1 /* $FreeBSD: src/sys/kern/uipc_mbuf2.c,v 1.2.2.5 2003/01/23 21:06:44 sam Exp $ */
2 /* $DragonFly: src/sys/kern/uipc_mbuf2.c,v 1.15 2007/10/20 10:28:44 sephe Exp $ */
3 /* $KAME: uipc_mbuf2.c,v 1.31 2001/11/28 11:08:53 itojun Exp $ */
4 /* $NetBSD: uipc_mbuf.c,v 1.40 1999/04/01 00:23:25 thorpej Exp $ */
7 * Copyright (C) 1999 WIDE Project.
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11 * modification, are permitted provided that the following conditions
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17 * documentation and/or other materials provided with the distribution.
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19 * may be used to endorse or promote products derived from this software
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37 * The Regents of the University of California. All rights reserved.
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40 * modification, are permitted provided that the following conditions
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43 * notice, this list of conditions and the following disclaimer.
44 * 2. Redistributions in binary form must reproduce the above copyright
45 * notice, this list of conditions and the following disclaimer in the
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48 * may be used to endorse or promote products derived from this software
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53 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
54 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
55 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
56 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
57 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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63 * @(#)uipc_mbuf.c 8.4 (Berkeley) 2/14/95
66 /*#define PULLDOWN_DEBUG*/
68 #include <sys/param.h>
69 #include <sys/systm.h>
70 #include <sys/kernel.h>
72 #include <sys/malloc.h>
75 MALLOC_DEFINE(M_PACKET_TAGS, "tag", "packet-attached information");
77 /* can't call it m_dup(), as freebsd[34] uses m_dup() with different arg */
78 static struct mbuf *m_dup1 (struct mbuf *, int, int, int);
81 * ensure that [off, off + len) is contiguous on the mbuf chain "m".
82 * packet chain before "off" is kept untouched.
83 * if offp == NULL, the target will start at <retval, 0> on resulting chain.
84 * if offp != NULL, the target will start at <retval, *offp> on resulting chain.
86 * on error return (NULL return value), original "m" will be freed.
88 * XXX M_TRAILINGSPACE/M_LEADINGSPACE on shared cluster (sharedcluster)
91 m_pulldown(struct mbuf *m, int off, int len, int *offp)
97 /* check invalid arguments. */
99 panic("m == NULL in m_pulldown()");
100 if (len > MCLBYTES) {
102 return NULL; /* impossible */
105 #ifdef PULLDOWN_DEBUG
109 for (t = m; t; t = t->m_next)
110 kprintf(" %d", t->m_len);
115 while (n != NULL && off > 0) {
121 /* be sure to point non-empty mbuf */
122 while (n != NULL && n->m_len == 0)
126 return NULL; /* mbuf chain too short */
129 sharedcluster = (m_sharecount(n) > 1);
132 * the target data is on <n, off>.
133 * if we got enough data on the mbuf "n", we're done.
135 if ((off == 0 || offp) && len <= n->m_len - off && !sharedcluster)
139 * when len <= n->m_len - off and off != 0, it is a special case.
140 * len bytes from <n, off> sits in single mbuf, but the caller does
141 * not like the starting position (off).
142 * chop the current mbuf into two pieces, set off to 0.
144 if (len <= n->m_len - off) {
145 o = m_dup1(n, off, n->m_len - off, MB_DONTWAIT);
148 return NULL; /* ENOBUFS */
151 o->m_next = n->m_next;
159 * we need to take hlen from <n, off> and tlen from <n->m_next, 0>,
160 * and construct contiguous mbuf with m_len == len.
161 * note that hlen + tlen == len, and tlen > 0.
163 hlen = n->m_len - off;
167 * ensure that we have enough trailing data on mbuf chain.
168 * if not, we can do nothing about the chain.
171 for (o = n->m_next; o != NULL; o = o->m_next)
173 if (hlen + olen < len) {
175 return NULL; /* mbuf chain too short */
180 * we need to use m_copydata() to get data from <n->m_next, 0>.
182 if ((off == 0 || offp) && M_TRAILINGSPACE(n) >= tlen &&
184 m_copydata(n->m_next, 0, tlen, mtod(n, caddr_t) + n->m_len);
186 m_adj(n->m_next, tlen);
189 if ((off == 0 || offp) && M_LEADINGSPACE(n->m_next) >= hlen &&
191 n->m_next->m_data -= hlen;
192 n->m_next->m_len += hlen;
193 bcopy(mtod(n, caddr_t) + off, mtod(n->m_next, caddr_t), hlen);
201 * now, we need to do the hard way. don't m_copy as there's no room
204 o = m_getl(len, MB_DONTWAIT, m->m_type, 0, NULL);
207 return NULL; /* ENOBUFS */
209 /* get hlen from <n, off> into <o, 0> */
211 bcopy(mtod(n, caddr_t) + off, mtod(o, caddr_t), hlen);
213 /* get tlen from <n->m_next, 0> into <o, hlen> */
214 m_copydata(n->m_next, 0, tlen, mtod(o, caddr_t) + o->m_len);
216 m_adj(n->m_next, tlen);
217 o->m_next = n->m_next;
223 #ifdef PULLDOWN_DEBUG
227 for (t = m; t; t = t->m_next)
228 kprintf("%c%d", t == n ? '*' : ' ', t->m_len);
229 kprintf(" (off=%d)\n", off);
238 m_dup1(struct mbuf *m, int off, int len, int wait)
244 n = m_getl(len, wait, m->m_type, m->m_flags, NULL);
247 if (off == 0 && (m->m_flags & M_PKTHDR) && !m_dup_pkthdr(n, m, wait)) {
251 m_copydata(m, off, len, mtod(n, caddr_t));
255 /* Get a packet tag structure along with specified data following. */
257 m_tag_alloc(uint32_t cookie, int type, int len, int wait)
263 t = kmalloc(len + sizeof(struct m_tag), M_PACKET_TAGS, MBTOM(wait));
268 t->m_tag_cookie = cookie;
273 /* Free a packet tag. */
275 m_tag_free(struct m_tag *t)
277 kfree(t, M_PACKET_TAGS);
280 /* Prepend a packet tag. */
282 m_tag_prepend(struct mbuf *m, struct m_tag *t)
284 KASSERT(m && t, ("m_tag_prepend: null argument, m %p t %p", m, t));
285 KASSERT(m->m_flags & M_PKTHDR, ("m_tag_prepend: mbuf %p non-header", m));
286 SLIST_INSERT_HEAD(&m->m_pkthdr.tags, t, m_tag_link);
289 /* Unlink a packet tag. */
291 m_tag_unlink(struct mbuf *m, struct m_tag *t)
293 KASSERT(m && t, ("m_tag_unlink: null argument, m %p t %p", m, t));
294 KASSERT(m->m_flags & M_PKTHDR, ("m_tag_unlink: mbuf %p non-header", m));
295 SLIST_REMOVE(&m->m_pkthdr.tags, t, m_tag, m_tag_link);
298 /* Unlink and free a packet tag. */
300 m_tag_delete(struct mbuf *m, struct m_tag *t)
302 KASSERT(m && t, ("m_tag_delete: null argument, m %p t %p", m, t));
303 KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete: mbuf %p non-header", m));
308 /* Unlink and free a packet tag chain, starting from given tag. */
310 m_tag_delete_chain(struct mbuf *m)
314 KASSERT(m, ("m_tag_delete_chain: null mbuf"));
315 KASSERT(m->m_flags & M_PKTHDR, ("m_tag_delete_chain: mbuf %p non-header", m));
316 p = SLIST_FIRST(&m->m_pkthdr.tags);
319 while ((q = SLIST_NEXT(p, m_tag_link)) != NULL)
324 /* Find a tag, starting from a given position. */
326 m_tag_locate(struct mbuf *m, uint32_t cookie, int type, struct m_tag *t)
330 KASSERT(m, ("m_tag_find: null mbuf"));
332 p = SLIST_FIRST(&m->m_pkthdr.tags);
334 p = SLIST_NEXT(t, m_tag_link);
336 if (p->m_tag_cookie == cookie && p->m_tag_id == type)
338 p = SLIST_NEXT(p, m_tag_link);
343 /* Copy a single tag. */
345 m_tag_copy(struct m_tag *t, int how)
349 KASSERT(t, ("m_tag_copy: null tag"));
350 p = m_tag_alloc(t->m_tag_cookie, t->m_tag_id, t->m_tag_len, how);
353 bcopy(t + 1, p + 1, t->m_tag_len); /* Copy the data */
358 * Copy two tag chains. The destination mbuf (to) loses any attached
359 * tags even if the operation fails. This should not be a problem, as
360 * m_tag_copy_chain() is typically called with a newly-allocated
364 m_tag_copy_chain(struct mbuf *to, const struct mbuf *from, int how)
366 struct m_tag *p, *t, *tprev = NULL;
369 ("m_tag_copy: null argument, to %p from %p", to, from));
370 m_tag_delete_chain(to);
371 SLIST_FOREACH(p, &from->m_pkthdr.tags, m_tag_link) {
372 t = m_tag_copy(p, how);
374 m_tag_delete_chain(to);
378 SLIST_INSERT_HEAD(&to->m_pkthdr.tags, t, m_tag_link);
380 SLIST_INSERT_AFTER(tprev, t, m_tag_link);
387 /* Initialize tags on an mbuf. */
389 m_tag_init(struct mbuf *m)
391 SLIST_INIT(&m->m_pkthdr.tags);
394 /* Get first tag in chain. */
396 m_tag_first(struct mbuf *m)
398 return SLIST_FIRST(&m->m_pkthdr.tags);
401 /* Get next tag in chain. */
403 m_tag_next(struct mbuf *m, struct m_tag *t)
405 return SLIST_NEXT(t, m_tag_link);