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freebsd-dev/sys/kern/subr_mbuf.c
Andrew Gallatin 1f88bad30a o Introduce a new external mbuf type, EXT_EXTREF. 
o Allow callers of m_extadd() to allocate their own reference
m_ext.ref_cnt pointer, rather than having the mbuf system allocate it
with a malloc() in the critical path.  This speeds m_extadd() up, and
also simplifies locking (malloc() may need Giant).

A driver or subsystem wishing to take use its own ref counter must
initialize m_ext.ref_cnt to point to its ref counter prior to
calling m_extadd(), and it must use EXT_EXTREF as its external type.

Eg:
	 m->m_ext.ref_cnt =  my_ref_cnt_ptr;
	 m_extadd(.....,EXT_EXTREF);

Reviewed by: bosko
2003-01-02 21:16:50 +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_DONTWAIT, 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_DONTWAIT, 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 == M_TRYWAIT ? M_WAITOK : M_NOWAIT);
if (bucket == NULL)
return (NULL);
p = (caddr_t)kmem_malloc(mb_list->ml_map, PAGE_SIZE,
how == M_TRYWAIT ? M_WAITOK : M_NOWAIT);
if (p == NULL) {
free(bucket, M_MBUF);
if (how == M_TRYWAIT)
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 (M_TRYWAIT).
*/
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 == M_TRYWAIT) {
/*
* 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
* M_TRYWAIT. 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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 and return the top of the provided (existing)
* 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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;
else
mtail = top;
return mtail;
failed:
if (top != NULL)
m_freem(top);
return NULL;
}
/*
* Allocate and return a single M_PKTHDR mbuf. NULL is returned on failure.
*
* Arguments:
* - how: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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: M_TRYWAIT to try to block for kern.ipc.mbuf_wait number of ticks
* if really starved for memory. M_DONTWAIT 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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