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Commit bf98c406 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds
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[PATCH] devfs: race fixes and cleanup 

From: Andrey Borzenkov <arvidjaar@mail.ru>

- use struct nameidata in devfs_d_revalidate_wait to detect when it is
  called without i_sem hold; take i_sem on parent in this case.  This
  prevents both deadlock with devfs_lookup by allowing it to drop i_sem
  consistently and oops in d_instantiate by ensuring that it always runs
  protected

- remove dead code that deals with major number allocation.  The only
  remaining user was devfs itself and patch changes it to

- use register_chardev to get device number for internal /dev/.devfsd and
  /dev/.statd.

- remove dead auto allocation flag as well

- remove code that does module get on dev open - it is handled by fops_get.
   Use init_special_inode consistently

- get rid of struct cdev_type and bdev_type - both have just single dev_t
  now
parent 01d1a791
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Inline Side-by-side
Showing with 198 additions and 368 deletions
fs/devfs/base.c
View file @ bf98c406
......@@ -676,6 +676,7 @@
#include <linux/smp.h>
#include <linux/rwsem.h>
#include <linux/sched.h>
#include <linux/namei.h>
#include <asm/uaccess.h>
#include <asm/io.h>
......@@ -685,9 +686,7 @@
#include <asm/bitops.h>
#include <asm/atomic.h>
#include "internal.h"
#define DEVFS_VERSION "1.22 (20021013)"
#define DEVFS_VERSION "2004-01-31"
#define DEVFS_NAME "devfs"
......@@ -762,18 +761,6 @@ struct directory_type
unsigned char no_more_additions:1;
};
struct bdev_type
{
dev_t dev;
};
struct cdev_type
{
struct file_operations *ops;
dev_t dev;
unsigned char autogen:1;
};
struct symlink_type
{
unsigned int length; /* Not including the NULL-termimator */
......@@ -801,8 +788,7 @@ struct devfs_entry
union
{
struct directory_type dir;
struct bdev_type bdev;
struct cdev_type cdev;
dev_t dev;
struct symlink_type symlink;
const char *name; /* Only used for (mode == 0) */
}
......@@ -813,7 +799,7 @@ struct devfs_entry
struct devfs_inode inode;
umode_t mode;
unsigned short namelen; /* I think 64k+ filenames are a way off... */
unsigned char vfs_deletable:1;/* Whether the VFS may delete the entry */
unsigned char vfs:1;/* Whether the VFS may delete the entry */
char name[1]; /* This is just a dummy: the allocated array
is bigger. This is NULL-terminated */
};
......@@ -925,8 +911,6 @@ static void devfs_put (devfs_handle_t de)
de->name, de, de->parent,
de->parent ? de->parent->name : "no parent");
if ( S_ISLNK (de->mode) ) kfree (de->u.symlink.linkname);
if ( S_ISCHR (de->mode) && de->u.cdev.autogen )
devfs_dealloc_devnum (de->mode, de->u.cdev.dev);
WRITE_ENTRY_MAGIC (de, 0);
#ifdef CONFIG_DEVFS_DEBUG
spin_lock (&stat_lock);
......@@ -1063,47 +1047,41 @@ static int _devfs_append_entry (devfs_handle_t dir, devfs_handle_t de,
return retval;
} /* End Function _devfs_append_entry */
/**
* _devfs_get_root_entry - Get the root devfs entry.
*
* Returns the root devfs entry on success, else %NULL.
*
* TODO it must be called asynchronously due to the fact
* that devfs is initialized relatively late. Proper way
* is to remove module_init from init_devfs_fs and manually
* call it early enough during system init
*/
static struct devfs_entry *_devfs_get_root_entry (void)
static struct devfs_entry *_devfs_get_root_entry(void)
{
struct devfs_entry *new;
static spinlock_t root_lock = SPIN_LOCK_UNLOCKED;
/* Always ensure the root is created */
if (root_entry) return root_entry;
if ( ( new = _devfs_alloc_entry (NULL, 0,MODE_DIR) ) == NULL ) return NULL;
spin_lock (&root_lock);
if (root_entry)
{
spin_unlock (&root_lock);
devfs_put (new);
return (root_entry);
return root_entry;
new = _devfs_alloc_entry(NULL, 0, MODE_DIR);
if (new == NULL )
return NULL;
spin_lock(&root_lock);
if (root_entry) {
spin_unlock(&root_lock);
devfs_put(new);
return root_entry;
}
root_entry = new;
spin_unlock (&root_lock);
/* And create the entry for ".devfsd" */
if ( ( new = _devfs_alloc_entry (".devfsd", 0, S_IFCHR |S_IRUSR |S_IWUSR) )
== NULL ) return NULL;
new->u.cdev.dev = devfs_alloc_devnum (S_IFCHR |S_IRUSR |S_IWUSR);
new->u.cdev.ops = &devfsd_fops;
_devfs_append_entry (root_entry, new, NULL);
#ifdef CONFIG_DEVFS_DEBUG
if ( ( new = _devfs_alloc_entry (".stat", 0, S_IFCHR | S_IRUGO | S_IWUGO) )
== NULL ) return NULL;
new->u.cdev.dev = devfs_alloc_devnum (S_IFCHR | S_IRUGO | S_IWUGO);
new->u.cdev.ops = &stat_fops;
_devfs_append_entry (root_entry, new, NULL);
#endif
spin_unlock(&root_lock);
return root_entry;
} /* End Function _devfs_get_root_entry */
/**
* _devfs_descend - Descend down a tree using the next component name.
* @dir: The directory to search.
......@@ -1237,6 +1215,7 @@ static devfs_handle_t _devfs_walk_path (struct devfs_entry *dir,
}
if (S_ISLNK (de->mode) && traverse_symlink)
{ /* Need to follow the link: this is a stack chomper */
/* FIXME what if it puts outside of mounted tree? */
link = _devfs_walk_path (dir, de->u.symlink.linkname,
de->u.symlink.length, TRUE);
devfs_put (de);
......@@ -1444,24 +1423,16 @@ static void devfsd_notify (struct devfs_entry *de,unsigned short type)
current->egid, &fs_info);
}
int devfs_mk_bdev(dev_t dev, umode_t mode, const char *fmt, ...)
static int devfs_mk_dev(dev_t dev, umode_t mode, const char *fmt, va_list args)
{
struct devfs_entry *dir = NULL, *de;
char buf[64];
va_list args;
int error, n;
va_start(args, fmt);
n = vsnprintf(buf, 64, fmt, args);
if (n >= 64 || !buf[0]) {
printk(KERN_WARNING "%s: invalid format string\n",
__FUNCTION__);
return -EINVAL;
}
if (!S_ISBLK(mode)) {
printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
__FUNCTION__, mode, buf);
n = vsnprintf(buf, sizeof(buf), fmt, args);
if (n >= sizeof(buf) || !buf[0]) {
printk(KERN_WARNING "%s: invalid format string %s\n",
__FUNCTION__, fmt);
return -EINVAL;
}
......@@ -1472,7 +1443,7 @@ int devfs_mk_bdev(dev_t dev, umode_t mode, const char *fmt, ...)
return -ENOMEM; /* could be more accurate... */
}
de->u.bdev.dev = dev;
de->u.dev = dev;
error = _devfs_append_entry(dir, de, NULL);
if (error) {
......@@ -1487,50 +1458,35 @@ int devfs_mk_bdev(dev_t dev, umode_t mode, const char *fmt, ...)
return error;
}
int devfs_mk_bdev(dev_t dev, umode_t mode, const char *fmt, ...)
{
va_list args;
if (!S_ISBLK(mode)) {
printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
__FUNCTION__, mode, fmt);
return -EINVAL;
}
va_start(args, fmt);
return devfs_mk_dev(dev, mode, fmt, args);
}
EXPORT_SYMBOL(devfs_mk_bdev);
int devfs_mk_cdev(dev_t dev, umode_t mode, const char *fmt, ...)
{
struct devfs_entry *dir = NULL, *de;
char buf[64];
va_list args;
int error, n;
va_start(args, fmt);
n = vsnprintf(buf, 64, fmt, args);
if (n >= 64 || !buf[0]) {
printk(KERN_WARNING "%s: invalid format string\n",
__FUNCTION__);
return -EINVAL;
}
if (!S_ISCHR(mode)) {
printk(KERN_WARNING "%s: invalide mode (%u) for %s\n",
__FUNCTION__, mode, buf);
__FUNCTION__, mode, fmt);
return -EINVAL;
}
de = _devfs_prepare_leaf(&dir, buf, mode);
if (!de) {
printk(KERN_WARNING "%s: could not prepare leaf for %s\n",
__FUNCTION__, buf);
return -ENOMEM; /* could be more accurate... */
}
de->u.cdev.dev = dev;
error = _devfs_append_entry(dir, de, NULL);
if (error) {
printk(KERN_WARNING "%s: could not append to parent for %s\n",
__FUNCTION__, buf);
goto out;
}
devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
out:
devfs_put(dir);
return error;
va_start(args, fmt);
return devfs_mk_dev(dev, mode, fmt, args);
}
EXPORT_SYMBOL(devfs_mk_cdev);
......@@ -1663,7 +1619,7 @@ int devfs_mk_symlink(const char *from, const char *to)
err = devfs_do_symlink(NULL, from, to, &de);
if (!err) {
de->vfs_deletable = TRUE;
de->vfs = TRUE;
devfsd_notify(de, DEVFSD_NOTIFY_REGISTERED);
}
......@@ -1732,8 +1688,8 @@ void devfs_remove(const char *fmt, ...)
int n;
va_start(args, fmt);
n = vsnprintf(buf, 64, fmt, args);
if (n < 64 && buf[0]) {
n = vsnprintf(buf, sizeof(buf), fmt, args);
if (n < sizeof(buf) && buf[0]) {
devfs_handle_t de = _devfs_find_entry(NULL, buf, 0);
if (!de) {
......@@ -1784,33 +1740,6 @@ static int devfs_generate_path (devfs_handle_t de, char *path, int buflen)
return pos;
} /* End Function devfs_generate_path */
/**
* devfs_get_ops - Get the device operations for a devfs entry.
* @de: The handle to the device entry.
*
* Returns a pointer to the device operations on success, else NULL.
* The use count for the module owning the operations will be incremented.
*/
static struct file_operations *devfs_get_ops (devfs_handle_t de)
{
struct file_operations *ops = de->u.cdev.ops;
struct module *owner;
if (!ops)
return NULL;
owner = ops->owner;
read_lock (&de->parent->u.dir.lock); /* Prevent module from unloading */
if ( (de->next == de) || !try_module_get (owner) )
{ /* Entry is already unhooked or module is unloading */
read_unlock (&de->parent->u.dir.lock);
return NULL;
}
read_unlock (&de->parent->u.dir.lock); /* Module can continue unloading*/
return ops;
} /* End Function devfs_get_ops */
/**
* devfs_setup - Process kernel boot options.
* @str: The boot options after the "devfs=".
......@@ -1876,7 +1805,6 @@ static int __init devfs_setup (char *str)
__setup("devfs=", devfs_setup);
EXPORT_SYMBOL(devfs_put);
EXPORT_SYMBOL(devfs_mk_symlink);
EXPORT_SYMBOL(devfs_mk_dir);
EXPORT_SYMBOL(devfs_remove);
......@@ -1996,6 +1924,7 @@ static struct inode *_devfs_get_vfs_inode (struct super_block *sb,
iput (inode);
return NULL;
}
/* FIXME where is devfs_put? */
inode->u.generic_ip = devfs_get (de);
inode->i_ino = de->inode.ino;
DPRINTK (DEBUG_I_GET, "(%d): VFS inode: %p devfs_entry: %p\n",
......@@ -2003,26 +1932,25 @@ static struct inode *_devfs_get_vfs_inode (struct super_block *sb,
inode->i_blocks = 0;
inode->i_blksize = FAKE_BLOCK_SIZE;
inode->i_op = &devfs_iops;
inode->i_fop = &devfs_fops;
if ( S_ISCHR (de->mode) )
{
inode->i_rdev = de->u.cdev.dev;
}
else if ( S_ISBLK (de->mode) )
init_special_inode(inode, de->mode, de->u.bdev.dev);
else if ( S_ISFIFO (de->mode) )
inode->i_fop = &def_fifo_fops;
else if ( S_ISDIR (de->mode) )
{
inode->i_mode = de->mode;
if (S_ISDIR(de->mode)) {
inode->i_op = &devfs_dir_iops;
inode->i_fop = &devfs_dir_fops;
}
else if ( S_ISLNK (de->mode) )
{
} else if (S_ISLNK(de->mode)) {
inode->i_op = &devfs_symlink_iops;
inode->i_size = de->u.symlink.length;
} else if (S_ISCHR(de->mode) || S_ISBLK(de->mode)) {
init_special_inode(inode, de->mode, de->u.dev);
} else if (S_ISFIFO(de->mode) || S_ISSOCK(de->mode)) {
init_special_inode(inode, de->mode, 0);
} else {
PRINTK("(%s): unknown mode %o de: %p\n",
de->name, de->mode, de);
iput(inode);
devfs_put(de);
return NULL;
}
inode->i_mode = de->mode;
inode->i_uid = de->inode.uid;
inode->i_gid = de->inode.gid;
inode->i_atime = de->inode.atime;
......@@ -2098,28 +2026,36 @@ static int devfs_readdir (struct file *file, void *dirent, filldir_t filldir)
return stored;
} /* End Function devfs_readdir */
/* Open devfs specific special files */
static int devfs_open (struct inode *inode, struct file *file)
{
int err = -ENODEV;
struct devfs_entry *de;
struct file_operations *ops;
int err;
int minor = MINOR(inode->i_rdev);
struct file_operations *old_fops, *new_fops;
de = get_devfs_entry_from_vfs_inode (inode);
if (de == NULL) return -ENODEV;
if ( S_ISDIR (de->mode) ) return 0;
file->private_data = de->info;
if (S_ISCHR(inode->i_mode)) {
ops = devfs_get_ops (de); /* Now have module refcount */
file->f_op = ops;
if (file->f_op)
{
lock_kernel ();
err = file->f_op->open ? (*file->f_op->open) (inode, file) : 0;
unlock_kernel ();
}
else
err = chrdev_open (inode, file);
}
switch (minor) {
case 0: /* /dev/.devfsd */
new_fops = fops_get(&devfsd_fops);
break;
#ifdef CONFIG_DEVFS_DEBUG
case 1: /* /dev/.stat */
new_fops = fops_get(&stat_fops);
break;
#endif
default:
return -ENODEV;
}
if (new_fops == NULL)
return -ENODEV;
old_fops = file->f_op;
file->f_op = new_fops;
err = new_fops->open ? new_fops->open(inode, file) : 0;
if (err) {
file->f_op = old_fops;
fops_put(new_fops);
} else
fops_put(old_fops);
return err;
} /* End Function devfs_open */
......@@ -2132,7 +2068,6 @@ static struct file_operations devfs_dir_fops =
{
.read = generic_read_dir,
.readdir = devfs_readdir,
.open = devfs_open,
};
......@@ -2223,6 +2158,34 @@ static int devfs_d_revalidate_wait (struct dentry *dentry, struct nameidata *nd)
devfs_handle_t parent = get_devfs_entry_from_vfs_inode (dir);
struct devfs_lookup_struct *lookup_info = dentry->d_fsdata;
DECLARE_WAITQUEUE (wait, current);
int need_lock;
/*
* FIXME HACK
*
* make sure that
* d_instantiate always runs under lock
* we release i_sem lock before going to sleep
*
* unfortunately sometimes d_revalidate is called with
* and sometimes without i_sem lock held. The following checks
* attempt to deduce when we need to add (and drop resp.) lock
* here. This relies on current (2.6.2) calling coventions:
*
* lookup_hash is always run under i_sem and is passing NULL
* as nd
*
* open(...,O_CREATE,...) calls _lookup_hash under i_sem
* and sets flags to LOOKUP_OPEN|LOOKUP_CREATE
*
* all other invocations of ->d_revalidate seem to happen
* outside of i_sem
*/
need_lock = nd &&
(!(nd->flags & LOOKUP_CREATE) || (nd->flags & LOOKUP_PARENT));
if (need_lock)
down(&dir->i_sem);
if ( is_devfsd_or_child (fs_info) )
{
......@@ -2233,33 +2196,40 @@ static int devfs_d_revalidate_wait (struct dentry *dentry, struct nameidata *nd)
"(%s): dentry: %p inode: %p de: %p by: \"%s\"\n",
dentry->d_name.name, dentry, dentry->d_inode, de,
current->comm);
if (dentry->d_inode) return 1;
if (dentry->d_inode)
goto out;
if (de == NULL)
{
read_lock (&parent->u.dir.lock);
de = _devfs_search_dir (parent, dentry->d_name.name,
dentry->d_name.len);
read_unlock (&parent->u.dir.lock);
if (de == NULL) return 1;
if (de == NULL)
goto out;
lookup_info->de = de;
}
/* Create an inode, now that the driver information is available */
inode = _devfs_get_vfs_inode (dir->i_sb, de, dentry);
if (!inode) return 1;
if (!inode)
goto out;
DPRINTK (DEBUG_I_LOOKUP,
"(%s): new VFS inode(%u): %p de: %p by: \"%s\"\n",
de->name, de->inode.ino, inode, de, current->comm);
d_instantiate (dentry, inode);
return 1;
goto out;
}
if (lookup_info == NULL) return 1; /* Early termination */
if (lookup_info == NULL)
goto out; /* Early termination */
read_lock (&parent->u.dir.lock);
if (dentry->d_fsdata)
{
set_current_state (TASK_UNINTERRUPTIBLE);
add_wait_queue (&lookup_info->wait_queue, &wait);
read_unlock (&parent->u.dir.lock);
/* at this point it is always (hopefully) locked */
up(&dir->i_sem);
schedule ();
down(&dir->i_sem);
/*
* This does not need nor should remove wait from wait_queue.
* Wait queue head is never reused - nothing is ever added to it
......@@ -2271,6 +2241,10 @@ static int devfs_d_revalidate_wait (struct dentry *dentry, struct nameidata *nd)
}
else read_unlock (&parent->u.dir.lock);
out:
if (need_lock)
up(&dir->i_sem);
return 1;
} /* End Function devfs_d_revalidate_wait */
......@@ -2320,6 +2294,7 @@ static struct dentry *devfs_lookup (struct inode *dir, struct dentry *dentry, st
revalidation */
up (&dir->i_sem);
wait_for_devfsd_finished (fs_info); /* If I'm not devfsd, must wait */
down (&dir->i_sem); /* Grab it again because them's the rules */
de = lookup_info.de;
/* If someone else has been so kind as to make the inode, we go home
early */
......@@ -2349,7 +2324,6 @@ static struct dentry *devfs_lookup (struct inode *dir, struct dentry *dentry, st
dentry->d_fsdata = NULL;
wake_up (&lookup_info.wait_queue);
write_unlock (&parent->u.dir.lock);
down (&dir->i_sem); /* Grab it again because them's the rules */
devfs_put (de);
return retval;
} /* End Function devfs_lookup */
......@@ -2364,7 +2338,7 @@ static int devfs_unlink (struct inode *dir, struct dentry *dentry)
de = get_devfs_entry_from_vfs_inode (inode);
DPRINTK (DEBUG_I_UNLINK, "(%s): de: %p\n", dentry->d_name.name, de);
if (de == NULL) return -ENOENT;
if (!de->vfs_deletable) return -EPERM;
if (!de->vfs) return -EPERM;
write_lock (&de->parent->u.dir.lock);
unhooked = _devfs_unhook (de);
write_unlock (&de->parent->u.dir.lock);
......@@ -2392,7 +2366,7 @@ static int devfs_symlink (struct inode *dir, struct dentry *dentry,
DPRINTK (DEBUG_DISABLED, "(%s): errcode from <devfs_do_symlink>: %d\n",
dentry->d_name.name, err);
if (err < 0) return err;
de->vfs_deletable = TRUE;
de->vfs = TRUE;
de->inode.uid = current->euid;
de->inode.gid = current->egid;
de->inode.atime = CURRENT_TIME;
......@@ -2421,7 +2395,7 @@ static int devfs_mkdir (struct inode *dir, struct dentry *dentry, int mode)
if (parent == NULL) return -ENOENT;
de = _devfs_alloc_entry (dentry->d_name.name, dentry->d_name.len, mode);
if (!de) return -ENOMEM;
de->vfs_deletable = TRUE;
de->vfs = TRUE;
if ( ( err = _devfs_append_entry (parent, de, NULL) ) != 0 )
return err;
de->inode.uid = current->euid;
......@@ -2451,7 +2425,7 @@ static int devfs_rmdir (struct inode *dir, struct dentry *dentry)
de = get_devfs_entry_from_vfs_inode (inode);
if (de == NULL) return -ENOENT;
if ( !S_ISDIR (de->mode) ) return -ENOTDIR;
if (!de->vfs_deletable) return -EPERM;
if (!de->vfs) return -EPERM;
/* First ensure the directory is empty and will stay that way */
write_lock (&de->u.dir.lock);
if (de->u.dir.first) err = -ENOTEMPTY;
......@@ -2485,11 +2459,9 @@ static int devfs_mknod (struct inode *dir, struct dentry *dentry, int mode,
if (parent == NULL) return -ENOENT;
de = _devfs_alloc_entry (dentry->d_name.name, dentry->d_name.len, mode);
if (!de) return -ENOMEM;
de->vfs_deletable = TRUE;
if (S_ISCHR (mode))
de->u.cdev.dev = rdev;
else if (S_ISBLK (mode))
de->u.bdev.dev = rdev;
de->vfs = TRUE;
if (S_ISCHR(mode) || S_ISBLK(mode))
de->u.dev = rdev;
if ( ( err = _devfs_append_entry (parent, de, NULL) ) != 0 )
return err;
de->inode.uid = current->euid;
......@@ -2642,12 +2614,9 @@ static ssize_t devfsd_read (struct file *file, char *buf, size_t len,
info->uid = entry->uid;
info->gid = entry->gid;
de = entry->de;
if (S_ISCHR(de->mode)) {
info->major = MAJOR(de->u.cdev.dev);
info->minor = MINOR(de->u.cdev.dev);
} else if (S_ISBLK (de->mode)) {
info->major = MAJOR(de->u.bdev.dev);
info->minor = MINOR(de->u.bdev.dev);
if (S_ISCHR(de->mode) || S_ISBLK(de->mode)) {
info->major = MAJOR(de->u.dev);
info->minor = MINOR(de->u.dev);
}
pos = devfs_generate_path (de, info->devname, DEVFS_PATHLEN);
if (pos < 0) return pos;
......@@ -2809,29 +2778,52 @@ static ssize_t stat_read (struct file *file, char *buf, size_t len,
} /* End Function stat_read */
#endif
static int __init init_devfs_fs (void)
static int __init init_devfs_fs(void)
{
int err;
int major;
struct devfs_entry *devfsd;
#ifdef CONFIG_DEVFS_DEBUG
struct devfs_entry *stat;
#endif
printk (KERN_INFO "%s: v%s Richard Gooch (rgooch@atnf.csiro.au)\n",
if (_devfs_get_root_entry() == NULL)
return -ENOMEM;
printk(KERN_INFO "%s: %s Richard Gooch (rgooch@atnf.csiro.au)\n",
DEVFS_NAME, DEVFS_VERSION);
devfsd_buf_cache = kmem_cache_create ("devfsd_event",
devfsd_buf_cache = kmem_cache_create("devfsd_event",
sizeof (struct devfsd_buf_entry),
0, 0, NULL, NULL);
if (!devfsd_buf_cache) OOPS ("(): unable to allocate event slab\n");
if (!devfsd_buf_cache)
OOPS("(): unable to allocate event slab\n");
#ifdef CONFIG_DEVFS_DEBUG
devfs_debug = devfs_debug_init;
printk (KERN_INFO "%s: devfs_debug: 0x%0x\n", DEVFS_NAME, devfs_debug);
printk(KERN_INFO "%s: devfs_debug: 0x%0x\n", DEVFS_NAME, devfs_debug);
#endif
printk (KERN_INFO "%s: boot_options: 0x%0x\n", DEVFS_NAME, boot_options);
err = register_filesystem (&devfs_fs_type);
if (!err)
{
struct vfsmount *devfs_mnt = kern_mount (&devfs_fs_type);
err = PTR_ERR (devfs_mnt);
if ( !IS_ERR (devfs_mnt) ) err = 0;
}
printk(KERN_INFO "%s: boot_options: 0x%0x\n", DEVFS_NAME, boot_options);
/* register special device for devfsd communication */
major = register_chrdev(0, "devfs", &devfs_fops);
if (major < 0)
return major;
/* And create the entry for ".devfsd" */
devfsd = _devfs_alloc_entry(".devfsd", 0, S_IFCHR|S_IRUSR|S_IWUSR);
if (devfsd == NULL )
return -ENOMEM;
devfsd->u.dev = MKDEV(major, 0);
_devfs_append_entry(root_entry, devfsd, NULL);
#ifdef CONFIG_DEVFS_DEBUG
stat = _devfs_alloc_entry(".stat", 0, S_IFCHR|S_IRUGO);
if (stat == NULL )
return -ENOMEM;
stat->u.dev = MKDEV(major, 1);
_devfs_append_entry (root_entry, stat, NULL);
#endif
err = register_filesystem(&devfs_fs_type);
return err;
} /* End Function init_devfs_fs */
......
fs/devfs/internal.h deleted 100644 → 0
View file @ 01d1a791
extern dev_t devfs_alloc_devnum(umode_t mode);
extern void devfs_dealloc_devnum(umode_t mode, dev_t devnum);
fs/devfs/util.c
View file @ bf98c406
......@@ -72,7 +72,6 @@
#include <linux/vmalloc.h>
#include <linux/genhd.h>
#include <asm/bitops.h>
#include "internal.h"
int devfs_register_tape(const char *name)
......@@ -96,161 +95,3 @@ void devfs_unregister_tape(int num)
}
EXPORT_SYMBOL(devfs_unregister_tape);
struct major_list
{
spinlock_t lock;
unsigned long bits[256 / BITS_PER_LONG];
};
#if BITS_PER_LONG == 32
# define INITIALISER64(low,high) (low), (high)
#else
# define INITIALISER64(low,high) ( (unsigned long) (high) << 32 | (low) )
#endif
/* Block majors already assigned:
0-3, 7-9, 11-63, 65-99, 101-113, 120-127, 199, 201, 240-255
Total free: 122
*/
static struct major_list block_major_list =
{SPIN_LOCK_UNLOCKED,
{INITIALISER64 (0xfffffb8f, 0xffffffff), /* Majors 0-31, 32-63 */
INITIALISER64 (0xfffffffe, 0xff03ffef), /* Majors 64-95, 96-127 */
INITIALISER64 (0x00000000, 0x00000000), /* Majors 128-159, 160-191 */
INITIALISER64 (0x00000280, 0xffff0000), /* Majors 192-223, 224-255 */
}
};
/* Char majors already assigned:
0-7, 9-151, 154-158, 160-211, 216-221, 224-230, 240-255
Total free: 19
*/
static struct major_list char_major_list =
{SPIN_LOCK_UNLOCKED,
{INITIALISER64 (0xfffffeff, 0xffffffff), /* Majors 0-31, 32-63 */
INITIALISER64 (0xffffffff, 0xffffffff), /* Majors 64-95, 96-127 */
INITIALISER64 (0x7cffffff, 0xffffffff), /* Majors 128-159, 160-191 */
INITIALISER64 (0x3f0fffff, 0xffff007f), /* Majors 192-223, 224-255 */
}
};
/**
* devfs_alloc_major - Allocate a major number.
* @mode: The file mode (must be block device or character device).
* Returns the allocated major, else -1 if none are available.
* This routine is thread safe and does not block.
*/
struct minor_list
{
int major;
unsigned long bits[256 / BITS_PER_LONG];
struct minor_list *next;
};
static struct device_list {
struct minor_list *first;
struct minor_list *last;
int none_free;
} block_list, char_list;
static DECLARE_MUTEX(device_list_mutex);
/**
* devfs_alloc_devnum - Allocate a device number.
* @mode: The file mode (must be block device or character device).
*
* Returns the allocated device number, else NODEV if none are available.
* This routine is thread safe and may block.
*/
dev_t devfs_alloc_devnum(umode_t mode)
{
struct device_list *list;
struct major_list *major_list;
struct minor_list *entry;
int minor;
if (S_ISCHR(mode)) {
major_list = &char_major_list;
list = &char_list;
} else {
major_list = &block_major_list;
list = &block_list;
}
down(&device_list_mutex);
if (list->none_free)
goto out_unlock;
for (entry = list->first; entry; entry = entry->next) {
minor = find_first_zero_bit (entry->bits, 256);
if (minor >= 256)
continue;
goto out_done;
}
/* Need to allocate a new major */
entry = kmalloc (sizeof *entry, GFP_KERNEL);
if (!entry)
goto out_full;
memset(entry, 0, sizeof *entry);
spin_lock(&major_list->lock);
entry->major = find_first_zero_bit(major_list->bits, 256);
if (entry->major >= 256) {
spin_unlock(&major_list->lock);
kfree(entry);
goto out_full;
}
__set_bit(entry->major, major_list->bits);
spin_unlock(&major_list->lock);
if (!list->first)
list->first = entry;
else
list->last->next = entry;
list->last = entry;
minor = 0;
out_done:
__set_bit(minor, entry->bits);
up(&device_list_mutex);
return MKDEV(entry->major, minor);
out_full:
list->none_free = 1;
out_unlock:
up(&device_list_mutex);
return 0;
}
/**
* devfs_dealloc_devnum - Dellocate a device number.
* @mode: The file mode (must be block device or character device).
* @devnum: The device number.
*
* This routine is thread safe and may block.
*/
void devfs_dealloc_devnum(umode_t mode, dev_t devnum)
{
struct device_list *list = S_ISCHR(mode) ? &char_list : &block_list;
struct minor_list *entry;
if (!devnum)
return;
down(&device_list_mutex);
for (entry = list->first; entry; entry = entry->next) {
if (entry->major == MAJOR(devnum)) {
if (__test_and_clear_bit(MINOR(devnum), entry->bits))
list->none_free = 0;
break;
}
}
up(&device_list_mutex);
}
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