userfaultfd: call userfaultfd_unmap_prep only if __split_vma succeeds

A __split_vma is not a worthy event to report, and it's definitely not a
unmap so it would be incorrect to report unmap for the whole region to
the userfaultfd manager if a __split_vma fails.

So only call userfaultfd_unmap_prep after the __vma_splitting is over
and do_munmap cannot fail anymore.

Also add unlikely because it's better to optimize for the vast majority
of apps that aren't using userfaultfd in a non cooperative way.  Ideally
we should also find a way to eliminate the branch entirely if
CONFIG_USERFAULTFD=n, but it would complicate things so stick to
unlikely for now.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrea Arcangeli <[email protected]>
Cc: "Dr. David Alan Gilbert" <[email protected]>
Cc: Alexey Perevalov <[email protected]>
Cc: Maxime Coquelin <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions