userfaultfd: provide pid in userfault msg - add feat union

aagit · torvalds · commit a36985d31a65 · 2017-09-06T17:27:29.000-07:00
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>
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
@@ -204,7 +204,7 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
 		 */
 		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 --git 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 {

Original file line number	Diff line number	Diff line change
`@@ -204,7 +204,7 @@ static inline struct uffd_msg userfault_msg(unsigned long address,`
`204`	`204`	`*/`
`205`	`205`	`msg.arg.pagefault.flags \|= UFFD_PAGEFAULT_FLAG_WP;`
`206`	`206`	`if (features & UFFD_FEATURE_THREAD_ID)`
`207`		`- msg.arg.pagefault.ptid = task_pid_vnr(current);`
	`207`	`+ msg.arg.pagefault.feat.ptid = task_pid_vnr(current);`
`208`	`208`	`return msg;`
`209`	`209`	`}`
`210`	`210`