Replace selwakeup() with KNOTE() in tun(4) and tap(4).
This patch makes the tun(4) and tap(4) event filters MP-safe.
This is similar to the change that just got committed to pppac(4)
and pppx(4). However, tun(4) and tap(4) can be destroyed abruptly,
so klist_invalidate() has to be kept in tun_clone_destroy().
The selwakeup() call in tun_dev_close() can be removed. If the device
is closed peacefully, the klists get cleared automatically and waiters
notified before the close routine is invoked. On abrupt detach,
klist_invalidate() in tun_clone_destroy() should clear any lingering
knotes.
OK?
Index: net/if_tun.c
===================================================================
RCS file: src/sys/net/if_tun.c,v
retrieving revision 1.237
diff -u -p -r1.237 if_tun.c
--- net/if_tun.c 2 Jul 2022 08:50:42 -0000 1.237
+++ net/if_tun.c 30 Jan 2023 03:32:36 -0000
@@ -47,13 +47,14 @@
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/syslog.h>
-#include <sys/selinfo.h>
#include <sys/fcntl.h>
#include <sys/time.h>
#include <sys/device.h>
#include <sys/vnode.h>
#include <sys/signalvar.h>
#include <sys/conf.h>
+#include <sys/event.h>
+#include <sys/mutex.h>
#include <sys/smr.h>
#include <net/if.h>
@@ -78,8 +79,9 @@
struct tun_softc {
struct arpcom sc_ac; /* ethernet common data */
#define sc_if sc_ac.ac_if
- struct selinfo sc_rsel; /* read select */
- struct selinfo sc_wsel; /* write select (not used) */
+ struct mutex sc_mtx;
+ struct klist sc_rklist; /* knotes for read */
+ struct klist sc_wklist; /* knotes for write (unused) */
SMR_LIST_ENTRY(tun_softc)
sc_entry; /* all tunnel interfaces */
int sc_unit;
@@ -125,22 +127,28 @@ int tun_init(struct tun_softc *);
void tun_start(struct ifnet *);
int filt_tunread(struct knote *, long);
int filt_tunwrite(struct knote *, long);
+int filt_tunmodify(struct kevent *, struct knote *);
+int filt_tunprocess(struct knote *, struct kevent *);
void filt_tunrdetach(struct knote *);
void filt_tunwdetach(struct knote *);
void tun_link_state(struct ifnet *, int);
const struct filterops tunread_filtops = {
- .f_flags = FILTEROP_ISFD,
+ .f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_tunrdetach,
.f_event = filt_tunread,
+ .f_modify = filt_tunmodify,
+ .f_process = filt_tunprocess,
};
const struct filterops tunwrite_filtops = {
- .f_flags = FILTEROP_ISFD,
+ .f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_tunwdetach,
.f_event = filt_tunwrite,
+ .f_modify = filt_tunmodify,
+ .f_process = filt_tunprocess,
};
SMR_LIST_HEAD(tun_list, tun_softc);
@@ -220,6 +228,9 @@ tun_create(struct if_clone *ifc, int uni
ifp = &sc->sc_if;
snprintf(ifp->if_xname, sizeof(ifp->if_xname),
"%s%d", ifc->ifc_name, unit);
+ mtx_init(&sc->sc_mtx, IPL_NET);
+ klist_init_mutex(&sc->sc_rklist, &sc->sc_mtx);
+ klist_init_mutex(&sc->sc_wklist, &sc->sc_mtx);
ifp->if_softc = sc;
/* this is enough state for tun_dev_open to work with */
@@ -275,6 +286,8 @@ tun_create(struct if_clone *ifc, int uni
return (0);
exists:
+ klist_free(&sc->sc_rklist);
+ klist_free(&sc->sc_wklist);
free(sc, M_DEVBUF, sizeof(*sc));
return (EEXIST);
}
@@ -284,7 +297,6 @@ tun_clone_destroy(struct ifnet *ifp)
{
struct tun_softc *sc = ifp->if_softc;
dev_t dev;
- int s;
KERNEL_ASSERT_LOCKED();
@@ -314,10 +326,11 @@ tun_clone_destroy(struct ifnet *ifp)
/* wait for device entrypoints to finish */
refcnt_finalize(&sc->sc_refs, "tundtor");
- s = splhigh();
- klist_invalidate(&sc->sc_rsel.si_note);
- klist_invalidate(&sc->sc_wsel.si_note);
- splx(s);
+ klist_invalidate(&sc->sc_rklist);
+ klist_invalidate(&sc->sc_wklist);
+
+ klist_free(&sc->sc_rklist);
+ klist_free(&sc->sc_wklist);
if (ISSET(sc->sc_flags, TUN_LAYER2))
ether_ifdetach(ifp);
@@ -488,7 +501,6 @@ tun_dev_close(dev_t dev, struct proc *p)
ifq_purge(&ifp->if_snd);
CLR(sc->sc_flags, TUN_ASYNC);
- selwakeup(&sc->sc_rsel);
sigio_free(&sc->sc_sigio);
if (!ISSET(sc->sc_flags, TUN_DEAD)) {
@@ -654,7 +666,10 @@ tun_wakeup(struct tun_softc *sc)
if (sc->sc_reading)
wakeup(&sc->sc_if.if_snd);
- selwakeup(&sc->sc_rsel);
+ mtx_enter(&sc->sc_mtx);
+ KNOTE(&sc->sc_rklist, 0);
+ mtx_leave(&sc->sc_mtx);
+
if (sc->sc_flags & TUN_ASYNC)
pgsigio(&sc->sc_sigio, SIGIO, 0);
}
@@ -960,7 +975,6 @@ tun_dev_kqfilter(dev_t dev, struct knote
struct ifnet *ifp;
struct klist *klist;
int error = 0;
- int s;
sc = tun_get(dev);
if (sc == NULL)
@@ -970,11 +984,11 @@ tun_dev_kqfilter(dev_t dev, struct knote
switch (kn->kn_filter) {
case EVFILT_READ:
- klist = &sc->sc_rsel.si_note;
+ klist = &sc->sc_rklist;
kn->kn_fop = &tunread_filtops;
break;
case EVFILT_WRITE:
- klist = &sc->sc_wsel.si_note;
+ klist = &sc->sc_wklist;
kn->kn_fop = &tunwrite_filtops;
break;
default:
@@ -982,11 +996,9 @@ tun_dev_kqfilter(dev_t dev, struct knote
goto put;
}
- kn->kn_hook = (caddr_t)sc; /* XXX give the sc_ref to the hook? */
+ kn->kn_hook = sc;
- s = splhigh();
- klist_insert_locked(klist, kn);
- splx(s);
+ klist_insert(klist, kn);
put:
tun_put(sc);
@@ -996,12 +1008,9 @@ put:
void
filt_tunrdetach(struct knote *kn)
{
- int s;
struct tun_softc *sc = kn->kn_hook;
- s = splhigh();
- klist_remove_locked(&sc->sc_rsel.si_note, kn);
- splx(s);
+ klist_remove(&sc->sc_rklist, kn);
}
int
@@ -1010,6 +1019,8 @@ filt_tunread(struct knote *kn, long hint
struct tun_softc *sc = kn->kn_hook;
struct ifnet *ifp = &sc->sc_if;
+ MUTEX_ASSERT_LOCKED(&sc->sc_mtx);
+
kn->kn_data = ifq_hdatalen(&ifp->if_snd);
return (kn->kn_data > 0);
@@ -1018,12 +1029,9 @@ filt_tunread(struct knote *kn, long hint
void
filt_tunwdetach(struct knote *kn)
{
- int s;
struct tun_softc *sc = kn->kn_hook;
- s = splhigh();
- klist_remove_locked(&sc->sc_wsel.si_note, kn);
- splx(s);
+ klist_remove(&sc->sc_wklist, kn);
}
int
@@ -1032,9 +1040,37 @@ filt_tunwrite(struct knote *kn, long hin
struct tun_softc *sc = kn->kn_hook;
struct ifnet *ifp = &sc->sc_if;
+ MUTEX_ASSERT_LOCKED(&sc->sc_mtx);
+
kn->kn_data = ifp->if_hdrlen + ifp->if_hardmtu;
return (1);
+}
+
+int
+filt_tunmodify(struct kevent *kev, struct knote *kn)
+{
+ struct tun_softc *sc = kn->kn_hook;
+ int active;
+
+ mtx_enter(&sc->sc_mtx);
+ active = knote_modify(kev, kn);
+ mtx_leave(&sc->sc_mtx);
+
+ return (active);
+}
+
+int
+filt_tunprocess(struct knote *kn, struct kevent *kev)
+{
+ struct tun_softc *sc = kn->kn_hook;
+ int active;
+
+ mtx_enter(&sc->sc_mtx);
+ active = knote_process(kn, kev);
+ mtx_leave(&sc->sc_mtx);
+
+ return (active);
}
void
