Re: [PATCH] RWSEM: Rewrite rwsem.c and rwsem-spinlock.c more simply.

[Andi Kleen <andi@firstfloor.org>]

> i'm not sure what this means -- which of the transformations in that
> patch is considered unsafe?  here's a typical simplification:

It is not unsafe, just generates slight worse code.

current is inline assembler and the compiler doesn't know that it could
cache it in a register because it is not marked pure 
for various reasons. That is why current is often cached explicitely
in a local variable to tell the compiler that.

Before you run off and do that everywhere: it is also not a large
win, just a small one unless current is used very often.

-Andi