PERFORCE change 161793 for review

[Marko Zec]

http://perforce.freebsd.org/chv.cgi?CH=161793

Change 161793 by zec at zec_tpx32 on 2009/05/08 21:43:51

	A controversial hack: when allocating if_unit numbers for
	cloning ifnets, do NOT resort to bitmap mappings, but
	iterate through all existing ifnets in a particular vnet
	as long as a free unit number is found.
	
	The problem here is that we are switchng from a O(n) to
	a O(n**2) search method with more work being done in each
	iteration.  So this should be revisited RSN.

Affected files ...

.. //depot/projects/vimage-commit2/src/sys/net/if_clone.c#5 edit

Differences ...

==== //depot/projects/vimage-commit2/src/sys/net/if_clone.c#5 (text+ko) ====

@@ -401,6 +401,25 @@
 	 * Find a free unit if none was given.
 	 */
 	if (wildcard) {
+#ifdef VIMAGE
+		/* XXX revisit - O(n**2) loop bellow! */
+		INIT_VNET_NET(curvnet);
+		char name[IFNAMSIZ];
+		struct ifnet *ifp;
+		int i = 0;
+
+		IFNET_RLOCK();
+again:
+		TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
+			sprintf(name, "%s%d", ifc->ifc_name, i);
+			if (strcmp(name, ifp->if_xname) == 0) {
+				i++;
+				goto again;
+			}
+		}
+		IFNET_RUNLOCK();
+		*unit = i;
+#else
 		while ((bytoff < ifc->ifc_bmlen)
 		    && (ifc->ifc_units[bytoff] == 0xff))
 			bytoff++;
@@ -411,6 +430,7 @@
 		while ((ifc->ifc_units[bytoff] & (1 << bitoff)) != 0)
 			bitoff++;
 		*unit = (bytoff << 3) + bitoff;
+#endif
 	}
 
 	if (*unit > ifc->ifc_maxunit) {
@@ -418,6 +438,7 @@
 		goto done;
 	}
 
+#ifndef VIMAGE
 	if (!wildcard) {
 		bytoff = *unit >> 3;
 		bitoff = *unit - (bytoff << 3);
@@ -433,6 +454,7 @@
 	KASSERT((ifc->ifc_units[bytoff] & (1 << bitoff)) == 0,
 	    ("%s: bit is already set", __func__));
 	ifc->ifc_units[bytoff] |= (1 << bitoff);
+#endif
 	IF_CLONE_ADDREF_LOCKED(ifc);
 
 done:
@@ -443,19 +465,22 @@
 void
 ifc_free_unit(struct if_clone *ifc, int unit)
 {
+#ifndef VIMAGE
 	int bytoff, bitoff;
 
-
 	/*
 	 * Compute offset in the bitmap and deallocate the unit.
 	 */
 	bytoff = unit >> 3;
 	bitoff = unit - (bytoff << 3);
+#endif
 
 	IF_CLONE_LOCK(ifc);
+#ifndef VIMAGE
 	KASSERT((ifc->ifc_units[bytoff] & (1 << bitoff)) != 0,
 	    ("%s: bit is already cleared", __func__));
 	ifc->ifc_units[bytoff] &= ~(1 << bitoff);
+#endif
 	IF_CLONE_REMREF_LOCKED(ifc);	/* releases lock */
 }