Date: Fri, 05 May 2000 09:08:25 +0200 From: Gary Jennejohn <garyj@peedub.muc.de> To: Bill Paul <wpaul@skynet.ctr.columbia.edu> Cc: dillon@apollo.backplane.com, freebsd-current@FreeBSD.ORG Subject: Re: NFS, rl0 and Alpha Message-ID: <200005050708.JAA37756@peedub.muc.de> In-Reply-To: Your message of "Fri, 05 May 2000 00:40:39 %2B0200." <200005042244.SAA07824@skynet.ctr.columbia.edu>
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Bill Paul writes:
>Of all the gin joints in all the towns in all the world, Gary Jennejohn
>had to walk into mine and say:
>
>> OK. Unfortunately, gdb core dumps when I try to analyze a crash dump
>> with a debugging kernel :( Even worse, gdb core dumps when I try to
>> run a debugging gdb in gdb to find out why gdb is core dumping when
>> I try to debug a kernel with symbols :(( Wonderful.
>
>I suspect this may have something to do with the way packets sometimes
>wrap from the end of the RX buffer pool to the beginning. This might
>result in fragmentation across multiple mbufs in some cases (I think).
>If I squint hard enough, I can see a way for the data to end up misaligned
>in one of the additional mbufs.
>
>Try this patch. It's an untested hack (I don't have a RealTek card
>in a test box right this second) but should fix the problem if it's
>what I think it is.
>
>
>*** if_rl.c.orig Sat Apr 29 14:15:10 2000
>--- if_rl.c Thu May 4 22:16:31 2000
>***************
>*** 913,919 ****
> goto fail;
> }
>
>! sc->rl_cdata.rl_rx_buf = contigmalloc(RL_RXBUFLEN + 32, M_DEVBUF,
> M_NOWAIT, 0, 0xffffffff, PAGE_SIZE, 0);
>
> if (sc->rl_cdata.rl_rx_buf == NULL) {
>--- 911,917 ----
> goto fail;
> }
>
>! sc->rl_cdata.rl_rx_buf = contigmalloc(RL_RXBUFLEN + 1518, M_DEVBUF,
> M_NOWAIT, 0, 0xffffffff, PAGE_SIZE, 0);
>
> if (sc->rl_cdata.rl_rx_buf == NULL) {
>***************
>*** 1122,1129 ****
> wrap = (sc->rl_cdata.rl_rx_buf + RL_RXBUFLEN) - rxbufpos;
>
> if (total_len > wrap) {
> m = m_devget(rxbufpos - RL_ETHER_ALIGN,
>! wrap + RL_ETHER_ALIGN, 0, ifp, NULL);
> if (m == NULL) {
> ifp->if_ierrors++;
> printf("rl%d: out of mbufs, tried to "
>--- 1120,1132 ----
> wrap = (sc->rl_cdata.rl_rx_buf + RL_RXBUFLEN) - rxbufpos;
>
> if (total_len > wrap) {
>+ /*
>+ * Fool m_devget() into thinking we want to copy
>+ * the whole buffer so we don't end up fragmenting
>+ * the data.
>+ */
> m = m_devget(rxbufpos - RL_ETHER_ALIGN,
>! total_len + RL_ETHER_ALIGN, 0, ifp, NULL);
> if (m == NULL) {
> ifp->if_ierrors++;
> printf("rl%d: out of mbufs, tried to "
>***************
>*** 1132,1145 ****
> m_adj(m, RL_ETHER_ALIGN);
> m_copyback(m, wrap, total_len - wrap,
> sc->rl_cdata.rl_rx_buf);
>- if (m->m_len < sizeof(struct ether_header))
>- m = m_pullup(m,
>- sizeof(struct ether_header));
>- if (m == NULL) {
>- printf("rl%d: m_pullup failed",
>- sc->rl_unit);
>- ifp->if_ierrors++;
>- }
> }
> cur_rx = (total_len - wrap + ETHER_CRC_LEN);
> } else {
>--- 1135,1140 ----
Yes, this patch fixes the problem. Thank you, Bill Paul !
---
Gary Jennejohn / garyj@muc.de gj@freebsd.org
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