base.c

《嵌入式系统设计与实例开发实验教材二源码》Linux内核移植与编译实验

  v0.82
    19991104   Richard Gooch <[e-mail]>
               Removed unused <devfs_set_symlink_destination>.
    19991105   Richard Gooch <[e-mail]>
               Do not hide entries from devfsd or children.
	       Removed DEVFS_ FL_TTY_COMPAT flag.
	       Removed "nottycompat" boot option.
	       Removed <devfs_mk_compat>.
	       Work sponsored by SGI.
  v0.83
    19991107   Richard Gooch <[e-mail]>
	       Added DEVFS_FL_WAIT flag.
	       Work sponsored by SGI.
  v0.84
    19991107   Richard Gooch <[e-mail]>
	       Support new "disc" naming scheme in <get_removable_partition>.
	       Allow NULL fops in <devfs_register>.
	       Work sponsored by SGI.
  v0.85
    19991110   Richard Gooch <[e-mail]>
	       Fall back to major table if NULL fops given to <devfs_register>.
	       Work sponsored by SGI.
  v0.86
    19991204   Richard Gooch <[e-mail]>
	       Support fifos when unregistering.
	       Work sponsored by SGI.
  v0.87
    19991209   Richard Gooch <[e-mail]>
	       Removed obsolete DEVFS_ FL_COMPAT and DEVFS_ FL_TOLERANT flags.
	       Work sponsored by SGI.
  v0.88
    19991214   Richard Gooch <[e-mail]>
	       Removed kmod support.
	       Work sponsored by SGI.
  v0.89
    19991216   Richard Gooch <[e-mail]>
	       Improved debugging in <get_vfs_inode>.
	       Ensure dentries created by devfsd will be cleaned up.
	       Work sponsored by SGI.
  v0.90
    19991223   Richard Gooch <[e-mail]>
	       Created <devfs_get_name>.
	       Work sponsored by SGI.
  v0.91
    20000203   Richard Gooch <[e-mail]>
	       Ported to kernel 2.3.42.
	       Removed <devfs_fill_file>.
	       Work sponsored by SGI.
  v0.92
    20000306   Richard Gooch <[e-mail]>
	       Added DEVFS_ FL_NO_PERSISTENCE flag.
	       Removed unnecessary call to <update_devfs_inode_from_entry> in
	       <devfs_readdir>.
	       Work sponsored by SGI.
  v0.93
    20000413   Richard Gooch <[e-mail]>
	       Set inode->i_size to correct size for symlinks.
    20000414   Richard Gooch <[e-mail]>
	       Only give lookup() method to directories to comply with new VFS
	       assumptions.
	       Work sponsored by SGI.
    20000415   Richard Gooch <[e-mail]>
	       Remove unnecessary tests in symlink methods.
	       Don't kill existing block ops in <devfs_read_inode>.
	       Work sponsored by SGI.
  v0.94
    20000424   Richard Gooch <[e-mail]>
	       Don't create missing directories in <devfs_find_handle>.
	       Work sponsored by SGI.
  v0.95
    20000430   Richard Gooch <[e-mail]>
	       Added CONFIG_DEVFS_MOUNT.
	       Work sponsored by SGI.
  v0.96
    20000608   Richard Gooch <[e-mail]>
	       Disabled multi-mount capability (use VFS bindings instead).
	       Work sponsored by SGI.
  v0.97
    20000610   Richard Gooch <[e-mail]>
	       Switched to FS_SINGLE to disable multi-mounts.
    20000612   Richard Gooch <[e-mail]>
	       Removed module support.
	       Removed multi-mount code.
	       Removed compatibility macros: VFS has changed too much.
	       Work sponsored by SGI.
  v0.98
    20000614   Richard Gooch <[e-mail]>
	       Merged devfs inode into devfs entry.
	       Work sponsored by SGI.
  v0.99
    20000619   Richard Gooch <[e-mail]>
	       Removed dead code in <devfs_register> which used to call
	       <free_dentries>.
	       Work sponsored by SGI.
  v0.100
    20000621   Richard Gooch <[e-mail]>
	       Changed interface to <devfs_register>.
	       Work sponsored by SGI.
  v0.101
    20000622   Richard Gooch <[e-mail]>
	       Simplified interface to <devfs_mk_symlink> and <devfs_mk_dir>.
	       Simplified interface to <devfs_find_handle>.
	       Work sponsored by SGI.
  v0.102
    20010519   Richard Gooch <[e-mail]>
	       Ensure <devfs_generate_path> terminates string for root entry.
	       Exported <devfs_get_name> to modules.
    20010520   Richard Gooch <[e-mail]>
	       Make <devfs_mk_symlink> send events to devfsd.
	       Cleaned up option processing in <devfs_setup>.
    20010521   Richard Gooch <[e-mail]>
	       Fixed bugs in handling symlinks: could leak or cause Oops.
    20010522   Richard Gooch <[e-mail]>
	       Cleaned up directory handling by separating fops.
  v0.103
    20010601   Richard Gooch <[e-mail]>
	       Fixed handling of inverted options in <devfs_setup>.
  v0.104
    20010604   Richard Gooch <[e-mail]>
	       Adjusted <try_modload> to account for <devfs_generate_path> fix.
  v0.105
    20010617   Richard Gooch <[e-mail]>
	       Answered question posed by Al Viro and removed his comments.
	       Moved setting of registered flag after other fields are changed.
	       Fixed race between <devfsd_close> and <devfsd_notify_one>.
	       Global VFS changes added bogus BKL to <devfsd_close>: removed.
	       Widened locking in <devfs_readlink> and <devfs_follow_link>.
	       Replaced <devfsd_read> stack usage with <devfsd_ioctl> kmalloc.
	       Simplified locking in <devfsd_ioctl> and fixed memory leak.
  v0.106
    20010709   Richard Gooch <[e-mail]>
	       Removed broken devnum allocation and use <devfs_alloc_devnum>.
	       Fixed old devnum leak by calling new <devfs_dealloc_devnum>.
  v0.107
    20010712   Richard Gooch <[e-mail]>
	       Fixed bug in <devfs_setup> which could hang boot process.
  v0.108
    20010730   Richard Gooch <[e-mail]>
	       Added DEVFSD_NOTIFY_DELETE event.
    20010801   Richard Gooch <[e-mail]>
	       Removed #include <asm/segment.h>.
  v0.109
    20010807   Richard Gooch <[e-mail]>
	       Fixed inode table races by removing it and using
	       inode->u.generic_ip instead.
	       Moved <devfs_read_inode> into <get_vfs_inode>.
	       Moved <devfs_write_inode> into <devfs_notify_change>.
  v0.110
    20010808   Richard Gooch <[e-mail]>
	       Fixed race in <devfs_do_symlink> for uni-processor.
  v0.111
    20010818   Richard Gooch <[e-mail]>
	       Removed remnant of multi-mount support in <devfs_mknod>.
               Removed unused DEVFS_FL_SHOW_UNREG flag.
  v0.112
    20010820   Richard Gooch <[e-mail]>
	       Removed nlink field from struct devfs_inode.
  v0.113
    20010823   Richard Gooch <[e-mail]>
	       Replaced BKL with global rwsem to protect symlink data (quick
	       and dirty hack).
  v0.114
    20010827   Richard Gooch <[e-mail]>
	       Replaced global rwsem for symlink with per-link refcount.
  v0.115
    20010919   Richard Gooch <[e-mail]>
	       Set inode->i_mapping->a_ops for block nodes in <get_vfs_inode>.
  v0.116
    20011008   Richard Gooch <[e-mail]>
	       Fixed overrun in <devfs_link> by removing function (not needed).
    20011009   Richard Gooch <[e-mail]>
	       Fixed buffer underrun in <try_modload>.
    20011029   Richard Gooch <[e-mail]>
	       Fixed race in <devfsd_ioctl> when setting event mask.
    20011114   Richard Gooch <[e-mail]>
	       First release of new locking code.
  v1.0
    20011117   Richard Gooch <[e-mail]>
	       Discard temporary buffer, now use "%s" for dentry names.
    20011118   Richard Gooch <[e-mail]>
	       Don't generate path in <try_modload>: use fake entry instead.
	       Use "existing" directory in <_devfs_make_parent_for_leaf>.
    20011122   Richard Gooch <[e-mail]>
	       Use slab cache rather than fixed buffer for devfsd events.
  v1.1
    20011125   Richard Gooch <[e-mail]>
	       Send DEVFSD_NOTIFY_REGISTERED events in <devfs_mk_dir>.
    20011127   Richard Gooch <[e-mail]>
	       Fixed locking bug in <devfs_d_revalidate_wait> due to typo.
	       Do not send CREATE, CHANGE, ASYNC_OPEN or DELETE events from
	       devfsd or children.
  v1.2
    20011202   Richard Gooch <[e-mail]>
	       Fixed bug in <devfsd_read>: was dereferencing freed pointer.
  v1.3
    20011203   Richard Gooch <[e-mail]>
	       Fixed bug in <devfsd_close>: was dereferencing freed pointer.
	       Added process group check for devfsd privileges.
  v1.4
    20011204   Richard Gooch <[e-mail]>
	       Use SLAB_ATOMIC in <devfsd_notify_de> from <devfs_d_delete>.
  v1.5
    20011211   Richard Gooch <[e-mail]>
	       Return old entry in <devfs_mk_dir> for 2.4.x kernels.
    20011212   Richard Gooch <[e-mail]>
	       Increment refcount on module in <check_disc_changed>.
    20011215   Richard Gooch <[e-mail]>
	       Created <devfs_get_handle> and exported <devfs_put>.
	       Increment refcount on module in <devfs_get_ops>.
	       Created <devfs_put_ops>.
  v1.6
    20011216   Richard Gooch <[e-mail]>
	       Added poisoning to <devfs_put>.
	       Improved debugging messages.
  v1.7
    20011221   Richard Gooch <[e-mail]>
	       Corrected (made useful) debugging message in <unregister>.
	       Moved <kmem_cache_create> in <mount_devfs_fs> to <init_devfs_fs>
    20011224   Richard Gooch <[e-mail]>
	       Added magic number to guard against scribbling drivers.
    20011226   Richard Gooch <[e-mail]>
	       Only return old entry in <devfs_mk_dir> if a directory.
	       Defined macros for error and debug messages.
  v1.8
    20020113   Richard Gooch <[e-mail]>
	       Fixed (rare, old) race in <devfs_lookup>.
  v1.9
    20020120   Richard Gooch <[e-mail]>
	       Fixed deadlock bug in <devfs_d_revalidate_wait>.
	       Tag VFS deletable in <devfs_mk_symlink> if handle ignored.
  v1.10
*/
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/timer.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/wait.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/ioport.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/devfs_fs.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/smp_lock.h>
#include <linux/smp.h>
#include <linux/version.h>
#include <linux/rwsem.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/bitops.h>
#include <asm/atomic.h>

#define DEVFS_VERSION            "1.10 (20020120)"

#define DEVFS_NAME "devfs"

#define FIRST_INODE 1

#define STRING_LENGTH 256
#define FAKE_BLOCK_SIZE 1024
#define POISON_PTR ( *(void **) poison_array )
#define MAGIC_VALUE 0x327db823

#ifndef TRUE
#  define TRUE 1
#  define FALSE 0
#endif

#define MODE_DIR (S_IFDIR | S_IWUSR | S_IRUGO | S_IXUGO)

#define IS_HIDDEN(de) ( (de)->hide && !is_devfsd_or_child(fs_info) )

#define DEBUG_NONE         0x0000000
#define DEBUG_MODULE_LOAD  0x0000001
#define DEBUG_REGISTER     0x0000002
#define DEBUG_UNREGISTER   0x0000004
#define DEBUG_FREE         0x0000008
#define DEBUG_SET_FLAGS    0x0000010
#define DEBUG_S_READ       0x0000100        /*  Break  */
#define DEBUG_I_LOOKUP     0x0001000        /*  Break  */
#define DEBUG_I_CREATE     0x0002000
#define DEBUG_I_GET        0x0004000
#define DEBUG_I_CHANGE     0x0008000
#define DEBUG_I_UNLINK     0x0010000
#define DEBUG_I_RLINK      0x0020000
#define DEBUG_I_FLINK      0x0040000
#define DEBUG_I_MKNOD      0x0080000
#define DEBUG_F_READDIR    0x0100000        /*  Break  */
#define DEBUG_D_DELETE     0x1000000        /*  Break  */
#define DEBUG_D_RELEASE    0x2000000
#define DEBUG_D_IPUT       0x4000000
#define DEBUG_ALL          0xfffffff
#define DEBUG_DISABLED     DEBUG_NONE

#define OPTION_NONE             0x00
#define OPTION_MOUNT            0x01
#define OPTION_ONLY             0x02

#define PRINTK(format, args...) \
   {printk (KERN_ERR "%s" format, __FUNCTION__ , ## args);}

#define OOPS(format, args...) \
   {printk (KERN_CRIT "%s" format, __FUNCTION__ , ## args); \
    printk ("Forcing Oops\n"); \
    BUG();}

#ifdef CONFIG_DEVFS_DEBUG
#  define VERIFY_ENTRY(de) \
   {if ((de) && (de)->magic_number != MAGIC_VALUE) \
        OOPS ("(%p): bad magic value: %x\n", (de), (de)->magic_number);}
#  define WRITE_ENTRY_MAGIC(de,magic) (de)->magic_number = (magic)
#  define DPRINTK(flag, format, args...) \
   {if (devfs_debug & flag) \
	printk (KERN_INFO "%s" format, __FUNCTION__ , ## args);}
#else
#  define VERIFY_ENTRY(de)
#  define WRITE_ENTRY_MAGIC(de,magic)
#  define DPRINTK(flag, format, args...)
#endif


struct directory_type
{
    rwlock_t lock;                   /*  Lock for searching(R)/updating(W)   */
    struct devfs_entry *first;
    struct devfs_entry *last;
    unsigned short num_removable;    /*  Lock for writing but not reading    */
    unsigned char no_more_additions:1;
};

struct file_type
{
    unsigned long size;
};

struct device_type
{
    unsigned short major;
    unsigned short minor;
};

struct fcb_type  /*  File, char, block type  */
{
    void *ops;
    union 
    {
	struct file_type file;
	struct device_type device;
    }
    u;
    unsigned char auto_owner:1;
    unsigned char aopen_notify:1;
    unsigned char removable:1;  /*  Belongs in device_type, but save space   */
    unsigned char open:1;       /*  Not entirely correct                     */
    unsigned char autogen:1;    /*  Belongs in device_type, but save space   */
};

struct symlink_type
{
    unsigned int length;         /*  Not including the NULL-termimator       */
    char *linkname;              /*  This is NULL-terminated                 */
};

struct devfs_inode     /*  This structure is for "persistent" inode storage  */
{
    struct dentry *dentry;
    time_t atime;
    time_t mtime;