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

[Linus Torvalds]

On Wed, 13 Aug 2008, Andrew Morton wrote:
> 
> #2:

I thought you said there were things that want to sleep in the region?

If so, spinlocks will work as long as you don't have CONFIG_PREEMPT or 
lock validation (there's no way to deadlock thanks to all the lock getters 
using the "trylock" variant), but will blow up because a successful 
trylock will obviously also disable preemption and/or trigger all the lock 
detection.

So if there are potential sleepers, you'd need the mutex instead.

		Linus