaries */ + do { + if (unlikely(q_space-- <= 0)) { + /* It might be that completions have + * happened since the xmit path last + * checked. Update the xmit path's + * copy of read_count. + */ + netif_tx_stop_queue(tx_queue->core_txq); + /* This memory barrier protects the + * change of queue state from the access + * of read_count. */ + smp_mb(); + tx_queue->old_read_count = + ACCESS_ONCE(tx_queue->read_count); + fill_level = (tx_queue->insert_count + - tx_queue->old_read_count); + q_space = efx->txq_entries - 1 - fill_level; + if (unlikely(q_space-- <= 0)) { + rc = NETDEV_TX_BUSY; + goto unwind; + } + smp_mb(); + if (likely(!efx->loopback_selftest)) + netif_tx_start_queue( + tx_queue->core_txq); + } + + insert_ptr = tx_queue->insert_count & tx_queue->ptr_mask; + buffer = &tx_queue->buffer[insert_ptr]; + efx_tsoh_free(tx_queue, buffer); + EFX_BUG_ON_PARANOID(buffer->tsoh); + EFX_BUG_ON_PARANOID(buffer->skb); + EFX_BUG_ON_PARANOID(buffer->len); + EFX_BUG_ON_PARANOID(!buffer->continuation); + EFX_BUG_ON_PARANOID(buffer->unmap_len); + + dma_len = efx_max_tx_len(efx, dma_addr); + if (likely(dma_len >= len)) + dma_len = len; + + /* Fill out per descriptor fields */ + buffer->len = dma_len; + buffer->dma_addr = dma_addr; + len -= dma_len; + dma_addr += dma_len; + ++tx_queue->insert_count; + } while (len); + + /* Transfer ownership of the unmapping to the final buffer */ + buffer->unmap_single = unmap_single; + buffer->unmap_len = unmap_len; + unmap_len = 0; + + /* Get address and size of next fragment */ + if (i >= skb_shinfo(skb)->nr_frags) + break; + fragment = &skb_shinfo(skb)->frags[i]; + len = skb_frag_size(fragment); + i++; + /* Map for DMA */ + unmap_single = false; + dma_addr = skb_frag_dma_map(&pci_dev->dev, fragment, 0, len, + DMA_TO_DEVICE); + } + + /* Transfer ownership of the skb to the final buffer */ + buffer->skb = skb; + buffer->continuation = false; + + /* Pass off to hardware */ + efx_nic_push_buffers(tx_queue); + + return NETDEV_TX_OK; + + pci_err: + netif_err(efx, tx_err, efx->net_dev, + " TX queue %d could not map skb with %d bytes %d " + "fragments for DMA\n", tx_queue->queue, skb->len, + skb_shinfo(skb)->nr_frags + 1); + + /* Mark the packet as transmitted, and free the SKB ourselves */ + dev_kfree_skb_any(skb); + + unwind: + /* Work backwards until we hit the original insert pointer value */ + while (tx_queue->insert_count != tx_queue->write_count) { + --tx_queue->insert_count; + insert_ptr = tx_queue->insert_count & tx_queue->ptr_mask; + buffer = &tx_queue->buffer[insert_ptr]; + efx_dequeue_buffer(tx_queue, buffer); + buffer->len = 0; + } + + /* Free the fragment we were mid-way through pushing */ + if (unmap_len) { + if (unmap_single) + pci_unmap_single(pci_dev, unmap_addr, unmap_len, + PCI_DMA_TODEVICE); + else + pci_unmap_page(pci_dev, unmap_addr, unmap_len, + PCI_DMA_TODEVICE); + } + + return rc; +} + +/* Remove packets from the TX queue + * + * This removes packets from the TX queue, up to and including the + * specified index. + */ +static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue, + unsigned int index) +{ + struct efx_nic *efx = tx_queue->efx; + unsigned int stop_index, read_ptr; + + stop_index = (index + 1) & tx_queue->ptr_mask; + read_ptr = tx_queue->read_count & tx_queue->ptr_mask; + + while (read_ptr != stop_index) { + struct efx_tx_buffer *buffer = &tx_queue->buffer[read_ptr]; + if (unlikely(buffer->len == 0)) { + netif_err(efx, tx_err, efx->net_dev, + "TX queue %d spurious TX completion id %x\n", + tx_queue->queue, read_ptr); + efx_schedule_reset(efx, RESET_TYPE_TX_SKIP); + return; + } + + efx_dequeue_buffer(tx_queue, buffer); + buffer->continuation = true; + buffer->len = 0; + + ++tx_queue->read_count; + read_ptr = tx_queue->read_count & tx_queue->ptr_mask; + } +} + +/* Initiate a packet transmission. We use one channel per CPU + * (sharing when we have more CPUs than channels). On Falcon, the TX + * completion events will be directed back to the CPU that transmitted + * the packet, which should be cache-efficient. + * + * Context: non-blocking. + * Note that returning anything other than NETDEV_TX_OK will cause the + * OS to free the skb. + */ +netdev_tx_t efx_hard_start_xmit(struct sk_buff *skb, + struct net_device *net_dev) +{ + struct efx_nic *efx = netdev_priv(net_dev); + struct efx_tx_queue *tx_queue; + unsigned index, type; + + EFX_WARN_ON_PARANOID(!netif_device_present(net_dev)); + + index = skb_get_queue_mapping(skb); + type = skb->ip_summed == CHECKSUM_PARTIAL ? EFX_TXQ_TYPE_OFFLOAD : 0; + if (index >= efx->n_tx_channels) { + index -= efx->n_tx_channels; + type |= EFX_TXQ_TYPE_HIGHPRI; + } + tx_queue = efx_get_tx_queue(efx, index, type); + + return efx_enqueue_skb(tx_queue, skb); +} + +void efx_init_tx_queue_core_txq(struct efx_tx_queue *tx_queue) +{ + struct efx_nic *efx = tx_queue->efx; + + /* Must be inverse of queue lookup in efx_hard_start_xmit() */ + tx_queue->core_txq = + netdev_get_tx_queue(efx->net_dev, + tx_queue->queue / EFX_TXQ_TYPES + + ((tx_queue->queue & EFX_TXQ_TYPE_HIGHPRI) ? + efx->n_tx_channels : 0)); +} + +int efx_setup_tc(struct net_device *net_dev, u8 num_tc) +{ + struct efx_nic *efx = netdev_priv(net_dev); + struct efx_channel *channel; + struct efx_tx_queue *tx_queue; + unsigned tc; + int rc; + + if (efx_nic_rev(efx) < EFX_REV_FALCON_B0 || num_tc > EFX_MAX_TX_TC) + return -EINVAL; + + if (num_tc == net_dev->num_tc) + return 0; + + for (tc = 0; tc < num_tc; tc++) { + net_dev->tc_to_txq[tc].offset = tc * efx->n_tx_channels; + net_dev->tc_to_txq[tc].count = efx->n_tx_channels; + } + + if (num_tc > net_dev->num_tc) { + /* Initialise high-priority queues as necessary */ + efx_for_each_channel(channel, efx) { + efx_for_each_possible_channel_tx_queue(tx_queue, + channel) { + if (!(tx_queue->queue & EFX_TXQ_TYPE_HIGHPRI)) + continue; + if (!tx_queue->buffer) { + rc = efx_probe_tx_queue(tx_queue); + if (rc) + return rc; + } + if (!tx_queue->initialised) + efx_init_tx_queue(tx_queue); + efx_init_tx_queue_core_txq(tx_queue); + } + } + } else { + /* Reduce number of classes before number of queues */ + net_dev->num_tc = num_tc; + } + + rc = netif_set_real_num_tx_queues(net_dev, + max_t(int, num_tc, 1) * + efx->n_tx_channels); + if (rc) + return rc; + + /* Do not destroy high-priority queues when they become + * unused. We would have to flush them first, and it is + * fairly difficult to flush a subset of TX queues. Leave + * it to efx_fini_channels(). + */ + + net_dev->num_tc = num_tc; + return 0; +} + +void efx_xmit_done(struct efx_tx_queue *tx_queue, unsigned int index) +{ + unsigned fill_level; + struct efx_nic *efx = tx_queue->efx; + + EFX_BUG_ON_PARANOID(index > tx_queue->ptr_mask); + + efx_dequeue_buffers(tx_queue, index); + + /* See if we need to restart the netif queue. This barrier + * separates the update of read_count from the test of the + * queue state. */ + smp_mb(); + if (unlikely(netif_tx_queue_stopped(tx_queue->core_txq)) && + likely(efx->port_enabled) && + likely(netif_device_present(efx->net_dev))) { + fill_level = tx_queue->insert_count - tx_queue->read_count; + if (fill_level < EFX_TXQ_THRESHOLD(efx)) { + EFX_BUG_ON_PARANOID(!efx_dev_registered(efx)); + netif_tx_wake_queue(tx_queue->core_txq); + } + } + + /* Check whether the hardware queue is now empty */ + if ((int)(tx_queue->read_count - tx_queue->old_write_count) >= 0) { + tx_queue->old_write_count = ACCESS_ONCE(tx_queue->write_count); + if (tx_queue->read_count == tx_queue->old_write_count) { + smp_mb(); + tx_queue->empty_read_count = + tx_queue->read_count | EFX_EMPTY_COUNT_VALID; + } + } +} + +int efx_probe_tx_queue(struct efx_tx_queue *tx_queue) +{ + struct efx_nic *efx = tx_queue->efx; + unsigned int entries; + int i, rc; + + /* Create the smallest power-of-two aligned ring */ + entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE); + EFX_BUG_ON_PARANOID(entries > EFX_MAX_DMAQ_SIZE); + tx_queue->ptr_mask = entries - 1; + + netif_dbg(efx, probe, efx->net_dev, + "creating TX queue %d size %#x mask %#x\n", + tx_queue->queue, efx->txq_entries, tx_queue->ptr_mask); + + /* Allocate software ring */ + tx_queue->buffer = kzalloc(entries * sizeof(*tx_queue->buffer), + GFP_KERNEL); + if (!tx_queue->buffer) + return -ENOMEM; + for (i = 0; i <= tx_queue->ptr_mask; ++i) + tx_queue->buffer[i].continuation = true; + + /* Allocate hardware ring */ + rc = efx_nic_probe_tx(tx_queue); + if (rc) + goto fail; + + return 0; + + fail: + kfree(tx_queue->buffer); + tx_queue->buffer = NULL; + return rc; +} + +void efx_init_tx_queue(struct efx_tx_queue *tx_queue) +{ + netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev, + "initialising TX queue %d\n", tx_queue->queue); + + tx_queue->insert_count = 0; + tx_queue->write_count = 0; + tx_queue->old_write_count = 0; + tx_queue->read_count = 0; + tx_queue->old_read_count = 0; + tx_queue->empty_read_count = 0 | EFX_EMPTY_COUNT_VALID; + + /* Set up TX descriptor ring */ + efx_nic_init_tx(tx_queue); + + tx_queue->initialised = true; +} + +void efx_release_tx_buffers(struct efx_tx_queue *tx_queue) +{ + struct efx_tx_buffer *buffer; + + if (!tx_queue->buffer) + return; + + /* Free any buffers left in the ring */ + while (tx_queue->read_count != tx_queue->write_count) { + buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask]; + efx_dequeue_buffer(tx_queue, buffer); + buffer->continuation = true; + buffer->len = 0; + + ++tx_queue->read_count; + } +} + +void efx_fini_tx_queue(struct efx_tx_queue *tx_queue) +{ + if (!tx_queue->initialised) + return; + + netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev, + "shutting down TX queue %d\n", tx_queue->queue); + + tx_queue->initialised = false; + + /* Flush TX queue, remove descriptor ring */ + efx_nic_fini_tx(tx_queue); + + efx_release_tx_buffers(tx_queue); + + /* Free up TSO header cache */ + efx_fini_tso(tx_queue); +} + +void efx_remove_tx_queue(struct efx_tx_queue *tx_queue) +{ + if (!tx_queue->buffer) + return; + + netif_dbg(tx_queue->efx, drv, tx_queue->efx->net_dev, + "destroying TX queue %d\n", tx_queue->queue); + efx_nic_remove_tx(tx_queue); + + kfree(tx_queue->buffer); + tx_queue->buffer = NULL; +} + + +/* Efx TCP segmentation acceleration. + * + * Why? Because by doing it here in the driver we can go significantly + * faster than the GSO. + * + * Requires TX checksum offload support. + */ + +/* Number of bytes inserted at the start of a TSO header buffer, + * similar to NET_IP_ALIGN. + */ +#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS +#define TSOH_OFFSET 0 +#else +#define TSOH_OFFSET NET_IP_ALIGN +#endif + +#define TSOH_BUFFER(tsoh) ((u8 *)(tsoh + 1) + TSOH_OFFSET) + +/* Total size of struct efx_tso_header, buffer and padding */ +#define TSOH_SIZE(hdr_len) \ + (sizeof(struct efx_tso_header) + TSOH_OFFSET + hdr_len) + +/* Size of blocks on free list. Larger blocks must be allocated from + * the heap. + */ +#define TSOH_STD_SIZE 128 + +#define PTR_DIFF(p1, p2) ((u8 *)(p1) - (u8 *)(p2)) +#define ETH_HDR_LEN(skb) (skb_network_header(skb) - (skb)->data) +#define SKB_TCP_OFF(skb) PTR_DIFF(tcp_hdr(skb), (skb)->data) +#define SKB_IPV4_OFF(skb) PTR_DIFF(ip_hdr(skb), (skb)->data) +#define SKB_IPV6_OFF(skb) PTR_DIFF(ipv6_hdr(skb), (skb)->data) + +/** + * struct tso_state - TSO state for an SKB + * @out_len: Remaining length in current segment + * @seqnum: Current sequence number + * @ipv4_id: Current IPv4 ID, host endian + * @packet_space: Remaining space in current packet + * @dma_addr: DMA address of current position + * @in_len: Remaining length in current SKB fragment + * @unmap_len: Length of SKB fragment + * @unmap_addr: DMA address of SKB fragment + * @unmap_single: DMA single vs page mapping flag + * @protocol: Network protocol (after any VLAN header) + * @header_len: Number of bytes of header + * @full_packet_size: Number of bytes to put in each outgoing segment + * + * The state used during segmentation. It is put into this data structure + * just to make it easy to pass into inline functions. + */ +struct tso_state { + /* Output position */ + unsigned out_len; + unsigned seqnum; + unsigned ipv4_id; + unsigned packet_space; + + /* Input position */ + dma_addr_t dma_addr; + unsigned in_len; + unsigned unmap_len; + dma_addr_t unmap_addr; + bool unmap_single; + + __be16 protocol; + unsigned header_len; + int full_packet_size; +}; + + +/* + * Verify that our various assumptions about sk_buffs and the conditions + * under which TSO will be attempted hold true. Return the protocol number. + */ +static __be16 efx_tso_check_protocol(struct sk_buff *skb) +{ + __be16 protocol = skb->protocol; + + EFX_BUG_ON_PARANOID(((struct ethhdr *)skb->data)->h_proto != + protocol); + if (protocol == htons(ETH_P_8021Q)) { + /* Find the encapsulated protocol; reset network header + * and transport header based on that. */ + struct vlan_ethhdr *veh = (struct vlan_ethhdr *)skb->data; + protocol = veh->h_vlan_encapsulated_proto; + skb_set_network_header(skb, sizeof(*veh)); + if (protocol == htons(ETH_P_IP)) + skb_set_transport_header(skb, sizeof(*veh) + + 4 * ip_hdr(skb)->ihl); + else if (protocol == htons(ETH_P_IPV6)) + skb_set_transport_header(skb, sizeof(*veh) + + sizeof(struct ipv6hdr)); + } + + if (protocol == htons(ETH_P_IP)) { + EFX_BUG_ON_PARANOID(ip_hdr(skb)->protocol != IPPROTO_TCP); + } else { + EFX_BUG_ON_PARANOID(protocol != htons(ETH_P_IPV6)); + EFX_BUG_ON_PARANOID(ipv6_hdr(skb)->nexthdr != NEXTHDR_TCP); + } + EFX_BUG_ON_PARANOID((PTR_DIFF(tcp_hdr(skb), skb->data) + + (tcp_hdr(skb)->doff << 2u)) > + skb_headlen(skb)); + + return protocol; +} + + +/* + * Allocate a page worth of efx_tso_header structures, and string them + * into the tx_queue->tso_headers_free linked list. Return 0 or -ENOMEM. + */ +static int efx_tsoh_block_alloc(struct efx_tx_queue *tx_queue) +{ + + struct pci_dev *pci_dev = tx_queue->efx->pci_dev; + struct efx_tso_header *tsoh; + dma_addr_t dma_addr; + u8 *base_kva, *kva; + + base_kva = pci_alloc_consistent(pci_dev, PAGE_SIZE, &dma_addr); + if (base_kva == NULL) { + netif_err(tx_queue->efx, tx_err, tx_queue->efx->net_dev, + "Unable to allocate page for TSO headers\n"); + return -ENOMEM; + } + + /* pci_alloc_consistent() allocates pages. */ + EFX_BUG_ON_PARANOID(dma_addr & (PAGE_SIZE - 1u)); + + for (kva = base_kva; kva < base_kva + PAGE_SIZE; kva += TSOH_STD_SIZE) { + tsoh = (struct efx_tso_header *)kva; + tsoh->dma_addr = dma_addr + (TSOH_BUFFER(tsoh) - base_kva); + tsoh->next = tx_queue->tso_headers_free; + tx_queue->tso_headers_free = tsoh; + } + + return 0; +} + + +/* Free up a TSO header, and all others in the same page. */ +static void efx_tsoh_block_free(struct efx_tx_queue *tx_queue, + struct efx_tso_header *tsoh, + struct pci_dev *pci_dev) +{ + struct efx_tso_header **p; + unsigned long base_kva; + dma_addr_t base_dma; + + base_kva = (unsigned long)tsoh & PAGE_MASK; + base_dma = tsoh->dma_addr & PAGE_MASK; + + p = &tx_queue->tso_headers_free; + while (*p != NULL) { + if (((unsigned long)*p & PAGE_MASK) == base_kva) + *p = (*p)->next; + else + p = &(*p)->next; + } + + pci_free_consistent(pci_dev, PAGE_SIZE, (void *)base_kva, base_dma); +} + +static struct efx_tso_header * +efx_tsoh_heap_alloc(struct efx_tx_queue *tx_queue, size_t header_len) +{ + struct efx_tso_header *tsoh; + + tsoh = kmalloc(TSOH_SIZE(header_len), GFP_ATOMIC | GFP_DMA); + if (unlikely(!tsoh)) + return NULL; + + tsoh->dma_addr = pci_map_single(tx_queue->efx->pci_dev, + TSOH_BUFFER(tsoh), header_len, + PCI_DMA_TODEVICE); + if (unlikely(pci_dma_mapping_error(tx_queue->efx->pci_dev, + tsoh->dma_addr))) { + kfree(tsoh); + return NULL; + } + + tsoh->unmap_len = header_len; + return tsoh; +} + +static void +efx_tsoh_heap_free(struct efx_tx_queue *tx_queue, struct efx_tso_header *tsoh) +{ + pci_unmap_single(tx_queue->efx->pci_dev, + tsoh->dma_addr, tsoh->unmap_len, + PCI_DMA_TODEVICE); + kfree(tsoh); +} + +/** + * efx_tx_queue_insert - push descriptors onto the TX queue + * @tx_queue: Efx TX queue + * @dma_addr: DMA address of fragment + * @len: Length of fragment + * @final_buffer: The final buffer inserted into the queue + * + * Push descriptors onto the TX queue. Return 0 on success or 1 if + * @tx_queue full. + */ +static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue, + dma_addr_t dma_addr, unsigned len, + struct efx_tx_buffer **final_buffer) +{ + struct efx_tx_buffer *buffer; + struct efx_nic *efx = tx_queue->efx; + unsigned dma_len, fill_level, insert_ptr; + int q_space; + + EFX_BUG_ON_PARANOID(len <= 0); + + fill_level = tx_queue->insert_count - tx_queue->old_read_count; + /* -1 as there is no way to represent all descriptors used */ + q_space = efx->txq_entries - 1 - fill_level; + + while (1) { + if (unlikely(q_space-- <= 0)) { + /* It might be that completions have happened + * since the xmit path last checked. Update + * the xmit path's copy of read_count. + */ + netif_tx_stop_queue(tx_queue->core_txq); + /* This memory barrier protects the change of + * queue state from the access of read_count. */ + smp_mb(); + tx_queue->old_read_count = + ACCESS_ONCE(tx_queue->read_count); + fill_level = (tx_queue->insert_count + - tx_queue->old_read_count); + q_space = efx->txq_entries - 1 - fill_level; + if (unlikely(q_space-- <= 0)) { + *final_buffer = NULL; + return 1; + } + smp_mb(); + netif_tx_start_queue(tx_queue->core_txq); + } + + insert_ptr = tx_queue->insert_count & tx_queue->ptr_mask; + buffer = &tx_queue->buffer[insert_ptr]; + ++tx_queue->insert_count; + + EFX_BUG_ON_PARANOID(tx_queue->insert_count - + tx_queue->read_count >= + efx->txq_entries); + + efx_tsoh_free(tx_queue, buffer); + EFX_BUG_ON_PARANOID(buffer->len); + EFX_BUG_ON_PARANOID(buffer->unmap_len); + EFX_BUG_ON_PARANOID(buffer->skb); + EFX_BUG_ON_PARANOID(!buffer->continuation); + EFX_BUG_ON_PARANOID(buffer->tsoh); + + buffer->dma_addr = dma_addr; + + dma_len = efx_max_tx_len(efx, dma_addr); + + /* If there is enough space to send then do so */ + if (dma_len >= len) + break; + + buffer->len = dma_len; /* Don't set the other members */ + dma_addr += dma_len; + len -= dma_len; + } + + EFX_BUG_ON_PARANOID(!len); + buffer->len = len; + *final_buffer = buffer; + return 0; +} + + +/* + * Put a TSO header into the TX queue. + * + * This is special-cased because we know that it is small enough to fit in + * a single fragment, and we know it doesn't cross a page boundary. It + * also allows us to not worry about end-of-packet etc. + */ +static void efx_tso_put_header(struct efx_tx_queue *tx_queue, + struct efx_tso_header *tsoh, unsigned len) +{ + struct efx_tx_buffer *buffer; + + buffer = &tx_queue->buffer[tx_queue->insert_count & tx_queue->ptr_mask]; + efx_tsoh_free(tx_queue, buffer); + EFX_BUG_ON_PARANOID(buffer->len); + EFX_BUG_ON_PARANOID(buffer->unmap_len); + EFX_BUG_ON_PARANOID(buffer->skb); + EFX_BUG_ON_PARANOID(!buffer->continuation); + EFX_BUG_ON_PARANOID(buffer->tsoh); + buffer->len = len; + buffer->dma_addr = tsoh->dma_addr; + buffer->tsoh = tsoh; + + ++tx_queue->insert_count; +} + + +/* Remove descriptors put into a tx_queue. */ +static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue) +{ + struct efx_tx_buffer *buffer; + dma_addr_t unmap_addr; + + /* Work backwards until we hit the original insert pointer value */ + while (tx_queue->insert_count != tx_queue->write_count) { + --tx_queue->insert_count; + buffer = &tx_queue->buffer[tx_queue->insert_count & + tx_queue->ptr_mask]; + efx_tsoh_free(tx_queue, buffer); + EFX_BUG_ON_PARANOID(buffer->skb); + if (buffer->unmap_len) { + unmap_addr = (buffer->dma_addr + buffer->len - + buffer->unmap_len); + if (buffer->unmap_single) + pci_unmap_single(tx_queue->efx->pci_dev, + unmap_addr, buffer->unmap_len, + PCI_DMA_TODEVICE); + else + pci_unmap_page(tx_queue->efx->pci_dev, + unmap_addr, buffer->unmap_len, + PCI_DMA_TODEVICE); + buffer->unmap_len = 0; + } + buffer->len = 0; + buffer->continuation = true; + } +} + + +/* Parse the SKB header and initialise state. */ +static void tso_start(struct tso_state *st, const struct sk_buff *skb) +{ + /* All ethernet/IP/TCP headers combined size is TCP header size + * plus offset of TCP header relative to start of packet. + */ + st->header_len = ((tcp_hdr(skb)->doff << 2u) + + PTR_DIFF(tcp_hdr(skb), skb->data)); + st->full_packet_size = st->header_len + skb_shinfo(skb)->gso_size; + + if (st->protocol == htons(ETH_P_IP)) + st->ipv4_id = ntohs(ip_hdr(skb)->id); + else + st->ipv4_id = 0; + st->seqnum = ntohl(tcp_hdr(skb)->seq); + + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->urg); + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->syn); + EFX_BUG_ON_PARANOID(tcp_hdr(skb)->rst); + + st->packet_space = st->full_packet_size; + st->out_len = skb->len - st->header_len; + st->unmap_len = 0; + st->unmap_single = false; +} + +static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx, + skb_frag_t *frag) +{ + st->unmap_addr = skb_frag_dma_map(&efx->pci_dev->dev, frag, 0, + skb_frag_size(frag), DMA_TO_DEVICE); + if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) { + st->unmap_single = false; + st->unmap_len = skb_frag_size(frag); + st->in_len = skb_frag_size(frag); + st->dma_addr = st->unmap_addr; + return 0; + } + return -ENOMEM; +} + +static int tso_get_head_fragment(struct tso_state *st, struct efx_nic *efx, + const struct sk_buff *skb) +{ + int hl = st->header_len; + int len = skb_headlen(skb) - hl; + + st->unmap_addr = pci_map_single(efx->pci_dev, skb->data + hl, + len, PCI_DMA_TODEVICE); + if (likely(!pci_dma_mapping_error(efx->pci_dev, st->unmap_addr))) { + st->unmap_single = true; + st->unmap_len = len; + st->in_len = len; + st->dma_addr = st->unmap_addr; + return 0; + } + return -ENOMEM; +} + + +/** + * tso_fill_packet_with_fragment - form descriptors for the current fragment + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * @st: TSO state + * + * Form descriptors for the current fragment, until we reach the end + * of fragment or end-of-packet. Return 0 on success, 1 if not enough + * space in @tx_queue. + */ +static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue, + const struct sk_buff *skb, + struct tso_state *st) +{ + struct efx_tx_buffer *buffer; + int n, end_of_packet, rc; + + if (st->in_len == 0) + return 0; + if (st->packet_space == 0) + return 0; + + EFX_BUG_ON_PARANOID(st->in_len <= 0); + EFX_BUG_ON_PARANOID(st->packet_space <= 0); + + n = min(st->in_len, st->packet_space); + + st->packet_space -= n; + st->out_len -= n; + st->in_len -= n; + + rc = efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer); + if (likely(rc == 0)) { + if (st->out_len == 0) + /* Transfer ownership of the skb */ + buffer->skb = skb; + + end_of_packet = st->out_len == 0 || st->packet_space == 0; + buffer->continuation = !end_of_packet; + + if (st->in_len == 0) { + /* Transfer ownership of the pci mapping */ + buffer->unmap_len = st->unmap_len; + buffer->unmap_single = st->unmap_single; + st->unmap_len = 0; + } + } + + st->dma_addr += n; + return rc; +} + + +/** + * tso_start_new_packet - generate a new header and prepare for the new packet + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * @st: TSO state + * + * Generate a new header and prepare for the new packet. Return 0 on + * success, or -1 if failed to alloc header. + */ +static int tso_start_new_packet(struct efx_tx_queue *tx_queue, + const struct sk_buff *skb, + struct tso_state *st) +{ + struct efx_tso_header *tsoh; + struct tcphdr *tsoh_th; + unsigned ip_length; + u8 *header; + + /* Allocate a DMA-mapped header buffer. */ + if (likely(TSOH_SIZE(st->header_len) <= TSOH_STD_SIZE)) { + if (tx_queue->tso_headers_free == NULL) { + if (efx_tsoh_block_alloc(tx_queue)) + return -1; + } + EFX_BUG_ON_PARANOID(!tx_queue->tso_headers_free); + tsoh = tx_queue->tso_headers_free; + tx_queue->tso_headers_free = tsoh->next; + tsoh->unmap_len = 0; + } else { + tx_queue->tso_long_headers++; + tsoh = efx_tsoh_heap_alloc(tx_queue, st->header_len); + if (unlikely(!tsoh)) + return -1; + } + + header = TSOH_BUFFER(tsoh); + tsoh_th = (struct tcphdr *)(header + SKB_TCP_OFF(skb)); + + /* Copy and update the headers. */ + memcpy(header, skb->data, st->header_len); + + tsoh_th->seq = htonl(st->seqnum); + st->seqnum += skb_shinfo(skb)->gso_size; + if (st->out_len > skb_shinfo(skb)->gso_size) { + /* This packet will not finish the TSO burst. */ + ip_length = st->full_packet_size - ETH_HDR_LEN(skb); + tsoh_th->fin = 0; + tsoh_th->psh = 0; + } else { + /* This packet will be the last in the TSO burst. */ + ip_length = st->header_len - ETH_HDR_LEN(skb) + st->out_len; + tsoh_th->fin = tcp_hdr(skb)->fin; + tsoh_th->psh = tcp_hdr(skb)->psh; + } + + if (st->protocol == htons(ETH_P_IP)) { + struct iphdr *tsoh_iph = + (struct iphdr *)(header + SKB_IPV4_OFF(skb)); + + tsoh_iph->tot_len = htons(ip_length); + + /* Linux leaves suitable gaps in the IP ID space for us to fill. */ + tsoh_iph->id = htons(st->ipv4_id); + st->ipv4_id++; + } else { + struct ipv6hdr *tsoh_iph = + (struct ipv6hdr *)(header + SKB_IPV6_OFF(skb)); + + tsoh_iph->payload_len = htons(ip_length - sizeof(*tsoh_iph)); + } + + st->packet_space = skb_shinfo(skb)->gso_size; + ++tx_queue->tso_packets; + + /* Form a descriptor for this header. */ + efx_tso_put_header(tx_queue, tsoh, st->header_len); + + return 0; +} + + +/** + * efx_enqueue_skb_tso - segment and transmit a TSO socket buffer + * @tx_queue: Efx TX queue + * @skb: Socket buffer + * + * Context: You must hold netif_tx_lock() to call this function. + * + * Add socket buffer @skb to @tx_queue, doing TSO or return != 0 if + * @skb was not enqueued. In all cases @skb is consumed. Return + * %NETDEV_TX_OK or %NETDEV_TX_BUSY. + */ +static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue, + struct sk_buff *skb) +{ + struct efx_nic *efx = tx_queue->efx; + int frag_i, rc, rc2 = NETDEV_TX_OK; + struct tso_state state; + + /* Find the packet protocol and sanity-check it */ + state.protocol = efx_tso_check_protocol(skb); + + EFX_BUG_ON_PARANOID(tx_queue->write_count != tx_queue->insert_count); + + tso_start(&state, skb); + + /* Assume that skb header area contains exactly the headers, and + * all payload is in the frag list. + */ + if (skb_headlen(skb) == state.header_len) { + /* Grab the first payload fragment. */ + EFX_BUG_ON_PARANOID(skb_shinfo(skb)->nr_frags < 1); + frag_i = 0; + rc = tso_get_fragment(&state, efx, + skb_shinfo(skb)->frags + frag_i); + if (rc) + goto mem_err; + } else { + rc = tso_get_head_fragment(&state, efx, skb); + if (rc) + goto mem_err; + frag_i = -1; + } + + if (tso_start_new_packet(tx_queue, skb, &state) < 0) + goto mem_err; + + while (1) { + rc = tso_fill_packet_with_fragment(tx_queue, skb, &state); + if (unlikely(rc)) { + rc2 = NETDEV_TX_BUSY; + goto unwind; + } + + /* Move onto the next fragment? */ + if (state.in_len == 0) { + if (++frag_i >= skb_shinfo(skb)->nr_frags) + /* End of payload reached. */ + break; + rc = tso_get_fragment(&state, efx, + skb_shinfo(skb)->frags + frag_i); + if (rc) + goto mem_err; + } + + /* Start at new packet? */ + if (state.packet_space == 0 && + tso_start_new_packet(tx_queue, skb, &state) < 0) + goto mem_err; + } + + /* Pass off to hardware */ + efx_nic_push_buffers(tx_queue); + + tx_queue->tso_bursts++; + return NETDEV_TX_OK; + + mem_err: + netif_err(efx, tx_err, efx->net_dev, + "Out of memory for TSO headers, or PCI mapping error\n"); + dev_kfree_skb_any(skb); + + unwind: + /* Free the DMA mapping we were in the process of writing out */ + if (state.unmap_len) { + if (state.unmap_single) + pci_unmap_single(efx->pci_dev, state.unmap_addr, + state.unmap_len, PCI_DMA_TODEVICE); + else + pci_unmap_page(efx->pci_dev, state.unmap_addr, + state.unmap_len, PCI_DMA_TODEVICE); + } + + efx_enqueue_unwind(tx_queue); + return rc2; +} + + +/* + * Free up all TSO datastructures associated with tx_queue. This + * routine should be called only once the tx_queue is both empty and + * will no longer be used. + */ +static void efx_fini_tso(struct efx_tx_queue *tx_queue) +{ + unsigned i; + + if (tx_queue->buffer) { + for (i = 0; i <= tx_queue->ptr_mask; ++i) + efx_tsoh_free(tx_queue, &tx_queue->buffer[i]); + } + + while (tx_queue->tso_headers_free != NULL) + efx_tsoh_block_free(tx_queue, tx_queue->tso_headers_free, + tx_queue->efx->pci_dev); +} |