[PATCH] Corrections to memory barrier doc

Apply some small corrections to the memory barrier document, as contributed by:

	Christoph Lameter <clameter@sgi.com>
	Kirill Smelkov <kirr@mns.spb.ru>
	Randy Dunlap <rdunlap@xenotime.net>

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt
index cc53f47..cf0d541 100644 (file)
--- a/Documentation/memory-barriers.txt
+++ b/Documentation/memory-barriers.txt
@@ -287,7 +287,7 @@ Memory barriers come in four basic varieties:
      A write barrier is a partial ordering on stores only; it is not required
      to have any effect on loads.
 
-     A CPU can be viewed as as commiting a sequence of store operations to the
+     A CPU can be viewed as committing a sequence of store operations to the
      memory system as time progresses.  All stores before a write barrier will
      occur in the sequence _before_ all the stores after the write barrier.
 
@@ -418,7 +418,7 @@ There are certain things that the Linux kernel memory barriers do not guarantee:
      indirect effect will be the order in which the second CPU sees the effects
      of the first CPU's accesses occur, but see the next point:
 
- (*) There is no guarantee that the a CPU will see the correct order of effects
+ (*) There is no guarantee that a CPU will see the correct order of effects
      from a second CPU's accesses, even _if_ the second CPU uses a memory
      barrier, unless the first CPU _also_ uses a matching memory barrier (see
      the subsection on "SMP Barrier Pairing").
@@ -489,7 +489,7 @@ lines.  The pointer P might be stored in an odd-numbered cache line, and the
 variable B might be stored in an even-numbered cache line.  Then, if the
 even-numbered bank of the reading CPU's cache is extremely busy while the
 odd-numbered bank is idle, one can see the new value of the pointer P (&B),
-but the old value of the variable B (1).
+but the old value of the variable B (2).
 
 
 Another example of where data dependency barriers might by required is where a
@@ -749,7 +749,7 @@ some effectively random order, despite the write barrier issued by CPU 1:
                                                :       :
 
 
-If, however, a read barrier were to be placed between the load of E and the
+If, however, a read barrier were to be placed between the load of B and the
 load of A on CPU 2:
 
        CPU 1                   CPU 2
@@ -1466,9 +1466,8 @@ instruction itself is complete.
 
 On a UP system - where this wouldn't be a problem - the smp_mb() is just a
 compiler barrier, thus making sure the compiler emits the instructions in the
-right order without actually intervening in the CPU.  Since there there's only
-one CPU, that CPU's dependency ordering logic will take care of everything
-else.
+right order without actually intervening in the CPU.  Since there's only one
+CPU, that CPU's dependency ordering logic will take care of everything else.
 
 
 ATOMIC OPERATIONS
@@ -1645,9 +1644,9 @@ functions:
 
      The PCI bus, amongst others, defines an I/O space concept - which on such
      CPUs as i386 and x86_64 cpus readily maps to the CPU's concept of I/O
-     space.  However, it may also mapped as a virtual I/O space in the CPU's
-     memory map, particularly on those CPUs that don't support alternate
-     I/O spaces.
+     space.  However, it may also be mapped as a virtual I/O space in the CPU's
+     memory map, particularly on those CPUs that don't support alternate I/O
+     spaces.
 
      Accesses to this space may be fully synchronous (as on i386), but
      intermediary bridges (such as the PCI host bridge) may not fully honour