commit b26cfc48e3e03126c183f1f3960e6d69460bb852
author pierre Kuo <vichy.kuo@gmail.com> Fri Apr 07 14:37:36 2017 +0800
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> Wed Apr 12 08:23:43 2017 -0700
tree ea7929ee20ba916595758350c958d1d81594d1e6
parent d3d3a3ccc4a8f1f254fb6788081f35bebe374174

doc: Update control-dependencies section of memory-barriers.txt

In the following example, if MAX is defined to be 1, then the compiler
knows (Q % MAX) is equal to zero.  The compiler can therefore throw
away the "then" branch (and the "if"), retaining only the "else" branch.

	q = READ_ONCE(a);
	if (q % MAX) {
		WRITE_ONCE(b, 1);
		do_something();
	} else {
		WRITE_ONCE(b, 2);
		do_something_else();
	}

It is therefore necessary to modify the example like this:

        q = READ_ONCE(a);
-       WRITE_ONCE(b, 1);
+       WRITE_ONCE(b, 2);
        do_something_else();

Signed-off-by: pierre Kuo <vichy.kuo@gmail.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>