The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_mbpool.c

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    1 /*-
    2  * Copyright (c) 2003
    3  *      Fraunhofer Institute for Open Communication Systems (FhG Fokus).
    4  *      All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *    notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *    notice, this list of conditions and the following disclaimer in the
   13  *    documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  *
   27  * Author: Hartmut Brandt <harti@freebsd.org>
   28  */
   29 
   30 #include <sys/cdefs.h>
   31 __FBSDID("$FreeBSD: stable/10/sys/kern/subr_mbpool.c 302234 2016-06-27 21:50:30Z bdrewery $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/lock.h>
   35 #include <sys/mutex.h>
   36 #include <sys/kernel.h>
   37 #include <sys/systm.h>
   38 #include <sys/malloc.h>
   39 #include <sys/module.h>
   40 
   41 #include <machine/bus.h>
   42 
   43 #include <sys/mbuf.h>
   44 #include <sys/mbpool.h>
   45 
   46 MODULE_VERSION(libmbpool, 1);
   47 
   48 /*
   49  * Memory is allocated as DMA-able pages. Each page is divided into a number
   50  * of equal chunks where the last 4 bytes of each chunk are occupied by
   51  * the page number and the chunk number. The caller must take these four
   52  * bytes into account when specifying the chunk size. Each page is mapped by
   53  * its own DMA map using the user specified DMA tag.
   54  *
   55  * Each chunk has a used and a card bit in the high bits of its page number.
   56  *  0    0      chunk is free and may be allocated
   57  *  1    1      chunk has been given to the interface
   58  *  0    1      chunk is traveling through the system
   59  *  1    0      illegal
   60  */
   61 struct mbtrail {
   62         uint16_t        chunk;
   63         uint16_t        page;
   64 };
   65 #define MBP_CARD        0x8000
   66 #define MBP_USED        0x4000
   67 #define MBP_PMSK        0x3fff          /* page number mask */
   68 #define MBP_CMSK        0x01ff          /* chunk number mask */
   69 
   70 struct mbfree {
   71         SLIST_ENTRY(mbfree) link;       /* link on free list */
   72 };
   73 
   74 struct mbpage {
   75         bus_dmamap_t    map;            /* map for this page */
   76         bus_addr_t      phy;            /* physical address */
   77         void            *va;            /* the memory */
   78 };
   79 
   80 struct mbpool {
   81         const char      *name;          /* a name for this pool */
   82         bus_dma_tag_t   dmat;           /* tag for mapping */
   83         u_int           max_pages;      /* maximum number of pages */
   84         size_t          page_size;      /* size of each allocation */
   85         size_t          chunk_size;     /* size of each external mbuf */
   86 
   87         struct mtx      free_lock;      /* lock of free list */
   88         SLIST_HEAD(, mbfree) free_list; /* free list */
   89         u_int           npages;         /* current number of pages */
   90         u_int           nchunks;        /* chunks per page */
   91         struct mbpage   pages[];        /* pages */
   92 };
   93 
   94 static MALLOC_DEFINE(M_MBPOOL, "mbpools", "mbuf pools");
   95 
   96 /*
   97  * Make a trail pointer from a chunk pointer
   98  */
   99 #define C2T(P, C)       ((struct mbtrail *)((char *)(C) + (P)->chunk_size - \
  100                             sizeof(struct mbtrail)))
  101 
  102 /*
  103  * Make a free chunk pointer from a chunk number
  104  */
  105 #define N2C(P, PG, C)   ((struct mbfree *)((char *)(PG)->va + \
  106                             (C) * (P)->chunk_size))
  107 
  108 /*
  109  * Make/parse handles
  110  */
  111 #define HMAKE(P, C)     ((((P) & MBP_PMSK) << 16) | ((C) << 7))
  112 #define HPAGE(H)        (((H) >> 16) & MBP_PMSK)
  113 #define HCHUNK(H)       (((H) >>  7) & MBP_CMSK)
  114 
  115 /*
  116  * initialize a pool
  117  */
  118 int
  119 mbp_create(struct mbpool **pp, const char *name, bus_dma_tag_t dmat,
  120     u_int max_pages, size_t page_size, size_t chunk_size)
  121 {
  122         u_int nchunks;
  123 
  124         if (max_pages > MBPOOL_MAX_MAXPAGES || chunk_size == 0)
  125                 return (EINVAL);
  126         nchunks = page_size / chunk_size;
  127         if (nchunks == 0 || nchunks > MBPOOL_MAX_CHUNKS)
  128                 return (EINVAL);
  129 
  130         (*pp) = malloc(sizeof(struct mbpool) +
  131             max_pages * sizeof(struct mbpage),
  132             M_MBPOOL, M_WAITOK | M_ZERO);
  133 
  134         (*pp)->name = name;
  135         (*pp)->dmat = dmat;
  136         (*pp)->max_pages = max_pages;
  137         (*pp)->page_size = page_size;
  138         (*pp)->chunk_size = chunk_size;
  139         (*pp)->nchunks = nchunks;
  140 
  141         SLIST_INIT(&(*pp)->free_list);
  142         mtx_init(&(*pp)->free_lock, name, NULL, MTX_DEF);
  143 
  144         return (0);
  145 }
  146 
  147 /*
  148  * destroy a pool
  149  */
  150 void
  151 mbp_destroy(struct mbpool *p)
  152 {
  153         u_int i;
  154         struct mbpage *pg;
  155 #ifdef DIAGNOSTIC
  156         struct mbtrail *tr;
  157         u_int b;
  158 #endif
  159 
  160         for (i = 0; i < p->npages; i++) {
  161                 pg = &p->pages[i];
  162 #ifdef DIAGNOSTIC
  163                 for (b = 0; b < p->nchunks; b++) {
  164                         tr = C2T(p, N2C(p, pg, b));
  165                         if (tr->page & MBP_CARD)
  166                                 printf("%s: (%s) buf still on card"
  167                                     " %u/%u\n", __func__, p->name, i, b);
  168                         if (tr->page & MBP_USED)
  169                                 printf("%s: (%s) sbuf still in use"
  170                                     " %u/%u\n", __func__, p->name, i, b);
  171                 }
  172 #endif
  173                 bus_dmamap_unload(p->dmat, pg->map);
  174                 bus_dmamem_free(p->dmat, pg->va, pg->map);
  175         }
  176         mtx_destroy(&p->free_lock);
  177 
  178         free(p, M_MBPOOL);
  179 }
  180 
  181 /*
  182  * Helper function when loading a one segment DMA buffer.
  183  */
  184 static void
  185 mbp_callback(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
  186 {
  187         if (error == 0)
  188                 *(bus_addr_t *)arg = segs[0].ds_addr;
  189 }
  190 
  191 /*
  192  * Allocate a new page
  193  */
  194 static void
  195 mbp_alloc_page(struct mbpool *p)
  196 {
  197         int error;
  198         struct mbpage *pg;
  199         u_int i;
  200         struct mbfree *f;
  201         struct mbtrail *t;
  202 
  203         if (p->npages == p->max_pages) {
  204 #ifdef DIAGNOSTIC
  205                 printf("%s: (%s) page limit reached %u\n", __func__,
  206                     p->name, p->max_pages);
  207 #endif
  208                 return;
  209         }
  210         pg = &p->pages[p->npages];
  211 
  212         error = bus_dmamem_alloc(p->dmat, &pg->va, BUS_DMA_NOWAIT, &pg->map);
  213         if (error != 0)
  214                 return;
  215 
  216         error = bus_dmamap_load(p->dmat, pg->map, pg->va, p->page_size,
  217             mbp_callback, &pg->phy, 0);
  218         if (error != 0) {
  219                 bus_dmamem_free(p->dmat, pg->va, pg->map);
  220                 return;
  221         }
  222 
  223         for (i = 0; i < p->nchunks; i++) {
  224                 f = N2C(p, pg, i);
  225                 t = C2T(p, f);
  226                 t->page = p->npages;
  227                 t->chunk = i;
  228                 SLIST_INSERT_HEAD(&p->free_list, f, link);
  229         }
  230 
  231         p->npages++;
  232 }
  233 
  234 /*
  235  * allocate a chunk
  236  */
  237 void *
  238 mbp_alloc(struct mbpool *p, bus_addr_t *pap, uint32_t *hp)
  239 {
  240         struct mbfree *cf;
  241         struct mbtrail *t;
  242 
  243         mtx_lock(&p->free_lock);
  244         if ((cf = SLIST_FIRST(&p->free_list)) == NULL) {
  245                 mbp_alloc_page(p);
  246                 cf = SLIST_FIRST(&p->free_list);
  247         }
  248         if (cf == NULL) {
  249                 mtx_unlock(&p->free_lock);
  250                 return (NULL);
  251         }
  252         SLIST_REMOVE_HEAD(&p->free_list, link);
  253         mtx_unlock(&p->free_lock);
  254 
  255         t = C2T(p, cf);
  256 
  257         *pap = p->pages[t->page].phy + t->chunk * p->chunk_size;
  258         *hp = HMAKE(t->page, t->chunk);
  259 
  260         t->page |= MBP_CARD | MBP_USED;
  261 
  262         return (cf);
  263 }
  264 
  265 /*
  266  * Free a chunk
  267  */
  268 void
  269 mbp_free(struct mbpool *p, void *ptr)
  270 {
  271         struct mbtrail *t;
  272 
  273         mtx_lock(&p->free_lock);
  274         t = C2T(p, ptr);
  275         t->page &= ~(MBP_USED | MBP_CARD);
  276         SLIST_INSERT_HEAD(&p->free_list, (struct mbfree *)ptr, link);
  277         mtx_unlock(&p->free_lock);
  278 }
  279 
  280 /*
  281  * Mbuf system external mbuf free routine
  282  */
  283 int
  284 mbp_ext_free(struct mbuf *m, void *buf, void *arg)
  285 {
  286         mbp_free(arg, buf);
  287 
  288         return (EXT_FREE_OK);
  289 }
  290 
  291 /*
  292  * Free all buffers that are marked as being on the card
  293  */
  294 void
  295 mbp_card_free(struct mbpool *p)
  296 {
  297         u_int i, b;
  298         struct mbpage *pg;
  299         struct mbtrail *tr;
  300         struct mbfree *cf;
  301 
  302         mtx_lock(&p->free_lock);
  303         for (i = 0; i < p->npages; i++) {
  304                 pg = &p->pages[i];
  305                 for (b = 0; b < p->nchunks; b++) {
  306                         cf = N2C(p, pg, b);
  307                         tr = C2T(p, cf);
  308                         if (tr->page & MBP_CARD) {
  309                                 tr->page &= MBP_PMSK;
  310                                 SLIST_INSERT_HEAD(&p->free_list, cf, link);
  311                         }
  312                 }
  313         }
  314         mtx_unlock(&p->free_lock);
  315 }
  316 
  317 /*
  318  * Count buffers
  319  */
  320 void
  321 mbp_count(struct mbpool *p, u_int *used, u_int *card, u_int *free)
  322 {
  323         u_int i, b;
  324         struct mbpage *pg;
  325         struct mbtrail *tr;
  326         struct mbfree *cf;
  327 
  328         *used = *card = *free = 0;
  329         for (i = 0; i < p->npages; i++) {
  330                 pg = &p->pages[i];
  331                 for (b = 0; b < p->nchunks; b++) {
  332                         tr = C2T(p, N2C(p, pg, b));
  333                         if (tr->page & MBP_CARD)
  334                                 (*card)++;
  335                         if (tr->page & MBP_USED)
  336                                 (*used)++;
  337                 }
  338         }
  339         mtx_lock(&p->free_lock);
  340         SLIST_FOREACH(cf, &p->free_list, link)
  341                 (*free)++;
  342         mtx_unlock(&p->free_lock);
  343 }
  344 
  345 /*
  346  * Get the buffer from a handle and clear the card flag.
  347  */
  348 void *
  349 mbp_get(struct mbpool *p, uint32_t h)
  350 {
  351         struct mbfree *cf;
  352         struct mbtrail *tr;
  353 
  354         cf = N2C(p, &p->pages[HPAGE(h)], HCHUNK(h));
  355         tr = C2T(p, cf);
  356 
  357 #ifdef DIAGNOSTIC
  358         if (!(tr->page & MBP_CARD))
  359                 printf("%s: (%s) chunk %u page %u not on card\n", __func__,
  360                     p->name, HCHUNK(h), HPAGE(h));
  361 #endif
  362 
  363         tr->page &= ~MBP_CARD;
  364         return (cf);
  365 }
  366 
  367 /*
  368  * Get the buffer from a handle and keep the card flag.
  369  */
  370 void *
  371 mbp_get_keep(struct mbpool *p, uint32_t h)
  372 {
  373         struct mbfree *cf;
  374         struct mbtrail *tr;
  375 
  376         cf = N2C(p, &p->pages[HPAGE(h)], HCHUNK(h));
  377         tr = C2T(p, cf);
  378 
  379 #ifdef DIAGNOSTIC
  380         if (!(tr->page & MBP_CARD))
  381                 printf("%s: (%s) chunk %u page %u not on card\n", __func__,
  382                     p->name, HCHUNK(h), HPAGE(h));
  383 #endif
  384 
  385         return (cf);
  386 }
  387 
  388 /*
  389  * sync the chunk
  390  */
  391 void
  392 mbp_sync(struct mbpool *p, uint32_t h, bus_addr_t off, bus_size_t len, u_int op)
  393 {
  394 
  395 #if 0
  396         bus_dmamap_sync_size(p->dmat, p->pages[HPAGE(h)].map,
  397             HCHUNK(h) * p->chunk_size + off, len, op);
  398 #endif
  399 }

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