/* Parse the SKB header and initialise state. */
static int tso_start(struct tso_state *st, struct efx_nic *efx,
struct efx_tx_queue *tx_queue,
const struct sk_buff *skb)
{
struct device *dma_dev = &efx->pci_dev->dev;
unsigned int header_len, in_len;
bool use_opt_desc = false;
dma_addr_t dma_addr;
if (tx_queue->tso_version == 1)
use_opt_desc = true;
st->ip_off = skb_network_header(skb) - skb->data;
st->tcp_off = skb_transport_header(skb) - skb->data;
header_len = st->tcp_off + (tcp_hdr(skb)->doff << 2u);
in_len = skb_headlen(skb) - header_len;
st->header_len = header_len;
st->in_len = in_len;
if (st->protocol == htons(ETH_P_IP)) {
st->ip_base_len = st->header_len - st->ip_off;
st->ipv4_id = ntohs(ip_hdr(skb)->id);
} else {
st->ip_base_len = st->header_len - st->tcp_off;
st->ipv4_id = 0;
}
st->seqnum = ntohl(tcp_hdr(skb)->seq);
EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->urg);
EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->syn);
EFX_WARN_ON_ONCE_PARANOID(tcp_hdr(skb)->rst);
st->out_len = skb->len - header_len;
if (!use_opt_desc) {
st->header_unmap_len = 0;
if (likely(in_len == 0)) {
st->dma_flags = 0;
st->unmap_len = 0;
return 0;
}
dma_addr = dma_map_single(dma_dev, skb->data + header_len,
in_len, DMA_TO_DEVICE);
st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
st->dma_addr = dma_addr;
st->unmap_addr = dma_addr;
st->unmap_len = in_len;
} else {
dma_addr = dma_map_single(dma_dev, skb->data,
skb_headlen(skb), DMA_TO_DEVICE);
st->header_dma_addr = dma_addr;
st->header_unmap_len = skb_headlen(skb);
st->dma_flags = 0;
st->dma_addr = dma_addr + header_len;
st->unmap_len = 0;
}
return unlikely(dma_mapping_error(dma_dev, dma_addr)) ? -ENOMEM : 0;
}
static u8 *efx_tsoh_get_buffer(struct efx_tx_queue *tx_queue,
struct efx_tx_buffer *buffer, unsigned int len)
{
u8 *result;
EFX_WARN_ON_ONCE_PARANOID(buffer->len);
EFX_WARN_ON_ONCE_PARANOID(buffer->flags);
EFX_WARN_ON_ONCE_PARANOID(buffer->unmap_len);
result = efx_tx_get_copy_buffer_limited(tx_queue, buffer, len);
if (result) {
buffer->flags = EFX_TX_BUF_CONT;
} else {
buffer->buf = kmalloc(NET_IP_ALIGN + len, GFP_ATOMIC);
if (unlikely(!buffer->buf))
return NULL;
tx_queue->tso_long_headers++;
result = (u8 *)buffer->buf + NET_IP_ALIGN;
buffer->flags = EFX_TX_BUF_CONT | EFX_TX_BUF_HEAP;
}
buffer->len = len;
return result;
}
static int efx_enqueue_skb_copy(struct efx_tx_queue *tx_queue,
struct sk_buff *skb)
{
unsigned int copy_len = skb->len;
struct efx_tx_buffer *buffer;
u8 *copy_buffer;
int rc;
EFX_WARN_ON_ONCE_PARANOID(copy_len > EFX_TX_CB_SIZE);
buffer = efx_tx_queue_get_insert_buffer(tx_queue);
copy_buffer = efx_tx_get_copy_buffer(tx_queue, buffer);
if (unlikely(!copy_buffer))
return -ENOMEM;
rc = skb_copy_bits(skb, 0, copy_buffer, copy_len);
EFX_WARN_ON_PARANOID(rc);
buffer->len = copy_len;
buffer->skb = skb;
buffer->flags = EFX_TX_BUF_SKB;
++tx_queue->insert_count;
return rc;
}
/**
* 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.
*/
static void 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;
if (st->in_len == 0)
return;
if (st->packet_space == 0)
return;
EFX_WARN_ON_ONCE_PARANOID(st->in_len <= 0);
EFX_WARN_ON_ONCE_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;
efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
if (st->out_len == 0) {
/* Transfer ownership of the skb */
buffer->skb = skb;
buffer->flags = EFX_TX_BUF_SKB;
} else if (st->packet_space != 0) {
buffer->flags = EFX_TX_BUF_CONT;
}
if (st->in_len == 0) {
/* Transfer ownership of the DMA mapping */
buffer->unmap_len = st->unmap_len;
buffer->dma_offset = buffer->unmap_len - buffer->len;
buffer->flags |= st->dma_flags;
st->unmap_len = 0;
}
st->dma_addr += n;
}
/**
* 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.
*/
static void efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
dma_addr_t dma_addr, unsigned int len,
struct efx_tx_buffer **final_buffer)
{
struct efx_tx_buffer *buffer;
unsigned int dma_len;
EFX_WARN_ON_ONCE_PARANOID(len <= 0);
while (1) {
buffer = efx_tx_queue_get_insert_buffer(tx_queue);
++tx_queue->insert_count;
EFX_WARN_ON_ONCE_PARANOID(tx_queue->insert_count -
tx_queue->read_count >=
tx_queue->efx->txq_entries);
buffer->dma_addr = dma_addr;
dma_len = tx_queue->efx->type->tx_limit_len(tx_queue,
dma_addr, len);
/* If there's space for everything this is our last buffer. */
if (dma_len >= len)
break;
buffer->len = dma_len;
buffer->flags = EFX_TX_BUF_CONT;
dma_addr += dma_len;
len -= dma_len;
}
EFX_WARN_ON_ONCE_PARANOID(!len);
buffer->len = len;
*final_buffer = buffer;
}
static void efx_tx_maybe_stop_queue(struct efx_tx_queue *txq1)
{
/* We need to consider both queues that the net core sees as one */
struct efx_tx_queue *txq2 = efx_tx_queue_partner(txq1);
struct efx_nic *efx = txq1->efx;
unsigned int fill_level;
fill_level = max(txq1->insert_count - txq1->old_read_count,
txq2->insert_count - txq2->old_read_count);
if (likely(fill_level < efx->txq_stop_thresh))
return;
/* We used the stale old_read_count above, which gives us a
* pessimistic estimate of the fill level (which may even
* validly be >= efx->txq_entries). Now try again using
* read_count (more likely to be a cache miss).
*
* If we read read_count and then conditionally stop the
* queue, it is possible for the completion path to race with
* us and complete all outstanding descriptors in the middle,
* after which there will be no more completions to wake it.
* Therefore we stop the queue first, then read read_count
* (with a memory barrier to ensure the ordering), then
* restart the queue if the fill level turns out to be low
* enough.
*/
netif_tx_stop_queue(txq1->core_txq);
smp_mb();
txq1->old_read_count = ACCESS_ONCE(txq1->read_count);
txq2->old_read_count = ACCESS_ONCE(txq2->read_count);
fill_level = max(txq1->insert_count - txq1->old_read_count,
txq2->insert_count - txq2->old_read_count);
EFX_WARN_ON_ONCE_PARANOID(fill_level >= efx->txq_entries);
if (likely(fill_level < efx->txq_stop_thresh)) {
smp_mb();
if (likely(!efx->loopback_selftest))
netif_tx_start_queue(txq1->core_txq);
}
}
/**
* efx_tx_tso_sw - segment and transmit a TSO socket buffer using SW or FATSOv1
* @tx_queue: Efx TX queue
* @skb: Socket buffer
* @data_mapped: Did we map the data? Always set to true
* by this on success.
*
* 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.
*/
int efx_tx_tso_sw(struct efx_tx_queue *tx_queue, struct sk_buff *skb,
bool *data_mapped)
{
struct efx_nic *efx = tx_queue->efx;
int frag_i, rc;
struct tso_state state;
#if defined(EFX_USE_KCOMPAT) && !defined(EFX_HAVE_GSO_MAX_SEGS)
/* Since the stack does not limit the number of segments per
* skb, we must do so. Otherwise an attacker may be able to
* make the TCP produce skbs that will never fit in our TX
* queue, causing repeated resets.
*/
if (unlikely(skb_shinfo(skb)->gso_segs > EFX_TSO_MAX_SEGS)) {
unsigned int excess =
(skb_shinfo(skb)->gso_segs - EFX_TSO_MAX_SEGS) *
skb_shinfo(skb)->gso_size;
if (__pskb_trim(skb, skb->len - excess))
return -E2BIG;
}
#endif
prefetch(skb->data);
/* Find the packet protocol and sanity-check it */
rc = efx_tso_check_protocol(skb, &state.protocol);
if (rc)
return rc;
rc = tso_start(&state, efx, tx_queue, skb);
if (rc)
goto mem_err;
if (likely(state.in_len == 0)) {
/* Grab the first payload fragment. */
EFX_WARN_ON_ONCE_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 {
/* Payload starts in the header area. */
frag_i = -1;
}
if (tso_start_new_packet(tx_queue, skb, &state, true) < 0)
goto mem_err;
prefetch_ptr(tx_queue);
while (1) {
tso_fill_packet_with_fragment(tx_queue, skb, &state);
/* 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, false) < 0)
goto mem_err;
}
*data_mapped = true;
return 0;
mem_err:
netif_err(efx, tx_err, efx->net_dev,
"Out of memory for TSO headers, or DMA mapping error\n");
/* Free the DMA mapping we were in the process of writing out */
if (state.unmap_len) {
if (state.dma_flags & EFX_TX_BUF_MAP_SINGLE)
dma_unmap_single(&efx->pci_dev->dev, state.unmap_addr,
state.unmap_len, DMA_TO_DEVICE);
else
dma_unmap_page(&efx->pci_dev->dev, state.unmap_addr,
state.unmap_len, DMA_TO_DEVICE);
}
/* Free the header DMA mapping, if using option descriptors */
if (state.header_unmap_len)
dma_unmap_single(&efx->pci_dev->dev, state.header_dma_addr,
state.header_unmap_len, DMA_TO_DEVICE);
return -ENOMEM;
}
