From a36985d31a65d5c0559fb582719e32eaf0ccec3b Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Wed, 6 Sep 2017 16:23:59 -0700
Subject: userfaultfd: provide pid in userfault msg - add feat union

No ABI change, but this will make it more explicit to software that ptid
is only available if requested by passing UFFD_FEATURE_THREAD_ID to
UFFDIO_API.  The fact it's a union will also self document it shouldn't
be taken for granted there's a tpid there.

Link: http://lkml.kernel.org/r/20170802165145.22628-7-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Alexey Perevalov <a.perevalov@samsung.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 include/uapi/linux/userfaultfd.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'include')

diff --git a/include/uapi/linux/userfaultfd.h b/include/uapi/linux/userfaultfd.h
index 2b24c28d99a7..d6d1f65cb3c3 100644
--- a/include/uapi/linux/userfaultfd.h
+++ b/include/uapi/linux/userfaultfd.h
@@ -80,7 +80,9 @@ struct uffd_msg {
 		struct {
 			__u64	flags;
 			__u64	address;
-			__u32   ptid;
+			union {
+				__u32 ptid;
+			} feat;
 		} pagefault;
 
 		struct {
-- 
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