Commit 2f41abeb authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds

[PATCH] 2.5.6-pre3. Documentation

atomic ops are *not* barriers any more.

Sebastian Wilhelmi <wilhelmi@ira.uka.de>: Re: Question on your "Unreliable Guide To Locking":
  > Yes, this is no longer true.  The modern assumptions are that they are
  > not barriers.
parent 8528eb38
...@@ -788,8 +788,18 @@ ...@@ -788,8 +788,18 @@
</para> </para>
<para> <para>
Note that the atomic operations are defined to act as both Note that the atomic operations do in general not act as memory
read and write barriers on all platforms. barriers. Instead you can insert a memory barrier before or
after <function>atomic_inc()</function> or
<function>atomic_dec()</function> by inserting
<function>smp_mb__before_atomic_inc()</function>,
<function>smp_mb__after_atomic_inc()</function>,
<function>smp_mb__before_atomic_dec()</function> or
<function>smp_mb__after_atomic_dec()</function>
respectively. The advantage of using those macros instead of
<function>smp_mb()</function> is, that they are cheaper on some
platforms.
<!-- Sebastian Wilhelmi <seppi@seppi.de> 2002-03-04 -->
</para> </para>
</sect1> </sect1>
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment