Commit 045098e9 authored Apr 07, 2017 by Mike Rapoport Committed by Linus Torvalds Apr 08, 2017

userfaultfd: report actual registered features in fdinfo

fdinfo for userfault file descriptor reports UFFD_API_FEATURES.  Up
until recently, the UFFD_API_FEATURES was defined as 0, therefore
corresponding field in fdinfo always contained zero.  Now, with
introduction of several additional features, UFFD_API_FEATURES is not
longer 0 and it seems better to report actual features requested for the
userfaultfd object described by the fdinfo.

First, the applications that were using userfault will still see zero at
the features field in fdinfo.  Next, reporting actual features rather
than available features, gives clear indication of what userfault
features are used by an application.

Link: http://lkml.kernel.org/r/1491140181-22121-1-git-send-email-rppt@linux.vnet.ibm.com


Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d75450ff

fs/userfaultfd.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1756,7 +1756,7 @@ static void userfaultfd_show_fdinfo(struct seq_file m, struct file f)
		* protocols: aa:... bb:...
		*/
		seq_printf(m, "pending:\t%lu\ntotal:\t%lu\nAPI:\t%Lx:%x:%Lx\n",
		pending, total, UFFD_API, UFFD_API_FEATURES,
		pending, total, UFFD_API, ctx->features,
		UFFD_API_IOCTLS\|UFFD_API_RANGE_IOCTLS);
		}
		#endif

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