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Extend m_apply() to support unmapped mbufs.

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m_apply() invokes the callback function separately on each segment of
an unmapped mbuf: the TLS header, individual pages, and the TLS
trailer.

Reviewed by:	markj
Sponsored by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D30132
This commit is contained in:
John Baldwin 2021-05-25 16:59:18 -07:00
parent a59f028537
commit 3c7a01d773
1 changed files with 57 additions and 1 deletions
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58
sys/kern/uipc_mbuf.c
View File

@ -1239,6 +1239,62 @@ m_append(struct mbuf *m0, int len, c_caddr_t cp)
return (remainder == 0);
}
static int
m_apply_extpg_one(struct mbuf *m, int off, int len,
int (*f)(void *, void *, u_int), void *arg)
{
void *p;
u_int i, count, pgoff, pglen;
int rval;
KASSERT(PMAP_HAS_DMAP,
("m_apply_extpg_one does not support unmapped mbufs"));
off += mtod(m, vm_offset_t);
if (off < m->m_epg_hdrlen) {
count = min(m->m_epg_hdrlen - off, len);
rval = f(arg, m->m_epg_hdr + off, count);
if (rval)
return (rval);
len -= count;
off = 0;
} else
off -= m->m_epg_hdrlen;
pgoff = m->m_epg_1st_off;
for (i = 0; i < m->m_epg_npgs && len > 0; i++) {
pglen = m_epg_pagelen(m, i, pgoff);
if (off < pglen) {
count = min(pglen - off, len);
p = (void *)PHYS_TO_DMAP(m->m_epg_pa[i] + pgoff);
rval = f(arg, p, count);
if (rval)
return (rval);
len -= count;
off = 0;
} else
off -= pglen;
pgoff = 0;
}
if (len > 0) {
KASSERT(off < m->m_epg_trllen,
("m_apply_extpg_one: offset beyond trailer"));
KASSERT(len <= m->m_epg_trllen - off,
("m_apply_extpg_one: length beyond trailer"));
return (f(arg, m->m_epg_trail + off, len));
}
return (0);
}
/* Apply function f to the data in a single mbuf. */
static int
m_apply_one(struct mbuf *m, int off, int len,
int (*f)(void *, void *, u_int), void *arg)
{
if ((m->m_flags & M_EXTPG) != 0)
return (m_apply_extpg_one(m, off, len, f, arg));
else
return (f(arg, mtod(m, caddr_t) + off, len));
}
/*
* Apply function f to the data in an mbuf chain starting "off" bytes from
* the beginning, continuing for "len" bytes.
@ -1262,7 +1318,7 @@ m_apply(struct mbuf *m, int off, int len,
while (len > 0) {
KASSERT(m != NULL, ("m_apply, offset > size of mbuf chain"));
count = min(m->m_len - off, len);
rval = (*f)(arg, mtod(m, caddr_t) + off, count);
rval = m_apply_one(m, off, count, f, arg);
if (rval)
return (rval);
len -= count;