Date: Sun, 30 Jul 2006 13:30:20 +0200 From: Fredrik Lindberg <fli+freebsd-current@shapeshifter.se> To: gurney_j@resnet.uoregon.edu Cc: freebsd-current@freebsd.org Subject: Re: Extending EVFILT_NETDEV to support ip-address changes Message-ID: <44CC984C.1010908@shapeshifter.se> In-Reply-To: <44C79A66.6000204@shapeshifter.se> References: <44C61470.3070005@shapeshifter.se> <20060725173924.GR96589@funkthat.com> <44C79A66.6000204@shapeshifter.se>
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Fredrik Lindberg wrote:
> The documented way of using EVFILT_NETDEV according to kqueue(2) is to
> obtain the status from fflags, but as it apparently sets data too
> somebody is using it, that's for sure.
>
> Users of EVFILT_NETDEV are required to pass a mask of
> NOTE_LINK{UP,DOWN,INV} in fflags with the initial kevent call, otherwise
> no events will fire.
>
> What if we add NOTE_ADDR{NEW,DEL} as bit masks and change filt_netdev to
> only set kn_data when a monitored event occurs instead of just setting
> it regardless of if the event is being monitored or not.
> If we also restrict the values of kn_data to NOTE_LINK{UP,DOWN,INV},
> existing applications shouldn't break as they would only receive the
> events they subscribed to and both data and fflags would be
> intact. NOTE_ADDR{NEW,DEL} would be obtain only through fflags and
> kn_data would be left as it is in these cases (0 with EV_CLEAR set).
>
> Doing it this way shouldn't break the API, as no fields would be touched
> because kn_sfflags & hint would fail for ADDR{NEW,DEL} on existing
> applications as they would only be subscribed to one or more of the
> NOTE_LINK{UP,DOWN,INV} events.
> But maybe I'm missing some rare edge case...
>
Replying to myself here, but anyway. I've attached a complete patch
with the modified filt_netdev as described above.
Fredrik Lindberg
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filename="kqueue-netdev-20060730.patch"
Index: sys/event.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/event.h,v
retrieving revision 1.36
diff -u -r1.36 event.h
--- sys/event.h 16 Mar 2006 11:19:36 -0000 1.36
+++ sys/event.h 30 Jul 2006 10:54:31 -0000
@@ -115,6 +115,8 @@
#define NOTE_LINKUP 0x0001 /* link is up */
#define NOTE_LINKDOWN 0x0002 /* link is down */
#define NOTE_LINKINV 0x0004 /* link state is invalid */
+#define NOTE_ADDRNEW 0x0008 /* ip-address added */
+#define NOTE_ADDRDEL 0x0010 /* ip-address removed */
struct knote;
SLIST_HEAD(klist, knote);
Index: netinet/in.c
===================================================================
RCS file: /home/ncvs/src/sys/netinet/in.c,v
retrieving revision 1.93
diff -u -r1.93 in.c
--- netinet/in.c 24 Jan 2006 16:19:31 -0000 1.93
+++ netinet/in.c 30 Jul 2006 10:54:31 -0000
@@ -399,8 +399,10 @@
(struct sockaddr_in *) &ifr->ifr_addr, 1);
if (error != 0 && iaIsNew)
break;
- if (error == 0)
+ if (error == 0) {
EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+ KNOTE_UNLOCKED(&ifp->if_klist, NOTE_ADDRNEW);
+ }
return (0);
case SIOCSIFNETMASK:
@@ -443,8 +445,10 @@
if ((ifp->if_flags & IFF_BROADCAST) &&
(ifra->ifra_broadaddr.sin_family == AF_INET))
ia->ia_broadaddr = ifra->ifra_broadaddr;
- if (error == 0)
+ if (error == 0) {
EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+ KNOTE_UNLOCKED(&ifp->if_klist, NOTE_ADDRNEW);
+ }
return (error);
case SIOCDIFADDR:
@@ -460,6 +464,7 @@
*/
in_ifadown(&ia->ia_ifa, 1);
EVENTHANDLER_INVOKE(ifaddr_event, ifp);
+ KNOTE_UNLOCKED(&ifp->if_klist, NOTE_ADDRDEL);
error = 0;
break;
Index: net/if.c
===================================================================
RCS file: /home/ncvs/src/sys/net/if.c,v
retrieving revision 1.261
diff -u -r1.261 if.c
--- net/if.c 9 Jul 2006 06:04:00 -0000 1.261
+++ net/if.c 30 Jul 2006 10:54:31 -0000
@@ -265,10 +265,12 @@
knlist_remove_inevent(klist, kn);
return (1);
}
- if (hint != 0)
- kn->kn_data = hint; /* current status */
- if (kn->kn_sfflags & hint)
+
+ if (kn->kn_sfflags & hint) {
kn->kn_fflags |= hint;
+ if (hint & (NOTE_LINKUP | NOTE_LINKDOWN))
+ kn->kn_data = hint; /* current link status */
+ }
return (kn->kn_fflags != 0);
}
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