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

     /*
      * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com> All rights reserved.
      * cdevsw from kern/kern_conf.c Copyright (c) 1995 Terrence R. Lambert
      * cdevsw from kern/kern_conf.c Copyright (c) 1995 Julian R. Elishcer,
      *                                                      All rights reserved.
      * Copyright (c) 1982, 1986, 1991, 1993
      *      The Regents of the University of California.  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.
     *
     * 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.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/sysctl.h>
    #include <sys/module.h>
    #include <sys/malloc.h>
    #include <sys/conf.h>
    #include <sys/bio.h>
    #include <sys/buf.h>
    #include <sys/vnode.h>
    #include <sys/queue.h>
    #include <sys/device.h>
    #include <sys/tree.h>
    #include <sys/syslink_rpc.h>
    #include <sys/proc.h>
    #include <machine/stdarg.h>
    #include <sys/devfs.h>
    #include <sys/dsched.h>
    
    #include <sys/thread2.h>
    #include <sys/mplock2.h>
    
    static int mpsafe_writes;
    static int mplock_writes;
    static int mpsafe_reads;
    static int mplock_reads;
    static int mpsafe_strategies;
    static int mplock_strategies;
    
    SYSCTL_INT(_kern, OID_AUTO, mpsafe_writes, CTLFLAG_RD, &mpsafe_writes,
               0, "mpsafe writes");
    SYSCTL_INT(_kern, OID_AUTO, mplock_writes, CTLFLAG_RD, &mplock_writes,
               0, "non-mpsafe writes");
    SYSCTL_INT(_kern, OID_AUTO, mpsafe_reads, CTLFLAG_RD, &mpsafe_reads,
               0, "mpsafe reads");
    SYSCTL_INT(_kern, OID_AUTO, mplock_reads, CTLFLAG_RD, &mplock_reads,
               0, "non-mpsafe reads");
    SYSCTL_INT(_kern, OID_AUTO, mpsafe_strategies, CTLFLAG_RD, &mpsafe_strategies,
               0, "mpsafe strategies");
    SYSCTL_INT(_kern, OID_AUTO, mplock_strategies, CTLFLAG_RD, &mplock_strategies,
               0, "non-mpsafe strategies");
    
    /*
     * system link descriptors identify the command in the
     * arguments structure.
     */
    #define DDESCNAME(name) __CONCAT(__CONCAT(dev_,name),_desc)
    
    #define DEVOP_DESC_INIT(name)                                           \
                struct syslink_desc DDESCNAME(name) = {                     \
                    __offsetof(struct dev_ops, __CONCAT(d_, name)), \
                #name }
    
    DEVOP_DESC_INIT(default);
    DEVOP_DESC_INIT(open);
    DEVOP_DESC_INIT(close);
    DEVOP_DESC_INIT(read);
    DEVOP_DESC_INIT(write);
    DEVOP_DESC_INIT(ioctl);
    DEVOP_DESC_INIT(dump);
    DEVOP_DESC_INIT(psize);
    DEVOP_DESC_INIT(mmap);
    DEVOP_DESC_INIT(mmap_single);
    DEVOP_DESC_INIT(strategy);
    DEVOP_DESC_INIT(kqfilter);
    DEVOP_DESC_INIT(revoke);
    DEVOP_DESC_INIT(clone);
    
    /*
    * Misc default ops
    */
   struct dev_ops dead_dev_ops;
   
   struct dev_ops default_dev_ops = {
           { "null" },
           .d_default = NULL,      /* must be NULL */
           .d_open = noopen,
           .d_close = noclose,
           .d_read = noread,
           .d_write = nowrite,
           .d_ioctl = noioctl,
           .d_mmap = nommap,
           .d_mmap_single = nommap_single,
           .d_strategy = nostrategy,
           .d_dump = nodump,
           .d_psize = nopsize,
           .d_kqfilter = nokqfilter,
           .d_revoke = norevoke,
           .d_clone = noclone
   };
   
   static __inline
   int
   dev_needmplock(cdev_t dev)
   {
       return((dev->si_ops->head.flags & D_MPSAFE) == 0);
   }
       
   /************************************************************************
    *                      GENERAL DEVICE API FUNCTIONS                    *
    ************************************************************************
    *
    * The MPSAFEness of these depends on dev->si_ops->head.flags
    */
   int
   dev_dopen(cdev_t dev, int oflags, int devtype, struct ucred *cred)
   {
           struct dev_open_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_open_desc;
           ap.a_head.a_dev = dev;
           ap.a_oflags = oflags;
           ap.a_devtype = devtype;
           ap.a_cred = cred;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_open(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int
   dev_dclose(cdev_t dev, int fflag, int devtype)
   {
           struct dev_close_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_close_desc;
           ap.a_head.a_dev = dev;
           ap.a_fflag = fflag;
           ap.a_devtype = devtype;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_close(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int
   dev_dread(cdev_t dev, struct uio *uio, int ioflag)
   {
           struct dev_read_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_read_desc;
           ap.a_head.a_dev = dev;
           ap.a_uio = uio;
           ap.a_ioflag = ioflag;
   
           if (needmplock) {
                   get_mplock();
                   ++mplock_reads;
           } else {
                   ++mpsafe_reads;
           }
           error = dev->si_ops->d_read(&ap);
           if (needmplock)
                   rel_mplock();
           if (error == 0)
                   dev->si_lastread = time_uptime;
           return (error);
   }
   
   int
   dev_dwrite(cdev_t dev, struct uio *uio, int ioflag)
   {
           struct dev_write_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           dev->si_lastwrite = time_uptime;
           ap.a_head.a_desc = &dev_write_desc;
           ap.a_head.a_dev = dev;
           ap.a_uio = uio;
           ap.a_ioflag = ioflag;
   
           if (needmplock) {
                   get_mplock();
                   ++mplock_writes;
           } else {
                   ++mpsafe_writes;
           }
           error = dev->si_ops->d_write(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int
   dev_dioctl(cdev_t dev, u_long cmd, caddr_t data, int fflag, struct ucred *cred,
              struct sysmsg *msg)
   {
           struct dev_ioctl_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_ioctl_desc;
           ap.a_head.a_dev = dev;
           ap.a_cmd = cmd;
           ap.a_data = data;
           ap.a_fflag = fflag;
           ap.a_cred = cred;
           ap.a_sysmsg = msg;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_ioctl(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int
   dev_dmmap(cdev_t dev, vm_offset_t offset, int nprot)
   {
           struct dev_mmap_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_mmap_desc;
           ap.a_head.a_dev = dev;
           ap.a_offset = offset;
           ap.a_nprot = nprot;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_mmap(&ap);
           if (needmplock)
                   rel_mplock();
   
           if (error == 0)
                   return(ap.a_result);
           return(-1);
   }
   
   int
   dev_dmmap_single(cdev_t dev, vm_ooffset_t *offset, vm_size_t size,
                    struct vm_object **object, int nprot)
   {
           struct dev_mmap_single_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_mmap_single_desc;
           ap.a_head.a_dev = dev;
           ap.a_offset = offset;
           ap.a_size = size;
           ap.a_object = object;
           ap.a_nprot = nprot;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_mmap_single(&ap);
           if (needmplock)
                   rel_mplock();
   
           return(error);
   }
   
   int
   dev_dclone(cdev_t dev)
   {
           struct dev_clone_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_clone_desc;
           ap.a_head.a_dev = dev;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_clone(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int
   dev_drevoke(cdev_t dev)
   {
           struct dev_revoke_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_revoke_desc;
           ap.a_head.a_dev = dev;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_revoke(&ap);
           if (needmplock)
                   rel_mplock();
   
           return (error);
   }
   
   /*
    * Core device strategy call, used to issue I/O on a device.  There are
    * two versions, a non-chained version and a chained version.  The chained
    * version reuses a BIO set up by vn_strategy().  The only difference is
    * that, for now, we do not push a new tracking structure when chaining
    * from vn_strategy.  XXX this will ultimately have to change.
    */
   void
   dev_dstrategy(cdev_t dev, struct bio *bio)
   {
           struct dev_strategy_args ap;
           struct bio_track *track;
           int needmplock = dev_needmplock(dev);
   
           ap.a_head.a_desc = &dev_strategy_desc;
           ap.a_head.a_dev = dev;
           ap.a_bio = bio;
   
           KKASSERT(bio->bio_track == NULL);
           KKASSERT(bio->bio_buf->b_cmd != BUF_CMD_DONE);
           if (bio->bio_buf->b_cmd == BUF_CMD_READ)
               track = &dev->si_track_read;
           else
               track = &dev->si_track_write;
           bio_track_ref(track);
           bio->bio_track = track;
   
           if (dsched_is_clear_buf_priv(bio->bio_buf))
                   dsched_new_buf(bio->bio_buf);
   
           KKASSERT((bio->bio_flags & BIO_DONE) == 0);
           if (needmplock) {
                   get_mplock();
                   ++mplock_strategies;
           } else {
                   ++mpsafe_strategies;
           }
           (void)dev->si_ops->d_strategy(&ap);
           if (needmplock)
                   rel_mplock();
   }
   
   void
   dev_dstrategy_chain(cdev_t dev, struct bio *bio)
   {
           struct dev_strategy_args ap;
           int needmplock = dev_needmplock(dev);
   
           ap.a_head.a_desc = &dev_strategy_desc;
           ap.a_head.a_dev = dev;
           ap.a_bio = bio;
   
           KKASSERT(bio->bio_track != NULL);
           KKASSERT((bio->bio_flags & BIO_DONE) == 0);
           if (needmplock)
                   get_mplock();
           (void)dev->si_ops->d_strategy(&ap);
           if (needmplock)
                   rel_mplock();
   }
   
   /*
    * note: the disk layer is expected to set count, blkno, and secsize before
    * forwarding the message.
    */
   int
   dev_ddump(cdev_t dev, void *virtual, vm_offset_t physical, off_t offset,
       size_t length)
   {
           struct dev_dump_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_dump_desc;
           ap.a_head.a_dev = dev;
           ap.a_count = 0;
           ap.a_blkno = 0;
           ap.a_secsize = 0;
           ap.a_virtual = virtual;
           ap.a_physical = physical;
           ap.a_offset = offset;
           ap.a_length = length;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_dump(&ap);
           if (needmplock)
                   rel_mplock();
           return (error);
   }
   
   int64_t
   dev_dpsize(cdev_t dev)
   {
           struct dev_psize_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_psize_desc;
           ap.a_head.a_dev = dev;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_psize(&ap);
           if (needmplock)
                   rel_mplock();
   
           if (error == 0)
                   return (ap.a_result);
           return(-1);
   }
   
   /*
    * Pass-thru to the device kqfilter.
    *
    * NOTE: We explicitly preset a_result to 0 so d_kqfilter() functions
    *       which return 0 do not have to bother setting a_result.
    */
   int
   dev_dkqfilter(cdev_t dev, struct knote *kn)
   {
           struct dev_kqfilter_args ap;
           int needmplock = dev_needmplock(dev);
           int error;
   
           ap.a_head.a_desc = &dev_kqfilter_desc;
           ap.a_head.a_dev = dev;
           ap.a_kn = kn;
           ap.a_result = 0;
   
           if (needmplock)
                   get_mplock();
           error = dev->si_ops->d_kqfilter(&ap);
           if (needmplock)
                   rel_mplock();
   
           if (error == 0) 
                   return(ap.a_result);
           return(ENODEV);
   }
   
   /************************************************************************
    *                      DEVICE HELPER FUNCTIONS                         *
    ************************************************************************/
   
   /*
    * MPSAFE
    */
   int
   dev_drefs(cdev_t dev)
   {
       return(dev->si_sysref.refcnt);
   }
   
   /*
    * MPSAFE
    */
   const char *
   dev_dname(cdev_t dev)
   {
       return(dev->si_ops->head.name);
   }
   
   /*
    * MPSAFE
    */
   int
   dev_dflags(cdev_t dev)
   {
       return(dev->si_ops->head.flags);
   }
   
   /*
    * MPSAFE
    */
   int
   dev_dmaj(cdev_t dev)
   {
       return(dev->si_ops->head.maj);
   }
   
   /*
    * Used when forwarding a request through layers.  The caller adjusts
    * ap->a_head.a_dev and then calls this function.
    */
   int
   dev_doperate(struct dev_generic_args *ap)
   {
       int (*func)(struct dev_generic_args *);
       int needmplock = dev_needmplock(ap->a_dev);
       int error;
   
       func = *(void **)((char *)ap->a_dev->si_ops + ap->a_desc->sd_offset);
   
       if (needmplock)
               get_mplock();
       error = func(ap);
       if (needmplock)
               rel_mplock();
   
       return (error);
   }
   
   /*
    * Used by the console intercept code only.  Issue an operation through
    * a foreign ops structure allowing the ops structure associated
    * with the device to remain intact.
    */
   int
   dev_doperate_ops(struct dev_ops *ops, struct dev_generic_args *ap)
   {
       int (*func)(struct dev_generic_args *);
       int needmplock = ((ops->head.flags & D_MPSAFE) == 0);
       int error;
   
       func = *(void **)((char *)ops + ap->a_desc->sd_offset);
   
       if (needmplock)
               get_mplock();
       error = func(ap);
       if (needmplock)
               rel_mplock();
   
       return (error);
   }
   
   /*
    * Convert a template dev_ops into the real thing by filling in 
    * uninitialized fields.
    */
   void
   compile_dev_ops(struct dev_ops *ops)
   {
           int offset;
   
           for (offset = offsetof(struct dev_ops, dev_ops_first_field);
                offset <= offsetof(struct dev_ops, dev_ops_last_field);
                offset += sizeof(void *)
           ) {
                   void **func_p = (void **)((char *)ops + offset);
                   void **def_p = (void **)((char *)&default_dev_ops + offset);
                   if (*func_p == NULL) {
                           if (ops->d_default)
                                   *func_p = ops->d_default;
                           else
                                   *func_p = *def_p;
                   }
           }
   }
   
   /************************************************************************
    *                      MAJOR/MINOR SPACE FUNCTION                      *
    ************************************************************************/
   
   /*
    * This makes a dev_ops entry visible to userland (e.g /dev/<blah>).
    *
    * Disk devices typically register their major, e.g. 'ad0', and then call
    * into the disk label management code which overloads its own onto e.g. 'ad0'
    * to support all the various slice and partition combinations.
    *
    * The mask/match supplied in this call are a full 32 bits and the same
    * mask and match must be specified in a later dev_ops_remove() call to
    * match this add.  However, the match value for the minor number should never
    * have any bits set in the major number's bit range (8-15).  The mask value
    * may be conveniently specified as -1 without creating any major number
    * interference.
    */
   
   static
   int
   rb_dev_ops_compare(struct dev_ops_maj *a, struct dev_ops_maj *b)
   {
       if (a->maj < b->maj)
           return(-1);
       else if (a->maj > b->maj)
           return(1);
       return(0);
   }
   
   RB_GENERATE2(dev_ops_rb_tree, dev_ops_maj, rbnode, rb_dev_ops_compare, int, maj);
   
   struct dev_ops_rb_tree dev_ops_rbhead = RB_INITIALIZER(dev_ops_rbhead);
   
   int
   dev_ops_remove_all(struct dev_ops *ops)
   {
           return devfs_destroy_dev_by_ops(ops, -1);
   }
   
   int
   dev_ops_remove_minor(struct dev_ops *ops, int minor)
   {
           return devfs_destroy_dev_by_ops(ops, minor);
   }
   
   struct dev_ops *
   dev_ops_intercept(cdev_t dev, struct dev_ops *iops)
   {
           struct dev_ops *oops = dev->si_ops;
   
           compile_dev_ops(iops);
           iops->head.maj = oops->head.maj;
           iops->head.data = oops->head.data;
           iops->head.flags = oops->head.flags;
           dev->si_ops = iops;
           dev->si_flags |= SI_INTERCEPTED;
   
           return (oops);
   }
   
   void
   dev_ops_restore(cdev_t dev, struct dev_ops *oops)
   {
           struct dev_ops *iops = dev->si_ops;
   
           dev->si_ops = oops;
           dev->si_flags &= ~SI_INTERCEPTED;
           iops->head.maj = 0;
           iops->head.data = NULL;
           iops->head.flags = 0;
   }
   
   /************************************************************************
    *                      DEFAULT DEV OPS FUNCTIONS                       *
    ************************************************************************/
   
   
   /*
    * Unsupported devswitch functions (e.g. for writing to read-only device).
    * XXX may belong elsewhere.
    */
   int
   norevoke(struct dev_revoke_args *ap)
   {
           /* take no action */
           return(0);
   }
   
   int
   noclone(struct dev_clone_args *ap)
   {
           /* take no action */
           return (0);     /* allow the clone */
   }
   
   int
   noopen(struct dev_open_args *ap)
   {
           return (ENODEV);
   }
   
   int
   noclose(struct dev_close_args *ap)
   {
           return (ENODEV);
   }
   
   int
   noread(struct dev_read_args *ap)
   {
           return (ENODEV);
   }
   
   int
   nowrite(struct dev_write_args *ap)
   {
           return (ENODEV);
   }
   
   int
   noioctl(struct dev_ioctl_args *ap)
   {
           return (ENODEV);
   }
   
   int
   nokqfilter(struct dev_kqfilter_args *ap)
   {
           return (ENODEV);
   }
   
   int
   nommap(struct dev_mmap_args *ap)
   {
           return (ENODEV);
   }
   
   int
   nommap_single(struct dev_mmap_single_args *ap)
   {
           return (ENODEV);
   }
   
   int
   nostrategy(struct dev_strategy_args *ap)
   {
           struct bio *bio = ap->a_bio;
   
           bio->bio_buf->b_flags |= B_ERROR;
           bio->bio_buf->b_error = EOPNOTSUPP;
           biodone(bio);
           return(0);
   }
   
   int
   nopsize(struct dev_psize_args *ap)
   {
           ap->a_result = 0;
           return(0);
   }
   
   int
   nodump(struct dev_dump_args *ap)
   {
           return (ENODEV);
   }
   
   /*
    * XXX this is probably bogus.  Any device that uses it isn't checking the
    * minor number.
    */
   int
   nullopen(struct dev_open_args *ap)
   {
           return (0);
   }
   
   int
   nullclose(struct dev_close_args *ap)
   {
           return (0);
   }
   

Cache object: 6db3352490a17ca0cdf64669ca7edea7