Date: Mon, 02 May 2005 09:38:49 -0700 From: Maksim Yevmenkin <maksim.yevmenkin@savvis.net> To: net@freebsd.org Cc: Julian Elischer <julian@elischer.org> Subject: Re: if_tap unaligned access problem Message-ID: <42765799.6090201@savvis.net> In-Reply-To: <20050429182819.GP2670@funkthat.com> References: <20050428135120.GB21428@cell.sick.ru> <427111BF.2050607@savvis.net> <42712BAA.4070201@elischer.org> <42715269.3010306@errno.com> <Pine.SOC.4.61.0504291132520.28551@tea.blinkenlights.nl> <4272743A.2030003@savvis.net> <20050429182819.GP2670@funkthat.com>
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Hello,
>>>>>>i think we have few options here:
>>>>>>
>>>>>>1) revert back original tapwrite function that was changed in v.
>>>>>>1.48 and set offset to 2 bytes in top mbuf
>>>>>>
>>>>>>2) change current version of tapwrite so it would m_prepend and
>>>>>>m_pullup mbuf after m_uiotombuf
>>>>>>
>>>>>>3) change m_uiotombuf to accept one more parameter - mbuf offset at
>>>>>>which data should be copied. there are not that many users of
>>>>>>m_uiotombuf
>>
>>please find and review the attached patch (untested) that implements
>>option (3) above.
any objections to the attached (revised) patch? can i commit it?
thanks,
max
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filename="m_uiotombuf.diff.txt"
Index: sys/kern/uipc_mbuf.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/uipc_mbuf.c,v
retrieving revision 1.147
diff -u -r1.147 uipc_mbuf.c
--- sys/kern/uipc_mbuf.c 17 Mar 2005 19:34:57 -0000 1.147
+++ sys/kern/uipc_mbuf.c 2 May 2005 16:33:41 -0000
@@ -1333,7 +1333,7 @@
#endif
struct mbuf *
-m_uiotombuf(struct uio *uio, int how, int len)
+m_uiotombuf(struct uio *uio, int how, int len, int align)
{
struct mbuf *m_new = NULL, *m_final = NULL;
int progress = 0, error = 0, length, total;
@@ -1342,12 +1342,15 @@
total = min(uio->uio_resid, len);
else
total = uio->uio_resid;
- if (total > MHLEN)
+ if (align >= MHLEN)
+ goto nospace;
+ if (total + align > MHLEN)
m_final = m_getcl(how, MT_DATA, M_PKTHDR);
else
m_final = m_gethdr(how, MT_DATA);
if (m_final == NULL)
goto nospace;
+ m_final->m_data += align;
m_new = m_final;
while (progress < total) {
length = total - progress;
Index: sys/kern/uipc_syscalls.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/uipc_syscalls.c,v
retrieving revision 1.219
diff -u -r1.219 uipc_syscalls.c
--- sys/kern/uipc_syscalls.c 16 Apr 2005 18:46:28 -0000 1.219
+++ sys/kern/uipc_syscalls.c 2 May 2005 16:33:41 -0000
@@ -1796,7 +1796,7 @@
hdr_uio->uio_td = td;
hdr_uio->uio_rw = UIO_WRITE;
if (hdr_uio->uio_resid > 0) {
- m_header = m_uiotombuf(hdr_uio, M_DONTWAIT, 0);
+ m_header = m_uiotombuf(hdr_uio, M_DONTWAIT, 0, 0);
if (m_header == NULL)
goto done;
headersize = m_header->m_pkthdr.len;
Index: sys/net/if_tap.c
===================================================================
RCS file: /home/ncvs/src/sys/net/if_tap.c,v
retrieving revision 1.52
diff -u -r1.52 if_tap.c
--- sys/net/if_tap.c 13 Apr 2005 00:30:19 -0000 1.52
+++ sys/net/if_tap.c 2 May 2005 16:33:41 -0000
@@ -827,7 +827,7 @@
return (EIO);
}
- if ((m = m_uiotombuf(uio, M_DONTWAIT, 0)) == NULL) {
+ if ((m = m_uiotombuf(uio, M_DONTWAIT, 0, ETHER_ALIGN)) == NULL) {
ifp->if_ierrors ++;
return (error);
}
Index: sys/net/if_tun.c
===================================================================
RCS file: /home/ncvs/src/sys/net/if_tun.c,v
retrieving revision 1.149
diff -u -r1.149 if_tun.c
--- sys/net/if_tun.c 31 Mar 2005 12:19:44 -0000 1.149
+++ sys/net/if_tun.c 2 May 2005 16:33:41 -0000
@@ -761,7 +761,7 @@
return (EIO);
}
- if ((m = m_uiotombuf(uio, M_DONTWAIT, 0)) == NULL) {
+ if ((m = m_uiotombuf(uio, M_DONTWAIT, 0, 0)) == NULL) {
ifp->if_ierrors++;
return (error);
}
Index: sys/netgraph/ng_device.c
===================================================================
RCS file: /home/ncvs/src/sys/netgraph/ng_device.c,v
retrieving revision 1.20
diff -u -r1.20 ng_device.c
--- sys/netgraph/ng_device.c 14 Mar 2005 16:02:53 -0000 1.20
+++ sys/netgraph/ng_device.c 2 May 2005 16:33:41 -0000
@@ -466,7 +466,7 @@
if (uio->uio_resid < 0 || uio->uio_resid > IP_MAXPACKET)
return (EIO);
- if ((m = m_uiotombuf(uio, M_DONTWAIT, 0)) == NULL)
+ if ((m = m_uiotombuf(uio, M_DONTWAIT, 0, 0)) == NULL)
return (ENOBUFS);
NG_SEND_DATA_ONLY(error, priv->hook, m);
Index: sys/sys/mbuf.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/mbuf.h,v
retrieving revision 1.169
diff -u -r1.169 mbuf.h
--- sys/sys/mbuf.h 17 Mar 2005 19:34:57 -0000 1.169
+++ sys/sys/mbuf.h 2 May 2005 16:33:41 -0000
@@ -582,7 +582,7 @@
struct mbuf *m_pulldown(struct mbuf *, int, int, int *);
struct mbuf *m_pullup(struct mbuf *, int);
struct mbuf *m_split(struct mbuf *, int, int);
-struct mbuf *m_uiotombuf(struct uio *, int, int);
+struct mbuf *m_uiotombuf(struct uio *, int, int, int);
/*-
* Network packets may have annotations attached by affixing a list
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