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Annotation of coherent/b/STREAMS/conf_79/assign.c, revision 1.1

1.1     ! root        1: #define        _DDI_DKI        1
        !             2: #define        _SYSV4          1
        !             3: 
        !             4: /*
        !             5:  * This file assigns device major and minor numbers based on configuration
        !             6:  * data read in by "mkdev.c".
        !             7:  */
        !             8: /*
        !             9:  *-IMPORTS:
        !            10:  *     <sys/compat.h>
        !            11:  *             CONST
        !            12:  *             PROTO
        !            13:  *             ARGS ()
        !            14:  *             LOCAL
        !            15:  *     <kernel/v_types.h>
        !            16:  *             NODEV
        !            17:  *             major_t
        !            18:  *             minor_t
        !            19:  *     <stddef.h>
        !            20:  *             size_t
        !            21:  *             offsetof ()
        !            22:  *     <stdlib.h>
        !            23:  *             NULL
        !            24:  *             free ()
        !            25:  *             malloc ()
        !            26:  *     "ehand.h"
        !            27:  *             throw_error ()
        !            28:  *     "mdev.h"
        !            29:  *             mdev_t
        !            30:  *             mdev_sort ()
        !            31:  */
        !            32: 
        !            33: #include <sys/compat.h>
        !            34: #include <kernel/v_types.h>
        !            35: #include <stddef.h>
        !            36: #include <stdlib.h>
        !            37: 
        !            38: #include "ehand.h"
        !            39: #include "mdev.h"
        !            40: 
        !            41: #include "assign.h"
        !            42: 
        !            43: /*
        !            44:  * Selection predicate for choosing enabled character devices.
        !            45:  */
        !            46: 
        !            47: #ifdef USE_PROTO
        !            48: LOCAL int (chr_sel) (mdev_t * mdevp)
        !            49: #else
        !            50: LOCAL int
        !            51: chr_sel ARGS ((mdevp))
        !            52: mdev_t       * mdevp;
        !            53: #endif
        !            54: {
        !            55:        return mdevp->md_configure == MD_ENABLED &&
        !            56:               mdev_flag (mdevp, MDEV_CHAR);
        !            57: }
        !            58: 
        !            59: 
        !            60: /*
        !            61:  * Predicate for comparing two mdevice entries on the basis of minimum
        !            62:  * external character-device number.
        !            63:  */
        !            64: 
        !            65: #ifdef USE_PROTO
        !            66: LOCAL int (chr_pred) (mdev_t * left, mdev_t * right)
        !            67: #else
        !            68: LOCAL int
        !            69: chr_pred ARGS ((left, right))
        !            70: mdev_t       * left;
        !            71: mdev_t       * right;
        !            72: #endif
        !            73: {
        !            74:        return left->md_chr_maj [0] < right->md_chr_maj [0];
        !            75: }
        !            76: 
        !            77: 
        !            78: /*
        !            79:  * Selection predicate for choosing enabled block devices.
        !            80:  */
        !            81: 
        !            82: #ifdef USE_PROTO
        !            83: LOCAL int (blk_sel) (mdev_t * mdevp)
        !            84: #else
        !            85: LOCAL int
        !            86: blk_sel ARGS ((mdevp))
        !            87: mdev_t       * mdevp;
        !            88: #endif
        !            89: {
        !            90:        return mdevp->md_configure == MD_ENABLED &&
        !            91:               mdev_flag (mdevp, MDEV_BLOCK);
        !            92: }
        !            93: 
        !            94: 
        !            95: /*
        !            96:  * Predicate for comparing two mdevice entries on the basis of minimum
        !            97:  * external block-device number.
        !            98:  */
        !            99: 
        !           100: #ifdef USE_PROTO
        !           101: LOCAL int (blk_pred) (mdev_t * left, mdev_t * right)
        !           102: #else
        !           103: LOCAL int
        !           104: blk_pred ARGS ((left, right))
        !           105: mdev_t       * left;
        !           106: mdev_t       * right;
        !           107: #endif
        !           108: {
        !           109:        return left->md_blk_maj [0] < right->md_blk_maj [0];
        !           110: }
        !           111: 
        !           112: 
        !           113: /*
        !           114:  * Predicate for selecting modules (streams drivers that are not devices).
        !           115:  */
        !           116: 
        !           117: #ifdef USE_PROTO
        !           118: LOCAL int (mod_sel) (mdev_t * mdevp)
        !           119: #else
        !           120: LOCAL int
        !           121: mod_sel ARGS ((mdevp))
        !           122: mdev_t       * mdevp;
        !           123: #endif
        !           124: {
        !           125:        return mdevp->md_configure == MD_ENABLED &&
        !           126:               mdev_flag (mdevp, MDEV_STREAM) &&
        !           127:               ! mdev_flag (mdevp, MDEV_CHAR);
        !           128: }
        !           129: 
        !           130: 
        !           131: /*
        !           132:  * This is where we build the external->internal major number mapping table.
        !           133:  *
        !           134:  * The external->internal device number system becomes immediately useful
        !           135:  * under STREAMS, where a) STREAMS cannot use device major numbers lower than
        !           136:  * MAJOR_RESERVED under Coherent, and b) Coherent uses old-style 16-bit
        !           137:  * dev_t's, so that the ability to transform a range of external majors into
        !           138:  * a contiguous sequence of internal minor numbers will be of immediate value
        !           139:  * in supporting connection-oriented services (although this is also pending
        !           140:  * on the addition of support for cloning to the kernel).
        !           141:  *
        !           142:  * Mapping between internal and external numbers is not simple; what makes it
        !           143:  * worse is that because there is a single mapping that has to be the same
        !           144:  * for both block and character tables, the construction of the bdevsw [] and
        !           145:  * cdevsw [] internal tables is constrained. This is only a problem if
        !           146:  * multiple external major numbers are allowed, and each device is only
        !           147:  * permitted to have a single internal major number. The interpretation of the
        !           148:  * 'M' flag in this circumstance is unclear.
        !           149:  *
        !           150:  * The assign_imajors () code should be able to deal with the most complex
        !           151:  * case, which is where multiple external majors may actually be mapped to
        !           152:  * multiple internal numbers, thus
        !           153:  *
        !           154:  *     Block external :            |-----scsi-------|
        !           155:  *     Character external:   |--tcp--| |-udp-|  |ttys|
        !           156:  *
        !           157:  * Might map 'tcp' to internal 0, 'udp' to internal 1, 'ttys' to internal 2,
        !           158:  * while 'scsi' would have 0, 1, and 2 as internal major numbers.
        !           159:  *
        !           160:  * This is all hypothetical at the moment, since multiple majors are new to
        !           161:  * Coherent anyway. For simplicity, we may constrain the above to be an error
        !           162:  * by requiring unique internal number for each device. However, the machinery
        !           163:  * in assign_imajors () will have to be flexible enough to deal with the
        !           164:  * above.
        !           165:  *
        !           166:  * NOTE: The complex model is only applicable if a device does not care what
        !           167:  * minor numbers are given to it, since there is a single shared table used
        !           168:  * to map a range of external major numbers into a range of internal minor
        !           169:  * numbers. Since this table is shared, it constrains even more heavily the
        !           170:  * circumstances in which numbers can overlap. Without a flag to detect when
        !           171:  * a driver doesn't care about minor numbers, we simply forget about the
        !           172:  * complex model.
        !           173:  */
        !           174: 
        !           175: /*
        !           176:  * Definitions used to control parts of the way assign_imajors () deals with
        !           177:  * the external->internal mapping (as discussed above). The main things we
        !           178:  * isolate here are the calculations of the upper bounds for table allocations
        !           179:  * since the constraint of a common mapping means that the cdevsw [] and
        !           180:  * bdevsw [] tables may be larger than a separate mapping would permit.
        !           181:  *
        !           182:  * In particular, if ncdevs is the number of character devices and nbdevs is
        !           183:  * the number of block devices, the upper bound on table size is:
        !           184:  *     Simple model:   block = char = max (ncdevs, nbdevs)
        !           185:  *     Complex model:  char = ncdevs + max (nbdevs - 1, 0)
        !           186:  *                     block = nbdevs + max (ncdevs - 1, 0)
        !           187:  */
        !           188: 
        !           189: #define        MAX(a,b)                ((a) > (b) ? (a) : (b))
        !           190: #define        MIN(a,b)                ((a) < (b) ? (a) : (b))
        !           191: 
        !           192: #define        MAX_CHR_IMAJORS(c,b)    MAX (c, b)
        !           193: #define        MAX_BLK_IMAJORS(c,b)    MAX (c, b)
        !           194: 
        !           195: 
        !           196: /*
        !           197:  * Assign internal major numbers to devices. For now, this function does not
        !           198:  * attempt to deal with assigning major number ranges.
        !           199:  */
        !           200: 
        !           201: #ifdef USE_PROTO
        !           202: extinfo_t * (assign_imajors) (void)
        !           203: #else
        !           204: extinfo_t *
        !           205: assign_imajors ARGS (())
        !           206: #endif
        !           207: {
        !           208:        extinfo_t     * extinfop;
        !           209:        mdlist_t        blklist;
        !           210:        mdlist_t        chrlist;
        !           211:        mdlist_t        modlist;
        !           212: 
        !           213:        int             nemajors;
        !           214:        int             i;
        !           215: 
        !           216: 
        !           217:        /*
        !           218:         * The algorithm for assigning internal numbers for the block and
        !           219:         * character-device tables will be able to run in a single pass if we
        !           220:         * are able to provide lists of character and block devices sorted by
        !           221:         * beginning external major number. This sort process also provides us
        !           222:         * a variety of other useful information directly, such as the maximum
        !           223:         * external number used.
        !           224:         */
        !           225: 
        !           226:        mdev_sort (& chrlist, chr_sel, chr_pred, offsetof (mdev_t, md_link1));
        !           227:        mdev_sort (& blklist, blk_sel, blk_pred, offsetof (mdev_t, md_link2));
        !           228:        mdev_sort (& modlist, mod_sel, NULL, offsetof (mdev_t, md_link3));
        !           229: 
        !           230:        nemajors = 0;
        !           231: 
        !           232:        if (chrlist.mdl_last != NULL)
        !           233:                nemajors = MAX (nemajors, chrlist.mdl_last->md_chr_maj [1]);
        !           234: 
        !           235:        if (blklist.mdl_last != NULL)
        !           236:                nemajors = MAX (nemajors, blklist.mdl_last->md_blk_maj [1]);
        !           237: 
        !           238:        nemajors ++;
        !           239: 
        !           240: 
        !           241:        /*
        !           242:         * Now we know how many of everything there is, allocate space for
        !           243:         * tables.
        !           244:         */
        !           245: 
        !           246:        i = sizeof (* extinfop) +
        !           247:            sizeof (mdev_t *) * (MAX_CHR_IMAJORS (chrlist.mdl_count,
        !           248:                                                  blklist.mdl_count) +
        !           249:                                 MAX_BLK_IMAJORS (chrlist.mdl_count,
        !           250:                                                  blklist.mdl_count) +
        !           251:                                 modlist.mdl_count) +
        !           252:            2 * sizeof (minor_t) * nemajors;
        !           253: 
        !           254:        if ((extinfop = (extinfo_t *) malloc (i)) == NULL)
        !           255:                throw_error ("insufficient memory in assign_imajors ()");
        !           256: 
        !           257:        extinfop->ei_etoimajor = (minor_t *) (extinfop + 1);
        !           258:        extinfop->ei_minoroffset = extinfop->ei_etoimajor + nemajors;
        !           259:        extinfop->ei_modules = (mdev_t **) (extinfop->ei_minoroffset +
        !           260:                                            nemajors);
        !           261:        extinfop->ei_cdevsw = extinfop->ei_modules + modlist.mdl_count;
        !           262:        extinfop->ei_bdevsw = extinfop->ei_cdevsw +
        !           263:                                MAX_CHR_IMAJORS (chrlist.mdl_count,
        !           264:                                                 blklist.mdl_count);
        !           265: 
        !           266:        /*
        !           267:         * Since we allocate space for the maximum number of table entries,
        !           268:         * the loops below assign internal numbers which may not be
        !           269:         * contiguous, or may be below the upper limit allocated.
        !           270:         */
        !           271: 
        !           272:        extinfop->ei_nemajors = nemajors;
        !           273:        extinfop->ei_ncdevs = 0;
        !           274:        extinfop->ei_nbdevs = 0;
        !           275:        extinfop->ei_nmodules = modlist.mdl_count;
        !           276: 
        !           277:        for (i = 0 ; i < nemajors ; i ++) {
        !           278: 
        !           279:                extinfop->ei_etoimajor [i] = NODEV;
        !           280:                extinfop->ei_minoroffset [i] = 0;
        !           281:        }
        !           282: 
        !           283: 
        !           284:        for (i = 0 ; i < MAX_CHR_IMAJORS (chrlist.mdl_count,
        !           285:                                          blklist.mdl_count) ; i ++) {
        !           286:                extinfop->ei_cdevsw [i] = NULL;
        !           287:        }
        !           288: 
        !           289:        for (i = 0 ; i < MAX_BLK_IMAJORS (chrlist.mdl_count,
        !           290:                                          blklist.mdl_count) ; i ++) {
        !           291:                extinfop->ei_bdevsw [i] = NULL;
        !           292:        }
        !           293: 
        !           294: 
        !           295: 
        !           296:        while (chrlist.mdl_first != NULL || blklist.mdl_first != NULL) {
        !           297:                mdev_t        * chrp;
        !           298:                mdev_t        * blkp;
        !           299:                int             extlo;
        !           300:                int             exthi;
        !           301:                int             internal;
        !           302:                int             minorinc;
        !           303:                int             minorofs;
        !           304: 
        !           305:                /*
        !           306:                 * Choose a range of external numbers that we are going to
        !           307:                 * assign to a single internal number. If our choice is not
        !           308:                 * constrained by an overlap between character and block
        !           309:                 * external numbers, then we deal with that.
        !           310:                 */
        !           311: 
        !           312:                blkp = blklist.mdl_first;
        !           313: 
        !           314:                if ((chrp = chrlist.mdl_first) != NULL) {
        !           315: 
        !           316:                        extlo = chrp->md_chr_maj [0];
        !           317:                        exthi = chrp->md_chr_maj [1];
        !           318:                        minorinc = chrp->md_minor_max;
        !           319: 
        !           320:                        if (blkp != NULL) {
        !           321: 
        !           322:                                if (blkp->md_blk_maj [1] < extlo) {
        !           323: 
        !           324:                                        chrp = NULL;
        !           325:                                        goto doblock;
        !           326:                                }
        !           327: 
        !           328:                                if (blkp->md_blk_maj [0] > exthi) {
        !           329:                                        blkp = NULL;
        !           330:                                        goto dochar;
        !           331:                                }
        !           332: 
        !           333:                                /*
        !           334:                                 * Because of minor-number mapping, overlap is
        !           335:                                 * only valid in special circumstances.
        !           336:                                 */
        !           337: 
        !           338:                                if (blkp->md_blk_maj [0] != extlo ||
        !           339:                                    (blkp->md_minor_max != minorinc &&
        !           340:                                     blkp->md_blk_maj [1] >
        !           341:                                                blkp->md_blk_maj [0] &&
        !           342:                                     exthi > extlo)) {
        !           343: 
        !           344:                                        free (extinfop);
        !           345:                                        throw_error ("minor number mapping conflict");
        !           346:                                }
        !           347: 
        !           348: 
        !           349:                                /*
        !           350:                                 * Choose a suitable internal major number.
        !           351:                                 */
        !           352: 
        !           353:                                if (exthi < blkp->md_blk_maj [1]) {
        !           354: 
        !           355:                                        exthi = blkp->md_blk_maj [1];
        !           356:                                        minorinc = blkp->md_minor_max;
        !           357:                                }
        !           358: 
        !           359:                                internal = MAX (extinfop->ei_ncdevs,
        !           360:                                                extinfop->ei_nbdevs);
        !           361: 
        !           362:                                goto done;
        !           363:                        }
        !           364: dochar:
        !           365:                        /*
        !           366:                         * Simple case, select an internal number.
        !           367:                         */
        !           368: 
        !           369:                        for (internal = 0 ;
        !           370:                             extinfop->ei_cdevsw [internal] != NULL ;
        !           371:                             internal ++)
        !           372:                                ;
        !           373: 
        !           374:                        if (internal > extinfop->ei_ncdevs) {
        !           375: 
        !           376:                                free (extinfop);
        !           377:                                throw_error ("internal check failed, assign_imajors ()");
        !           378:                        }
        !           379:                } else {
        !           380:                        /*
        !           381:                         * Simple case for block device, select an internal
        !           382:                         * number.
        !           383:                         */
        !           384: 
        !           385: doblock:
        !           386:                        extlo = blkp->md_blk_maj [0];
        !           387:                        exthi = blkp->md_blk_maj [1];
        !           388:                        minorinc = blkp->md_minor_max;
        !           389: 
        !           390:                        for (internal = 0 ;
        !           391:                             extinfop->ei_bdevsw [internal] != NULL ;
        !           392:                             internal ++)
        !           393:                                ;
        !           394: 
        !           395:                        if (internal > extinfop->ei_nbdevs) {
        !           396: 
        !           397:                                free (extinfop);
        !           398:                                throw_error ("internal check failed, assign_imajors ()");
        !           399:                        }
        !           400:                }
        !           401: done:
        !           402:                /*
        !           403:                 * Now we have decided when, where, and how much, fill in the
        !           404:                 * table.
        !           405:                 */
        !           406: 
        !           407:                minorofs = 0;
        !           408: 
        !           409:                while (extlo <= exthi) {
        !           410: 
        !           411:                        if (extinfop->ei_etoimajor [extlo] != NODEV) {
        !           412: 
        !           413:                                free (extinfop);
        !           414:                                throw_error ("major-number mapping conflict");
        !           415:                        }
        !           416: 
        !           417:                        extinfop->ei_etoimajor [extlo] = internal;
        !           418:                        extinfop->ei_minoroffset [extlo] = minorofs;
        !           419: 
        !           420:                        minorofs += minorinc;
        !           421:                        extlo ++;
        !           422:                }
        !           423: 
        !           424:                if ((extinfop->ei_cdevsw [internal] = chrp) != NULL) {
        !           425: 
        !           426:                        if (internal >= extinfop->ei_ncdevs)
        !           427:                                extinfop->ei_ncdevs = internal + 1;
        !           428: 
        !           429:                        chrlist.mdl_first = chrp->md_link1;
        !           430:                }
        !           431: 
        !           432: 
        !           433:                if ((extinfop->ei_bdevsw [internal] = blkp) != NULL) {
        !           434: 
        !           435:                        if (internal >= extinfop->ei_nbdevs)
        !           436:                                extinfop->ei_nbdevs = internal + 1;
        !           437: 
        !           438:                        blklist.mdl_first = blkp->md_link2;
        !           439:                }
        !           440:        }
        !           441: 
        !           442: 
        !           443:        /*
        !           444:         * Now we can build a table of all the STREAMS modules.
        !           445:         */
        !           446: 
        !           447:        i = 0;
        !           448: 
        !           449:        while (modlist.mdl_first != NULL) {
        !           450: 
        !           451:                extinfop->ei_modules [i ++] = modlist.mdl_first;
        !           452: 
        !           453:                modlist.mdl_first = modlist.mdl_first->md_link3;
        !           454:        }
        !           455: 
        !           456:        if (i != modlist.mdl_count) {
        !           457: 
        !           458:                free (extinfop);
        !           459:                throw_error ("internal consistency check failed in assign_imajors ()");
        !           460:         }
        !           461: 
        !           462:        return extinfop;
        !           463: }
        !           464: 

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