Author: adrian
Date: Wed May 27 06:04:38 2009
New Revision: 192876
URL: http://svn.freebsd.org/changeset/base/192876
Log:
Enforce that there are actually enough xenbus TX ring descriptors available
before attempting to queue the packet.
Modified:
head/sys/dev/xen/netfront/netfront.c
Modified: head/sys/dev/xen/netfront/netfront.c
==============================================================================
--- head/sys/dev/xen/netfront/netfront.c Wed May 27 05:37:04 2009
(r192875)
+++ head/sys/dev/xen/netfront/netfront.c Wed May 27 06:04:38 2009
(r192876)
@@ -1478,10 +1478,20 @@ xn_start_locked(struct ifnet *ifp)
}
/*
- * XXX TODO - make sure there's actually space available
- * in the Xen TX ring for this rather than the hacky way
- * its currently done.
+ * Make sure there's actually space available in the
+ * Xen TX ring for this. Overcompensate for the possibility
+ * of having a TCP offload fragment just in case for now
+ * (the +1) rather than adding logic to accurately calculate
+ * the required size.
*/
+ if (RING_FREE_REQUESTS(&sc->tx) < (nfrags + 1)) {
+ printf("xn_start_locked: free ring slots (%d) < (nfrags
+ 1) (%d); must be full!\n",
+ (int) RING_FREE_REQUESTS(&sc->tx),
+ (int) (nfrags + 1));
+ IF_PREPEND(&ifp->if_snd, m_head);
+ ifp->if_drv_flags |= IFF_DRV_OACTIVE;
+ break;
+ }
/*
* Start packing the mbufs in this chain into
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