Return to kern_physio.c CVS log

Up to [Apple XNU] / XNU / bsd / kern

Annotation of XNU/bsd/kern/kern_physio.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*-
        !            23:  * Copyright (c) 1982, 1986, 1990, 1993
        !            24:  *     The Regents of the University of California.  All rights reserved.
        !            25:  * (c) UNIX System Laboratories, Inc.
        !            26:  * All or some portions of this file are derived from material licensed
        !            27:  * to the University of California by American Telephone and Telegraph
        !            28:  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
        !            29:  * the permission of UNIX System Laboratories, Inc.
        !            30:  *
        !            31:  * Redistribution and use in source and binary forms, with or without
        !            32:  * modification, are permitted provided that the following conditions
        !            33:  * are met:
        !            34:  * 1. Redistributions of source code must retain the above copyright
        !            35:  *    notice, this list of conditions and the following disclaimer.
        !            36:  * 2. Redistributions in binary form must reproduce the above copyright
        !            37:  *    notice, this list of conditions and the following disclaimer in the
        !            38:  *    documentation and/or other materials provided with the distribution.
        !            39:  * 3. All advertising materials mentioning features or use of this software
        !            40:  *    must display the following acknowledgement:
        !            41:  *     This product includes software developed by the University of
        !            42:  *     California, Berkeley and its contributors.
        !            43:  * 4. Neither the name of the University nor the names of its contributors
        !            44:  *    may be used to endorse or promote products derived from this software
        !            45:  *    without specific prior written permission.
        !            46:  *
        !            47:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            48:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            49:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            50:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            51:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            52:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            53:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            54:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            55:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            56:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            57:  * SUCH DAMAGE.
        !            58:  *
        !            59:  *     from: @(#)kern_physio.c 8.1 (Berkeley) 6/10/93
        !            60:  */
        !            61: /*
        !            62:  * HISTORY
        !            63:  * 27-July-97  Umesh Vaishampayan  ([email protected])
        !            64:  *     Allow physio() to kernel space.
        !            65:  */
        !            66: 
        !            67: #include <sys/param.h>
        !            68: #include <sys/systm.h>
        !            69: #include <sys/buf.h>
        !            70: #include <sys/conf.h>
        !            71: #include <sys/proc.h>
        !            72: 
        !            73: int
        !            74: physio(strategy, bp, dev, flags, minphys, uio, blocksize)
        !            75:        void (*strategy)(); 
        !            76:        struct buf *bp;
        !            77:        dev_t dev;
        !            78:        int flags;
        !            79:        u_int (*minphys)();
        !            80:        struct uio *uio;
        !            81:        int blocksize;
        !            82: {
        !            83:        struct iovec *iovp;
        !            84:        struct proc *p = current_proc();
        !            85:        int error, done, i, nobuf, s, todo;
        !            86: 
        !            87:        error = 0;
        !            88:        flags &= B_READ | B_WRITE;
        !            89: 
        !            90:        /*
        !            91:         * [check user read/write access to the data buffer]
        !            92:         *
        !            93:         * Check each iov one by one.  Note that we know if we're reading or
        !            94:         * writing, so we ignore the uio's rw parameter.  Also note that if
        !            95:         * we're doing a read, that's a *write* to user-space.
        !            96:         */
        !            97:        for (i = 0; i < uio->uio_iovcnt; i++) {
        !            98:                if(uio->uio_segflg != UIO_SYSSPACE) {
        !            99:                        if (!useracc(uio->uio_iov[i].iov_base,
        !           100:                                uio->uio_iov[i].iov_len,
        !           101:                                (flags == B_READ) ? B_WRITE : B_READ))
        !           102:                        return (EFAULT);
        !           103:                }
        !           104:        }
        !           105:        /* Make sure we have a buffer, creating one if necessary. */
        !           106:        if (nobuf = (bp == NULL)) {
        !           107: //             bp = getphysbuf();
        !           108:                panic("physio: null buf pointer\n");
        !           109:                }
        !           110: 
        !           111:        /* [raise the processor priority level to splbio;] */
        !           112:        s = splbio();
        !           113: 
        !           114:        /* [while the buffer is marked busy] */
        !           115:        while (bp->b_flags & B_BUSY) {
        !           116:                /* [mark the buffer wanted] */
        !           117:                bp->b_flags |= B_WANTED;
        !           118:                /* [wait until the buffer is available] */
        !           119:                tsleep((caddr_t)bp, PRIBIO+1, "physbuf", 0);
        !           120:        }
        !           121: 
        !           122:        /* Mark it busy, so nobody else will use it. */
        !           123:        bp->b_flags |= B_BUSY;
        !           124: 
        !           125:        /* [lower the priority level] */
        !           126:        splx(s);
        !           127: 
        !           128:        /* [set up the fixed part of the buffer for a transfer] */
        !           129:        bp->b_dev = dev;
        !           130:        bp->b_error = 0;
        !           131:        bp->b_proc = p;
        !           132: 
        !           133:        /*
        !           134:         * [while there are data to transfer and no I/O error]
        !           135:         * Note that I/O errors are handled with a 'goto' at the bottom
        !           136:         * of the 'while' loop.
        !           137:         */
        !           138:        for (i = 0; i < uio->uio_iovcnt; i++) {
        !           139:                iovp = &uio->uio_iov[i];
        !           140:                while (iovp->iov_len > 0) {
        !           141:                        /*
        !           142:                         * [mark the buffer busy for physical I/O]
        !           143:                         * (i.e. set B_PHYS (because it's an I/O to user
        !           144:                         * memory, and B_RAW, because B_RAW is to be
        !           145:                         * "Set by physio for raw transfers.", in addition
        !           146:                         * to the "busy" and read/write flag.)
        !           147:                         */
        !           148:                        s = splbio();
        !           149:                        bp->b_flags = B_BUSY | B_PHYS | B_RAW | flags;
        !           150:                        splx(s);
        !           151: 
        !           152:                        /* [set up the buffer for a maximum-sized transfer] */
        !           153:                        bp->b_blkno = uio->uio_offset / blocksize;
        !           154:                        bp->b_bcount = iovp->iov_len;
        !           155:                        bp->b_data = iovp->iov_base;
        !           156:                        
        !           157:                        /*
        !           158:                         * [call minphys to bound the tranfer size]
        !           159:                         * and remember the amount of data to transfer,
        !           160:                         * for later comparison.
        !           161:                         */
        !           162:                        (*minphys)(bp);
        !           163:                        todo = bp->b_bcount;
        !           164: 
        !           165:                        /*
        !           166:                         * [lock the part of the user address space involved
        !           167:                         *    in the transfer]
        !           168:                         * Beware vmapbuf(); it clobbers b_data and
        !           169:                         * saves it in b_saveaddr.  However, vunmapbuf()
        !           170:                         * restores it.
        !           171:                         */
        !           172: 
        !           173:                        if(uio->uio_segflg == UIO_SYSSPACE)
        !           174:                                bp->b_flags |= B_KERNSPACE;
        !           175:                        else
        !           176:                                vslock(bp->b_data, todo);
        !           177:                        
        !           178: #if 0
        !           179:                        vmapbuf(bp, todo);
        !           180: #endif /* 0 */
        !           181:                        /* [call strategy to start the transfer] */
        !           182:                        (*strategy)(bp);
        !           183: 
        !           184:                        /*
        !           185:                         * Note that the raise/wait/lower/get error
        !           186:                         * steps below would be done by biowait(), but
        !           187:                         * we want to unlock the address space before
        !           188:                         * we lower the priority.
        !           189:                         *
        !           190:                         * [raise the priority level to splbio]
        !           191:                         */
        !           192:                        s = splbio();
        !           193: 
        !           194:                        /* [wait for the transfer to complete] */
        !           195:                        while ((bp->b_flags & B_DONE) == 0)
        !           196:                                tsleep((caddr_t) bp, PRIBIO + 1, "physio", 0);
        !           197: 
        !           198:                        /*
        !           199:                         * [unlock the part of the address space previously
        !           200:                         *    locked]
        !           201:                         */
        !           202: #if 0
        !           203:                        vunmapbuf(bp, todo);
        !           204: #endif /* 0 */
        !           205:                        if(uio->uio_segflg != UIO_SYSSPACE)
        !           206:                                vsunlock(bp->b_data, todo);
        !           207: 
        !           208:                        /* remember error value (save a splbio/splx pair) */
        !           209:                        if (bp->b_flags & B_ERROR)
        !           210:                                error = (bp->b_error ? bp->b_error : EIO);
        !           211: 
        !           212:                        /* [lower the priority level] */
        !           213:                        splx(s);
        !           214: 
        !           215:                        /*
        !           216:                         * [deduct the transfer size from the total number
        !           217:                         *    of data to transfer]
        !           218:                         */
        !           219:                        done = bp->b_bcount - bp->b_resid;
        !           220:                        iovp->iov_len -= done;
        !           221:                         iovp->iov_base += done;
        !           222:                         uio->uio_offset += done;
        !           223:                         uio->uio_resid -= done;
        !           224: 
        !           225:                        /*
        !           226:                         * Now, check for an error.
        !           227:                         * Also, handle weird end-of-disk semantics.
        !           228:                         */
        !           229:                        if (error || done < todo)
        !           230:                                goto done;
        !           231:                }
        !           232:        }
        !           233: 
        !           234: done:
        !           235:        /*
        !           236:         * [clean up the state of the buffer]
        !           237:         * Remember if somebody wants it, so we can wake them up below.
        !           238:         * Also, if we had to steal it, give it back.
        !           239:         */
        !           240:        s = splbio();
        !           241:        bp->b_flags &= ~(B_BUSY | B_PHYS | B_RAW);
        !           242: #if 0
        !           243:        if (nobuf)
        !           244:                putphysbuf(bp);
        !           245: 
        !           246:        else 
        !           247: #endif /* 0 */
        !           248:                {
        !           249:                /*
        !           250:                 * [if another process is waiting for the raw I/O buffer,
        !           251:                 *    wake up processes waiting to do physical I/O;
        !           252:                 */
        !           253:                if (bp->b_flags & B_WANTED) {
        !           254:                        bp->b_flags &= ~B_WANTED;
        !           255:                        wakeup(bp);
        !           256:                }
        !           257:        }
        !           258:        splx(s);
        !           259: 
        !           260:        return (error);
        !           261: }
        !           262: 
        !           263: /*
        !           264:  * Leffler, et al., says on p. 231:
        !           265:  * "The minphys() routine is called by physio() to adjust the
        !           266:  * size of each I/O transfer before the latter is passed to
        !           267:  * the strategy routine..." 
        !           268:  *
        !           269:  * so, just adjust the buffer's count accounting to MAXPHYS here,
        !           270:  * and return the new count;
        !           271:  */
        !           272: u_int
        !           273: minphys(bp)
        !           274:        struct buf *bp;
        !           275: {
        !           276: 
        !           277:        bp->b_bcount = min(MAXPHYS, bp->b_bcount);
        !           278:         return bp->b_bcount;
        !           279: }
        !           280: 
        !           281: /*
        !           282:  * Do a read on a device for a user process.
        !           283:  */
        !           284: rawread(dev, uio)
        !           285:        dev_t dev;
        !           286:        struct uio *uio;
        !           287: {
        !           288:        return (physio(cdevsw[major(dev)].d_strategy, (struct buf *)NULL,
        !           289:            dev, B_READ, minphys, uio, DEV_BSIZE));
        !           290: }
        !           291: 
        !           292: /*
        !           293:  * Do a write on a device for a user process.
        !           294:  */
        !           295: rawwrite(dev, uio)
        !           296:        dev_t dev;
        !           297:        struct uio *uio;
        !           298: {
        !           299:        return (physio(cdevsw[major(dev)].d_strategy, (struct buf *)NULL,
        !           300:            dev, B_WRITE, minphys, uio, DEV_BSIZE));
        !           301: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.