[src/trunk]: src/sys/arch/xen/xen Try to be smarted in the rx path: if the pa...

[bouyer <bouyer%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/19044d51b47d
branches:  trunk
changeset: 822148:19044d51b47d
user:      bouyer <bouyer%NetBSD.org@localhost>
date:      Sat Mar 04 19:11:01 2017 +0000

description:
Try to be smarted in the rx path: if the packet is small enough copy the
data to the mbuf's data area instead of allocating a new page from the pool.
While there fix a struct xennet_rxreq leak if xennet_checksum_fill()
fails with ENOMEM.

diffstat:

 sys/arch/xen/xen/if_xennet_xenbus.c |  43 ++++++++++++++++++++++--------------
 1 files changed, 26 insertions(+), 17 deletions(-)

diffs (69 lines):

diff -r 4841aa7c3d00 -r 19044d51b47d sys/arch/xen/xen/if_xennet_xenbus.c
--- a/sys/arch/xen/xen/if_xennet_xenbus.c       Sat Mar 04 11:16:33 2017 +0000
+++ b/sys/arch/xen/xen/if_xennet_xenbus.c       Sat Mar 04 19:11:01 2017 +0000
@@ -1,4 +1,4 @@
-/*      $NetBSD: if_xennet_xenbus.c,v 1.69 2016/12/15 09:28:04 ozaki-r Exp $      */
+/*      $NetBSD: if_xennet_xenbus.c,v 1.70 2017/03/04 19:11:01 bouyer Exp $      */
 
 /*
  * Copyright (c) 2006 Manuel Bouyer.
@@ -85,7 +85,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_xennet_xenbus.c,v 1.69 2016/12/15 09:28:04 ozaki-r Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_xennet_xenbus.c,v 1.70 2017/03/04 19:11:01 bouyer Exp $");
 
 #include "opt_xen.h"
 #include "opt_nfs_boot.h"
@@ -1074,26 +1074,35 @@
                MCLAIM(m, &sc->sc_ethercom.ec_rx_mowner);
 
                m_set_rcvif(m, ifp);
-               req->rxreq_va = (vaddr_t)pool_cache_get_paddr(
-                   if_xennetrxbuf_cache, PR_NOWAIT, &req->rxreq_pa);
-               if (__predict_false(req->rxreq_va == 0)) {
-                       printf("%s: rx no buf\n", ifp->if_xname);
-                       ifp->if_ierrors++;
-                       req->rxreq_va = va;
-                       req->rxreq_pa = pa;
-                       xennet_rx_free_req(req);
-                       m_freem(m);
-                       continue;
+               if (rx->status <= MHLEN) {
+                       /* small packet; copy to mbuf data area */
+                       m_copyback(m, 0, rx->status, pktp);
+                       KASSERT(m->m_pkthdr.len == rx->status);
+                       KASSERT(m->m_len == rx->status);
+               } else {
+                       /* large packet; attach buffer to mbuf */
+                       req->rxreq_va = (vaddr_t)pool_cache_get_paddr(
+                           if_xennetrxbuf_cache, PR_NOWAIT, &req->rxreq_pa);
+                       if (__predict_false(req->rxreq_va == 0)) {
+                               printf("%s: rx no buf\n", ifp->if_xname);
+                               ifp->if_ierrors++;
+                               req->rxreq_va = va;
+                               req->rxreq_pa = pa;
+                               xennet_rx_free_req(req);
+                               m_freem(m);
+                               continue;
+                       }
+                       m->m_len = m->m_pkthdr.len = rx->status;
+                       MEXTADD(m, pktp, rx->status,
+                           M_DEVBUF, xennet_rx_mbuf_free, NULL);
+                       m->m_ext.ext_paddr = pa;
+                       m->m_flags |= M_EXT_RW; /* we own the buffer */
                }
-               m->m_len = m->m_pkthdr.len = rx->status;
-               MEXTADD(m, pktp, rx->status,
-                   M_DEVBUF, xennet_rx_mbuf_free, NULL);
-               m->m_flags |= M_EXT_RW; /* we own the buffer */
-               m->m_ext.ext_paddr = pa;
                if ((rx->flags & NETRXF_csum_blank) != 0) {
                        xennet_checksum_fill(&m);
                        if (m == NULL) {
                                ifp->if_ierrors++;
+                               xennet_rx_free_req(req);
                                continue;
                        }
                }