Re: [PATCH] kexec jump: fix compiling warning on xchg(&kexec_lock,0) in kernel_kexec()

[Linus Torvalds]

On Wed, 13 Aug 2008, Andrew Morton wrote:
>
> We don't need to create that local.  I queued this:

No, please don't. 

Just don't take this whole patch-series until it's cleaned up. There is 
absolutely no excuse for using xchg as a locking primitive. Nothing like 
this should be queued anywhere, it should be burned and the ashes should 
be scattered over the atlantic so that nobody will ever see them again.

F*ck me with a spoon, if you have to use xchg() to do a trylock, why the 
hell isn't the unlock sequence then

	smp_mb();
	var = 0;

instead? Not that that's really right either, but at least it avoids the 
_ridiculous_ crap. The real solution is probably to use a spinlock and 
trylock/unlock.

		Linus
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