It adds cond_resched_softirq() which can be used by _process context_
softirqs-disabled codepaths to preempt if necessary.  The function will
enable softirqs before scheduling.  (Later patches will use this
primitive.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>