userfaultfd: convert BUG() to WARN_ON_ONCE()

Avoid BUG_ON()s and only WARN instead.  This is just a cleanup, it can't
make any runtime difference.  This BUG_ON has never triggered and cannot
trigger.

Link: http://lkml.kernel.org/r/20161216144821.5183-4-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index cf1856cb25d201c4e26af8e211d8c21e607189d0..71e917387ec386866c19d5a31db9bef0b8100b9c 100644 (file)
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -574,7 +574,8 @@ static unsigned int userfaultfd_poll(struct file *file, poll_table *wait)
                        ret = POLLIN;
                return ret;
        default:
-               BUG();
+               WARN_ON_ONCE(1);
+               return POLLERR;
        }
 }