sched/wait: Remove might_sleep() from wait_event_cmd()

sched/wait: Remove might_sleep() from wait_event_cmd()

The patch e22b886a8a43 ("sched/wait: Add might_sleep() checks")
introduced a bug in the raid5 subsystem.

The function raid5_quiesce() (and resize_stripes()) uses the 'cmd'
part to release and acquire a spinlock (so we call the sleep
primitives in atomic context), and therefore we cannot do the
might_sleep() check.

Remove it.

Fixes: e22b886a8a43 ("sched/wait: Add might_sleep() checks")
Signed-off-by: Mikulas Patocka <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1502020935580.13510@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Ingo Molnar <[email protected]>