This function still depends on the big kernel lock in some cases.  Push
locking into the function ready for removal of the BKL from ioctl call paths.
Signed-off-by: NAlan Cox <alan@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>