Commit 103e6e39 authored by Rusty Russell's avatar Rusty Russell Committed by Linus Torvalds

[PATCH] Sparc no longer F*cked Up

From: Keith M Wesolowski <wesolows@foobazco.org>

As of 2.6.3, restore_flags will no longer modify cwp on sparc.
Therefore you can apply this patch to the locking guide.

[ Indeed.  I'll also remove the atomic comments from Hacking
  Guide as part of my revision there when I get back to it.  --RR ]
parent 1dfbdec9
......@@ -1444,27 +1444,6 @@ as Alan Cox says, <quote>Lock data, not code</quote>.
</para>
</sect1>
<sect1 id="sparc">
<title>The Fucked Up Sparc</title>
<para>
Alan Cox says <quote>the irq disable/enable is in the register
window on a sparc</quote>. Andi Kleen says <quote>when you do
restore_flags in a different function you mess up all the
register windows</quote>.
</para>
<para>
So never pass the flags word set by
<function>spin_lock_irqsave()</function> and brethren to another
function (unless it's declared <type>inline</type>). Usually no-one
does this, but now you've been warned. Dave Miller can never do
anything in a straightforward manner (I can say that, because I have
pictures of him and a certain PowerPC maintainer in a compromising
position).
</para>
</sect1>
</chapter>
<chapter id="Efficiency">
......
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