Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

Pull networking fixes from David Miller:
 "This set fixes a bunch of fallout from the changes that went in during
  this merge window, particularly:

   - Fix fsl_pq_mdio (Claudiu Manoil) and fm10k (Pranith Kumar) build
     failures.

   - Several networking drivers do atomic_set() on page counts where
     that's not exactly legal.  From Eric Dumazet.

   - Make __skb_flow_get_ports() work cleanly with unaligned data, from
     Alexander Duyck.

   - Fix some kernel-doc buglets in rfkill and netlabel, from Fabian
     Frederick.

   - Unbalanced enable_irq_wake usage in bcmgenet and systemport
     drivers, from Florian Fainelli.

   - pxa168_eth needs to depend on HAS_DMA, from Geert Uytterhoeven.

   - Multi-dequeue in the qdisc layer severely bypasses the fairness
     limits the previous code used to enforce, reintroduce in a way that
     at the same time doesn't compromise bulk dequeue opportunities.
     From Jesper Dangaard Brouer.

   - macvlan receive path unnecessarily hops through a softirq by using
     netif_rx() instead of netif_receive_skb().  From Jason Baron"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (51 commits)
  net: systemport: avoid unbalanced enable_irq_wake calls
  net: bcmgenet: avoid unbalanced enable_irq_wake calls
  net: bcmgenet: fix off-by-one in incrementing read pointer
  net: fix races in page->_count manipulation
  mlx4: fix race accessing page->_count
  ixgbe: fix race accessing page->_count
  igb: fix race accessing page->_count
  fm10k: fix race accessing page->_count
  net/phy: micrel: Add clock support for KSZ8021/KSZ8031
  flow-dissector: Fix alignment issue in __skb_flow_get_ports
  net: filter: fix the comments
  Documentation: replace __sk_run_filter with __bpf_prog_run
  macvlan: optimize the receive path
  macvlan: pass 'bool' type to macvlan_count_rx()
  drivers: net: xgene: Add 10GbE ethtool support
  drivers: net: xgene: Add 10GbE support
  drivers: net: xgene: Preparing for adding 10GbE support
  dtb: Add 10GbE node to APM X-Gene SoC device tree
  Documentation: dts: Update section header for APM X-Gene
  MAINTAINERS: Update APM X-Gene section
  ...

1 files changed, 23 insertions, 12 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 7b3df0d518a..829d013745a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -360,18 +360,29 @@ refill:
 				goto end;
 		}
 		nc->frag.size = PAGE_SIZE << order;
-recycle:
-		atomic_set(&nc->frag.page->_count, NETDEV_PAGECNT_MAX_BIAS);
+		/* Even if we own the page, we do not use atomic_set().
+		 * This would break get_page_unless_zero() users.
+		 */
+		atomic_add(NETDEV_PAGECNT_MAX_BIAS - 1,
+			   &nc->frag.page->_count);
 		nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS;
 		nc->frag.offset = 0;
 	}
 
 	if (nc->frag.offset + fragsz > nc->frag.size) {
-		/* avoid unnecessary locked operations if possible */
-		if ((atomic_read(&nc->frag.page->_count) == nc->pagecnt_bias) ||
-		    atomic_sub_and_test(nc->pagecnt_bias, &nc->frag.page->_count))
-			goto recycle;
-		goto refill;
+		if (atomic_read(&nc->frag.page->_count) != nc->pagecnt_bias) {
+			if (!atomic_sub_and_test(nc->pagecnt_bias,
+						 &nc->frag.page->_count))
+				goto refill;
+			/* OK, page count is 0, we can safely set it */
+			atomic_set(&nc->frag.page->_count,
+				   NETDEV_PAGECNT_MAX_BIAS);
+		} else {
+			atomic_add(NETDEV_PAGECNT_MAX_BIAS - nc->pagecnt_bias,
+				   &nc->frag.page->_count);
+		}
+		nc->pagecnt_bias = NETDEV_PAGECNT_MAX_BIAS;
+		nc->frag.offset = 0;
 	}
 
 	data = page_address(nc->frag.page) + nc->frag.offset;
@@ -4126,11 +4137,11 @@ EXPORT_SYMBOL(skb_vlan_untag);
 /**
  * alloc_skb_with_frags - allocate skb with page frags
  *
- * header_len: size of linear part
- * data_len: needed length in frags
- * max_page_order: max page order desired.
- * errcode: pointer to error code if any
- * gfp_mask: allocation mask
+ * @header_len: size of linear part
+ * @data_len: needed length in frags
+ * @max_page_order: max page order desired.
+ * @errcode: pointer to error code if any
+ * @gfp_mask: allocation mask
  *
  * This can be used to allocate a paged skb, given a maximal order for frags.
  */