sched: Use rq->rd in sched_setaffinity() under RCU read lock

sched: Use rq->rd in sched_setaffinity() under RCU read lock

commit f1e3a0932f3a9554371792a7daaf1e0eb19f66d5 upstream.

Probability of use-after-free isn't zero in this place.

Signed-off-by: Kirill Tkhai <ktkhai@parallels.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20140922183636.11015.83611.stgit@localhost
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>