sfc: Add support for reading packet length from prefix

Define a flag for struct efx_rx_buffer and efx_rx_packet() that
indicates packet length must be read from the prefix.  If this
is set, read the length in __efx_rx_packet() (when the prefix
should have arrived in cache).

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 f52b38c..e85bed0 100644 (file)
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h
@@ -263,6 +263,7 @@ struct efx_rx_buffer {
 #define EFX_RX_PKT_CSUMMED     0x0002
 #define EFX_RX_PKT_DISCARD     0x0004
 #define EFX_RX_PKT_TCP         0x0040
+#define EFX_RX_PKT_PREFIX_LEN  0x0080  /* length is in prefix only */
 
 /**
  * struct efx_rx_page_state - Page-based rx buffer state
@@ -668,6 +669,8 @@ struct vfdi_status;
  * @rx_prefix_size: Size of RX prefix before packet data
  * @rx_packet_hash_offset: Offset of RX flow hash from start of packet data
  *     (valid only if @rx_prefix_size != 0; always negative)
+ * @rx_packet_len_offset: Offset of RX packet length from start of packet data
+ *     (valid only for NICs that set %EFX_RX_PKT_PREFIX_LEN; always negative)
  * @rx_hash_key: Toeplitz hash key for RSS
  * @rx_indir_table: Indirection table for RSS
  * @rx_scatter: Scatter mode enabled for receives
@@ -800,6 +803,7 @@ struct efx_nic {
        unsigned int rx_pages_per_batch;
        unsigned int rx_prefix_size;
        int rx_packet_hash_offset;
+       int rx_packet_len_offset;
        u8 rx_hash_key[40];
        u32 rx_indir_table[128];
        bool rx_scatter;

diff --git a/drivers/net/ethernet/sfc/rx.c b/drivers/net/ethernet/sfc/rx.c
index 7646bb3..864b6ff 100644 (file)
--- a/drivers/net/ethernet/sfc/rx.c
+++ b/drivers/net/ethernet/sfc/rx.c
@@ -526,7 +526,8 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
 
        /* Validate the number of fragments and completed length */
        if (n_frags == 1) {
-               efx_rx_packet__check_len(rx_queue, rx_buf, len);
+               if (!(flags & EFX_RX_PKT_PREFIX_LEN))
+                       efx_rx_packet__check_len(rx_queue, rx_buf, len);
        } else if (unlikely(n_frags > EFX_RX_MAX_FRAGS) ||
                   unlikely(len <= (n_frags - 1) * EFX_RX_USR_BUF_SIZE) ||
                   unlikely(len > n_frags * EFX_RX_USR_BUF_SIZE) ||
@@ -554,7 +555,7 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
                return;
        }
 
-       if (n_frags == 1)
+       if (n_frags == 1 && !(flags & EFX_RX_PKT_PREFIX_LEN))
                rx_buf->len = len;
 
        /* Release and/or sync the DMA mapping - assumes all RX buffers
@@ -633,6 +634,13 @@ void __efx_rx_packet(struct efx_channel *channel)
                efx_rx_buffer(&channel->rx_queue, channel->rx_pkt_index);
        u8 *eh = efx_rx_buf_va(rx_buf);
 
+       /* Read length from the prefix if necessary.  This already
+        * excludes the length of the prefix itself.
+        */
+       if (rx_buf->flags & EFX_RX_PKT_PREFIX_LEN)
+               rx_buf->len = le16_to_cpup((__le16 *)
+                                          (eh + efx->rx_packet_len_offset));
+
        /* If we're in loopback test, then pass the packet directly to the
         * loopback layer, and free the rx_buf here
         */