tree 3fa6ed6ea9288daa19426a5402d5bcb08f6edcbe
parent bb3bf7052de520f2d21a1275e95fac7a84d89e4c
author Paul E. McKenney <paul.mckenney@linaro.org> 1320957716 -0800
committer Paul E. McKenney <paulmck@linux.vnet.ibm.com> 1323628307 -0800

sched: Add is_idle_task() to handle invalidated uses of idle_cpu()

Commit 908a3283 (Fix idle_cpu()) invalidated some uses of idle_cpu(),
which used to say whether or not the CPU was running the idle task,
but now instead says whether or not the CPU is running the idle task
in the absence of pending wakeups.  Although this new implementation
gives a better answer to the question "is this CPU idle?", it also
invalidates other uses that were made of idle_cpu().

This commit therefore introduces a new is_idle_task() API member
that determines whether or not the specified task is one of the
idle tasks, allowing open-coded "->pid == 0" sequences to be replaced
by something more meaningful.

Suggested-by: Josh Triplett <josh@joshtriplett.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>