On 08.07.2010 11:42, Kostik Belousov wrote:
On Thu, Jul 08, 2010 at 11:40:05AM +0300, Andriy Gapon wrote:
on 08/07/2010 11:29 Kostik Belousov said the following:
Right, the patch maps the page in sf buffer read-only (on i386 only).
But note the parallel posting with m_cat() change. It is still not enough,
and I am not set up for the real network testing ATM.
Could you also try to experiment with mb_dupcl?
Namely transfer M_RDONLY from source mbuf.
Right, it is it.
Below is my current patch including debugging facilities that seems to work.
Real changes that needed are in m_cat and mb_dupcl.
...
diff --git a/sys/kern/uipc_mbuf.c b/sys/kern/uipc_mbuf.c
index f41eb03..1701ef2 100644
--- a/sys/kern/uipc_mbuf.c
+++ b/sys/kern/uipc_mbuf.c
@@ -301,7 +301,7 @@ mb_dupcl(struct mbuf *n, struct mbuf *m)
n->m_ext.ext_size = m->m_ext.ext_size;
n->m_ext.ref_cnt = m->m_ext.ref_cnt;
n->m_ext.ext_type = m->m_ext.ext_type;
- n->m_flags |= M_EXT;
+ n->m_flags |= M_EXT | (M_RDONLY & m->m_flags);
}
Having the M_EXT flag always implies readonly and M_WRITABLE gets this
right. Not inheriting all the flags from the source seems questionable.
So IMHO this should be done here:
n->m_flags |= (M_EXT | m->m_flags)
/*
@@ -911,7 +911,8 @@ m_cat(struct mbuf *m, struct mbuf *n)
m = m->m_next;
while (n) {
if (m->m_flags& M_EXT ||
- m->m_data + m->m_len + n->m_len>=&m->m_dat[MLEN]) {
+ m->m_data + m->m_len + n->m_len>=&m->m_dat[MLEN] ||
+ !M_WRITABLE(m)) {
Here you can fully replace the (m->m_flags & M_EXT) test with
M_WRITABLE(). The M_EXT test is included in it.
/* just join the two chains */
m->m_next = n;
return;
--
Andre
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