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

Pull another networking update from David Miller:
 "Small follow-up to the main merge pull from the other day:

  1) Alexander Duyck's DMA memory barrier patch set.

  2) cxgb4 driver fixes from Karen Xie.

  3) Add missing export of fixed_phy_register() to modules, from Mark
     Salter.

  4) DSA bug fixes from Florian Fainelli"

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (24 commits)
  net/macb: add TX multiqueue support for gem
  linux/interrupt.h: remove the definition of unused tasklet_hi_enable
  jme: replace calls to redundant function
  net: ethernet: davicom: Allow to select DM9000 for nios2
  net: ethernet: smsc: Allow to select SMC91X for nios2
  cxgb4: Add support for QSA modules
  libcxgbi: fix freeing skb prematurely
  cxgb4i: use set_wr_txq() to set tx queues
  cxgb4i: handle non-pdu-aligned rx data
  cxgb4i: additional types of negative advice
  cxgb4/cxgb4i: set the max. pdu length in firmware
  cxgb4i: fix credit check for tx_data_wr
  cxgb4i: fix tx immediate data credit check
  net: phy: export fixed_phy_register()
  fib_trie: Fix trie balancing issue if new node pushes down existing node
  vlan: Add ability to always enable TSO/UFO
  r8169:update rtl8168g pcie ephy parameter
  net: dsa: bcm_sf2: force link for all fixed PHY devices
  fm10k/igb/ixgbe: Use dma_rmb on Rx descriptor reads
  r8169: Use dma_rmb() and dma_wmb() for DescOwn checks
  ...

1 files changed, 51 insertions, 0 deletions

diff --git a/arch/blackfin/include/asm/barrier.h b/arch/blackfin/include/asm/barrier.h
index 420006877998..dfb66fe88b34 100644
--- a/arch/blackfin/include/asm/barrier.h
+++ b/arch/blackfin/include/asm/barrier.h
@@ -22,6 +22,57 @@
 # define mb()	do { barrier(); smp_check_barrier(); smp_mark_barrier(); } while (0)
 # define rmb()	do { barrier(); smp_check_barrier(); } while (0)
 # define wmb()	do { barrier(); smp_mark_barrier(); } while (0)
+/*
+ * read_barrier_depends - Flush all pending reads that subsequents reads
+ * depend on.
+ *
+ * No data-dependent reads from memory-like regions are ever reordered
+ * over this barrier.  All reads preceding this primitive are guaranteed
+ * to access memory (but not necessarily other CPUs' caches) before any
+ * reads following this primitive that depend on the data return by
+ * any of the preceding reads.  This primitive is much lighter weight than
+ * rmb() on most CPUs, and is never heavier weight than is
+ * rmb().
+ *
+ * These ordering constraints are respected by both the local CPU
+ * and the compiler.
+ *
+ * Ordering is not guaranteed by anything other than these primitives,
+ * not even by data dependencies.  See the documentation for
+ * memory_barrier() for examples and URLs to more information.
+ *
+ * For example, the following code would force ordering (the initial
+ * value of "a" is zero, "b" is one, and "p" is "&a"):
+ *
+ * <programlisting>
+ *	CPU 0				CPU 1
+ *
+ *	b = 2;
+ *	memory_barrier();
+ *	p = &b;				q = p;
+ *					read_barrier_depends();
+ *					d = *q;
+ * </programlisting>
+ *
+ * because the read of "*q" depends on the read of "p" and these
+ * two reads are separated by a read_barrier_depends().  However,
+ * the following code, with the same initial values for "a" and "b":
+ *
+ * <programlisting>
+ *	CPU 0				CPU 1
+ *
+ *	a = 2;
+ *	memory_barrier();
+ *	b = 3;				y = b;
+ *					read_barrier_depends();
+ *					x = a;
+ * </programlisting>
+ *
+ * does not enforce ordering, since there is no data dependency between
+ * the read of "a" and the read of "b".  Therefore, on some CPUs, such
+ * as Alpha, "y" could be set to 3 and "x" to 0.  Use rmb()
+ * in cases like this where there are no data dependencies.
+ */
 # define read_barrier_depends()	do { barrier(); smp_check_barrier(); } while (0)
 #endif