ifnet: Refactor out the detaching of address family dependent data to dedicated function

[zlei]

Summary

This makes the main logic of if_detach_internal() more clear. It is also easier to read the logic of attaching and detaching address family dependent data.

No functional change intended.

MFC after: 1 week

[zlei]

@glebius This may conflict with your local work ~

[glebius]

No, I don't agree this makes code more clear. A single time use function just requires the reader to jump more around the file to understand how things work, also keeping in mind what resources are held or not during those calls.

So my approval of D49444 is in the scope of the original function, not on top of this revision.

sys/net/if.c

 
 /*
  * XXX: Style; these should be sorted alphabetically, and unprototyped
  * static functions should be prototyped. Currently they are sorted by
  * declaration order.
  */
 static void        if_attachdomain(void *);
 static void        if_attachdomain1(struct ifnet *);
+static void        if_detachdomain1(struct ifnet *);
 static int        ifconf(u_long, caddr_t);
 static void        if_input_default(struct ifnet *, struct mbuf *);
 static int        if_requestencap_default(struct ifnet *, struct if_encap_req *);
 static int        if_setflag(struct ifnet *, int, int, int *, int);
 static int        if_transmit_default(struct ifnet *ifp, struct mbuf *m);
 static int        if_delmulti_locked(struct ifnet *, struct ifmultiaddr *, int);
 static void        do_link_state_change(void *, int);
 static int        if_getgroup(struct ifgroupreq *, struct ifnet *);
if_attachdomain1(struct ifnet *ifp)
         bzero(ifp->if_afdata, sizeof(ifp->if_afdata));
         SLIST_FOREACH(dp, &domains, dom_next) {
                 if (dp->dom_ifattach)
                         ifp->if_afdata[dp->dom_family] =
                             (*dp->dom_ifattach)(ifp);
         }
 }
 
+static void
+if_detachdomain1(struct ifnet *ifp)
+{
+        int i;
+        struct domain *dp;
+
         /*
+         * We cannot hold the lock over dom_ifdetach calls as they might
+         * sleep, for example trying to drain a callout, thus open up the
+         * theoretical race with re-attaching.
+         */
+        IF_AFDATA_LOCK(ifp);
+        i = ifp->if_afdata_initialized;
+        ifp->if_afdata_initialized = 0;
+        IF_AFDATA_UNLOCK(ifp);
+        if (i == 0)
+                return;
+        SLIST_FOREACH(dp, &domains, dom_next) {
+                if (dp->dom_ifdetach && ifp->if_afdata[dp->dom_family]) {
+                        (*dp->dom_ifdetach)(ifp,
+                            ifp->if_afdata[dp->dom_family]);
+                        ifp->if_afdata[dp->dom_family] = NULL;
+                }
+        }
+}
+
+/*
  * Remove any unicast or broadcast network addresses from an interface.
  */
 void
 if_purgeaddrs(struct ifnet *ifp)
 {
         struct ifaddr *ifa;
 
 #ifdef INET6

  * vnet_if_return SYSUNINIT function sets it.  Note: we can be called
  * on a vnet instance shutdown without this flag being set, e.g., when
  * the cloned interfaces are destoyed as first thing of teardown.
  */
 static void
 if_detach_internal(struct ifnet *ifp, bool vmove)
 {
         struct ifaddr *ifa;
-        int i;
-        struct domain *dp;
 #ifdef VIMAGE
         bool shutdown;
 
         shutdown = VNET_IS_SHUTTING_DOWN(ifp->if_vnet);
 #endif
 
         sx_assert(&ifnet_detach_sxlock, SX_XLOCKED);
 
if (!CK_STAILQ_EMPTY(&ifp->if_addrhead)) {
                         IF_ADDR_WUNLOCK(ifp);
         }
 
         rt_flushifroutes(ifp);
 
 #ifdef VIMAGE
 finish_vnet_shutdown:
 #endif
-        /*
-         * We cannot hold the lock over dom_ifdetach calls as they might
-         * sleep, for example trying to drain a callout, thus open up the
-         * theoretical race with re-attaching.
-         */
-        IF_AFDATA_LOCK(ifp);
-        i = ifp->if_afdata_initialized;
-        ifp->if_afdata_initialized = 0;
-        IF_AFDATA_UNLOCK(ifp);
-        if (i == 0)
-                return;
-        SLIST_FOREACH(dp, &domains, dom_next) {
-                if (dp->dom_ifdetach && ifp->if_afdata[dp->dom_family]) {
-                        (*dp->dom_ifdetach)(ifp,
-                            ifp->if_afdata[dp->dom_family]);
-                        ifp->if_afdata[dp->dom_family] = NULL;
-                }
-        }
+        if_detachdomain1(ifp);
 }
 
 #ifdef VIMAGE
 /*
  * if_vmove() performs a limited version of if_detach() in current
  * vnet and if_attach()es the ifnet to the vnet specified as 2nd arg.
  */
 static void