---

yaml
---
r: 202620
b: refs/heads/master
c: 2445580
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f7d6f379db61233a1740cb2c6818b9c97531771f
+refs/heads/master: 244558006cf02f0096fb247f3a54dc7e7d81a256

trunk/drivers/net/sfc/rx.c

@@ -82,9 +82,10 @@ static unsigned int rx_refill_limit = 95;
  * RX maximum head room required.
  *
  * This must be at least 1 to prevent overflow and at least 2 to allow
- * pipelined receives.
+ * pipelined receives. Then a further 1 because efx_recycle_rx_buffer()
+ * might insert two buffers.
  */
-#define EFX_RXD_HEAD_ROOM 2
+#define EFX_RXD_HEAD_ROOM 3
 
 static inline unsigned int efx_rx_buf_offset(struct efx_rx_buffer *buf)
 {
@@ -250,6 +251,70 @@ static void efx_fini_rx_buffer(struct efx_rx_queue *rx_queue,
 	efx_free_rx_buffer(rx_queue->efx, rx_buf);
 }
 
+/* Attempt to resurrect the other receive buffer that used to share this page,
+ * which had previously been passed up to the kernel and freed. */
+static void efx_resurrect_rx_buffer(struct efx_rx_queue *rx_queue,
+				    struct efx_rx_buffer *rx_buf)
+{
+	struct efx_rx_buffer *new_buf;
+	unsigned index;
+
+	/* We could have recycled the 1st half, then refilled
+	 * the queue, and now recycle the 2nd half.
+	 * EFX_RXD_HEAD_ROOM ensures that there is always room
+	 * to reinsert two buffers (once). */
+	get_page(rx_buf->page);
+
+	index = rx_queue->added_count & EFX_RXQ_MASK;
+	new_buf = efx_rx_buffer(rx_queue, index);
+	new_buf->dma_addr = rx_buf->dma_addr - (PAGE_SIZE >> 1);
+	new_buf->skb = NULL;
+	new_buf->page = rx_buf->page;
+	new_buf->data = rx_buf->data - (PAGE_SIZE >> 1);
+	new_buf->len = rx_buf->len;
+	++rx_queue->added_count;
+}
+
+/* Recycle the given rx buffer directly back into the rx_queue. There is
+ * always room to add this buffer, because we've just popped a buffer. */
+static void efx_recycle_rx_buffer(struct efx_channel *channel,
+				  struct efx_rx_buffer *rx_buf)
+{
+	struct efx_nic *efx = channel->efx;
+	struct efx_rx_queue *rx_queue = &efx->rx_queue[channel->channel];
+	struct efx_rx_buffer *new_buf;
+	unsigned index;
+
+	if (rx_buf->page != NULL && efx->rx_buffer_len < (PAGE_SIZE >> 1)) {
+		if (efx_rx_buf_offset(rx_buf) & (PAGE_SIZE >> 1)) {
+			/* This is the 2nd half of a page split between two
+			 * buffers, If page_count() is > 1 then the kernel
+			 * is holding onto the previous buffer */
+			if (page_count(rx_buf->page) != 1) {
+				efx_fini_rx_buffer(rx_queue, rx_buf);
+				return;
+			}
+
+			efx_resurrect_rx_buffer(rx_queue, rx_buf);
+		} else {
+			/* Free the 1st buffer's reference on the page. If the
+			 * 2nd buffer is also discarded, this buffer will be
+			 * resurrected above */
+			put_page(rx_buf->page);
+			rx_buf->page = NULL;
+			return;
+		}
+	}
+
+	index = rx_queue->added_count & EFX_RXQ_MASK;
+	new_buf = efx_rx_buffer(rx_queue, index);
+
+	memcpy(new_buf, rx_buf, sizeof(*new_buf));
+	rx_buf->page = NULL;
+	rx_buf->skb = NULL;
+	++rx_queue->added_count;
+}
+
 /**
  * efx_fast_push_rx_descriptors - push new RX descriptors quickly
  * @rx_queue:		RX descriptor queue
@@ -271,7 +336,7 @@ void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
 	fill_level = (rx_queue->added_count - rx_queue->removed_count);
 	EFX_BUG_ON_PARANOID(fill_level > EFX_RXQ_SIZE);
 	if (fill_level >= rx_queue->fast_fill_trigger)
-		return;
+		goto out;
 
 	/* Record minimum fill level */
 	if (unlikely(fill_level < rx_queue->min_fill)) {
@@ -281,7 +346,7 @@ void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
 
 	space = rx_queue->fast_fill_limit - fill_level;
 	if (space < EFX_RX_BATCH)
-		return;
+		goto out;
 
 	EFX_TRACE(rx_queue->efx, "RX queue %d fast-filling descriptor ring from"
 		  " level %d to level %d using %s allocation\n",
@@ -306,8 +371,8 @@ void efx_fast_push_rx_descriptors(struct efx_rx_queue *rx_queue)
 		  rx_queue->added_count - rx_queue->removed_count);
 
  out:
-	/* Send write pointer to card. */
-	efx_nic_notify_rx_desc(rx_queue);
+	if (rx_queue->notified_count != rx_queue->added_count)
+		efx_nic_notify_rx_desc(rx_queue);
 }
 
 void efx_rx_slow_fill(unsigned long context)
@@ -418,6 +483,7 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
 		   unsigned int len, bool checksummed, bool discard)
 {
 	struct efx_nic *efx = rx_queue->efx;
+	struct efx_channel *channel = rx_queue->channel;
 	struct efx_rx_buffer *rx_buf;
 	bool leak_packet = false;
 
@@ -445,12 +511,13 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
 	/* Discard packet, if instructed to do so */
 	if (unlikely(discard)) {
 		if (unlikely(leak_packet))
-			rx_queue->channel->n_skbuff_leaks++;
+			channel->n_skbuff_leaks++;
 		else
-			/* We haven't called efx_unmap_rx_buffer yet,
-			 * so fini the entire rx_buffer here */
-			efx_fini_rx_buffer(rx_queue, rx_buf);
-		return;
+			efx_recycle_rx_buffer(channel, rx_buf);
+
+		/* Don't hold off the previous receive */
+		rx_buf = NULL;
+		goto out;
 	}
 
 	/* Release card resources - assumes all RX buffers consumed in-order
@@ -467,6 +534,7 @@ void efx_rx_packet(struct efx_rx_queue *rx_queue, unsigned int index,
 	 * prefetched into cache.
 	 */
 	rx_buf->len = len;
+out:
 	if (rx_queue->channel->rx_pkt)
 		__efx_rx_packet(rx_queue->channel,
 				rx_queue->channel->rx_pkt,