[PATCH] POLLRDHUP/EPOLLRDHUP handling for half-closed devices notifications
Implement the half-closed devices notifiation, by adding a new POLLRDHUP
(and its alias EPOLLRDHUP) bit to the existing poll/select sets. Since the
existing POLLHUP handling, that does not report correctly half-closed
devices, was feared to be changed, this implementation leaves the current
POLLHUP reporting unchanged and simply add a new bit that is set in the few
places where it makes sense. The same thing was discussed and conceptually
agreed quite some time ago:
http://lkml.org/lkml/2003/7/12/116
Since this new event bit is added to the existing Linux poll infrastruture,
even the existing poll/select system calls will be able to use it. As far
as the existing POLLHUP handling, the patch leaves it as is. The
pollrdhup-2.6.16.rc5-0.10.diff defines the POLLRDHUP for all the existing
archs and sets the bit in the six relevant files. The other attached diff
is the simple change required to sys/epoll.h to add the EPOLLRDHUP
definition.
There is "a stupid program" to test POLLRDHUP delivery here:
http://www.xmailserver.org/pollrdhup-test.c
It tests poll(2), but since the delivery is same epoll(2) will work equally.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 1c2b16f..a0f682c 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -599,7 +599,7 @@
switch (op) {
case EPOLL_CTL_ADD:
if (!epi) {
- epds.events |= POLLERR | POLLHUP;
+ epds.events |= POLLERR | POLLHUP | POLLRDHUP;
error = ep_insert(ep, &epds, tfile, fd);
} else
@@ -613,7 +613,7 @@
break;
case EPOLL_CTL_MOD:
if (epi) {
- epds.events |= POLLERR | POLLHUP;
+ epds.events |= POLLERR | POLLHUP | POLLRDHUP;
error = ep_modify(ep, epi, &epds);
} else
error = -ENOENT;