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

[Linus Torvalds]

On Wed, 13 Aug 2008, Huang Ying wrote:
>
> -	xchg(&kexec_lock, 0);
> +	locked = xchg(&kexec_lock, 0);
> +	BUG_ON(!locked);

Why do you want to do this at all? 

And why do you implement your locks with xchg() in the first place? That's 
total and utter crap.

Hint: we have _real_ locking primitives in the kernel.

			Linus