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Commit f348d70a authored by Davide Libenzi's avatar Davide Libenzi Committed by Linus Torvalds
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[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: default avatarDavide Libenzi <davidel@xmailserver.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 501f2499

fs/eventpoll.c

+2 −2
Original line number Diff line number Diff line
@@ -599,7 +599,7 @@ sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event) 
	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 @@ sys_epoll_ctl(int epfd, int op, int fd, struct epoll_event __user *event) 
		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;

include/asm-alpha/poll.h

+2 −0
Original line number Diff line number Diff line
@@ -13,6 +13,8 @@ 
#define POLLWRBAND	(1 << 9)

#define POLLMSG		(1 << 10)

#define POLLREMOVE	(1 << 11)

#define POLLRDHUP       (1 << 12)





struct pollfd {

	int fd;

include/asm-arm/poll.h

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#define POLLWRBAND	0x0200

#define POLLMSG		0x0400

#define POLLREMOVE	0x1000

#define POLLRDHUP       0x2000



struct pollfd {

	int fd;

include/asm-arm26/poll.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#define POLLWRNORM	0x0100

#define POLLWRBAND	0x0200

#define POLLMSG		0x0400

#define POLLRDHUP       0x2000



struct pollfd {

	int fd;

include/asm-cris/poll.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
#define POLLWRBAND	512

#define POLLMSG		1024

#define POLLREMOVE	4096

#define POLLRDHUP       8192



struct pollfd {

	int fd;