locking/lockdep: Add IRQs disabled/enabled assertion APIs: lockdep_assert_irqs_enable...

locking/lockdep: Add IRQs disabled/enabled assertion APIs: lockdep_assert_irqs_enabled()/disabled()

Checking whether IRQs are enabled or disabled is a very common sanity
check, however not free of overhead especially on fastpath where such
assertion is very common.

Lockdep is a good host for such concurrency correctness check and it
even already tracks down IRQs disablement state. Just reuse its
machinery. This will allow us to get rid of the flags pop and check
overhead from fast path when kernel is built for production.

Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
Acked-by: Thomas Gleixner <[email protected]>
Cc: David S . Miller <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Tejun Heo <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>