sysctl: add support for poll()

Adding support for poll() in sysctl fs allows userspace to receive
notifications of changes in sysctl entries.  This adds a infrastructure to
allow files in sysctl fs to be pollable and implements it for hostname and

[ s/declare/define/ for definitions]
Signed-off-by: Lucas De Marchi <>
Cc: Greg KH <>
Cc: Kay Sievers <>
Cc: Al Viro <>
Cc: "Eric W. Biederman" <>
Cc: Alexey Dobriyan <>
Signed-off-by: Andrew Morton <>
Signed-off-by: Linus Torvalds <>
5 files changed