* [patch 097/119] userfaultfd: provide pid in userfault msg - add feat union
@ 2017-09-06 23:23 akpm
0 siblings, 0 replies; only message in thread
From: akpm @ 2017-09-06 23:23 UTC (permalink / raw)
To: a.perevalov, aarcange, akpm, dgilbert, maxime.coquelin,
mike.kravetz, mm-commits, rppt, torvalds
From: Andrea Arcangeli <aarcange@redhat.com>
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>
---
fs/userfaultfd.c | 2 +-
include/uapi/linux/userfaultfd.h | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff -puN fs/userfaultfd.c~userfaultfd-provide-pid-in-userfault-msg-add-feat-union fs/userfaultfd.c
--- a/fs/userfaultfd.c~userfaultfd-provide-pid-in-userfault-msg-add-feat-union
+++ a/fs/userfaultfd.c
@@ -204,7 +204,7 @@ static inline struct uffd_msg userfault_
*/
msg.arg.pagefault.flags |= UFFD_PAGEFAULT_FLAG_WP;
if (features & UFFD_FEATURE_THREAD_ID)
- msg.arg.pagefault.ptid = task_pid_vnr(current);
+ msg.arg.pagefault.feat.ptid = task_pid_vnr(current);
return msg;
}
diff -puN include/uapi/linux/userfaultfd.h~userfaultfd-provide-pid-in-userfault-msg-add-feat-union include/uapi/linux/userfaultfd.h
--- a/include/uapi/linux/userfaultfd.h~userfaultfd-provide-pid-in-userfault-msg-add-feat-union
+++ a/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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