Re: kern/52211: vioif stops on dmamap load error

[Masanobu SAITOH <msaitoh%execsw.org@localhost>]

On 2017/05/11 18:20, Masanobu SAITOH wrote:
> The following reply was made to PR kern/52211; it has been noted by GNATS.
>
> From: Masanobu SAITOH <msaitoh%execsw.org@localhost>
> To: gnats-bugs%NetBSD.org@localhost, kern-bug-people%netbsd.org@localhost,
>   gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, hannken%eis.cs.tu-bs.de@localhost
> Cc: msaitoh%execsw.org@localhost
> Subject: Re: kern/52211: vioif stops on dmamap load error
> Date: Thu, 11 May 2017 18:17:51 +0900
>
>   On 2017/05/11 18:11, Masanobu SAITOH wrote:
>   > On 2017/05/11 17:33, Masanobu SAITOH wrote:
>   >> On 2017/05/11 17:20, J. Hannken-Illjes wrote:
>   >>> The following reply was made to PR kern/52211; it has been noted by GNATS.
>   >>>
>   >>> From: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
>   >>> To: gnats-bugs%NetBSD.org@localhost
>   >>> Cc:
>   >>> Subject: Re: kern/52211: vioif stops on dmamap load error
>   >>> Date: Thu, 11 May 2017 10:18:09 +0200
>   >>>
>   >>>   > On 11. May 2017, at 10:10, Masanobu SAITOH <msaitoh%execsw.org@localhost> wrote:
>   >>>   >
>   >>>   >   Coudl you show me the output of ifconfig vioif0?
>   >>>   vioif0: flags=8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> mtu 1500
>   >>>       address: XX:XX:XX:XX:XX:XX
>   >>>       inet XXX.XXX.XXX.XXX netmask 0xffffff00 broadcast XXX.XXX.XXX.255
>   >>>       inet6 fe80::XXXX:XXXX:XXXX:XXXX%vioif0 prefixlen 64 scopeid 0x1
>   >>>       inet6 XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX:XXXX prefixlen 64
>   >>
>   >> Yes, it has neither TSO nor JUMBO_MTU.
>   >>
>   >> If a lof of mbuf chain is a normal case for vioif(4) it would
>   >> worth to try m_defrag(), but I suspect it's not a normal case
>   >> and it's caused by a bug in vioif or the upper layer.
>   >>
>   >>>   --
>   >>>   J. Hannken-Illjes - hannken%eis.cs.tu-bs.de@localhost - TU Braunschweig (Germany)
>   >>>
>   >
>   > Could you test with the following diff?
>   >

(snip)

>   Oops. The above patch is broken. Don't use it.
>   Please wait a little.
>   

New one:

Index: if_vioif.c
===================================================================
RCS file: /cvsroot/src/sys/dev/pci/if_vioif.c,v
retrieving revision 1.34
diff -u -p -r1.34 if_vioif.c
--- if_vioif.c	28 Mar 2017 04:10:33 -0000	1.34
+++ if_vioif.c	11 May 2017 09:20:00 -0000
@@ -812,6 +812,7 @@ vioif_start(struct ifnet *ifp)
 
 	for (;;) {
 		int slot, r;
+		struct mbuf *newm;
 
 		IFQ_DEQUEUE(&ifp->if_snd, m);
 
@@ -833,7 +834,23 @@ retry:
 		r = bus_dmamap_load_mbuf(virtio_dmat(vsc),
 					 sc->sc_tx_dmamaps[slot],
 					 m, BUS_DMA_WRITE|BUS_DMA_NOWAIT);
-		if (r != 0) {
+		switch (r) {
+		case 0:
+			break;
+		case EFBIG:
+			printf("%s: loadup_mbuf() returned EFBIG (%d segs)\n",
+			    device_xname(sc->sc_dev),
+			    sc->sc_tx_dmamaps[slot]->dm_nsegs);
+			newm = m_defrag(m, M_NOWAIT);
+			if ((newm != NULL) &&
+			    (bus_dmamap_load_mbuf(virtio_dmat(vsc),
+				sc->sc_tx_dmamaps[slot],
+				newm, BUS_DMA_WRITE|BUS_DMA_NOWAIT) == 0)) {
+				m = newm;
+				break;
+			}
+			/* FALLTHROUGH */
+		default:
 			virtio_enqueue_abort(vsc, vq, slot);
 			aprint_error_dev(sc->sc_dev,
 			    "tx dmamap load failed, error code %d\n", r);



BTW, what hypervisor are you using?

--
-----------------------------------------------
                SAITOH Masanobu (msaitoh%execsw.org@localhost
                                 msaitoh%netbsd.org@localhost)