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freebsd-nq/sys/kern/subr_mbuf.c
Bosko Milekic 9e7225808e Make m_getm() always return the top of the newly allocated chain, as 
opposed to returning the top of the old chain when there was one and
the top of the newly allocated chain if there was no old chain.

Actually, it should be noted that prior to this fix, although the
comment above m_getm() advertised that m_getm() would return the
top of the old chain (if an old chain was being passed in) it
actually [wrongly] was returning the tail mbuf in the old chain
instead.  This is a bug but since the one use of m_getm() in
the tree luckily did not depend on the behavior, it happened
to work out without notice.

Harti Brandt pointed out that the advertised behavior was actually
not the real behavior and so this change makes m_getm() ALWAYS
return the newly allocated chain (and fixes the comment).  This
is less confusing and is the best course of action as then the
caller is always able to have both a reference to the top of
the original chain (because it's passing it in in the call) and
a reference to the newly attached chain.  Although the API is
slightly modified, I don't think that any third-party code uses
m_getm() and if it does, it surely can't be working properly
because the old behavior was bogus.

API bug pointed out by: Harti Brandt <brandt@fokus.fraunhofer.de>
2003-02-14 16:50:13 +00:00

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/*-
* Copyright (c) 2001, 2002
* Bosko Milekic <bmilekic@FreeBSD.org>. 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. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*
* $FreeBSD$
*/
#include "opt_mac.h"
#include "opt_param.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mac.h>
#include <sys/mbuf.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/smp.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <vm/vm.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
/******************************************************************************
* mb_alloc mbuf and cluster allocator.
*
* Maximum number of PCPU containers. If you know what you're doing you could
* explicitly define MBALLOC_NCPU to be exactly the number of CPUs on your
* system during compilation, and thus prevent kernel structure bloat.
*
* SMP and non-SMP kernels clearly have a different number of possible CPUs,
* but because we cannot assume a dense array of CPUs, we always allocate
* and traverse PCPU containers up to NCPU amount and merely check for
* CPU availability.
*/
#ifdef MBALLOC_NCPU
#define NCPU MBALLOC_NCPU
#else
#define NCPU MAXCPU
#endif
/*-
* The mbuf allocator is heavily based on Alfred Perlstein's
* (alfred@FreeBSD.org) "memcache" allocator which is itself based
* on concepts from several per-CPU memory allocators. The difference
* between this allocator and memcache is that, among other things:
*
* (i) We don't free back to the map from the free() routine - we leave the
* option of implementing lazy freeing (from a kproc) in the future.
*
* (ii) We allocate from separate sub-maps of kmem_map, thus limiting the
* maximum number of allocatable objects of a given type. Further,
* we handle blocking on a cv in the case that the map is starved and
* we have to rely solely on cached (circulating) objects.
*
* The mbuf allocator keeps all objects that it allocates in mb_buckets.
* The buckets keep a page worth of objects (an object can be an mbuf or an
* mbuf cluster) and facilitate moving larger sets of contiguous objects
* from the per-CPU lists to the main list for the given object. The buckets
* also have an added advantage in that after several moves from a per-CPU
* list to the main list and back to the per-CPU list, contiguous objects
* are kept together, thus trying to put the TLB cache to good use.
*
* The buckets are kept on singly-linked lists called "containers." A container
* is protected by a mutex lock in order to ensure consistency. The mutex lock
* itself is allocated separately and attached to the container at boot time,
* thus allowing for certain containers to share the same mutex lock. Per-CPU
* containers for mbufs and mbuf clusters all share the same per-CPU
* lock whereas the "general system" containers (i.e., the "main lists") for
* these objects share one global lock.
*/
struct mb_bucket {
SLIST_ENTRY(mb_bucket) mb_blist;
int mb_owner;
int mb_numfree;
void *mb_free[0];
};
struct mb_container {
SLIST_HEAD(mc_buckethd, mb_bucket) mc_bhead;
struct mtx *mc_lock;
int mc_numowner;
u_int mc_starved;
long *mc_types;
u_long *mc_objcount;
u_long *mc_numpgs;
};
struct mb_gen_list {
struct mb_container mb_cont;
struct cv mgl_mstarved;
};
struct mb_pcpu_list {
struct mb_container mb_cont;
};
/*
* Boot-time configurable object counts that will determine the maximum
* number of permitted objects in the mbuf and mcluster cases. In the
* ext counter (nmbcnt) case, it's just an indicator serving to scale
* kmem_map size properly - in other words, we may be allowed to allocate
* more than nmbcnt counters, whereas we will never be allowed to allocate
* more than nmbufs mbufs or nmbclusters mclusters.
* As for nsfbufs, it is used to indicate how many sendfile(2) buffers will be
* allocatable by the sfbuf allocator (found in uipc_syscalls.c)
*/
#ifndef NMBCLUSTERS
#define NMBCLUSTERS (1024 + maxusers * 64)
#endif
#ifndef NMBUFS
#define NMBUFS (nmbclusters * 2)
#endif
#ifndef NSFBUFS
#define NSFBUFS (512 + maxusers * 16)
#endif
#ifndef NMBCNTS
#define NMBCNTS (nmbclusters + nsfbufs)
#endif
int nmbufs;
int nmbclusters;
int nmbcnt;
int nsfbufs;
/*
* Perform sanity checks of tunables declared above.
*/
static void
tunable_mbinit(void *dummy)
{
/*
* This has to be done before VM init.
*/
nmbclusters = NMBCLUSTERS;
TUNABLE_INT_FETCH("kern.ipc.nmbclusters", &nmbclusters);
nmbufs = NMBUFS;
TUNABLE_INT_FETCH("kern.ipc.nmbufs", &nmbufs);
nsfbufs = NSFBUFS;
TUNABLE_INT_FETCH("kern.ipc.nsfbufs", &nsfbufs);
nmbcnt = NMBCNTS;
TUNABLE_INT_FETCH("kern.ipc.nmbcnt", &nmbcnt);
/* Sanity checks */
if (nmbufs < nmbclusters * 2)
nmbufs = nmbclusters * 2;
if (nmbcnt < nmbclusters + nsfbufs)
nmbcnt = nmbclusters + nsfbufs;
}
SYSINIT(tunable_mbinit, SI_SUB_TUNABLES, SI_ORDER_ANY, tunable_mbinit, NULL);
/*
* The freelist structures and mutex locks. The number statically declared
* here depends on the number of CPUs.
*
* We set up in such a way that all the objects (mbufs, clusters)
* share the same mutex lock. It has been established that we do not benefit
* from different locks for different objects, so we use the same lock,
* regardless of object type. This also allows us to do optimised
* multi-object allocations without dropping the lock in between.
*/
struct mb_lstmngr {
struct mb_gen_list *ml_genlist;
struct mb_pcpu_list *ml_cntlst[NCPU];
struct mb_bucket **ml_btable;
vm_map_t ml_map;
vm_offset_t ml_mapbase;
vm_offset_t ml_maptop;
int ml_mapfull;
u_int ml_objsize;
u_int *ml_wmhigh;
};
static struct mb_lstmngr mb_list_mbuf, mb_list_clust;
static struct mtx mbuf_gen, mbuf_pcpu[NCPU];
u_int *cl_refcntmap;
/*
* Local macros for internal allocator structure manipulations.
*/
#ifdef SMP
#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[PCPU_GET(cpuid)]
#else
#define MB_GET_PCPU_LIST(mb_lst) (mb_lst)->ml_cntlst[0]
#endif
#define MB_GET_GEN_LIST(mb_lst) (mb_lst)->ml_genlist
#define MB_LOCK_CONT(mb_cnt) mtx_lock((mb_cnt)->mb_cont.mc_lock)
#define MB_UNLOCK_CONT(mb_cnt) mtx_unlock((mb_cnt)->mb_cont.mc_lock)
#define MB_GET_PCPU_LIST_NUM(mb_lst, num) \
(mb_lst)->ml_cntlst[(num)]
#define MB_BUCKET_INDX(mb_obj, mb_lst) \
(int)(((caddr_t)(mb_obj) - (caddr_t)(mb_lst)->ml_mapbase) / PAGE_SIZE)
#define MB_GET_OBJECT(mb_objp, mb_bckt, mb_lst) \
{ \
struct mc_buckethd *_mchd = &((mb_lst)->mb_cont.mc_bhead); \
\
(mb_bckt)->mb_numfree--; \
(mb_objp) = (mb_bckt)->mb_free[((mb_bckt)->mb_numfree)]; \
(*((mb_lst)->mb_cont.mc_objcount))--; \
if ((mb_bckt)->mb_numfree == 0) { \
SLIST_REMOVE_HEAD(_mchd, mb_blist); \
SLIST_NEXT((mb_bckt), mb_blist) = NULL; \
(mb_bckt)->mb_owner |= MB_BUCKET_FREE; \
} \
}
#define MB_PUT_OBJECT(mb_objp, mb_bckt, mb_lst) \
(mb_bckt)->mb_free[((mb_bckt)->mb_numfree)] = (mb_objp); \
(mb_bckt)->mb_numfree++; \
(*((mb_lst)->mb_cont.mc_objcount))++;
#define MB_MBTYPES_INC(mb_cnt, mb_type, mb_num) \
if ((mb_type) != MT_NOTMBUF) \
(*((mb_cnt)->mb_cont.mc_types + (mb_type))) += (mb_num)
#define MB_MBTYPES_DEC(mb_cnt, mb_type, mb_num) \
if ((mb_type) != MT_NOTMBUF) \
(*((mb_cnt)->mb_cont.mc_types + (mb_type))) -= (mb_num)
/*
* Ownership of buckets/containers is represented by integers. The PCPU
* lists range from 0 to NCPU-1. We need a free numerical id for the general
* list (we use NCPU). We also need a non-conflicting free bit to indicate
* that the bucket is free and removed from a container, while not losing
* the bucket's originating container id. We use the highest bit
* for the free marker.
*/
#define MB_GENLIST_OWNER (NCPU)
#define MB_BUCKET_FREE (1 << (sizeof(int) * 8 - 1))
/* Statistics structures for allocator (per-CPU and general). */
static struct mbpstat mb_statpcpu[NCPU + 1];
struct mbstat mbstat;
/* Sleep time for wait code (in ticks). */
static int mbuf_wait = 64;
static u_int mbuf_limit = 512; /* Upper limit on # of mbufs per CPU. */
static u_int clust_limit = 128; /* Upper limit on # of clusters per CPU. */
/*
* Objects exported by sysctl(8).
*/
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, 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,
"Number used to scale kmem_map to ensure sufficient space for counters");
SYSCTL_INT(_kern_ipc, OID_AUTO, nsfbufs, CTLFLAG_RD, &nsfbufs, 0,
"Maximum number of sendfile(2) sf_bufs available");
SYSCTL_INT(_kern_ipc, OID_AUTO, mbuf_wait, CTLFLAG_RW, &mbuf_wait, 0,
"Sleep time of mbuf subsystem wait allocations during exhaustion");
SYSCTL_UINT(_kern_ipc, OID_AUTO, mbuf_limit, CTLFLAG_RW, &mbuf_limit, 0,
"Upper limit of number of mbufs allowed on each PCPU list");
SYSCTL_UINT(_kern_ipc, OID_AUTO, clust_limit, CTLFLAG_RW, &clust_limit, 0,
"Upper limit of number of mbuf clusters allowed on each PCPU list");
SYSCTL_STRUCT(_kern_ipc, OID_AUTO, mbstat, CTLFLAG_RD, &mbstat, mbstat,
"Mbuf general information and statistics");
SYSCTL_OPAQUE(_kern_ipc, OID_AUTO, mb_statpcpu, CTLFLAG_RD, mb_statpcpu,
sizeof(mb_statpcpu), "S,", "Mbuf allocator per CPU statistics");
/*
* Prototypes of local allocator routines.
*/
static void *mb_alloc_wait(struct mb_lstmngr *, short);
static struct mb_bucket *mb_pop_cont(struct mb_lstmngr *, int,
struct mb_pcpu_list *);
static void mb_reclaim(void);
static void mbuf_init(void *);
/*
* Initial allocation numbers. Each parameter represents the number of buckets
* of each object that will be placed initially in each PCPU container for
* said object.
*/
#define NMB_MBUF_INIT 4
#define NMB_CLUST_INIT 16
/*
* Internal flags that allow for cache locks to remain "persistent" across
* allocation and free calls. They may be used in combination.
*/
#define MBP_PERSIST 0x1 /* Return with lock still held. */
#define MBP_PERSISTENT 0x2 /* Cache lock is already held coming in. */
/*
* Initialize the mbuf subsystem.
*
* We sub-divide the kmem_map into several submaps; this way, we don't have
* to worry about artificially limiting the number of mbuf or mbuf cluster
* allocations, due to fear of one type of allocation "stealing" address
* space initially reserved for another.
*
* Set up both the general containers and all the PCPU containers. Populate
* the PCPU containers with initial numbers.
*/
MALLOC_DEFINE(M_MBUF, "mbufmgr", "mbuf subsystem management structures");
SYSINIT(mbuf, SI_SUB_MBUF, SI_ORDER_FIRST, mbuf_init, NULL)
static void
mbuf_init(void *dummy)
{
struct mb_pcpu_list *pcpu_cnt;
vm_size_t mb_map_size;
int i, j;
/*
* Set up all the submaps, for each type of object that we deal
* with in this allocator. We also allocate space for the cluster
* ref. counts in the mbuf map (and not the cluster map) in order to
* give clusters a nice contiguous address space without any holes.
*/
mb_map_size = (vm_size_t)(nmbufs * MSIZE + nmbclusters * sizeof(u_int));
mb_map_size = rounddown(mb_map_size, PAGE_SIZE);
mb_list_mbuf.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE *
sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT);
if (mb_list_mbuf.ml_btable == NULL)
goto bad;
mb_list_mbuf.ml_map = kmem_suballoc(kmem_map,&(mb_list_mbuf.ml_mapbase),
&(mb_list_mbuf.ml_maptop), mb_map_size);
mb_list_mbuf.ml_map->system_map = 1;
mb_list_mbuf.ml_mapfull = 0;
mb_list_mbuf.ml_objsize = MSIZE;
mb_list_mbuf.ml_wmhigh = &mbuf_limit;
mb_map_size = (vm_size_t)(nmbclusters * MCLBYTES);
mb_map_size = rounddown(mb_map_size, PAGE_SIZE);
mb_list_clust.ml_btable = malloc((unsigned long)mb_map_size / PAGE_SIZE
* sizeof(struct mb_bucket *), M_MBUF, M_NOWAIT);
if (mb_list_clust.ml_btable == NULL)
goto bad;
mb_list_clust.ml_map = kmem_suballoc(kmem_map,
&(mb_list_clust.ml_mapbase), &(mb_list_clust.ml_maptop),
mb_map_size);
mb_list_clust.ml_map->system_map = 1;
mb_list_clust.ml_mapfull = 0;
mb_list_clust.ml_objsize = MCLBYTES;
mb_list_clust.ml_wmhigh = &clust_limit;
/*
* Allocate required general (global) containers for each object type.
*/
mb_list_mbuf.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF,
M_NOWAIT);
mb_list_clust.ml_genlist = malloc(sizeof(struct mb_gen_list), M_MBUF,
M_NOWAIT);
if ((mb_list_mbuf.ml_genlist == NULL) ||
(mb_list_clust.ml_genlist == NULL))
goto bad;
/*
* Initialize condition variables and general container mutex locks.
*/
mtx_init(&mbuf_gen, "mbuf subsystem general lists lock", NULL, 0);
cv_init(&(mb_list_mbuf.ml_genlist->mgl_mstarved), "mbuf pool starved");
cv_init(&(mb_list_clust.ml_genlist->mgl_mstarved),
"mcluster pool starved");
mb_list_mbuf.ml_genlist->mb_cont.mc_lock =
mb_list_clust.ml_genlist->mb_cont.mc_lock = &mbuf_gen;
/*
* Set up the general containers for each object.
*/
mb_list_mbuf.ml_genlist->mb_cont.mc_numowner =
mb_list_clust.ml_genlist->mb_cont.mc_numowner = MB_GENLIST_OWNER;
mb_list_mbuf.ml_genlist->mb_cont.mc_starved =
mb_list_clust.ml_genlist->mb_cont.mc_starved = 0;
mb_list_mbuf.ml_genlist->mb_cont.mc_objcount =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbfree);
mb_list_clust.ml_genlist->mb_cont.mc_objcount =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_clfree);
mb_list_mbuf.ml_genlist->mb_cont.mc_numpgs =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbpgs);
mb_list_clust.ml_genlist->mb_cont.mc_numpgs =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_clpgs);
mb_list_mbuf.ml_genlist->mb_cont.mc_types =
&(mb_statpcpu[MB_GENLIST_OWNER].mb_mbtypes[0]);
mb_list_clust.ml_genlist->mb_cont.mc_types = NULL;
SLIST_INIT(&(mb_list_mbuf.ml_genlist->mb_cont.mc_bhead));
SLIST_INIT(&(mb_list_clust.ml_genlist->mb_cont.mc_bhead));
/*
* Allocate all the required counters for clusters. This makes
* cluster allocations/deallocations much faster.
*/
cl_refcntmap = (u_int *)kmem_malloc(mb_list_mbuf.ml_map,
roundup(nmbclusters * sizeof(u_int), MSIZE), M_NOWAIT);
if (cl_refcntmap == NULL)
goto bad;
/*
* Initialize general mbuf statistics.
*/
mbstat.m_msize = MSIZE;
mbstat.m_mclbytes = MCLBYTES;
mbstat.m_minclsize = MINCLSIZE;
mbstat.m_mlen = MLEN;
mbstat.m_mhlen = MHLEN;
mbstat.m_numtypes = MT_NTYPES;
/*
* Allocate and initialize PCPU containers.
*/
for (i = 0; i < NCPU; i++) {
if (CPU_ABSENT(i))
continue;
mb_list_mbuf.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list),
M_MBUF, M_NOWAIT);
mb_list_clust.ml_cntlst[i] = malloc(sizeof(struct mb_pcpu_list),
M_MBUF, M_NOWAIT);
if ((mb_list_mbuf.ml_cntlst[i] == NULL) ||
(mb_list_clust.ml_cntlst[i] == NULL))
goto bad;
mtx_init(&mbuf_pcpu[i], "mbuf PCPU list lock", NULL, 0);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_lock =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_lock = &mbuf_pcpu[i];
mb_statpcpu[i].mb_active = 1;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numowner =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_numowner = i;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_starved =
mb_list_clust.ml_cntlst[i]->mb_cont.mc_starved = 0;
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_objcount =
&(mb_statpcpu[i].mb_mbfree);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_objcount =
&(mb_statpcpu[i].mb_clfree);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_numpgs =
&(mb_statpcpu[i].mb_mbpgs);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_numpgs =
&(mb_statpcpu[i].mb_clpgs);
mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_types =
&(mb_statpcpu[i].mb_mbtypes[0]);
mb_list_clust.ml_cntlst[i]->mb_cont.mc_types = NULL;
SLIST_INIT(&(mb_list_mbuf.ml_cntlst[i]->mb_cont.mc_bhead));
SLIST_INIT(&(mb_list_clust.ml_cntlst[i]->mb_cont.mc_bhead));
/*
* Perform initial allocations.
*/
pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_mbuf, i);
MB_LOCK_CONT(pcpu_cnt);
for (j = 0; j < NMB_MBUF_INIT; j++) {
if (mb_pop_cont(&mb_list_mbuf, M_NOWAIT, pcpu_cnt)
== NULL)
goto bad;
}
MB_UNLOCK_CONT(pcpu_cnt);
pcpu_cnt = MB_GET_PCPU_LIST_NUM(&mb_list_clust, i);
MB_LOCK_CONT(pcpu_cnt);
for (j = 0; j < NMB_CLUST_INIT; j++) {
if (mb_pop_cont(&mb_list_clust, M_NOWAIT, pcpu_cnt)
== NULL)
goto bad;
}
MB_UNLOCK_CONT(pcpu_cnt);
}
return;
bad:
panic("mbuf_init(): failed to initialize mbuf subsystem!");
}
/*
* Populate a given mbuf PCPU container with a bucket full of fresh new
* buffers. Return a pointer to the new bucket (already in the container if
* successful), or return NULL on failure.
*
* LOCKING NOTES:
* PCPU container lock must be held when this is called.
* The lock is dropped here so that we can cleanly call the underlying VM
* code. If we fail, we return with no locks held. If we succeed (i.e., return
* non-NULL), we return with the PCPU lock held, ready for allocation from
* the returned bucket.
*/
static struct mb_bucket *
mb_pop_cont(struct mb_lstmngr *mb_list, int how, struct mb_pcpu_list *cnt_lst)
{
struct mb_bucket *bucket;
caddr_t p;
int i;
MB_UNLOCK_CONT(cnt_lst);
/*
* If our object's (finite) map is starved now (i.e., no more address
* space), bail out now.
*/
if (mb_list->ml_mapfull)
return (NULL);
bucket = malloc(sizeof(struct mb_bucket) +
PAGE_SIZE / mb_list->ml_objsize * sizeof(void *), M_MBUF,
how == 0 ? 0 : M_NOWAIT);
if (bucket == NULL)
return (NULL);
p = (caddr_t)kmem_malloc(mb_list->ml_map, PAGE_SIZE,
how == 0 ? 0 : M_NOWAIT);
if (p == NULL) {
free(bucket, M_MBUF);
if (how == 0)
mb_list->ml_mapfull = 1;
return (NULL);
}
bucket->mb_numfree = 0;
mb_list->ml_btable[MB_BUCKET_INDX(p, mb_list)] = bucket;
for (i = 0; i < (PAGE_SIZE / mb_list->ml_objsize); i++) {
bucket->mb_free[i] = p;
bucket->mb_numfree++;
p += mb_list->ml_objsize;
}
MB_LOCK_CONT(cnt_lst);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead), bucket, mb_blist);
(*(cnt_lst->mb_cont.mc_numpgs))++;
*(cnt_lst->mb_cont.mc_objcount) += bucket->mb_numfree;
return (bucket);
}
/*
* Allocate an mbuf-subsystem type object.
* The general case is very easy. Complications only arise if our PCPU
* container is empty. Things get worse if the PCPU container is empty,
* the general container is empty, and we've run out of address space
* in our map; then we try to block if we're willing to wait.
*/
static __inline
void *
mb_alloc(struct mb_lstmngr *mb_list, int how, short type, short persist,
int *pers_list)
{
static int last_report;
struct mb_pcpu_list *cnt_lst;
struct mb_bucket *bucket;
void *m;
m = NULL;
if ((persist & MBP_PERSISTENT) != 0) {
/*
* If we're a "persistent" call, then the per-CPU #(pers_list)
* cache lock is already held, and we just need to refer to
* the correct cache descriptor.
*/
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, *pers_list);
} else {
cnt_lst = MB_GET_PCPU_LIST(mb_list);
MB_LOCK_CONT(cnt_lst);
}
if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) != NULL) {
/*
* This is the easy allocation case. We just grab an object
* from a bucket in the PCPU container. At worst, we
* have just emptied the bucket and so we remove it
* from the container.
*/
MB_GET_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_INC(cnt_lst, type, 1);
/* If asked to persist, do not drop the lock. */
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list = cnt_lst->mb_cont.mc_numowner;
} else {
struct mb_gen_list *gen_list;
/*
* This is the less-common more difficult case. We must
* first verify if the general list has anything for us
* and if that also fails, we must allocate a page from
* the map and create a new bucket to place in our PCPU
* container (already locked). If the map is starved then
* we're really in for trouble, as we have to wait on
* the general container's condition variable.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead)))
!= NULL) {
/*
* Give ownership of the bucket to our CPU's
* container, but only actually put the bucket
* in the container if it doesn't become free
* upon removing an mbuf from it.
*/
SLIST_REMOVE_HEAD(&(gen_list->mb_cont.mc_bhead),
mb_blist);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
(*(gen_list->mb_cont.mc_numpgs))--;
(*(cnt_lst->mb_cont.mc_numpgs))++;
*(gen_list->mb_cont.mc_objcount) -= bucket->mb_numfree;
bucket->mb_numfree--;
m = bucket->mb_free[(bucket->mb_numfree)];
if (bucket->mb_numfree == 0) {
SLIST_NEXT(bucket, mb_blist) = NULL;
bucket->mb_owner |= MB_BUCKET_FREE;
} else {
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead),
bucket, mb_blist);
*(cnt_lst->mb_cont.mc_objcount) +=
bucket->mb_numfree;
}
MB_UNLOCK_CONT(gen_list);
MB_MBTYPES_INC(cnt_lst, type, 1);
/* If asked to persist, do not drop the lock. */
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list = cnt_lst->mb_cont.mc_numowner;
} else {
/*
* We'll have to allocate a new page.
*/
MB_UNLOCK_CONT(gen_list);
bucket = mb_pop_cont(mb_list, how, cnt_lst);
if (bucket != NULL) {
MB_GET_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_INC(cnt_lst, type, 1);
/* If asked to persist, do not drop the lock. */
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list=cnt_lst->mb_cont.mc_numowner;
} else {
if (how == 0) {
/*
* Absolute worst-case scenario.
* We block if we're willing to, but
* only after trying to steal from
* other lists.
*/
m = mb_alloc_wait(mb_list, type);
} else {
/* XXX: No consistency. */
mbstat.m_drops++;
if (ticks < last_report ||
(ticks - last_report) >= hz) {
last_report = ticks;
printf(
"All mbufs or mbuf clusters exhausted, please see tuning(7).\n");
}
}
if (m != NULL && (persist & MBP_PERSIST) != 0) {
cnt_lst = MB_GET_PCPU_LIST(mb_list);
MB_LOCK_CONT(cnt_lst);
*pers_list=cnt_lst->mb_cont.mc_numowner;
}
}
}
}
return (m);
}
/*
* This is the worst-case scenario called only if we're allocating with
* 0. We first drain all the protocols, then try to find an mbuf
* by looking in every PCPU container. If we're still unsuccesful, we
* try the general container one last time and possibly block on our
* starved cv.
*/
static void *
mb_alloc_wait(struct mb_lstmngr *mb_list, short type)
{
struct mb_pcpu_list *cnt_lst;
struct mb_gen_list *gen_list;
struct mb_bucket *bucket;
void *m;
int i, cv_ret;
/*
* Try to reclaim mbuf-related objects (mbufs, clusters).
*/
mb_reclaim();
/*
* Cycle all the PCPU containers. Increment starved counts if found
* empty.
*/
for (i = 0; i < NCPU; i++) {
if (CPU_ABSENT(i))
continue;
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, i);
MB_LOCK_CONT(cnt_lst);
/*
* If container is non-empty, get a single object from it.
* If empty, increment starved count.
*/
if ((bucket = SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead))) !=
NULL) {
MB_GET_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_INC(cnt_lst, type, 1);
MB_UNLOCK_CONT(cnt_lst);
mbstat.m_wait++; /* XXX: No consistency. */
return (m);
} else
cnt_lst->mb_cont.mc_starved++;
MB_UNLOCK_CONT(cnt_lst);
}
/*
* We're still here, so that means it's time to get the general
* container lock, check it one more time (now that mb_reclaim()
* has been called) and if we still get nothing, block on the cv.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL) {
MB_GET_OBJECT(m, bucket, gen_list);
MB_MBTYPES_INC(gen_list, type, 1);
MB_UNLOCK_CONT(gen_list);
mbstat.m_wait++; /* XXX: No consistency. */
return (m);
}
gen_list->mb_cont.mc_starved++;
cv_ret = cv_timedwait(&(gen_list->mgl_mstarved),
gen_list->mb_cont.mc_lock, mbuf_wait);
gen_list->mb_cont.mc_starved--;
if ((cv_ret == 0) &&
((bucket = SLIST_FIRST(&(gen_list->mb_cont.mc_bhead))) != NULL)) {
MB_GET_OBJECT(m, bucket, gen_list);
MB_MBTYPES_INC(gen_list, type, 1);
mbstat.m_wait++; /* XXX: No consistency. */
} else {
mbstat.m_drops++; /* XXX: No consistency. */
m = NULL;
}
MB_UNLOCK_CONT(gen_list);
return (m);
}
/*-
* Free an object to its rightful container.
* In the very general case, this operation is really very easy.
* Complications arise primarily if:
* (a) We've hit the high limit on number of free objects allowed in
* our PCPU container.
* (b) We're in a critical situation where our container has been
* marked 'starved' and we need to issue wakeups on the starved
* condition variable.
* (c) Minor (odd) cases: our bucket has migrated while we were
* waiting for the lock; our bucket is in the general container;
* our bucket is empty.
*/
static __inline
void
mb_free(struct mb_lstmngr *mb_list, void *m, short type, short persist,
int *pers_list)
{
struct mb_pcpu_list *cnt_lst;
struct mb_gen_list *gen_list;
struct mb_bucket *bucket;
u_int owner;
bucket = mb_list->ml_btable[MB_BUCKET_INDX(m, mb_list)];
/*
* Make sure that if after we lock the bucket's present container the
* bucket has migrated, that we drop the lock and get the new one.
*/
retry_lock:
owner = bucket->mb_owner & ~MB_BUCKET_FREE;
switch (owner) {
case MB_GENLIST_OWNER:
gen_list = MB_GET_GEN_LIST(mb_list);
if (((persist & MBP_PERSISTENT) != 0) && (*pers_list >= 0)) {
if (*pers_list != MB_GENLIST_OWNER) {
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list,
*pers_list);
MB_UNLOCK_CONT(cnt_lst);
MB_LOCK_CONT(gen_list);
}
} else {
MB_LOCK_CONT(gen_list);
}
if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) {
MB_UNLOCK_CONT(gen_list);
*pers_list = -1;
goto retry_lock;
}
/*
* If we're intended for the general container, this is
* real easy: no migrating required. The only `bogon'
* is that we're now contending with all the threads
* dealing with the general list, but this is expected.
*/
MB_PUT_OBJECT(m, bucket, gen_list);
MB_MBTYPES_DEC(gen_list, type, 1);
if (gen_list->mb_cont.mc_starved > 0)
cv_signal(&(gen_list->mgl_mstarved));
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(gen_list);
else
*pers_list = MB_GENLIST_OWNER;
break;
default:
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list, owner);
if (((persist & MBP_PERSISTENT) != 0) && (*pers_list >= 0)) {
if (*pers_list == MB_GENLIST_OWNER) {
gen_list = MB_GET_GEN_LIST(mb_list);
MB_UNLOCK_CONT(gen_list);
MB_LOCK_CONT(cnt_lst);
} else {
cnt_lst = MB_GET_PCPU_LIST_NUM(mb_list,
*pers_list);
owner = *pers_list;
}
} else {
MB_LOCK_CONT(cnt_lst);
}
if (owner != (bucket->mb_owner & ~MB_BUCKET_FREE)) {
MB_UNLOCK_CONT(cnt_lst);
*pers_list = -1;
goto retry_lock;
}
MB_PUT_OBJECT(m, bucket, cnt_lst);
MB_MBTYPES_DEC(cnt_lst, type, 1);
if (cnt_lst->mb_cont.mc_starved > 0) {
/*
* This is a tough case. It means that we've
* been flagged at least once to indicate that
* we're empty, and that the system is in a critical
* situation, so we ought to migrate at least one
* bucket over to the general container.
* There may or may not be a thread blocking on
* the starved condition variable, but chances
* are that one will eventually come up soon so
* it's better to migrate now than never.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
KASSERT((bucket->mb_owner & MB_BUCKET_FREE) != 0,
("mb_free: corrupt bucket %p\n", bucket));
SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = MB_GENLIST_OWNER;
(*(cnt_lst->mb_cont.mc_objcount))--;
(*(gen_list->mb_cont.mc_objcount))++;
(*(cnt_lst->mb_cont.mc_numpgs))--;
(*(gen_list->mb_cont.mc_numpgs))++;
/*
* Determine whether or not to keep transferring
* buckets to the general list or whether we've
* transferred enough already.
* We realize that although we may flag another
* bucket to be migrated to the general container
* that in the meantime, the thread that was
* blocked on the cv is already woken up and
* long gone. But in that case, the worst
* consequence is that we will end up migrating
* one bucket too many, which is really not a big
* deal, especially if we're close to a critical
* situation.
*/
if (gen_list->mb_cont.mc_starved > 0) {
cnt_lst->mb_cont.mc_starved--;
cv_signal(&(gen_list->mgl_mstarved));
} else
cnt_lst->mb_cont.mc_starved = 0;
MB_UNLOCK_CONT(gen_list);
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list = owner;
break;
}
if (*(cnt_lst->mb_cont.mc_objcount) > *(mb_list->ml_wmhigh)) {
/*
* We've hit the high limit of allowed numbers of mbufs
* on this PCPU list. We must now migrate a bucket
* over to the general container.
*/
gen_list = MB_GET_GEN_LIST(mb_list);
MB_LOCK_CONT(gen_list);
if ((bucket->mb_owner & MB_BUCKET_FREE) == 0) {
bucket =
SLIST_FIRST(&(cnt_lst->mb_cont.mc_bhead));
SLIST_REMOVE_HEAD(&(cnt_lst->mb_cont.mc_bhead),
mb_blist);
}
SLIST_INSERT_HEAD(&(gen_list->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = MB_GENLIST_OWNER;
*(cnt_lst->mb_cont.mc_objcount) -= bucket->mb_numfree;
*(gen_list->mb_cont.mc_objcount) += bucket->mb_numfree;
(*(cnt_lst->mb_cont.mc_numpgs))--;
(*(gen_list->mb_cont.mc_numpgs))++;
/*
* While we're at it, transfer some of the mbtypes
* "count load" onto the general list's mbtypes
* array, seeing as how we're moving the bucket
* there now, meaning that the freeing of objects
* there will now decrement the _general list's_
* mbtypes counters, and no longer our PCPU list's
* mbtypes counters. We do this for the type presently
* being freed in an effort to keep the mbtypes
* counters approximately balanced across all lists.
*/
MB_MBTYPES_DEC(cnt_lst, type, (PAGE_SIZE /
mb_list->ml_objsize) - bucket->mb_numfree);
MB_MBTYPES_INC(gen_list, type, (PAGE_SIZE /
mb_list->ml_objsize) - bucket->mb_numfree);
MB_UNLOCK_CONT(gen_list);
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list = owner;
break;
}
if (bucket->mb_owner & MB_BUCKET_FREE) {
SLIST_INSERT_HEAD(&(cnt_lst->mb_cont.mc_bhead),
bucket, mb_blist);
bucket->mb_owner = cnt_lst->mb_cont.mc_numowner;
}
if ((persist & MBP_PERSIST) == 0)
MB_UNLOCK_CONT(cnt_lst);
else
*pers_list = owner;
break;
}
}
/*
* Drain protocols in hopes to free up some resources.
*
* LOCKING NOTES:
* No locks should be held when this is called. 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
mb_reclaim(void)
{
struct domain *dp;
struct protosw *pr;
/*
* XXX: Argh, we almost always trip here with witness turned on now-a-days
* XXX: because we often come in with Giant held. For now, there's no way
* XXX: to avoid this.
*/
#ifdef WITNESS
KASSERT(witness_list(curthread) == 0,
("mb_reclaim() called with locks held"));
#endif
mbstat.m_drain++; /* XXX: No consistency. */
for (dp = domains; dp != NULL; dp = dp->dom_next)
for (pr = dp->dom_protosw; pr < dp->dom_protoswNPROTOSW; pr++)
if (pr->pr_drain != NULL)
(*pr->pr_drain)();
}
/******************************************************************************
* Internal setup macros.
*/
#define _mb_setup(m, type) do { \
(m)->m_type = (type); \
(m)->m_next = NULL; \
(m)->m_nextpkt = NULL; \
(m)->m_data = (m)->m_dat; \
(m)->m_flags = 0; \
} while (0)
#define _mbhdr_setup(m, type) do { \
(m)->m_type = (type); \
(m)->m_next = NULL; \
(m)->m_nextpkt = NULL; \
(m)->m_data = (m)->m_pktdat; \
(m)->m_flags = M_PKTHDR; \
(m)->m_pkthdr.rcvif = NULL; \
(m)->m_pkthdr.csum_flags = 0; \
SLIST_INIT(&(m)->m_pkthdr.tags); \
} while (0)
#define _mcl_setup(m) do { \
(m)->m_data = (m)->m_ext.ext_buf; \
(m)->m_flags |= M_EXT; \
(m)->m_ext.ext_free = NULL; \
(m)->m_ext.ext_args = NULL; \
(m)->m_ext.ext_size = MCLBYTES; \
(m)->m_ext.ext_type = EXT_CLUSTER; \
} while (0)
#define _mext_init_ref(m, ref) do { \
(m)->m_ext.ref_cnt = ((ref) == NULL) ? \
malloc(sizeof(u_int), M_MBUF, M_NOWAIT) : (u_int *)(ref); \
if ((m)->m_ext.ref_cnt != NULL) { \
*((m)->m_ext.ref_cnt) = 0; \
MEXT_ADD_REF((m)); \
} \
} while (0)
#define cl2ref(cl) \
(((uintptr_t)(cl) - (uintptr_t)cl_refcntmap) >> MCLSHIFT)
#define _mext_dealloc_ref(m) \
if ((m)->m_ext.ext_type != EXT_EXTREF) \
free((m)->m_ext.ref_cnt, M_MBUF)
/******************************************************************************
* Internal routines.
*
* Because mb_alloc() and mb_free() are inlines (to keep the common
* cases down to a maximum of one function call), below are a few
* routines used only internally for the sole purpose of making certain
* functions smaller.
*
* - _mext_free(): frees associated storage when the ref. count is
* exactly one and we're freeing.
*
* - _mgetm_internal(): common "persistent-lock" routine that allocates
* an mbuf and a cluster in one shot, but where the lock is already
* held coming in (which is what makes it different from the exported
* m_getcl()). The lock is dropped when done. This is used by m_getm()
* and, therefore, is very m_getm()-specific.
*/
static struct mbuf *_mgetm_internal(int, short, short, int);
void
_mext_free(struct mbuf *mb)
{
if (mb->m_ext.ext_type == EXT_CLUSTER) {
mb_free(&mb_list_clust, (caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF,
0, NULL);
} else {
(*(mb->m_ext.ext_free))(mb->m_ext.ext_buf, mb->m_ext.ext_args);
_mext_dealloc_ref(mb);
}
}
static struct mbuf *
_mgetm_internal(int how, short type, short persist, int cchnum)
{
struct mbuf *mb;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type, persist,&cchnum);
if (mb == NULL)
return NULL;
_mb_setup(mb, type);
if ((persist & MBP_PERSIST) != 0) {
mb->m_ext.ext_buf = (caddr_t)mb_alloc(&mb_list_clust,
how, MT_NOTMBUF, MBP_PERSISTENT, &cchnum);
if (mb->m_ext.ext_buf == NULL) {
(void)m_free(mb);
mb = NULL;
}
_mcl_setup(mb);
_mext_init_ref(mb, &cl_refcntmap[cl2ref(mb->m_ext.ext_buf)]);
}
return (mb);
}
/******************************************************************************
* Exported buffer allocation and de-allocation routines.
*/
/*
* Allocate and return a single (normal) mbuf. NULL is returned on failure.
*
* Arguments:
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
*/
struct mbuf *
m_get(int how, short type)
{
struct mbuf *mb;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type, 0, NULL);
if (mb != NULL)
_mb_setup(mb, type);
return (mb);
}
/*
* Allocate a given length worth of mbufs and/or clusters (whatever fits
* best) and return a pointer to the top of the allocated chain. If an
* existing mbuf chain is provided, then we will append the new chain
* to the existing one but still return the top of the newly allocated
* chain. NULL is returned on failure, in which case the [optional]
* provided chain is left untouched, and any memory already allocated
* is freed.
*
* Arguments:
* - m: existing chain to which to append new chain (optional).
* - len: total length of data to append, either in mbufs or clusters
* (we allocate whatever combination yields the best fit).
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
*/
struct mbuf *
m_getm(struct mbuf *m, int len, int how, short type)
{
struct mbuf *mb, *top, *cur, *mtail;
int num, rem, cchnum;
short persist;
int i;
KASSERT(len >= 0, ("m_getm(): len is < 0"));
/* If m != NULL, we will append to the end of that chain. */
if (m != NULL)
for (mtail = m; mtail->m_next != NULL; mtail = mtail->m_next);
else
mtail = NULL;
/*
* In the best-case scenario (which should be the common case
* unless we're in a starvation situation), we will be able to
* go through the allocation of all the desired mbufs and clusters
* here without dropping our per-CPU cache lock in between.
*/
num = len / MCLBYTES;
rem = len % MCLBYTES;
persist = 0;
cchnum = -1;
top = cur = NULL;
for (i = 0; i < num; i++) {
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type,
MBP_PERSIST | persist, &cchnum);
if (mb == NULL)
goto failed;
_mb_setup(mb, type);
mb->m_len = 0;
persist = (i != (num - 1) || rem > 0) ? MBP_PERSIST : 0;
mb->m_ext.ext_buf = (caddr_t)mb_alloc(&mb_list_clust,
how, MT_NOTMBUF, persist | MBP_PERSISTENT, &cchnum);
if (mb->m_ext.ext_buf == NULL) {
(void)m_free(mb);
goto failed;
}
_mcl_setup(mb);
_mext_init_ref(mb, &cl_refcntmap[cl2ref(mb->m_ext.ext_buf)]);
persist = MBP_PERSISTENT;
if (cur == NULL)
top = cur = mb;
else
cur = (cur->m_next = mb);
}
if (rem > 0) {
if (cchnum >= 0) {
persist = MBP_PERSISTENT;
persist |= (rem > MINCLSIZE) ? MBP_PERSIST : 0;
mb = _mgetm_internal(how, type, persist, cchnum);
if (mb == NULL)
goto failed;
} else if (rem > MINCLSIZE) {
mb = m_getcl(how, type, 0);
} else {
mb = m_get(how, type);
}
if (mb != NULL) {
mb->m_len = 0;
if (cur == NULL)
top = mb;
else
cur->m_next = mb;
} else
goto failed;
}
if (mtail != NULL)
mtail->m_next = top;
return top;
failed:
if (top != NULL)
m_freem(top);
return NULL;
}
/*
* Allocate and return a single M_PKTHDR mbuf. NULL is returned on failure.
*
* Arguments:
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
*/
struct mbuf *
m_gethdr(int how, short type)
{
struct mbuf *mb;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type, 0, NULL);
if (mb != NULL) {
_mbhdr_setup(mb, type);
#ifdef MAC
if (mac_init_mbuf(mb, how) != 0) {
m_free(mb);
return NULL;
}
#endif
}
return (mb);
}
/*
* Allocate and return a single (normal) pre-zero'd mbuf. NULL is
* returned on failure.
*
* Arguments:
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
*/
struct mbuf *
m_get_clrd(int how, short type)
{
struct mbuf *mb;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type, 0, NULL);
if (mb != NULL) {
_mb_setup(mb, type);
bzero(mtod(mb, caddr_t), MLEN);
}
return (mb);
}
/*
* Allocate and return a single M_PKTHDR pre-zero'd mbuf. NULL is
* returned on failure.
*
* Arguments:
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
*/
struct mbuf *
m_gethdr_clrd(int how, short type)
{
struct mbuf *mb;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type, 0, NULL);
if (mb != NULL) {
_mbhdr_setup(mb, type);
#ifdef MAC
if (mac_init_mbuf(mb, how) != 0) {
m_free(mb);
return NULL;
}
#endif
bzero(mtod(mb, caddr_t), MHLEN);
}
return (mb);
}
/*
* Free a single mbuf and any associated storage that it may have attached
* to it. The associated storage may not be immediately freed if its
* reference count is above 1. Returns the next mbuf in the chain following
* the mbuf being freed.
*
* Arguments:
* - mb: the mbuf to free.
*/
struct mbuf *
m_free(struct mbuf *mb)
{
struct mbuf *nb;
int cchnum;
short persist = 0;
if ((mb->m_flags & M_PKTHDR) != 0)
m_tag_delete_chain(mb, NULL);
#ifdef MAC
if ((mb->m_flags & M_PKTHDR) &&
(mb->m_pkthdr.label.l_flags & MAC_FLAG_INITIALIZED))
mac_destroy_mbuf(mb);
#endif
nb = mb->m_next;
if ((mb->m_flags & M_EXT) != 0) {
MEXT_REM_REF(mb);
if (atomic_cmpset_int(mb->m_ext.ref_cnt, 0, 1)) {
if (mb->m_ext.ext_type == EXT_CLUSTER) {
mb_free(&mb_list_clust,
(caddr_t)mb->m_ext.ext_buf, MT_NOTMBUF,
MBP_PERSIST, &cchnum);
persist = MBP_PERSISTENT;
} else {
(*(mb->m_ext.ext_free))(mb->m_ext.ext_buf,
mb->m_ext.ext_args);
_mext_dealloc_ref(mb);
persist = 0;
}
}
}
mb_free(&mb_list_mbuf, mb, mb->m_type, persist, &cchnum);
return (nb);
}
/*
* Free an entire chain of mbufs and associated external buffers, if
* applicable. Right now, we only optimize a little so that the cache
* lock may be held across a single mbuf+cluster free. Hopefully,
* we'll eventually be holding the lock across more than merely two
* consecutive frees but right now this is hard to implement because of
* things like _mext_dealloc_ref (may do a free()) and atomic ops in the
* loop.
*
* - mb: the mbuf chain to free.
*/
void
m_freem(struct mbuf *mb)
{
struct mbuf *m;
int cchnum;
short persist;
while (mb != NULL) {
if ((mb->m_flags & M_PKTHDR) != 0)
m_tag_delete_chain(mb, NULL);
#ifdef MAC
if ((mb->m_flags & M_PKTHDR) &&
(mb->m_pkthdr.label.l_flags & MAC_FLAG_INITIALIZED))
mac_destroy_mbuf(mb);
#endif
persist = 0;
m = mb;
mb = mb->m_next;
if ((m->m_flags & M_EXT) != 0) {
MEXT_REM_REF(m);
if (atomic_cmpset_int(m->m_ext.ref_cnt, 0, 1)) {
if (m->m_ext.ext_type == EXT_CLUSTER) {
mb_free(&mb_list_clust,
(caddr_t)m->m_ext.ext_buf,
MT_NOTMBUF, MBP_PERSIST, &cchnum);
persist = MBP_PERSISTENT;
} else {
(*(m->m_ext.ext_free))(m->m_ext.ext_buf,
m->m_ext.ext_args);
_mext_dealloc_ref(m);
persist = 0;
}
}
}
mb_free(&mb_list_mbuf, m, m->m_type, persist, &cchnum);
}
}
/*
* Fetch an mbuf with a cluster attached to it. If one of the
* allocations fails, the entire allocation fails. This routine is
* the preferred way of fetching both the mbuf and cluster together,
* as it avoids having to unlock/relock between allocations. Returns
* NULL on failure.
*
* Arguments:
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
* - type: the type of the mbuf being allocated.
* - flags: any flags to pass to the mbuf being allocated; if this includes
* the M_PKTHDR bit, then the mbuf is configured as a M_PKTHDR mbuf.
*/
struct mbuf *
m_getcl(int how, short type, int flags)
{
struct mbuf *mb;
int cchnum;
mb = (struct mbuf *)mb_alloc(&mb_list_mbuf, how, type,
MBP_PERSIST, &cchnum);
if (mb == NULL)
return NULL;
mb->m_type = type;
mb->m_next = NULL;
mb->m_flags = flags;
if ((flags & M_PKTHDR) != 0) {
mb->m_nextpkt = NULL;
mb->m_pkthdr.rcvif = NULL;
mb->m_pkthdr.csum_flags = 0;
SLIST_INIT(&mb->m_pkthdr.tags);
}
mb->m_ext.ext_buf = (caddr_t)mb_alloc(&mb_list_clust, how,
MT_NOTMBUF, MBP_PERSISTENT, &cchnum);
if (mb->m_ext.ext_buf == NULL) {
(void)m_free(mb);
mb = NULL;
} else {
_mcl_setup(mb);
_mext_init_ref(mb, &cl_refcntmap[cl2ref(mb->m_ext.ext_buf)]);
}
#ifdef MAC
if ((flags & M_PKTHDR) && (mac_init_mbuf(mb, how) != 0)) {
m_free(mb);
return NULL;
}
#endif
return (mb);
}
/*
* Fetch a single mbuf cluster and attach it to an existing mbuf. If
* successfull, configures the provided mbuf to have mbuf->m_ext.ext_buf
* pointing to the cluster, and sets the M_EXT bit in the mbuf's flags.
* The M_EXT bit is not set on failure.
*
* Arguments:
* - mb: the existing mbuf to which to attach the allocated cluster.
* - how: 0 to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_NOWAIT to never block.
*/
void
m_clget(struct mbuf *mb, int how)
{
mb->m_ext.ext_buf= (caddr_t)mb_alloc(&mb_list_clust,how,MT_NOTMBUF,
0, NULL);
if (mb->m_ext.ext_buf != NULL) {
_mcl_setup(mb);
_mext_init_ref(mb, &cl_refcntmap[cl2ref(mb->m_ext.ext_buf)]);
}
}
/*
* Configure a provided mbuf to refer to the provided external storage
* buffer and setup a reference count for said buffer. If the setting
* up of the reference count fails, the M_EXT bit will not be set. If
* successfull, the M_EXT bit is set in the mbuf's flags.
*
* Arguments:
* - mb: the existing mbuf to which to attach the provided buffer.
* - buf: the address of the provided external storage buffer.
* - size: the size of the provided buffer.
* - freef: a pointer to a routine that is responsible for freeing the
* provided external storage buffer.
* - args: a pointer to an argument structure (of any type) to be passed
* to the provided freef routine (may be NULL).
* - flags: any other flags to be passed to the provided mbuf.
* - type: the type that the external storage buffer should be labeled with.
*/
void
m_extadd(struct mbuf *mb, caddr_t buf, u_int size,
void (*freef)(void *, void *), void *args, int flags, int type)
{
u_int *ref_cnt = NULL;
if (type == EXT_CLUSTER)
ref_cnt = &cl_refcntmap[cl2ref(mb->m_ext.ext_buf)];
else if (type == EXT_EXTREF)
ref_cnt = mb->m_ext.ref_cnt;
_mext_init_ref(mb, ref_cnt);
if (mb->m_ext.ref_cnt != NULL) {
mb->m_flags |= (M_EXT | flags);
mb->m_ext.ext_buf = buf;
mb->m_data = mb->m_ext.ext_buf;
mb->m_ext.ext_size = size;
mb->m_ext.ext_free = freef;
mb->m_ext.ext_args = args;
mb->m_ext.ext_type = type;
}
}
/*
* Change type of provided mbuf. This is a relatively expensive operation
* (due to the cost of statistics manipulations) and should be avoided, where
* possible.
*
* Arguments:
* - mb: the provided mbuf for which the type needs to be changed.
* - new_type: the new type to change the mbuf to.
*/
void
m_chtype(struct mbuf *mb, short new_type)
{
struct mb_gen_list *gen_list;
gen_list = MB_GET_GEN_LIST(&mb_list_mbuf);
MB_LOCK_CONT(gen_list);
MB_MBTYPES_DEC(gen_list, mb->m_type, 1);
MB_MBTYPES_INC(gen_list, new_type, 1);
MB_UNLOCK_CONT(gen_list);
mb->m_type = new_type;
}
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