Date: Fri, 29 Apr 2005 11:35:25 -0700 From: Maksim Yevmenkin <maksim.yevmenkin@savvis.net> To: John-Mark Gurney <gurney_j@resnet.uoregon.edu> Cc: Sam Leffler <sam@errno.com> Subject: Re: if_tap unaligned access problem Message-ID: <42727E6D.5020304@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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[...]
>>>I could try to port the changes netbsd made using m_copyup and
>>>send you the resulting patchfile. IPv4 has already been serviced by
>>>John-Mark Gurney in perforce.
>>
>>having these changes in the tree is a good thing, but it will require
>>more testing. maybe for now we could get away with simpler changes?
>
>
>>@@ -1342,12 +1342,15 @@
>> total = min(uio->uio_resid, len);
>> else
>> total = uio->uio_resid;
>>+ if (align >= MHLEN)
>>+ goto nospace;
>> if (total > MHLEN)
>
>
> Shouldn't this check be total + align > MHLEN?
ops. yes it should, thanks for catching this!
>> m_final = m_getcl(how, MT_DATA, M_PKTHDR);
>> else
>> m_final = m_gethdr(how, MT_DATA);
>> if (m_final == NULL)
>> goto nospace;
>>+ m_adj(m_final, align);
>> m_new = m_final;
>> while (progress < total) {
>> length = total - progress;
also, there is probably no good reason to call m_adj, we could just
"m_final->m_data += align" like so
Index: 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
--- uipc_mbuf.c 17 Mar 2005 19:34:57 -0000 1.147
+++ uipc_mbuf.c 29 Apr 2005 18:31:51 -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;
thanks,
max
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