sfc: Refactor struct efx_tx_buffer to use a flags field

Add a flags field to struct efx_tx_buffer, replacing the
continuation and map_single booleans.

Since a single descriptor cannot be both a TSO header and the last
descriptor for an skb, unionise efx_tx_buffer::{skb,tsoh} and add
flags for validity of these fields.

Clear all flags in free buffers (whereas previously the continuation
flag would be set).

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index cd9c0a9..0ac01fa 100644 (file)
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -91,29 +91,30 @@ struct efx_special_buffer {
 };
 
 /**
- * struct efx_tx_buffer - An Efx TX buffer
- * @skb: The associated socket buffer.
- *     Set only on the final fragment of a packet; %NULL for all other
- *     fragments.  When this fragment completes, then we can free this
- *     skb.
- * @tsoh: The associated TSO header structure, or %NULL if this
- *     buffer is not a TSO header.
+ * struct efx_tx_buffer - buffer state for a TX descriptor
+ * @skb: When @flags & %EFX_TX_BUF_SKB, the associated socket buffer to be
+ *     freed when descriptor completes
+ * @tsoh: When @flags & %EFX_TX_BUF_TSOH, the associated TSO header structure.
  * @dma_addr: DMA address of the fragment.
+ * @flags: Flags for allocation and DMA mapping type
  * @len: Length of this fragment.
  *     This field is zero when the queue slot is empty.
- * @continuation: True if this fragment is not the end of a packet.
- * @unmap_single: True if dma_unmap_single should be used.
  * @unmap_len: Length of this fragment to unmap
  */
 struct efx_tx_buffer {
-       const struct sk_buff *skb;
-       struct efx_tso_header *tsoh;
+       union {
+               const struct sk_buff *skb;
+               struct efx_tso_header *tsoh;
+       };
        dma_addr_t dma_addr;
+       unsigned short flags;
        unsigned short len;
-       bool continuation;
-       bool unmap_single;
        unsigned short unmap_len;
 };
+#define EFX_TX_BUF_CONT                1       /* not last descriptor of packet */
+#define EFX_TX_BUF_SKB         2       /* buffer is last part of skb */
+#define EFX_TX_BUF_TSOH                4       /* buffer is TSO header */
+#define EFX_TX_BUF_MAP_SINGLE  8       /* buffer was mapped with dma_map_single() */
 
 /**
  * struct efx_tx_queue - An Efx TX queue

diff --git a/drivers/net/ethernet/sfc/nic.c b/drivers/net/ethernet/sfc/nic.c
index 326d799..aa11370 100644 (file)
--- a/drivers/net/ethernet/sfc/nic.c
+++ b/drivers/net/ethernet/sfc/nic.c
@@ -401,8 +401,10 @@ void efx_nic_push_buffers(struct efx_tx_queue *tx_queue)
                ++tx_queue->write_count;
 
                /* Create TX descriptor ring entry */
+               BUILD_BUG_ON(EFX_TX_BUF_CONT != 1);
                EFX_POPULATE_QWORD_4(*txd,
-                                    FSF_AZ_TX_KER_CONT, buffer->continuation,
+                                    FSF_AZ_TX_KER_CONT,
+                                    buffer->flags & EFX_TX_BUF_CONT,
                                     FSF_AZ_TX_KER_BYTE_COUNT, buffer->len,
                                     FSF_AZ_TX_KER_BUF_REGION, 0,
                                     FSF_AZ_TX_KER_BUF_ADDR, buffer->dma_addr);

diff --git a/drivers/net/ethernet/sfc/tx.c b/drivers/net/ethernet/sfc/tx.c
index 1871343..24c82f3 100644 (file)
--- a/drivers/net/ethernet/sfc/tx.c
+++ b/drivers/net/ethernet/sfc/tx.c
@@ -39,25 +39,25 @@ static void efx_dequeue_buffer(struct efx_tx_queue *tx_queue,
                struct device *dma_dev = &tx_queue->efx->pci_dev->dev;
                dma_addr_t unmap_addr = (buffer->dma_addr + buffer->len -
                                         buffer->unmap_len);
-               if (buffer->unmap_single)
+               if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
                        dma_unmap_single(dma_dev, unmap_addr, buffer->unmap_len,
                                         DMA_TO_DEVICE);
                else
                        dma_unmap_page(dma_dev, unmap_addr, buffer->unmap_len,
                                       DMA_TO_DEVICE);
                buffer->unmap_len = 0;
-               buffer->unmap_single = false;
        }
 
-       if (buffer->skb) {
+       if (buffer->flags & EFX_TX_BUF_SKB) {
                (*pkts_compl)++;
                (*bytes_compl) += buffer->skb->len;
                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);
        }
+
+       buffer->flags &= EFX_TX_BUF_TSOH;
 }
 
 /**
@@ -89,14 +89,14 @@ static void efx_tsoh_heap_free(struct efx_tx_queue *tx_queue,
 static void efx_tsoh_free(struct efx_tx_queue *tx_queue,
                          struct efx_tx_buffer *buffer)
 {
-       if (buffer->tsoh) {
+       if (buffer->flags & EFX_TX_BUF_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;
+               buffer->flags &= ~EFX_TX_BUF_TSOH;
        }
 }
 
@@ -163,7 +163,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
        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;
+       unsigned short dma_flags;
        int q_space, i = 0;
        netdev_tx_t rc = NETDEV_TX_OK;
 
@@ -190,7 +190,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
         * since this is more efficient on machines with sparse
         * memory.
         */
-       unmap_single = true;
+       dma_flags = EFX_TX_BUF_MAP_SINGLE;
        dma_addr = dma_map_single(dma_dev, skb->data, len, PCI_DMA_TODEVICE);
 
        /* Process all fragments */
@@ -234,10 +234,8 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                        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->flags);
                        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);
@@ -247,13 +245,14 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                        /* Fill out per descriptor fields */
                        buffer->len = dma_len;
                        buffer->dma_addr = dma_addr;
+                       buffer->flags = EFX_TX_BUF_CONT;
                        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->flags = EFX_TX_BUF_CONT | dma_flags;
                buffer->unmap_len = unmap_len;
                unmap_len = 0;
 
@@ -264,14 +263,14 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
                len = skb_frag_size(fragment);
                i++;
                /* Map for DMA */
-               unmap_single = false;
+               dma_flags = 0;
                dma_addr = skb_frag_dma_map(dma_dev, fragment, 0, len,
                                            DMA_TO_DEVICE);
        }
 
        /* Transfer ownership of the skb to the final buffer */
        buffer->skb = skb;
-       buffer->continuation = false;
+       buffer->flags = EFX_TX_BUF_SKB | dma_flags;
 
        netdev_tx_sent_queue(tx_queue->core_txq, skb->len);
 
@@ -302,7 +301,7 @@ netdev_tx_t efx_enqueue_skb(struct efx_tx_queue *tx_queue, struct sk_buff *skb)
 
        /* Free the fragment we were mid-way through pushing */
        if (unmap_len) {
-               if (unmap_single)
+               if (dma_flags & EFX_TX_BUF_MAP_SINGLE)
                        dma_unmap_single(dma_dev, unmap_addr, unmap_len,
                                         DMA_TO_DEVICE);
                else
@@ -340,7 +339,6 @@ static void efx_dequeue_buffers(struct efx_tx_queue *tx_queue,
                }
 
                efx_dequeue_buffer(tx_queue, buffer, pkts_compl, bytes_compl);
-               buffer->continuation = true;
                buffer->len = 0;
 
                ++tx_queue->read_count;
@@ -484,7 +482,7 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
 {
        struct efx_nic *efx = tx_queue->efx;
        unsigned int entries;
-       int i, rc;
+       int rc;
 
        /* Create the smallest power-of-two aligned ring */
        entries = max(roundup_pow_of_two(efx->txq_entries), EFX_MIN_DMAQ_SIZE);
@@ -500,8 +498,6 @@ int efx_probe_tx_queue(struct efx_tx_queue *tx_queue)
                                   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);
@@ -546,7 +542,6 @@ void efx_release_tx_buffers(struct efx_tx_queue *tx_queue)
                unsigned int pkts_compl = 0, bytes_compl = 0;
                buffer = &tx_queue->buffer[tx_queue->read_count & tx_queue->ptr_mask];
                efx_dequeue_buffer(tx_queue, buffer, &pkts_compl, &bytes_compl);
-               buffer->continuation = true;
                buffer->len = 0;
 
                ++tx_queue->read_count;
@@ -631,7 +626,7 @@ void efx_remove_tx_queue(struct efx_tx_queue *tx_queue)
  * @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
+ * @dma_flags: TX buffer flags for DMA mapping - %EFX_TX_BUF_MAP_SINGLE or 0
  * @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
@@ -651,7 +646,7 @@ struct tso_state {
        unsigned in_len;
        unsigned unmap_len;
        dma_addr_t unmap_addr;
-       bool unmap_single;
+       unsigned short dma_flags;
 
        __be16 protocol;
        unsigned header_len;
@@ -833,9 +828,7 @@ static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
                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);
+               EFX_BUG_ON_PARANOID(buffer->flags);
 
                buffer->dma_addr = dma_addr;
 
@@ -845,7 +838,8 @@ static int efx_tx_queue_insert(struct efx_tx_queue *tx_queue,
                if (dma_len >= len)
                        break;
 
-               buffer->len = dma_len; /* Don't set the other members */
+               buffer->len = dma_len;
+               buffer->flags = EFX_TX_BUF_CONT;
                dma_addr += dma_len;
                len -= dma_len;
        }
@@ -873,12 +867,11 @@ static void efx_tso_put_header(struct efx_tx_queue *tx_queue,
        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);
+       EFX_BUG_ON_PARANOID(buffer->flags);
        buffer->len = len;
        buffer->dma_addr = tsoh->dma_addr;
        buffer->tsoh = tsoh;
+       buffer->flags = EFX_TX_BUF_TSOH | EFX_TX_BUF_CONT;
 
        ++tx_queue->insert_count;
 }
@@ -896,11 +889,11 @@ static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
                buffer = &tx_queue->buffer[tx_queue->insert_count &
                                           tx_queue->ptr_mask];
                efx_tsoh_free(tx_queue, buffer);
-               EFX_BUG_ON_PARANOID(buffer->skb);
+               EFX_BUG_ON_PARANOID(buffer->flags & EFX_TX_BUF_SKB);
                if (buffer->unmap_len) {
                        unmap_addr = (buffer->dma_addr + buffer->len -
                                      buffer->unmap_len);
-                       if (buffer->unmap_single)
+                       if (buffer->flags & EFX_TX_BUF_MAP_SINGLE)
                                dma_unmap_single(&tx_queue->efx->pci_dev->dev,
                                                 unmap_addr, buffer->unmap_len,
                                                 DMA_TO_DEVICE);
@@ -911,7 +904,7 @@ static void efx_enqueue_unwind(struct efx_tx_queue *tx_queue)
                        buffer->unmap_len = 0;
                }
                buffer->len = 0;
-               buffer->continuation = true;
+               buffer->flags = 0;
        }
 }
 
@@ -938,7 +931,7 @@ static void tso_start(struct tso_state *st, const struct sk_buff *skb)
 
        st->out_len = skb->len - st->header_len;
        st->unmap_len = 0;
-       st->unmap_single = false;
+       st->dma_flags = 0;
 }
 
 static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
@@ -947,7 +940,7 @@ static int tso_get_fragment(struct tso_state *st, struct efx_nic *efx,
        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->dma_flags = 0;
                st->unmap_len = skb_frag_size(frag);
                st->in_len = skb_frag_size(frag);
                st->dma_addr = st->unmap_addr;
@@ -965,7 +958,7 @@ static int tso_get_head_fragment(struct tso_state *st, struct efx_nic *efx,
        st->unmap_addr = dma_map_single(&efx->pci_dev->dev, skb->data + hl,
                                        len, DMA_TO_DEVICE);
        if (likely(!dma_mapping_error(&efx->pci_dev->dev, st->unmap_addr))) {
-               st->unmap_single = true;
+               st->dma_flags = EFX_TX_BUF_MAP_SINGLE;
                st->unmap_len = len;
                st->in_len = len;
                st->dma_addr = st->unmap_addr;
@@ -990,7 +983,7 @@ static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
                                         struct tso_state *st)
 {
        struct efx_tx_buffer *buffer;
-       int n, end_of_packet, rc;
+       int n, rc;
 
        if (st->in_len == 0)
                return 0;
@@ -1008,17 +1001,18 @@ static int tso_fill_packet_with_fragment(struct efx_tx_queue *tx_queue,
 
        rc = efx_tx_queue_insert(tx_queue, st->dma_addr, n, &buffer);
        if (likely(rc == 0)) {
-               if (st->out_len == 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;
+                       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->unmap_single = st->unmap_single;
+                       buffer->flags |= st->dma_flags;
                        st->unmap_len = 0;
                }
        }
@@ -1195,7 +1189,7 @@ static int efx_enqueue_skb_tso(struct efx_tx_queue *tx_queue,
  unwind:
        /* Free the DMA mapping we were in the process of writing out */
        if (state.unmap_len) {
-               if (state.unmap_single)
+               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