ice: Get rid of ice_pull_tail

Instead of adding a frag and later when dealing with EOP frame accessing
that frag in order to copy the headers onto linear part of skb, we can do
this in ice_add_rx_frag in case where the data_len is still 0 and frame
won't fit onto the linear part as a whole.

Function comment of ice_pull_tail was a bit misleading because of
mentioned optimizations that can be performed (drop a frag/maintaining
accurate truesize of skb) - it seems that this part of logic was dropped
and the comment was not updated to reflect this change.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -562,13 +562,17 @@ ice_add_rx_frag(struct ice_rx_buf *rx_buf, struct sk_buff *skb,
 	unsigned int truesize = ALIGN(size, L1_CACHE_BYTES);
 #endif /* PAGE_SIZE < 8192) */
 	struct page *page = rx_buf->page;
+	unsigned int pull_len;
+	unsigned char *va;
+
+	va = page_address(page) + rx_buf->page_offset;
+	if (unlikely(skb_is_nonlinear(skb)))
+		goto add_tail_frag;
 
 	/* will the data fit in the skb we allocated? if so, just
 	 * copy it as it is pretty small anyway
 	 */
-	if (size <= ICE_RX_HDR_SIZE && !skb_is_nonlinear(skb)) {
-		unsigned char *va = page_address(page) + rx_buf->page_offset;
-
+	if (size <= ICE_RX_HDR_SIZE) {
 		memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));
 
 		/* page is not reserved, we can reuse buffer as-is */
@@ -580,8 +584,24 @@ ice_add_rx_frag(struct ice_rx_buf *rx_buf, struct sk_buff *skb,
 		return false;
 	}
 
+	/* we need the header to contain the greater of either ETH_HLEN or
+	 * 60 bytes if the skb->len is less than 60 for skb_pad.
+	 */
+	pull_len = eth_get_headlen(va, ICE_RX_HDR_SIZE);
+
+	/* align pull length to size of long to optimize memcpy performance */
+	memcpy(__skb_put(skb, pull_len), va, ALIGN(pull_len, sizeof(long)));
+
+	/* the header from the frame that we're adding as a frag was added to
+	 * linear part of skb so move the pointer past that header and
+	 * reduce the size of data
+	 */
+	va += pull_len;
+	size -= pull_len;
+
+add_tail_frag:
 	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
-			rx_buf->page_offset, size, truesize);
+			(unsigned long)va & ~PAGE_MASK, size, truesize);
 
 	return ice_can_reuse_rx_page(rx_buf, truesize);
 }
@@ -691,44 +711,6 @@ ice_fetch_rx_buf(struct ice_ring *rx_ring, struct ice_rx_buf *rx_buf,
 	return skb;
 }
 
-/**
- * ice_pull_tail - ice specific version of skb_pull_tail
- * @skb: pointer to current skb being adjusted
- *
- * This function is an ice specific version of __pskb_pull_tail. The
- * main difference between this version and the original function is that
- * this function can make several assumptions about the state of things
- * that allow for significant optimizations versus the standard function.
- * As a result we can do things like drop a frag and maintain an accurate
- * truesize for the skb.
- */
-static void ice_pull_tail(struct sk_buff *skb)
-{
-	struct skb_frag_struct *frag = &skb_shinfo(skb)->frags[0];
-	unsigned int pull_len;
-	unsigned char *va;
-
-	/* it is valid to use page_address instead of kmap since we are
-	 * working with pages allocated out of the lomem pool per
-	 * alloc_page(GFP_ATOMIC)
-	 */
-	va = skb_frag_address(frag);
-
-	/* we need the header to contain the greater of either ETH_HLEN or
-	 * 60 bytes if the skb->len is less than 60 for skb_pad.
-	 */
-	pull_len = eth_get_headlen(va, ICE_RX_HDR_SIZE);
-
-	/* align pull length to size of long to optimize memcpy performance */
-	skb_copy_to_linear_data(skb, va, ALIGN(pull_len, sizeof(long)));
-
-	/* update all of the pointers */
-	skb_frag_size_sub(frag, pull_len);
-	frag->page_offset += pull_len;
-	skb->data_len -= pull_len;
-	skb->tail += pull_len;
-}
-
 /**
  * ice_cleanup_headers - Correct empty headers
  * @skb: pointer to current skb being fixed
@@ -743,10 +725,6 @@ static void ice_pull_tail(struct sk_buff *skb)
  */
 static bool ice_cleanup_headers(struct sk_buff *skb)
 {
-	/* place header in linear portion of buffer */
-	if (skb_is_nonlinear(skb))
-		ice_pull_tail(skb);
-
 	/* if eth_skb_pad returns an error the skb was freed */
 	if (eth_skb_pad(skb))
 		return true;