tree c825e36dd160760cda8093e4ef384583a279dcb8
parent 91c9afaf97ee554d2cd3042a5ad01ad21c99e8c4
author Andy Lutomirski <luto@amacapital.net> 1429213487 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1429275838 -0400

errno.h: Improve ENOSYS's comment

ENOSYS is the mechanism used by user code to detect whether the running
kernel implements a given system call.  It should not be returned by
anything except an unimplemented system call.

Unfortunately, it is rather frequently used in the kernel to indicate that
various new functions of existing system calls are not implemented.  This
should be discouraged.

Improve the comment in errno.h to help clarify ENOSYS's purpose.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>