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freebsd-skq/sys/sys/conf.h
Poul-Henning Kamp e606a3c63e Rewamp DEVFS internals pretty severely [1]. 
Give DEVFS a proper inode called struct cdev_priv.  It is important
to keep in mind that this "inode" is shared between all DEVFS
mountpoints, therefore it is protected by the global device mutex.

Link the cdev_priv's into a list, protected by the global device
mutex.  Keep track of each cdev_priv's state with a flag bit and
of references from mountpoints with a dedicated usecount.

Reap the benefits of much improved kernel memory allocator and the
generally better defined device driver APIs to get rid of the tables
of pointers + serial numbers, their overflow tables,  the atomics
to muck about in them and all the trouble that resulted in.

This makes RAM the only limit on how many devices we can have.

The cdev_priv is actually a super struct containing the normal cdev
as the "public" part, and therefore allocation and freeing has moved
to devfs_devs.c from kern_conf.c.

The overall responsibility is (to be) split such that kern/kern_conf.c
is the stuff that deals with drivers and struct cdev and fs/devfs
handles filesystems and struct cdev_priv and their private liason
exposed only in devfs_int.h.

Move the inode number from cdev to cdev_priv and allocate inode
numbers properly with unr.  Local dirents in the mountpoints
(directories, symlinks) allocate inodes from the same pool to
guarantee against overlaps.

Various other fields are going to migrate from cdev to cdev_priv
in the future in order to hide them.  A few fields may migrate
from devfs_dirent to cdev_priv as well.

Protect the DEVFS mountpoint with an sx lock instead of lockmgr,
this lock also protects the directory tree of the mountpoint.

Give each mountpoint a unique integer index, allocated with unr.
Use it into an array of devfs_dirent pointers in each cdev_priv.
Initially the array points to a single element also inside cdev_priv,
but as more devfs instances are mounted, the array is extended with
malloc(9) as necessary when the filesystem populates its directory
tree.

Retire the cdev alias lists, the cdev_priv now know about all the
relevant devfs_dirents (and their vnodes) and devfs_revoke() will
pick them up from there.  We still spelunk into other mountpoints
and fondle their data without 100% good locking.  It may make better
sense to vector the revoke event into the tty code and there do a
destroy_dev/make_dev on the tty's devices, but that's for further
study.

Lots of shuffling of stuff and churn of bits for no good reason[2].

XXX: There is still nothing preventing the dev_clone EVENTHANDLER
from being invoked at the same time in two devfs mountpoints.  It
is not obvious what the best course of action is here.

XXX: comment out an if statement that lost its body, until I can
find out what should go there so it doesn't do damage in the meantime.

XXX: Leave in a few extra malloc types and KASSERTS to help track
down any remaining issues.

Much testing provided by:		Kris
Much confusion caused by (races in):	md(4)

[1] You are not supposed to understand anything past this point.

[2] This line should simplify life for the peanut gallery.
2005-09-19 19:56:48 +00:00

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/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
* Copyright (c) 2000
* Poul-Henning Kamp. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)conf.h 8.5 (Berkeley) 1/9/95
* $FreeBSD$
*/
#ifndef _SYS_CONF_H_
#define _SYS_CONF_H_
#ifdef _KERNEL
#include <sys/eventhandler.h>
#else
#include <sys/queue.h>
#endif
struct tty;
struct snapdata;
struct devfs_dirent;
struct cdevsw;
struct cdev {
struct cdev_priv *si_priv;
u_int si_flags;
#define SI_ALIAS 0x0002 /* carrier of alias name */
#define SI_NAMED 0x0004 /* make_dev{_alias} has been called */
#define SI_CHEAPCLONE 0x0008 /* can be removed_dev'ed when vnode reclaims */
#define SI_CHILD 0x0010 /* child of another struct cdev **/
#define SI_DEVOPEN 0x0020 /* opened by device */
#define SI_CONSOPEN 0x0040 /* opened by console */
#define SI_DUMPDEV 0x0080 /* is kernel dumpdev */
#define SI_CANDELETE 0x0100 /* can do BIO_DELETE */
#define SI_CLONELIST 0x0200 /* on a clone list */
struct timespec si_atime;
struct timespec si_ctime;
struct timespec si_mtime;
uid_t si_uid;
gid_t si_gid;
mode_t si_mode;
struct ucred *si_cred; /* cached clone-time credential */
u_int si_drv0;
int si_refcount;
LIST_ENTRY(cdev) si_list;
LIST_ENTRY(cdev) si_clone;
LIST_HEAD(, cdev) si_children;
LIST_ENTRY(cdev) si_siblings;
struct cdev *si_parent;
char *si_name;
void *si_drv1, *si_drv2;
struct cdevsw *si_devsw;
int si_iosize_max; /* maximum I/O size (for physio &al) */
u_long si_usecount;
u_long si_threadcount;
union {
struct tty *__sit_tty;
struct snapdata *__sid_snapdata;
} __si_u;
char __si_namebuf[SPECNAMELEN + 1];
};
#define si_tty __si_u.__sit_tty
#define si_snapdata __si_u.__sid_snapdata
#ifdef _KERNEL
/*
* Definitions of device driver entry switches
*/
struct bio;
struct buf;
struct thread;
struct uio;
struct knote;
struct clonedevs;
/*
* Note: d_thread_t is provided as a transition aid for those drivers
* that treat struct proc/struct thread as an opaque data type and
* exist in substantially the same form in both 4.x and 5.x. Writers
* of drivers that dips into the d_thread_t structure should use
* struct thread or struct proc as appropriate for the version of the
* OS they are using. It is provided in lieu of each device driver
* inventing its own way of doing this. While it does violate style(9)
* in a number of ways, this violation is deemed to be less
* important than the benefits that a uniform API between releases
* gives.
*
* Users of struct thread/struct proc that aren't device drivers should
* not use d_thread_t.
*/
typedef struct thread d_thread_t;
typedef int d_open_t(struct cdev *dev, int oflags, int devtype, struct thread *td);
typedef int d_fdopen_t(struct cdev *dev, int oflags, struct thread *td, int fdidx);
typedef int d_close_t(struct cdev *dev, int fflag, int devtype, struct thread *td);
typedef void d_strategy_t(struct bio *bp);
typedef int d_ioctl_t(struct cdev *dev, u_long cmd, caddr_t data,
int fflag, struct thread *td);
typedef int d_read_t(struct cdev *dev, struct uio *uio, int ioflag);
typedef int d_write_t(struct cdev *dev, struct uio *uio, int ioflag);
typedef int d_poll_t(struct cdev *dev, int events, struct thread *td);
typedef int d_kqfilter_t(struct cdev *dev, struct knote *kn);
typedef int d_mmap_t(struct cdev *dev, vm_offset_t offset, vm_paddr_t *paddr,
int nprot);
typedef void d_purge_t(struct cdev *dev);
typedef int d_spare2_t(struct cdev *dev);
typedef int dumper_t(
void *priv, /* Private to the driver. */
void *virtual, /* Virtual (mapped) address. */
vm_offset_t physical, /* Physical address of virtual. */
off_t offset, /* Byte-offset to write at. */
size_t length); /* Number of bytes to dump. */
#endif /* _KERNEL */
/*
* Types for d_flags.
*/
#define D_TAPE 0x0001
#define D_DISK 0x0002
#define D_TTY 0x0004
#define D_MEM 0x0008
#ifdef _KERNEL
#define D_TYPEMASK 0xffff
/*
* Flags for d_flags which the drivers can set.
*/
#define D_MEMDISK 0x00010000 /* memory type disk */
#define D_TRACKCLOSE 0x00080000 /* track all closes */
#define D_MMAP_ANON 0x00100000 /* special treatment in vm_mmap.c */
#define D_PSEUDO 0x00200000 /* make_dev() can return NULL */
#define D_NEEDGIANT 0x00400000 /* driver want Giant */
/*
* Version numbers.
*/
#define D_VERSION_00 0x20011966
#define D_VERSION_01 0x17032005 /* Add d_uid,gid,mode & kind */
#define D_VERSION D_VERSION_01
/*
* Flags used for internal housekeeping
*/
#define D_INIT 0x80000000 /* cdevsw initialized */
/*
* Character device switch table
*/
struct cdevsw {
int d_version;
u_int d_flags;
const char *d_name;
d_open_t *d_open;
d_fdopen_t *d_fdopen;
d_close_t *d_close;
d_read_t *d_read;
d_write_t *d_write;
d_ioctl_t *d_ioctl;
d_poll_t *d_poll;
d_mmap_t *d_mmap;
d_strategy_t *d_strategy;
dumper_t *d_dump;
d_kqfilter_t *d_kqfilter;
d_purge_t *d_purge;
d_spare2_t *d_spare2;
uid_t d_uid;
gid_t d_gid;
mode_t d_mode;
const char *d_kind;
/* These fields should not be messed with by drivers */
LIST_ENTRY(cdevsw) d_list;
LIST_HEAD(, cdev) d_devs;
int d_spare3;
struct cdevsw *d_gianttrick;
};
#define NUMCDEVSW 256
#define MAXMINOR 0xffff00ffU
struct module;
struct devsw_module_data {
int (*chainevh)(struct module *, int, void *); /* next handler */
void *chainarg; /* arg for next event handler */
/* Do not initialize fields hereafter */
};
#define DEV_MODULE(name, evh, arg) \
static moduledata_t name##_mod = { \
#name, \
evh, \
arg \
}; \
DECLARE_MODULE(name, name##_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE)
void clone_setup(struct clonedevs **cdp);
void clone_cleanup(struct clonedevs **);
#define CLONE_UNITMASK 0xfffff
#define CLONE_FLAG0 (CLONE_UNITMASK + 1)
int clone_create(struct clonedevs **, struct cdevsw *, int *unit, struct cdev **dev, u_int extra);
int count_dev(struct cdev *_dev);
void destroy_dev(struct cdev *_dev);
struct cdevsw *dev_refthread(struct cdev *_dev);
void dev_relthread(struct cdev *_dev);
void dev_depends(struct cdev *_pdev, struct cdev *_cdev);
void dev_ref(struct cdev *dev);
void dev_refl(struct cdev *dev);
void dev_rel(struct cdev *dev);
void dev_strategy(struct cdev *dev, struct buf *bp);
struct cdev *make_dev(struct cdevsw *_devsw, int _minor, uid_t _uid, gid_t _gid,
int _perms, const char *_fmt, ...) __printflike(6, 7);
struct cdev *make_dev_cred(struct cdevsw *_devsw, int _minor,
struct ucred *_cr, uid_t _uid, gid_t _gid, int _perms,
const char *_fmt, ...) __printflike(7, 8);
struct cdev *make_dev_alias(struct cdev *_pdev, const char *_fmt, ...) __printflike(2, 3);
int dev2unit(struct cdev *_dev);
void dev_lock(void);
void dev_unlock(void);
int unit2minor(int _unit);
u_int minor2unit(u_int _minor);
void setconf(void);
#define UID_ROOT 0
#define UID_BIN 3
#define UID_UUCP 66
#define GID_WHEEL 0
#define GID_KMEM 2
#define GID_OPERATOR 5
#define GID_BIN 7
#define GID_GAMES 13
#define GID_DIALER 68
typedef void (*dev_clone_fn)(void *arg, struct ucred *cred, char *name,
int namelen, struct cdev **result);
int dev_stdclone(char *_name, char **_namep, const char *_stem, int *_unit);
EVENTHANDLER_DECLARE(dev_clone, dev_clone_fn);
/* Stuff relating to kernel-dump */
struct dumperinfo {
dumper_t *dumper; /* Dumping function. */
void *priv; /* Private parts. */
u_int blocksize; /* Size of block in bytes. */
off_t mediaoffset; /* Initial offset in bytes. */
off_t mediasize; /* Space available in bytes. */
};
int set_dumper(struct dumperinfo *);
void dumpsys(struct dumperinfo *);
extern int dumping; /* system is dumping */
/* D_TTY related functions */
d_close_t ttyclose;
d_ioctl_t ttyioctl;
d_kqfilter_t ttykqfilter;
d_open_t ttyopen;
d_poll_t ttypoll;
d_read_t ttyread;
d_write_t ttywrite;
#endif /* _KERNEL */
#endif /* !_SYS_CONF_H_ */
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