/* * Copyright (c) 1982, 1986, 1988, 1991, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94 * $FreeBSD$ */ #include "opt_param.h" #include #include #include #include #include #include #include #include #include #include #include #include static void mbinit(void *); SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbinit, NULL) struct mbuf *mbutl; struct mbstat mbstat; u_long mbtypes[MT_NTYPES]; int max_linkhdr; int max_protohdr; int max_hdr; int max_datalen; int nmbclusters; int nmbufs; int nmbcnt; u_long m_mballoc_wid = 0; u_long m_clalloc_wid = 0; /* * freelist header structures... * mbffree_lst, mclfree_lst, mcntfree_lst */ struct mbffree_lst mmbfree; struct mclfree_lst mclfree; struct mcntfree_lst mcntfree; /* * sysctl(8) exported objects */ SYSCTL_DECL(_kern_ipc); SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, &max_linkhdr, 0, ""); SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, &max_protohdr, 0, ""); SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, &max_datalen, 0, ""); SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW, &mbuf_wait, 0, ""); SYSCTL_STRUCT(_kern_ipc, KIPC_MBSTAT, mbstat, CTLFLAG_RD, &mbstat, mbstat, ""); SYSCTL_OPAQUE(_kern_ipc, OID_AUTO, mbtypes, CTLFLAG_RD, mbtypes, sizeof(mbtypes), "LU", ""); SYSCTL_INT(_kern_ipc, KIPC_NMBCLUSTERS, nmbclusters, CTLFLAG_RD, &nmbclusters, 0, "Maximum number of mbuf clusters available"); SYSCTL_INT(_kern_ipc, OID_AUTO, nmbufs, CTLFLAG_RD, &nmbufs, 0, "Maximum number of mbufs available"); SYSCTL_INT(_kern_ipc, OID_AUTO, nmbcnt, CTLFLAG_RD, &nmbcnt, 0, "Maximum number of ext_buf counters available"); #ifndef NMBCLUSTERS #define NMBCLUSTERS (512 + MAXUSERS * 16) #endif TUNABLE_INT_DECL("kern.ipc.nmbclusters", NMBCLUSTERS, nmbclusters); TUNABLE_INT_DECL("kern.ipc.nmbufs", NMBCLUSTERS * 4, nmbufs); TUNABLE_INT_DECL("kern.ipc.nmbcnt", EXT_COUNTERS, nmbcnt); static void m_reclaim(void); /* Initial allocation numbers */ #define NCL_INIT 2 #define NMB_INIT 16 #define REF_INIT NMBCLUSTERS /* * Full mbuf subsystem initialization done here. * * XXX: If ever we have system specific map setups to do, then move them to * machdep.c - for now, there is no reason for this stuff to go there. */ static void mbinit(void *dummy) { vm_offset_t maxaddr, mb_map_size; /* * Setup the mb_map, allocate requested VM space. */ mb_map_size = nmbufs * MSIZE + nmbclusters * MCLBYTES + nmbcnt * sizeof(union mext_refcnt); mb_map_size = roundup2(mb_map_size, PAGE_SIZE); mb_map = kmem_suballoc(kmem_map, (vm_offset_t *)&mbutl, &maxaddr, mb_map_size); /* XXX XXX XXX: mb_map->system_map = 1; */ /* * Initialize the free list headers, and setup locks for lists. */ mmbfree.m_head = NULL; mclfree.m_head = NULL; mcntfree.m_head = NULL; mtx_init(&mmbfree.m_mtx, "mbuf free list lock", MTX_DEF); mtx_init(&mclfree.m_mtx, "mcluster free list lock", MTX_DEF); mtx_init(&mcntfree.m_mtx, "m_ext counter free list lock", MTX_DEF); /* * Initialize mbuf subsystem (sysctl exported) statistics structure. */ mbstat.m_msize = MSIZE; mbstat.m_mclbytes = MCLBYTES; mbstat.m_minclsize = MINCLSIZE; mbstat.m_mlen = MLEN; mbstat.m_mhlen = MHLEN; /* * Perform some initial allocations. */ mtx_lock(&mcntfree.m_mtx); if (m_alloc_ref(REF_INIT, M_DONTWAIT) == 0) goto bad; mtx_unlock(&mcntfree.m_mtx); mtx_lock(&mmbfree.m_mtx); if (m_mballoc(NMB_INIT, M_DONTWAIT) == 0) goto bad; mtx_unlock(&mmbfree.m_mtx); mtx_lock(&mclfree.m_mtx); if (m_clalloc(NCL_INIT, M_DONTWAIT) == 0) goto bad; mtx_unlock(&mclfree.m_mtx); return; bad: panic("mbinit: failed to initialize mbuf subsystem!"); } /* * Allocate at least nmb reference count structs and place them * on the ref cnt free list. * * Must be called with the mcntfree lock held. */ int m_alloc_ref(u_int nmb, int how) { caddr_t p; u_int nbytes; int i; /* * We don't cap the amount of memory that can be used * by the reference counters, like we do for mbufs and * mbuf clusters. In fact, we're absolutely sure that we * won't ever be going over our allocated space. We keep enough * space in mb_map to accomodate maximum values of allocatable * external buffers including, but not limited to, clusters. * (That's also why we won't have to have wait routines for * counters). * * If we're in here, we're absolutely certain to be returning * succesfully, as long as there is physical memory to accomodate * us. And if there isn't, but we're willing to wait, then * kmem_malloc() will do the only waiting needed. */ nbytes = round_page(nmb * sizeof(union mext_refcnt)); mtx_unlock(&mcntfree.m_mtx); if ((p = (caddr_t)kmem_malloc(mb_map, nbytes, how == M_TRYWAIT ? M_WAITOK : M_NOWAIT)) == NULL) { mtx_lock(&mcntfree.m_mtx); return (0); } nmb = nbytes / sizeof(union mext_refcnt); /* * We don't let go of the mutex in order to avoid a race. * It is up to the caller to let go of the mutex. */ mtx_lock(&mcntfree.m_mtx); for (i = 0; i < nmb; i++) { ((union mext_refcnt *)p)->next_ref = mcntfree.m_head; mcntfree.m_head = (union mext_refcnt *)p; p += sizeof(union mext_refcnt); mbstat.m_refree++; } mbstat.m_refcnt += nmb; return (1); } /* * Allocate at least nmb mbufs and place on mbuf free list. * * Must be called with the mmbfree lock held. */ int m_mballoc(int nmb, int how) { caddr_t p; int i; int nbytes; nbytes = round_page(nmb * MSIZE); nmb = nbytes / MSIZE; /* * If we've hit the mbuf limit, stop allocating from mb_map. * Also, once we run out of map space, it will be impossible to * get any more (nothing is ever freed back to the map). */ if (mb_map_full || ((nmb + mbstat.m_mbufs) > nmbufs)) return (0); mtx_unlock(&mmbfree.m_mtx); p = (caddr_t)kmem_malloc(mb_map, nbytes, M_NOWAIT); if (p == NULL && how == M_TRYWAIT) { atomic_add_long(&mbstat.m_wait, 1); p = (caddr_t)kmem_malloc(mb_map, nbytes, M_WAITOK); } mtx_lock(&mmbfree.m_mtx); /* * Either the map is now full, or `how' is M_DONTWAIT and there * are no pages left. */ if (p == NULL) return (0); /* * We don't let go of the mutex in order to avoid a race. * It is up to the caller to let go of the mutex when done * with grabbing the mbuf from the free list. */ for (i = 0; i < nmb; i++) { ((struct mbuf *)p)->m_next = mmbfree.m_head; mmbfree.m_head = (struct mbuf *)p; p += MSIZE; } mbstat.m_mbufs += nmb; mbtypes[MT_FREE] += nmb; return (1); } /* * Once the mb_map has been exhausted and if the call to the allocation macros * (or, in some cases, functions) is with M_TRYWAIT, then it is necessary to * rely solely on reclaimed mbufs. * * Here we request for the protocols to free up some resources and, if we * still cannot get anything, then we wait for an mbuf to be freed for a * designated (mbuf_wait) time. * * Must be called with the mmbfree mutex held. */ struct mbuf * m_mballoc_wait(void) { struct mbuf *p = NULL; /* * See if we can drain some resources out of the protocols. * We drop the mmbfree mutex to avoid recursing into it in some of * the drain routines. Clearly, we're faced with a race here because * once something is freed during the drain, it may be grabbed right * from under us by some other thread. But we accept this possibility * in order to avoid a potentially large lock recursion and, more * importantly, to avoid a potential lock order reversal which may * result in deadlock (See comment above m_reclaim()). */ mtx_unlock(&mmbfree.m_mtx); m_reclaim(); mtx_lock(&mmbfree.m_mtx); _MGET(p, M_DONTWAIT); if (p == NULL) { m_mballoc_wid++; msleep(&m_mballoc_wid, &mmbfree.m_mtx, PVM, "mballc", mbuf_wait); m_mballoc_wid--; /* * Try again (one last time). * * We retry to fetch _even_ if the sleep timed out. This * is left this way, purposely, in the [unlikely] case * that an mbuf was freed but the sleep was not awoken * in time. * * If the sleep didn't time out (i.e. we got woken up) then * we have the lock so we just grab an mbuf, hopefully. */ _MGET(p, M_DONTWAIT); } /* If we waited and got something... */ if (p != NULL) { atomic_add_long(&mbstat.m_wait, 1); if (mmbfree.m_head != NULL) MBWAKEUP(m_mballoc_wid); } return (p); } /* * Allocate some number of mbuf clusters * and place on cluster free list. * * Must be called with the mclfree lock held. */ int m_clalloc(int ncl, int how) { caddr_t p; int i; int npg_sz; npg_sz = round_page(ncl * MCLBYTES); ncl = npg_sz / MCLBYTES; /* * If the map is now full (nothing will ever be freed to it). * If we've hit the mcluster number limit, stop allocating from * mb_map. */ if (mb_map_full || ((ncl + mbstat.m_clusters) > nmbclusters)) return (0); mtx_unlock(&mclfree.m_mtx); p = (caddr_t)kmem_malloc(mb_map, npg_sz, how == M_TRYWAIT ? M_WAITOK : M_NOWAIT); mtx_lock(&mclfree.m_mtx); /* * Either the map is now full, or `how' is M_DONTWAIT and there * are no pages left. */ if (p == NULL) return (0); /* * We don't let go of the mutex in order to avoid a race. */ for (i = 0; i < ncl; i++) { ((union mcluster *)p)->mcl_next = mclfree.m_head; mclfree.m_head = (union mcluster *)p; p += MCLBYTES; mbstat.m_clfree++; } mbstat.m_clusters += ncl; return (1); } /* * Once the mb_map submap has been exhausted and the allocation is called with * M_TRYWAIT, we rely on the mclfree list. If nothing is free, we will * sleep for a designated amount of time (mbuf_wait) or until we're woken up * due to sudden mcluster availability. * * Must be called with the mclfree lock held. */ caddr_t m_clalloc_wait(void) { caddr_t p = NULL; m_clalloc_wid++; msleep(&m_clalloc_wid, &mclfree.m_mtx, PVM, "mclalc", mbuf_wait); m_clalloc_wid--; /* * Now that we (think) that we've got something, try again. */ _MCLALLOC(p, M_DONTWAIT); /* If we waited and got something ... */ if (p != NULL) { atomic_add_long(&mbstat.m_wait, 1); if (mclfree.m_head != NULL) MBWAKEUP(m_clalloc_wid); } return (p); } /* * m_reclaim: drain protocols in hopes to free up some resources... * * XXX: No locks should be held going in here. The drain routines have * to presently acquire some locks which raises the possibility of lock * order violation if we're holding any mutex if that mutex is acquired in * reverse order relative to one of the locks in the drain routines. */ static void m_reclaim(void) { struct domain *dp; struct protosw *pr; #ifdef WITNESS KASSERT(witness_list(CURPROC) == 0, ("m_reclaim called with locks held")); #endif for (dp = domains; dp; dp = dp->dom_next) for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++) if (pr->pr_drain) (*pr->pr_drain)(); mbstat.m_drain++; } /* * Space allocation routines. * Some of these are also available as macros * for critical paths. */ struct mbuf * m_get(int how, int type) { struct mbuf *m; MGET(m, how, type); return (m); } struct mbuf * m_gethdr(int how, int type) { struct mbuf *m; MGETHDR(m, how, type); return (m); } struct mbuf * m_getclr(int how, int type) { struct mbuf *m; MGET(m, how, type); if (m == NULL) return (NULL); bzero(mtod(m, caddr_t), MLEN); return (m); } struct mbuf * m_free(struct mbuf *m) { struct mbuf *n; MFREE(m, n); return (n); } /* * struct mbuf * * m_getm(m, len, how, type) * * This will allocate len-worth of mbufs and/or mbuf clusters (whatever fits * best) and return a pointer to the top of the allocated chain. If m is * non-null, then we assume that it is a single mbuf or an mbuf chain to * which we want len bytes worth of mbufs and/or clusters attached, and so * if we succeed in allocating it, we will just return a pointer to m. * * If we happen to fail at any point during the allocation, we will free * up everything we have already allocated and return NULL. * */ struct mbuf * m_getm(struct mbuf *m, int len, int how, int type) { struct mbuf *top, *tail, *mp, *mtail = NULL; KASSERT(len >= 0, ("len is < 0 in m_getm")); MGET(mp, how, type); if (mp == NULL) return (NULL); else if (len > MINCLSIZE) { MCLGET(mp, how); if ((mp->m_flags & M_EXT) == 0) { m_free(mp); return (NULL); } } mp->m_len = 0; len -= M_TRAILINGSPACE(mp); if (m != NULL) for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next); else m = mp; top = tail = mp; while (len > 0) { MGET(mp, how, type); if (mp == NULL) goto failed; tail->m_next = mp; tail = mp; if (len > MINCLSIZE) { MCLGET(mp, how); if ((mp->m_flags & M_EXT) == 0) goto failed; } mp->m_len = 0; len -= M_TRAILINGSPACE(mp); } if (mtail != NULL) mtail->m_next = top; return (m); failed: m_freem(top); return (NULL); } void m_freem(struct mbuf *m) { struct mbuf *n; if (m == NULL) return; do { /* * we do need to check non-first mbuf, since some of existing * code does not call M_PREPEND properly. * (example: call to bpf_mtap from drivers) */ if ((m->m_flags & M_PKTHDR) != 0 && m->m_pkthdr.aux) { m_freem(m->m_pkthdr.aux); m->m_pkthdr.aux = NULL; } MFREE(m, n); m = n; } while (m); } /* * Lesser-used path for M_PREPEND: * allocate new mbuf to prepend to chain, * copy junk along. */ struct mbuf * m_prepend(struct mbuf *m, int len, int how) { struct mbuf *mn; MGET(mn, how, m->m_type); if (mn == NULL) { m_freem(m); return (NULL); } if (m->m_flags & M_PKTHDR) { M_COPY_PKTHDR(mn, m); m->m_flags &= ~M_PKTHDR; } mn->m_next = m; m = mn; if (len < MHLEN) MH_ALIGN(m, len); m->m_len = len; return (m); } /* * Make a copy of an mbuf chain starting "off0" bytes from the beginning, * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller. * Note that the copy is read-only, because clusters are not copied, * only their reference counts are incremented. */ #define MCFail (mbstat.m_mcfail) struct mbuf * m_copym(struct mbuf *m, int off0, int len, int wait) { struct mbuf *n, **np; int off = off0; struct mbuf *top; int copyhdr = 0; KASSERT(off >= 0, ("m_copym, negative off %d", off)); KASSERT(len >= 0, ("m_copym, negative len %d", len)); if (off == 0 && m->m_flags & M_PKTHDR) copyhdr = 1; while (off > 0) { KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); if (off < m->m_len) break; off -= m->m_len; m = m->m_next; } np = ⊤ top = 0; while (len > 0) { if (m == NULL) { KASSERT(len == M_COPYALL, ("m_copym, length > size of mbuf chain")); break; } MGET(n, wait, m->m_type); *np = n; if (n == NULL) goto nospace; if (copyhdr) { M_COPY_PKTHDR(n, m); if (len == M_COPYALL) n->m_pkthdr.len -= off0; else n->m_pkthdr.len = len; copyhdr = 0; } n->m_len = min(len, m->m_len - off); if (m->m_flags & M_EXT) { n->m_data = m->m_data + off; n->m_ext = m->m_ext; n->m_flags |= M_EXT; MEXT_ADD_REF(m); } else bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), (unsigned)n->m_len); if (len != M_COPYALL) len -= n->m_len; off = 0; m = m->m_next; np = &n->m_next; } if (top == NULL) atomic_add_long(&MCFail, 1); return (top); nospace: m_freem(top); atomic_add_long(&MCFail, 1); return (NULL); } /* * Copy an entire packet, including header (which must be present). * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. * Note that the copy is read-only, because clusters are not copied, * only their reference counts are incremented. * Preserve alignment of the first mbuf so if the creator has left * some room at the beginning (e.g. for inserting protocol headers) * the copies still have the room available. */ struct mbuf * m_copypacket(struct mbuf *m, int how) { struct mbuf *top, *n, *o; MGET(n, how, m->m_type); top = n; if (n == NULL) goto nospace; M_COPY_PKTHDR(n, m); n->m_len = m->m_len; if (m->m_flags & M_EXT) { n->m_data = m->m_data; n->m_ext = m->m_ext; n->m_flags |= M_EXT; MEXT_ADD_REF(m); } else { n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); bcopy(mtod(m, char *), mtod(n, char *), n->m_len); } m = m->m_next; while (m) { MGET(o, how, m->m_type); if (o == NULL) goto nospace; n->m_next = o; n = n->m_next; n->m_len = m->m_len; if (m->m_flags & M_EXT) { n->m_data = m->m_data; n->m_ext = m->m_ext; n->m_flags |= M_EXT; MEXT_ADD_REF(m); } else { bcopy(mtod(m, char *), mtod(n, char *), n->m_len); } m = m->m_next; } return top; nospace: m_freem(top); atomic_add_long(&MCFail, 1); return (NULL); } /* * Copy data from an mbuf chain starting "off" bytes from the beginning, * continuing for "len" bytes, into the indicated buffer. */ void m_copydata(struct mbuf *m, int off, int len, caddr_t cp) { unsigned count; KASSERT(off >= 0, ("m_copydata, negative off %d", off)); KASSERT(len >= 0, ("m_copydata, negative len %d", len)); while (off > 0) { KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); if (off < m->m_len) break; off -= m->m_len; m = m->m_next; } while (len > 0) { KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); count = min(m->m_len - off, len); bcopy(mtod(m, caddr_t) + off, cp, count); len -= count; cp += count; off = 0; m = m->m_next; } } /* * Copy a packet header mbuf chain into a completely new chain, including * copying any mbuf clusters. Use this instead of m_copypacket() when * you need a writable copy of an mbuf chain. */ struct mbuf * m_dup(struct mbuf *m, int how) { struct mbuf **p, *top = NULL; int remain, moff, nsize; /* Sanity check */ if (m == NULL) return (NULL); KASSERT((m->m_flags & M_PKTHDR) != 0, ("%s: !PKTHDR", __FUNCTION__)); /* While there's more data, get a new mbuf, tack it on, and fill it */ remain = m->m_pkthdr.len; moff = 0; p = ⊤ while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ struct mbuf *n; /* Get the next new mbuf */ MGET(n, how, m->m_type); if (n == NULL) goto nospace; if (top == NULL) { /* first one, must be PKTHDR */ M_COPY_PKTHDR(n, m); nsize = MHLEN; } else /* not the first one */ nsize = MLEN; if (remain >= MINCLSIZE) { MCLGET(n, how); if ((n->m_flags & M_EXT) == 0) { (void)m_free(n); goto nospace; } nsize = MCLBYTES; } n->m_len = 0; /* Link it into the new chain */ *p = n; p = &n->m_next; /* Copy data from original mbuf(s) into new mbuf */ while (n->m_len < nsize && m != NULL) { int chunk = min(nsize - n->m_len, m->m_len - moff); bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); moff += chunk; n->m_len += chunk; remain -= chunk; if (moff == m->m_len) { m = m->m_next; moff = 0; } } /* Check correct total mbuf length */ KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), ("%s: bogus m_pkthdr.len", __FUNCTION__)); } return (top); nospace: m_freem(top); atomic_add_long(&MCFail, 1); return (NULL); } /* * Concatenate mbuf chain n to m. * Both chains must be of the same type (e.g. MT_DATA). * Any m_pkthdr is not updated. */ void m_cat(struct mbuf *m, struct mbuf *n) { while (m->m_next) 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]) { /* just join the two chains */ m->m_next = n; return; } /* splat the data from one into the other */ bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, (u_int)n->m_len); m->m_len += n->m_len; n = m_free(n); } } void m_adj(struct mbuf *mp, int req_len) { int len = req_len; struct mbuf *m; int count; if ((m = mp) == NULL) return; if (len >= 0) { /* * Trim from head. */ while (m != NULL && len > 0) { if (m->m_len <= len) { len -= m->m_len; m->m_len = 0; m = m->m_next; } else { m->m_len -= len; m->m_data += len; len = 0; } } m = mp; if (mp->m_flags & M_PKTHDR) m->m_pkthdr.len -= (req_len - len); } else { /* * Trim from tail. Scan the mbuf chain, * calculating its length and finding the last mbuf. * If the adjustment only affects this mbuf, then just * adjust and return. Otherwise, rescan and truncate * after the remaining size. */ len = -len; count = 0; for (;;) { count += m->m_len; if (m->m_next == (struct mbuf *)0) break; m = m->m_next; } if (m->m_len >= len) { m->m_len -= len; if (mp->m_flags & M_PKTHDR) mp->m_pkthdr.len -= len; return; } count -= len; if (count < 0) count = 0; /* * Correct length for chain is "count". * Find the mbuf with last data, adjust its length, * and toss data from remaining mbufs on chain. */ m = mp; if (m->m_flags & M_PKTHDR) m->m_pkthdr.len = count; for (; m; m = m->m_next) { if (m->m_len >= count) { m->m_len = count; break; } count -= m->m_len; } while (m->m_next) (m = m->m_next) ->m_len = 0; } } /* * Rearange an mbuf chain so that len bytes are contiguous * and in the data area of an mbuf (so that mtod and dtom * will work for a structure of size len). Returns the resulting * mbuf chain on success, frees it and returns null on failure. * If there is room, it will add up to max_protohdr-len extra bytes to the * contiguous region in an attempt to avoid being called next time. */ #define MPFail (mbstat.m_mpfail) struct mbuf * m_pullup(struct mbuf *n, int len) { struct mbuf *m; int count; int space; /* * If first mbuf has no cluster, and has room for len bytes * without shifting current data, pullup into it, * otherwise allocate a new mbuf to prepend to the chain. */ if ((n->m_flags & M_EXT) == 0 && n->m_data + len < &n->m_dat[MLEN] && n->m_next) { if (n->m_len >= len) return (n); m = n; n = n->m_next; len -= m->m_len; } else { if (len > MHLEN) goto bad; MGET(m, M_DONTWAIT, n->m_type); if (m == NULL) goto bad; m->m_len = 0; if (n->m_flags & M_PKTHDR) { M_COPY_PKTHDR(m, n); n->m_flags &= ~M_PKTHDR; } } space = &m->m_dat[MLEN] - (m->m_data + m->m_len); do { count = min(min(max(len, max_protohdr), space), n->m_len); bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, (unsigned)count); len -= count; m->m_len += count; n->m_len -= count; space -= count; if (n->m_len) n->m_data += count; else n = m_free(n); } while (len > 0 && n); if (len > 0) { (void) m_free(m); goto bad; } m->m_next = n; return (m); bad: m_freem(n); atomic_add_long(&MPFail, 1); return (NULL); } /* * Partition an mbuf chain in two pieces, returning the tail -- * all but the first len0 bytes. In case of failure, it returns NULL and * attempts to restore the chain to its original state. */ struct mbuf * m_split(struct mbuf *m0, int len0, int wait) { struct mbuf *m, *n; unsigned len = len0, remain; for (m = m0; m && len > m->m_len; m = m->m_next) len -= m->m_len; if (m == NULL) return (NULL); remain = m->m_len - len; if (m0->m_flags & M_PKTHDR) { MGETHDR(n, wait, m0->m_type); if (n == NULL) return (NULL); n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; n->m_pkthdr.len = m0->m_pkthdr.len - len0; m0->m_pkthdr.len = len0; if (m->m_flags & M_EXT) goto extpacket; if (remain > MHLEN) { /* m can't be the lead packet */ MH_ALIGN(n, 0); n->m_next = m_split(m, len, wait); if (n->m_next == NULL) { (void) m_free(n); return (NULL); } else return (n); } else MH_ALIGN(n, remain); } else if (remain == 0) { n = m->m_next; m->m_next = NULL; return (n); } else { MGET(n, wait, m->m_type); if (n == NULL) return (NULL); M_ALIGN(n, remain); } extpacket: if (m->m_flags & M_EXT) { n->m_flags |= M_EXT; n->m_ext = m->m_ext; MEXT_ADD_REF(m); m->m_ext.ext_size = 0; /* For Accounting XXXXXX danger */ n->m_data = m->m_data + len; } else { bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); } n->m_len = remain; m->m_len = len; n->m_next = m->m_next; m->m_next = NULL; return (n); } /* * Routine to copy from device local memory into mbufs. */ struct mbuf * m_devget(char *buf, int totlen, int off0, struct ifnet *ifp, void (*copy)(char *from, caddr_t to, u_int len)) { struct mbuf *m; struct mbuf *top = 0, **mp = ⊤ int off = off0, len; char *cp; char *epkt; cp = buf; epkt = cp + totlen; if (off) { cp += off + 2 * sizeof(u_short); totlen -= 2 * sizeof(u_short); } MGETHDR(m, M_DONTWAIT, MT_DATA); if (m == NULL) return (NULL); m->m_pkthdr.rcvif = ifp; m->m_pkthdr.len = totlen; m->m_len = MHLEN; while (totlen > 0) { if (top) { MGET(m, M_DONTWAIT, MT_DATA); if (m == NULL) { m_freem(top); return (NULL); } m->m_len = MLEN; } len = min(totlen, epkt - cp); if (len >= MINCLSIZE) { MCLGET(m, M_DONTWAIT); if (m->m_flags & M_EXT) m->m_len = len = min(len, MCLBYTES); else len = m->m_len; } else { /* * Place initial small packet/header at end of mbuf. */ if (len < m->m_len) { if (top == NULL && len + max_linkhdr <= m->m_len) m->m_data += max_linkhdr; m->m_len = len; } else len = m->m_len; } if (copy) copy(cp, mtod(m, caddr_t), (unsigned)len); else bcopy(cp, mtod(m, caddr_t), (unsigned)len); cp += len; *mp = m; mp = &m->m_next; totlen -= len; if (cp == epkt) cp = buf; } return (top); } /* * Copy data from a buffer back into the indicated mbuf chain, * starting "off" bytes from the beginning, extending the mbuf * chain if necessary. */ void m_copyback(struct mbuf *m0, int off, int len, caddr_t cp) { int mlen; struct mbuf *m = m0, *n; int totlen = 0; if (m0 == NULL) return; while (off > (mlen = m->m_len)) { off -= mlen; totlen += mlen; if (m->m_next == NULL) { n = m_getclr(M_DONTWAIT, m->m_type); if (n == NULL) goto out; n->m_len = min(MLEN, len + off); m->m_next = n; } m = m->m_next; } while (len > 0) { mlen = min (m->m_len - off, len); bcopy(cp, off + mtod(m, caddr_t), (unsigned)mlen); cp += mlen; len -= mlen; mlen += off; off = 0; totlen += mlen; if (len == 0) break; if (m->m_next == NULL) { n = m_get(M_DONTWAIT, m->m_type); if (n == NULL) break; n->m_len = min(MLEN, len); m->m_next = n; } m = m->m_next; } out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) m->m_pkthdr.len = totlen; } void m_print(const struct mbuf *m) { int len; const struct mbuf *m2; len = m->m_pkthdr.len; m2 = m; while (len) { printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-"); len -= m2->m_len; m2 = m2->m_next; } return; }