FreeBSD/Linux Kernel Cross Reference
sys/net/socket.c

     /*
      * NET          An implementation of the SOCKET network access protocol.
      *
      * Version:     @(#)socket.c    1.1.93  18/02/95
      *
      * Authors:     Orest Zborowski, <obz@Kodak.COM>
      *              Ross Biro, <bir7@leland.Stanford.Edu>
      *              Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
      *
     * Fixes:
     *              Anonymous       :       NOTSOCK/BADF cleanup. Error fix in
     *                                      shutdown()
     *              Alan Cox        :       verify_area() fixes
     *              Alan Cox        :       Removed DDI
     *              Jonathan Kamens :       SOCK_DGRAM reconnect bug
     *              Alan Cox        :       Moved a load of checks to the very
     *                                      top level.
     *              Alan Cox        :       Move address structures to/from user
     *                                      mode above the protocol layers.
     *              Rob Janssen     :       Allow 0 length sends.
     *              Alan Cox        :       Asynchronous I/O support (cribbed from the
     *                                      tty drivers).
     *              Niibe Yutaka    :       Asynchronous I/O for writes (4.4BSD style)
     *              Jeff Uphoff     :       Made max number of sockets command-line
     *                                      configurable.
     *              Matti Aarnio    :       Made the number of sockets dynamic,
     *                                      to be allocated when needed, and mr.
     *                                      Uphoff's max is used as max to be
     *                                      allowed to allocate.
     *              Linus           :       Argh. removed all the socket allocation
     *                                      altogether: it's in the inode now.
     *              Alan Cox        :       Made sock_alloc()/sock_release() public
     *                                      for NetROM and future kernel nfsd type
     *                                      stuff.
     *              Alan Cox        :       sendmsg/recvmsg basics.
     *              Tom Dyas        :       Export net symbols.
     *              Marcin Dalecki  :       Fixed problems with CONFIG_NET="n".
     *              Alan Cox        :       Added thread locking to sys_* calls
     *                                      for sockets. May have errors at the
     *                                      moment.
     *              Kevin Buhr      :       Fixed the dumb errors in the above.
     *              Andi Kleen      :       Some small cleanups, optimizations,
     *                                      and fixed a copy_from_user() bug.
     *              Tigran Aivazian :       sys_send(args) calls sys_sendto(args, NULL, 0)
     *              Tigran Aivazian :       Made listen(2) backlog sanity checks 
     *                                      protocol-independent
     *
     *
     *              This program is free software; you can redistribute it and/or
     *              modify it under the terms of the GNU General Public License
     *              as published by the Free Software Foundation; either version
     *              2 of the License, or (at your option) any later version.
     *
     *
     *      This module is effectively the top level interface to the BSD socket
     *      paradigm. 
     *
     */
    
    #include <linux/config.h>
    #include <linux/mm.h>
    #include <linux/smp_lock.h>
    #include <linux/socket.h>
    #include <linux/file.h>
    #include <linux/net.h>
    #include <linux/interrupt.h>
    #include <linux/netdevice.h>
    #include <linux/proc_fs.h>
    #include <linux/wanrouter.h>
    #include <linux/netlink.h>
    #include <linux/rtnetlink.h>
    #include <linux/init.h>
    #include <linux/poll.h>
    #include <linux/cache.h>
    #include <linux/module.h>
    #include <linux/highmem.h>
    
    #if defined(CONFIG_KMOD) && defined(CONFIG_NET)
    #include <linux/kmod.h>
    #endif
    
    #include <asm/uaccess.h>
    
    #include <net/sock.h>
    #include <net/scm.h>
    #include <linux/netfilter.h>
    
    static int sock_no_open(struct inode *irrelevant, struct file *dontcare);
    static ssize_t sock_read(struct file *file, char *buf,
                             size_t size, loff_t *ppos);
    static ssize_t sock_write(struct file *file, const char *buf,
                              size_t size, loff_t *ppos);
    static int sock_mmap(struct file *file, struct vm_area_struct * vma);
    
    static int sock_close(struct inode *inode, struct file *file);
    static unsigned int sock_poll(struct file *file,
                                  struct poll_table_struct *wait);
    static int sock_ioctl(struct inode *inode, struct file *file,
                          unsigned int cmd, unsigned long arg);
   static int sock_fasync(int fd, struct file *filp, int on);
   static ssize_t sock_readv(struct file *file, const struct iovec *vector,
                             unsigned long count, loff_t *ppos);
   static ssize_t sock_writev(struct file *file, const struct iovec *vector,
                             unsigned long count, loff_t *ppos);
   static ssize_t sock_sendpage(struct file *file, struct page *page,
                                int offset, size_t size, loff_t *ppos, int more);
   
   
   /*
    *      Socket files have a set of 'special' operations as well as the generic file ones. These don't appear
    *      in the operation structures but are done directly via the socketcall() multiplexor.
    */
   
   static struct file_operations socket_file_ops = {
           llseek:         no_llseek,
           read:           sock_read,
           write:          sock_write,
           poll:           sock_poll,
           ioctl:          sock_ioctl,
           mmap:           sock_mmap,
           open:           sock_no_open,   /* special open code to disallow open via /proc */
           release:        sock_close,
           fasync:         sock_fasync,
           readv:          sock_readv,
           writev:         sock_writev,
           sendpage:       sock_sendpage
   };
   
   /*
    *      The protocol list. Each protocol is registered in here.
    */
   
   static struct net_proto_family *net_families[NPROTO];
   
   #ifdef CONFIG_SMP
   static atomic_t net_family_lockct = ATOMIC_INIT(0);
   static spinlock_t net_family_lock = SPIN_LOCK_UNLOCKED;
   
   /* The strategy is: modifications net_family vector are short, do not
      sleep and veeery rare, but read access should be free of any exclusive
      locks.
    */
   
   static void net_family_write_lock(void)
   {
           spin_lock(&net_family_lock);
           while (atomic_read(&net_family_lockct) != 0) {
                   spin_unlock(&net_family_lock);
   
                   yield();
   
                   spin_lock(&net_family_lock);
           }
   }
   
   static __inline__ void net_family_write_unlock(void)
   {
           spin_unlock(&net_family_lock);
   }
   
   static __inline__ void net_family_read_lock(void)
   {
           atomic_inc(&net_family_lockct);
           spin_unlock_wait(&net_family_lock);
   }
   
   static __inline__ void net_family_read_unlock(void)
   {
           atomic_dec(&net_family_lockct);
   }
   
   #else
   #define net_family_write_lock() do { } while(0)
   #define net_family_write_unlock() do { } while(0)
   #define net_family_read_lock() do { } while(0)
   #define net_family_read_unlock() do { } while(0)
   #endif
   
   
   /*
    *      Statistics counters of the socket lists
    */
   
   static union {
           int     counter;
           char    __pad[SMP_CACHE_BYTES];
   } sockets_in_use[NR_CPUS] __cacheline_aligned = {{0}};
   
   /*
    *      Support routines. Move socket addresses back and forth across the kernel/user
    *      divide and look after the messy bits.
    */
   
   #define MAX_SOCK_ADDR   128             /* 108 for Unix domain - 
                                              16 for IP, 16 for IPX,
                                              24 for IPv6,
                                              about 80 for AX.25 
                                              must be at least one bigger than
                                              the AF_UNIX size (see net/unix/af_unix.c
                                              :unix_mkname()).  
                                            */
                                            
   /**
    *      move_addr_to_kernel     -       copy a socket address into kernel space
    *      @uaddr: Address in user space
    *      @kaddr: Address in kernel space
    *      @ulen: Length in user space
    *
    *      The address is copied into kernel space. If the provided address is
    *      too long an error code of -EINVAL is returned. If the copy gives
    *      invalid addresses -EFAULT is returned. On a success 0 is returned.
    */
   
   int move_addr_to_kernel(void *uaddr, int ulen, void *kaddr)
   {
           if(ulen<0||ulen>MAX_SOCK_ADDR)
                   return -EINVAL;
           if(ulen==0)
                   return 0;
           if(copy_from_user(kaddr,uaddr,ulen))
                   return -EFAULT;
           return 0;
   }
   
   /**
    *      move_addr_to_user       -       copy an address to user space
    *      @kaddr: kernel space address
    *      @klen: length of address in kernel
    *      @uaddr: user space address
    *      @ulen: pointer to user length field
    *
    *      The value pointed to by ulen on entry is the buffer length available.
    *      This is overwritten with the buffer space used. -EINVAL is returned
    *      if an overlong buffer is specified or a negative buffer size. -EFAULT
    *      is returned if either the buffer or the length field are not
    *      accessible.
    *      After copying the data up to the limit the user specifies, the true
    *      length of the data is written over the length limit the user
    *      specified. Zero is returned for a success.
    */
    
   int move_addr_to_user(void *kaddr, int klen, void *uaddr, int *ulen)
   {
           int err;
           int len;
   
           if((err=get_user(len, ulen)))
                   return err;
           if(len>klen)
                   len=klen;
           if(len<0 || len> MAX_SOCK_ADDR)
                   return -EINVAL;
           if(len)
           {
                   if(copy_to_user(uaddr,kaddr,len))
                           return -EFAULT;
           }
           /*
            *      "fromlen shall refer to the value before truncation.."
            *                      1003.1g
            */
           return __put_user(klen, ulen);
   }
   
   #define SOCKFS_MAGIC 0x534F434B
   static int sockfs_statfs(struct super_block *sb, struct statfs *buf)
   {
           buf->f_type = SOCKFS_MAGIC;
           buf->f_bsize = 1024;
           buf->f_namelen = 255;
           return 0;
   }
   
   static struct super_operations sockfs_ops = {
           statfs:         sockfs_statfs,
   };
   
   static struct super_block * sockfs_read_super(struct super_block *sb, void *data, int silent)
   {
           struct inode *root = new_inode(sb);
           if (!root)
                   return NULL;
           root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR;
           root->i_uid = root->i_gid = 0;
           root->i_atime = root->i_mtime = root->i_ctime = CURRENT_TIME;
           sb->s_blocksize = 1024;
           sb->s_blocksize_bits = 10;
           sb->s_magic = SOCKFS_MAGIC;
           sb->s_op        = &sockfs_ops;
           sb->s_root = d_alloc(NULL, &(const struct qstr) { "socket:", 7, 0 });
           if (!sb->s_root) {
                   iput(root);
                   return NULL;
           }
           sb->s_root->d_sb = sb;
           sb->s_root->d_parent = sb->s_root;
           d_instantiate(sb->s_root, root);
           return sb;
   }
   
   static struct vfsmount *sock_mnt;
   static DECLARE_FSTYPE(sock_fs_type, "sockfs", sockfs_read_super, FS_NOMOUNT);
   static int sockfs_delete_dentry(struct dentry *dentry)
   {
           return 1;
   }
   static struct dentry_operations sockfs_dentry_operations = {
           d_delete:       sockfs_delete_dentry,
   };
   
   /*
    *      Obtains the first available file descriptor and sets it up for use.
    *
    *      This function creates file structure and maps it to fd space
    *      of current process. On success it returns file descriptor
    *      and file struct implicitly stored in sock->file.
    *      Note that another thread may close file descriptor before we return
    *      from this function. We use the fact that now we do not refer
    *      to socket after mapping. If one day we will need it, this
    *      function will increment ref. count on file by 1.
    *
    *      In any case returned fd MAY BE not valid!
    *      This race condition is unavoidable
    *      with shared fd spaces, we cannot solve it inside kernel,
    *      but we take care of internal coherence yet.
    */
   
   static int sock_map_fd(struct socket *sock)
   {
           int fd;
           struct qstr this;
           char name[32];
   
           /*
            *      Find a file descriptor suitable for return to the user. 
            */
   
           fd = get_unused_fd();
           if (fd >= 0) {
                   struct file *file = get_empty_filp();
   
                   if (!file) {
                           put_unused_fd(fd);
                           fd = -ENFILE;
                           goto out;
                   }
   
                   sprintf(name, "[%lu]", sock->inode->i_ino);
                   this.name = name;
                   this.len = strlen(name);
                   this.hash = sock->inode->i_ino;
   
                   file->f_dentry = d_alloc(sock_mnt->mnt_sb->s_root, &this);
                   if (!file->f_dentry) {
                           put_filp(file);
                           put_unused_fd(fd);
                           fd = -ENOMEM;
                           goto out;
                   }
                   file->f_dentry->d_op = &sockfs_dentry_operations;
                   d_add(file->f_dentry, sock->inode);
                   file->f_vfsmnt = mntget(sock_mnt);
   
                   sock->file = file;
                   file->f_op = sock->inode->i_fop = &socket_file_ops;
                   file->f_mode = 3;
                   file->f_flags = O_RDWR;
                   file->f_pos = 0;
                   fd_install(fd, file);
           }
   
   out:
           return fd;
   }
   
   extern __inline__ struct socket *socki_lookup(struct inode *inode)
   {
           return &inode->u.socket_i;
   }
   
   /**
    *      sockfd_lookup   -       Go from a file number to its socket slot
    *      @fd: file handle
    *      @err: pointer to an error code return
    *
    *      The file handle passed in is locked and the socket it is bound
    *      too is returned. If an error occurs the err pointer is overwritten
    *      with a negative errno code and NULL is returned. The function checks
    *      for both invalid handles and passing a handle which is not a socket.
    *
    *      On a success the socket object pointer is returned.
    */
   
   struct socket *sockfd_lookup(int fd, int *err)
   {
           struct file *file;
           struct inode *inode;
           struct socket *sock;
   
           if (!(file = fget(fd)))
           {
                   *err = -EBADF;
                   return NULL;
           }
   
           inode = file->f_dentry->d_inode;
           if (!inode->i_sock || !(sock = socki_lookup(inode)))
           {
                   *err = -ENOTSOCK;
                   fput(file);
                   return NULL;
           }
   
           if (sock->file != file) {
                   printk(KERN_ERR "socki_lookup: socket file changed!\n");
                   sock->file = file;
           }
           return sock;
   }
   
   extern __inline__ void sockfd_put(struct socket *sock)
   {
           fput(sock->file);
   }
   
   /**
    *      sock_alloc      -       allocate a socket
    *      
    *      Allocate a new inode and socket object. The two are bound together
    *      and initialised. The socket is then returned. If we are out of inodes
    *      NULL is returned.
    */
   
   struct socket *sock_alloc(void)
   {
           struct inode * inode;
           struct socket * sock;
   
           inode = new_inode(sock_mnt->mnt_sb);
           if (!inode)
                   return NULL;
   
           inode->i_dev = NODEV;
           sock = socki_lookup(inode);
   
           inode->i_mode = S_IFSOCK|S_IRWXUGO;
           inode->i_sock = 1;
           inode->i_uid = current->fsuid;
           inode->i_gid = current->fsgid;
   
           sock->inode = inode;
           init_waitqueue_head(&sock->wait);
           sock->fasync_list = NULL;
           sock->state = SS_UNCONNECTED;
           sock->flags = 0;
           sock->ops = NULL;
           sock->sk = NULL;
           sock->file = NULL;
   
           sockets_in_use[smp_processor_id()].counter++;
           return sock;
   }
   
   /*
    *      In theory you can't get an open on this inode, but /proc provides
    *      a back door. Remember to keep it shut otherwise you'll let the
    *      creepy crawlies in.
    */
     
   static int sock_no_open(struct inode *irrelevant, struct file *dontcare)
   {
           return -ENXIO;
   }
   
   /**
    *      sock_release    -       close a socket
    *      @sock: socket to close
    *
    *      The socket is released from the protocol stack if it has a release
    *      callback, and the inode is then released if the socket is bound to
    *      an inode not a file. 
    */
    
   void sock_release(struct socket *sock)
   {
           if (sock->ops) 
                   sock->ops->release(sock);
   
           if (sock->fasync_list)
                   printk(KERN_ERR "sock_release: fasync list not empty!\n");
   
           sockets_in_use[smp_processor_id()].counter--;
           if (!sock->file) {
                   iput(sock->inode);
                   return;
           }
           sock->file=NULL;
   }
   
   int sock_sendmsg(struct socket *sock, struct msghdr *msg, int size)
   {
           int err;
           struct scm_cookie scm;
   
           err = scm_send(sock, msg, &scm);
           if (err >= 0) {
                   err = sock->ops->sendmsg(sock, msg, size, &scm);
                   scm_destroy(&scm);
           }
           return err;
   }
   
   int sock_recvmsg(struct socket *sock, struct msghdr *msg, int size, int flags)
   {
           struct scm_cookie scm;
   
           memset(&scm, 0, sizeof(scm));
   
           size = sock->ops->recvmsg(sock, msg, size, flags, &scm);
           if (size >= 0)
                   scm_recv(sock, msg, &scm, flags);
   
           return size;
   }
   
   
   /*
    *      Read data from a socket. ubuf is a user mode pointer. We make sure the user
    *      area ubuf...ubuf+size-1 is writable before asking the protocol.
    */
   
   static ssize_t sock_read(struct file *file, char *ubuf,
                            size_t size, loff_t *ppos)
   {
           struct socket *sock;
           struct iovec iov;
           struct msghdr msg;
           int flags;
   
           if (ppos != &file->f_pos)
                   return -ESPIPE;
           if (size==0)            /* Match SYS5 behaviour */
                   return 0;
   
           sock = socki_lookup(file->f_dentry->d_inode); 
   
           msg.msg_name=NULL;
           msg.msg_namelen=0;
           msg.msg_iov=&iov;
           msg.msg_iovlen=1;
           msg.msg_control=NULL;
           msg.msg_controllen=0;
           iov.iov_base=ubuf;
           iov.iov_len=size;
           flags = !(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT;
   
           return sock_recvmsg(sock, &msg, size, flags);
   }
   
   
   /*
    *      Write data to a socket. We verify that the user area ubuf..ubuf+size-1
    *      is readable by the user process.
    */
   
   static ssize_t sock_write(struct file *file, const char *ubuf,
                             size_t size, loff_t *ppos)
   {
           struct socket *sock;
           struct msghdr msg;
           struct iovec iov;
           
           if (ppos != &file->f_pos)
                   return -ESPIPE;
           if(size==0)             /* Match SYS5 behaviour */
                   return 0;
   
           sock = socki_lookup(file->f_dentry->d_inode); 
   
           msg.msg_name=NULL;
           msg.msg_namelen=0;
           msg.msg_iov=&iov;
           msg.msg_iovlen=1;
           msg.msg_control=NULL;
           msg.msg_controllen=0;
           msg.msg_flags=!(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT;
           if (sock->type == SOCK_SEQPACKET)
                   msg.msg_flags |= MSG_EOR;
           iov.iov_base=(void *)ubuf;
           iov.iov_len=size;
           
           return sock_sendmsg(sock, &msg, size);
   }
   
   ssize_t sock_sendpage(struct file *file, struct page *page,
                         int offset, size_t size, loff_t *ppos, int more)
   {
           struct socket *sock;
           int flags;
   
           if (ppos != &file->f_pos)
                   return -ESPIPE;
   
           sock = socki_lookup(file->f_dentry->d_inode);
   
           flags = !(file->f_flags & O_NONBLOCK) ? 0 : MSG_DONTWAIT;
           if (more)
                   flags |= MSG_MORE;
   
           return sock->ops->sendpage(sock, page, offset, size, flags);
   }
   
   int sock_readv_writev(int type, struct inode * inode, struct file * file,
                         const struct iovec * iov, long count, long size)
   {
           struct msghdr msg;
           struct socket *sock;
   
           sock = socki_lookup(inode);
   
           msg.msg_name = NULL;
           msg.msg_namelen = 0;
           msg.msg_control = NULL;
           msg.msg_controllen = 0;
           msg.msg_iov = (struct iovec *) iov;
           msg.msg_iovlen = count;
           msg.msg_flags = (file->f_flags & O_NONBLOCK) ? MSG_DONTWAIT : 0;
   
           /* read() does a VERIFY_WRITE */
           if (type == VERIFY_WRITE)
                   return sock_recvmsg(sock, &msg, size, msg.msg_flags);
   
           if (sock->type == SOCK_SEQPACKET)
                   msg.msg_flags |= MSG_EOR;
   
           return sock_sendmsg(sock, &msg, size);
   }
   
   static ssize_t sock_readv(struct file *file, const struct iovec *vector,
                             unsigned long count, loff_t *ppos)
   {
           size_t tot_len = 0;
           int i;
           for (i = 0 ; i < count ; i++)
                   tot_len += vector[i].iov_len;
           return sock_readv_writev(VERIFY_WRITE, file->f_dentry->d_inode,
                                    file, vector, count, tot_len);
   }
           
   static ssize_t sock_writev(struct file *file, const struct iovec *vector,
                              unsigned long count, loff_t *ppos)
   {
           size_t tot_len = 0;
           int i;
           for (i = 0 ; i < count ; i++)
                   tot_len += vector[i].iov_len;
           return sock_readv_writev(VERIFY_READ, file->f_dentry->d_inode,
                                    file, vector, count, tot_len);
   }
   
   /*
    *      With an ioctl arg may well be a user mode pointer, but we don't know what to do
    *      with it - that's up to the protocol still.
    */
   
   int sock_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
              unsigned long arg)
   {
           struct socket *sock;
           int err;
   
           unlock_kernel();
           sock = socki_lookup(inode);
           err = sock->ops->ioctl(sock, cmd, arg);
           lock_kernel();
   
           return err;
   }
   
   
   /* No kernel lock held - perfect */
   static unsigned int sock_poll(struct file *file, poll_table * wait)
   {
           struct socket *sock;
   
           /*
            *      We can't return errors to poll, so it's either yes or no. 
            */
           sock = socki_lookup(file->f_dentry->d_inode);
           return sock->ops->poll(file, sock, wait);
   }
   
   static int sock_mmap(struct file * file, struct vm_area_struct * vma)
   {
           struct socket *sock = socki_lookup(file->f_dentry->d_inode);
   
           return sock->ops->mmap(file, sock, vma);
   }
   
   int sock_close(struct inode *inode, struct file *filp)
   {
           /*
            *      It was possible the inode is NULL we were 
            *      closing an unfinished socket. 
            */
   
           if (!inode)
           {
                   printk(KERN_DEBUG "sock_close: NULL inode\n");
                   return 0;
           }
           sock_fasync(-1, filp, 0);
           sock_release(socki_lookup(inode));
           return 0;
   }
   
   /*
    *      Update the socket async list
    *
    *      Fasync_list locking strategy.
    *
    *      1. fasync_list is modified only under process context socket lock
    *         i.e. under semaphore.
    *      2. fasync_list is used under read_lock(&sk->callback_lock)
    *         or under socket lock.
    *      3. fasync_list can be used from softirq context, so that
    *         modification under socket lock have to be enhanced with
    *         write_lock_bh(&sk->callback_lock).
    *                                                      --ANK (990710)
    */
   
   static int sock_fasync(int fd, struct file *filp, int on)
   {
           struct fasync_struct *fa, *fna=NULL, **prev;
           struct socket *sock;
           struct sock *sk;
   
           if (on)
           {
                   fna=(struct fasync_struct *)kmalloc(sizeof(struct fasync_struct), GFP_KERNEL);
                   if(fna==NULL)
                           return -ENOMEM;
           }
   
           sock = socki_lookup(filp->f_dentry->d_inode);
           
           if ((sk=sock->sk) == NULL) {
                   if (fna)
                           kfree(fna);
                   return -EINVAL;
           }
   
           lock_sock(sk);
   
           prev=&(sock->fasync_list);
   
           for (fa=*prev; fa!=NULL; prev=&fa->fa_next,fa=*prev)
                   if (fa->fa_file==filp)
                           break;
   
           if(on)
           {
                   if(fa!=NULL)
                   {
                           write_lock_bh(&sk->callback_lock);
                           fa->fa_fd=fd;
                           write_unlock_bh(&sk->callback_lock);
   
                           kfree(fna);
                           goto out;
                   }
                   fna->fa_file=filp;
                   fna->fa_fd=fd;
                   fna->magic=FASYNC_MAGIC;
                   fna->fa_next=sock->fasync_list;
                   write_lock_bh(&sk->callback_lock);
                   sock->fasync_list=fna;
                   write_unlock_bh(&sk->callback_lock);
           }
           else
           {
                   if (fa!=NULL)
                   {
                           write_lock_bh(&sk->callback_lock);
                           *prev=fa->fa_next;
                           write_unlock_bh(&sk->callback_lock);
                           kfree(fa);
                   }
           }
   
   out:
           release_sock(sock->sk);
           return 0;
   }
   
   /* This function may be called only under socket lock or callback_lock */
   
   int sock_wake_async(struct socket *sock, int how, int band)
   {
           if (!sock || !sock->fasync_list)
                   return -1;
           switch (how)
           {
           case 1:
                   
                   if (test_bit(SOCK_ASYNC_WAITDATA, &sock->flags))
                           break;
                   goto call_kill;
           case 2:
                   if (!test_and_clear_bit(SOCK_ASYNC_NOSPACE, &sock->flags))
                           break;
                   /* fall through */
           case 0:
           call_kill:
                   __kill_fasync(sock->fasync_list, SIGIO, band);
                   break;
           case 3:
                   __kill_fasync(sock->fasync_list, SIGURG, band);
           }
           return 0;
   }
   
   
   int sock_create(int family, int type, int protocol, struct socket **res)
   {
           int i;
           struct socket *sock;
   
           /*
            *      Check protocol is in range
            */
           if (family < 0 || family >= NPROTO)
                   return -EAFNOSUPPORT;
           if (type < 0 || type >= SOCK_MAX)
                   return -EINVAL;
   
           /* Compatibility.
   
              This uglymoron is moved from INET layer to here to avoid
              deadlock in module load.
            */
           if (family == PF_INET && type == SOCK_PACKET) {
                   static int warned; 
                   if (!warned) {
                           warned = 1;
                           printk(KERN_INFO "%s uses obsolete (PF_INET,SOCK_PACKET)\n", current->comm);
                   }
                   family = PF_PACKET;
           }
                   
   #if defined(CONFIG_KMOD) && defined(CONFIG_NET)
           /* Attempt to load a protocol module if the find failed. 
            * 
            * 12/09/1996 Marcin: But! this makes REALLY only sense, if the user 
            * requested real, full-featured networking support upon configuration.
            * Otherwise module support will break!
            */
           if (net_families[family]==NULL)
           {
                   char module_name[30];
                   sprintf(module_name,"net-pf-%d",family);
                   request_module(module_name);
           }
   #endif
   
           net_family_read_lock();
           if (net_families[family] == NULL) {
                   i = -EAFNOSUPPORT;
                   goto out;
           }
   
   /*
    *      Allocate the socket and allow the family to set things up. if
    *      the protocol is 0, the family is instructed to select an appropriate
    *      default.
    */
   
           if (!(sock = sock_alloc())) 
           {
                   printk(KERN_WARNING "socket: no more sockets\n");
                   i = -ENFILE;            /* Not exactly a match, but its the
                                              closest posix thing */
                   goto out;
           }
   
           sock->type  = type;
   
           if ((i = net_families[family]->create(sock, protocol)) < 0) 
           {
                   sock_release(sock);
                   goto out;
           }
   
           *res = sock;
   
   out:
           net_family_read_unlock();
           return i;
   }
   
   asmlinkage long sys_socket(int family, int type, int protocol)
   {
           int retval;
           struct socket *sock;
   
           retval = sock_create(family, type, protocol, &sock);
           if (retval < 0)
                   goto out;
   
           retval = sock_map_fd(sock);
           if (retval < 0)
                   goto out_release;
   
   out:
           /* It may be already another descriptor 8) Not kernel problem. */
           return retval;
   
   out_release:
           sock_release(sock);
           return retval;
   }
   
   /*
    *      Create a pair of connected sockets.
    */
   
   asmlinkage long sys_socketpair(int family, int type, int protocol, int usockvec[2])
   {
           struct socket *sock1, *sock2;
           int fd1, fd2, err;
   
           /*
            * Obtain the first socket and check if the underlying protocol
            * supports the socketpair call.
            */
   
           err = sock_create(family, type, protocol, &sock1);
           if (err < 0)
                   goto out;
   
           err = sock_create(family, type, protocol, &sock2);
           if (err < 0)
                   goto out_release_1;
   
           err = sock1->ops->socketpair(sock1, sock2);
           if (err < 0) 
                   goto out_release_both;
   
           fd1 = fd2 = -1;
   
           err = sock_map_fd(sock1);
           if (err < 0)
                   goto out_release_both;
           fd1 = err;
   
           err = sock_map_fd(sock2);
           if (err < 0)
                   goto out_close_1;
           fd2 = err;
   
           /* fd1 and fd2 may be already another descriptors.
            * Not kernel problem.
            */
   
           err = put_user(fd1, &usockvec[0]); 
           if (!err)
                   err = put_user(fd2, &usockvec[1]);
           if (!err)
                   return 0;
   
           sys_close(fd2);
           sys_close(fd1);
           return err;
   
   out_close_1:
           sock_release(sock2);
           sys_close(fd1);
           return err;
   
   out_release_both:
           sock_release(sock2);
   out_release_1:
           sock_release(sock1);
   out:
           return err;
   }
   
   
   /*
    *      Bind a name to a socket. Nothing much to do here since it's
    *      the protocol's responsibility to handle the local address.
    *
    *      We move the socket address to kernel space before we call
    *      the protocol layer (having also checked the address is ok).
    */
   
   asmlinkage long sys_bind(int fd, struct sockaddr *umyaddr, int addrlen)
   {
           struct socket *sock;
          char address[MAX_SOCK_ADDR];
          int err;
  
          if((sock = sockfd_lookup(fd,&err))!=NULL)
          {
                  if((err=move_addr_to_kernel(umyaddr,addrlen,address))>=0)
                          err = sock->ops->bind(sock, (struct sockaddr *)address, addrlen);
                  sockfd_put(sock);
          }                       
          return err;
  }
  
  
  /*
   *      Perform a listen. Basically, we allow the protocol to do anything
   *      necessary for a listen, and if that works, we mark the socket as
   *      ready for listening.
   */
  
  asmlinkage long sys_listen(int fd, int backlog)
  {
          struct socket *sock;
          int err;
          
          if ((sock = sockfd_lookup(fd, &err)) != NULL) {
                  if ((unsigned) backlog > SOMAXCONN)
                          backlog = SOMAXCONN;
                  err=sock->ops->listen(sock, backlog);
                  sockfd_put(sock);
          }
          return err;
  }
  
  
  /*
   *      For accept, we attempt to create a new socket, set up the link
   *      with the client, wake up the client, then return the new
   *      connected fd. We collect the address of the connector in kernel
   *      space and move it to user at the very end. This is unclean because
   *      we open the socket then return an error.
   *
   *      1003.1g adds the ability to recvmsg() to query connection pending
   *      status to recvmsg. We need to add that support in a way thats
   *      clean when we restucture accept also.
   */
  
  asmlinkage long sys_accept(int fd, struct sockaddr *upeer_sockaddr, int *upeer_addrlen)
  {
          struct socket *sock, *newsock;
          int err, len;
          char address[MAX_SOCK_ADDR];
  
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
  
          err = -EMFILE;
          if (!(newsock = sock_alloc())) 
                  goto out_put;
  
          newsock->type = sock->type;
          newsock->ops = sock->ops;
  
          err = sock->ops->accept(sock, newsock, sock->file->f_flags);
          if (err < 0)
                  goto out_release;
  
          if (upeer_sockaddr) {
                  if(newsock->ops->getname(newsock, (struct sockaddr *)address, &len, 2)<0) {
                          err = -ECONNABORTED;
                          goto out_release;
                  }
                  err = move_addr_to_user(address, len, upeer_sockaddr, upeer_addrlen);
                  if (err < 0)
                          goto out_release;
          }
  
          /* File flags are not inherited via accept() unlike another OSes. */
  
          if ((err = sock_map_fd(newsock)) < 0)
                  goto out_release;
  
  out_put:
          sockfd_put(sock);
  out:
          return err;
  
  out_release:
          sock_release(newsock);
          goto out_put;
  }
  
  
  /*
   *      Attempt to connect to a socket with the server address.  The address
   *      is in user space so we verify it is OK and move it to kernel space.
   *
   *      For 1003.1g we need to add clean support for a bind to AF_UNSPEC to
   *      break bindings
   *
   *      NOTE: 1003.1g draft 6.3 is broken with respect to AX.25/NetROM and
   *      other SEQPACKET protocols that take time to connect() as it doesn't
   *      include the -EINPROGRESS status for such sockets.
   */
  
  asmlinkage long sys_connect(int fd, struct sockaddr *uservaddr, int addrlen)
  {
          struct socket *sock;
          char address[MAX_SOCK_ADDR];
          int err;
  
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
          err = move_addr_to_kernel(uservaddr, addrlen, address);
          if (err < 0)
                  goto out_put;
          err = sock->ops->connect(sock, (struct sockaddr *) address, addrlen,
                                   sock->file->f_flags);
  out_put:
          sockfd_put(sock);
  out:
          return err;
  }
  
  /*
   *      Get the local address ('name') of a socket object. Move the obtained
   *      name to user space.
   */
  
  asmlinkage long sys_getsockname(int fd, struct sockaddr *usockaddr, int *usockaddr_len)
  {
          struct socket *sock;
          char address[MAX_SOCK_ADDR];
          int len, err;
          
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
          err = sock->ops->getname(sock, (struct sockaddr *)address, &len, 0);
          if (err)
                  goto out_put;
          err = move_addr_to_user(address, len, usockaddr, usockaddr_len);
  
  out_put:
          sockfd_put(sock);
  out:
          return err;
  }
  
  /*
   *      Get the remote address ('name') of a socket object. Move the obtained
   *      name to user space.
   */
  
  asmlinkage long sys_getpeername(int fd, struct sockaddr *usockaddr, int *usockaddr_len)
  {
          struct socket *sock;
          char address[MAX_SOCK_ADDR];
          int len, err;
  
          if ((sock = sockfd_lookup(fd, &err))!=NULL)
          {
                  err = sock->ops->getname(sock, (struct sockaddr *)address, &len, 1);
                  if (!err)
                          err=move_addr_to_user(address,len, usockaddr, usockaddr_len);
                  sockfd_put(sock);
          }
          return err;
  }
  
  /*
   *      Send a datagram to a given address. We move the address into kernel
   *      space and check the user space data area is readable before invoking
   *      the protocol.
   */
  
  asmlinkage long sys_sendto(int fd, void * buff, size_t len, unsigned flags,
                             struct sockaddr *addr, int addr_len)
  {
          struct socket *sock;
          char address[MAX_SOCK_ADDR];
          int err;
          struct msghdr msg;
          struct iovec iov;
          
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
          iov.iov_base=buff;
          iov.iov_len=len;
          msg.msg_name=NULL;
          msg.msg_iov=&iov;
          msg.msg_iovlen=1;
          msg.msg_control=NULL;
          msg.msg_controllen=0;
          msg.msg_namelen=0;
          if(addr)
          {
                  err = move_addr_to_kernel(addr, addr_len, address);
                  if (err < 0)
                          goto out_put;
                  msg.msg_name=address;
                  msg.msg_namelen=addr_len;
          }
          if (sock->file->f_flags & O_NONBLOCK)
                  flags |= MSG_DONTWAIT;
          msg.msg_flags = flags;
          err = sock_sendmsg(sock, &msg, len);
  
  out_put:                
          sockfd_put(sock);
  out:
          return err;
  }
  
  /*
   *      Send a datagram down a socket. 
   */
  
  asmlinkage long sys_send(int fd, void * buff, size_t len, unsigned flags)
  {
          return sys_sendto(fd, buff, len, flags, NULL, 0);
  }
  
  /*
   *      Receive a frame from the socket and optionally record the address of the 
   *      sender. We verify the buffers are writable and if needed move the
   *      sender address from kernel to user space.
   */
  
  asmlinkage long sys_recvfrom(int fd, void * ubuf, size_t size, unsigned flags,
                               struct sockaddr *addr, int *addr_len)
  {
          struct socket *sock;
          struct iovec iov;
          struct msghdr msg;
          char address[MAX_SOCK_ADDR];
          int err,err2;
  
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
  
          msg.msg_control=NULL;
          msg.msg_controllen=0;
          msg.msg_iovlen=1;
          msg.msg_iov=&iov;
          iov.iov_len=size;
          iov.iov_base=ubuf;
          msg.msg_name=address;
          msg.msg_namelen=MAX_SOCK_ADDR;
          if (sock->file->f_flags & O_NONBLOCK)
                  flags |= MSG_DONTWAIT;
          err=sock_recvmsg(sock, &msg, size, flags);
  
          if(err >= 0 && addr != NULL)
          {
                  err2=move_addr_to_user(address, msg.msg_namelen, addr, addr_len);
                  if(err2<0)
                          err=err2;
          }
          sockfd_put(sock);                       
  out:
          return err;
  }
  
  /*
   *      Receive a datagram from a socket. 
   */
  
  asmlinkage long sys_recv(int fd, void * ubuf, size_t size, unsigned flags)
  {
          return sys_recvfrom(fd, ubuf, size, flags, NULL, NULL);
  }
  
  /*
   *      Set a socket option. Because we don't know the option lengths we have
   *      to pass the user mode parameter for the protocols to sort out.
   */
  
  asmlinkage long sys_setsockopt(int fd, int level, int optname, char *optval, int optlen)
  {
          int err;
          struct socket *sock;
  
          if (optlen < 0)
                  return -EINVAL;
                          
          if ((sock = sockfd_lookup(fd, &err))!=NULL)
          {
                  if (level == SOL_SOCKET)
                          err=sock_setsockopt(sock,level,optname,optval,optlen);
                  else
                          err=sock->ops->setsockopt(sock, level, optname, optval, optlen);
                  sockfd_put(sock);
          }
          return err;
  }
  
  /*
   *      Get a socket option. Because we don't know the option lengths we have
   *      to pass a user mode parameter for the protocols to sort out.
   */
  
  asmlinkage long sys_getsockopt(int fd, int level, int optname, char *optval, int *optlen)
  {
          int err;
          struct socket *sock;
  
          if ((sock = sockfd_lookup(fd, &err))!=NULL)
          {
                  if (level == SOL_SOCKET)
                          err=sock_getsockopt(sock,level,optname,optval,optlen);
                  else
                          err=sock->ops->getsockopt(sock, level, optname, optval, optlen);
                  sockfd_put(sock);
          }
          return err;
  }
  
  
  /*
   *      Shutdown a socket.
   */
  
  asmlinkage long sys_shutdown(int fd, int how)
  {
          int err;
          struct socket *sock;
  
          if ((sock = sockfd_lookup(fd, &err))!=NULL)
          {
                  err=sock->ops->shutdown(sock, how);
                  sockfd_put(sock);
          }
          return err;
  }
  
  /*
   *      BSD sendmsg interface
   */
  
  asmlinkage long sys_sendmsg(int fd, struct msghdr *msg, unsigned flags)
  {
          struct socket *sock;
          char address[MAX_SOCK_ADDR];
          struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
          unsigned char ctl[sizeof(struct cmsghdr) + 20]; /* 20 is size of ipv6_pktinfo */
          unsigned char *ctl_buf = ctl;
          struct msghdr msg_sys;
          int err, ctl_len, iov_size, total_len;
          
          err = -EFAULT;
          if (copy_from_user(&msg_sys,msg,sizeof(struct msghdr)))
                  goto out; 
  
          sock = sockfd_lookup(fd, &err);
          if (!sock) 
                  goto out;
  
          /* do not move before msg_sys is valid */
          err = -EMSGSIZE;
          if (msg_sys.msg_iovlen > UIO_MAXIOV)
                  goto out_put;
  
          /* Check whether to allocate the iovec area*/
          err = -ENOMEM;
          iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
          if (msg_sys.msg_iovlen > UIO_FASTIOV) {
                  iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
                  if (!iov)
                          goto out_put;
          }
  
          /* This will also move the address data into kernel space */
          err = verify_iovec(&msg_sys, iov, address, VERIFY_READ);
          if (err < 0) 
                  goto out_freeiov;
          total_len = err;
  
          err = -ENOBUFS;
  
          if (msg_sys.msg_controllen > INT_MAX)
                  goto out_freeiov;
          ctl_len = msg_sys.msg_controllen; 
          if (ctl_len) 
          {
                  if (ctl_len > sizeof(ctl))
                  {
                          ctl_buf = sock_kmalloc(sock->sk, ctl_len, GFP_KERNEL);
                          if (ctl_buf == NULL) 
                                  goto out_freeiov;
                  }
                  err = -EFAULT;
                  if (copy_from_user(ctl_buf, msg_sys.msg_control, ctl_len))
                          goto out_freectl;
                  msg_sys.msg_control = ctl_buf;
          }
          msg_sys.msg_flags = flags;
  
          if (sock->file->f_flags & O_NONBLOCK)
                  msg_sys.msg_flags |= MSG_DONTWAIT;
          err = sock_sendmsg(sock, &msg_sys, total_len);
  
  out_freectl:
          if (ctl_buf != ctl)    
                  sock_kfree_s(sock->sk, ctl_buf, ctl_len);
  out_freeiov:
          if (iov != iovstack)
                  sock_kfree_s(sock->sk, iov, iov_size);
  out_put:
          sockfd_put(sock);
  out:       
          return err;
  }
  
  /*
   *      BSD recvmsg interface
   */
  
  asmlinkage long sys_recvmsg(int fd, struct msghdr *msg, unsigned int flags)
  {
          struct socket *sock;
          struct iovec iovstack[UIO_FASTIOV];
          struct iovec *iov=iovstack;
          struct msghdr msg_sys;
          unsigned long cmsg_ptr;
          int err, iov_size, total_len, len;
  
          /* kernel mode address */
          char addr[MAX_SOCK_ADDR];
  
          /* user mode address pointers */
          struct sockaddr *uaddr;
          int *uaddr_len;
          
          err=-EFAULT;
          if (copy_from_user(&msg_sys,msg,sizeof(struct msghdr)))
                  goto out;
  
          sock = sockfd_lookup(fd, &err);
          if (!sock)
                  goto out;
  
          err = -EMSGSIZE;
          if (msg_sys.msg_iovlen > UIO_MAXIOV)
                  goto out_put;
          
          /* Check whether to allocate the iovec area*/
          err = -ENOMEM;
          iov_size = msg_sys.msg_iovlen * sizeof(struct iovec);
          if (msg_sys.msg_iovlen > UIO_FASTIOV) {
                  iov = sock_kmalloc(sock->sk, iov_size, GFP_KERNEL);
                  if (!iov)
                          goto out_put;
          }
  
          /*
           *      Save the user-mode address (verify_iovec will change the
           *      kernel msghdr to use the kernel address space)
           */
           
          uaddr = msg_sys.msg_name;
          uaddr_len = &msg->msg_namelen;
          err = verify_iovec(&msg_sys, iov, addr, VERIFY_WRITE);
          if (err < 0)
                  goto out_freeiov;
          total_len=err;
  
          cmsg_ptr = (unsigned long)msg_sys.msg_control;
          msg_sys.msg_flags = 0;
          
          if (sock->file->f_flags & O_NONBLOCK)
                  flags |= MSG_DONTWAIT;
          err = sock_recvmsg(sock, &msg_sys, total_len, flags);
          if (err < 0)
                  goto out_freeiov;
          len = err;
  
          if (uaddr != NULL) {
                  err = move_addr_to_user(addr, msg_sys.msg_namelen, uaddr, uaddr_len);
                  if (err < 0)
                          goto out_freeiov;
          }
          err = __put_user(msg_sys.msg_flags, &msg->msg_flags);
          if (err)
                  goto out_freeiov;
          err = __put_user((unsigned long)msg_sys.msg_control-cmsg_ptr, 
                                                           &msg->msg_controllen);
          if (err)
                  goto out_freeiov;
          err = len;
  
  out_freeiov:
          if (iov != iovstack)
                  sock_kfree_s(sock->sk, iov, iov_size);
  out_put:
          sockfd_put(sock);
  out:
          return err;
  }
  
  
  /*
   *      Perform a file control on a socket file descriptor.
   *
   *      Doesn't acquire a fd lock, because no network fcntl
   *      function sleeps currently.
   */
  
  int sock_fcntl(struct file *filp, unsigned int cmd, unsigned long arg)
  {
          struct socket *sock;
  
          sock = socki_lookup (filp->f_dentry->d_inode);
          if (sock && sock->ops)
                  return sock_no_fcntl(sock, cmd, arg);
          return(-EINVAL);
  }
  
  /* Argument list sizes for sys_socketcall */
  #define AL(x) ((x) * sizeof(unsigned long))
  static unsigned char nargs[18]={AL(0),AL(3),AL(3),AL(3),AL(2),AL(3),
                                  AL(3),AL(3),AL(4),AL(4),AL(4),AL(6),
                                  AL(6),AL(2),AL(5),AL(5),AL(3),AL(3)};
  #undef AL
  
  /*
   *      System call vectors. 
   *
   *      Argument checking cleaned up. Saved 20% in size.
   *  This function doesn't need to set the kernel lock because
   *  it is set by the callees. 
   */
  
  asmlinkage long sys_socketcall(int call, unsigned long *args)
  {
          unsigned long a[6];
          unsigned long a0,a1;
          int err;
  
          if(call<1||call>SYS_RECVMSG)
                  return -EINVAL;
  
          /* copy_from_user should be SMP safe. */
          if (copy_from_user(a, args, nargs[call]))
                  return -EFAULT;
                  
          a0=a[0];
          a1=a[1];
          
          switch(call) 
          {
                  case SYS_SOCKET:
                          err = sys_socket(a0,a1,a[2]);
                          break;
                  case SYS_BIND:
                          err = sys_bind(a0,(struct sockaddr *)a1, a[2]);
                          break;
                  case SYS_CONNECT:
                          err = sys_connect(a0, (struct sockaddr *)a1, a[2]);
                          break;
                  case SYS_LISTEN:
                          err = sys_listen(a0,a1);
                          break;
                  case SYS_ACCEPT:
                          err = sys_accept(a0,(struct sockaddr *)a1, (int *)a[2]);
                          break;
                  case SYS_GETSOCKNAME:
                          err = sys_getsockname(a0,(struct sockaddr *)a1, (int *)a[2]);
                          break;
                  case SYS_GETPEERNAME:
                          err = sys_getpeername(a0, (struct sockaddr *)a1, (int *)a[2]);
                          break;
                  case SYS_SOCKETPAIR:
                          err = sys_socketpair(a0,a1, a[2], (int *)a[3]);
                          break;
                  case SYS_SEND:
                          err = sys_send(a0, (void *)a1, a[2], a[3]);
                          break;
                  case SYS_SENDTO:
                          err = sys_sendto(a0,(void *)a1, a[2], a[3],
                                           (struct sockaddr *)a[4], a[5]);
                          break;
                  case SYS_RECV:
                          err = sys_recv(a0, (void *)a1, a[2], a[3]);
                          break;
                  case SYS_RECVFROM:
                          err = sys_recvfrom(a0, (void *)a1, a[2], a[3],
                                             (struct sockaddr *)a[4], (int *)a[5]);
                          break;
                  case SYS_SHUTDOWN:
                          err = sys_shutdown(a0,a1);
                          break;
                  case SYS_SETSOCKOPT:
                          err = sys_setsockopt(a0, a1, a[2], (char *)a[3], a[4]);
                          break;
                  case SYS_GETSOCKOPT:
                          err = sys_getsockopt(a0, a1, a[2], (char *)a[3], (int *)a[4]);
                          break;
                  case SYS_SENDMSG:
                          err = sys_sendmsg(a0, (struct msghdr *) a1, a[2]);
                          break;
                  case SYS_RECVMSG:
                          err = sys_recvmsg(a0, (struct msghdr *) a1, a[2]);
                          break;
                  default:
                          err = -EINVAL;
                          break;
          }
          return err;
  }
  
  /*
   *      This function is called by a protocol handler that wants to
   *      advertise its address family, and have it linked into the
   *      SOCKET module.
   */
  
  int sock_register(struct net_proto_family *ops)
  {
          int err;
  
          if (ops->family >= NPROTO) {
                  printk(KERN_CRIT "protocol %d >= NPROTO(%d)\n", ops->family, NPROTO);
                  return -ENOBUFS;
          }
          net_family_write_lock();
          err = -EEXIST;
          if (net_families[ops->family] == NULL) {
                  net_families[ops->family]=ops;
                  err = 0;
          }
          net_family_write_unlock();
          return err;
  }
  
  /*
   *      This function is called by a protocol handler that wants to
   *      remove its address family, and have it unlinked from the
   *      SOCKET module.
   */
  
  int sock_unregister(int family)
  {
          if (family < 0 || family >= NPROTO)
                  return -1;
  
          net_family_write_lock();
          net_families[family]=NULL;
          net_family_write_unlock();
          return 0;
  }
  
  
  extern void sk_init(void);
  
  #ifdef CONFIG_WAN_ROUTER
  extern void wanrouter_init(void);
  #endif
  
  #ifdef CONFIG_BLUEZ
  extern void bluez_init(void);
  #endif
  
  void __init sock_init(void)
  {
          int i;
  
          printk(KERN_INFO "Linux NET4.0 for Linux 2.4\n");
          printk(KERN_INFO "Based upon Swansea University Computer Society NET3.039\n");
  
          /*
           *      Initialize all address (protocol) families. 
           */
           
          for (i = 0; i < NPROTO; i++) 
                  net_families[i] = NULL;
  
          /*
           *      Initialize sock SLAB cache.
           */
           
          sk_init();
  
  #ifdef SLAB_SKB
          /*
           *      Initialize skbuff SLAB cache 
           */
          skb_init();
  #endif
  
          /*
           *      Wan router layer. 
           */
  
  #ifdef CONFIG_WAN_ROUTER         
          wanrouter_init();
  #endif
  
          /*
           *      Initialize the protocols module. 
           */
  
          register_filesystem(&sock_fs_type);
          sock_mnt = kern_mount(&sock_fs_type);
          /* The real protocol initialization is performed when
           *  do_initcalls is run.  
           */
  
  
          /*
           * The netlink device handler may be needed early.
           */
  
  #ifdef CONFIG_NET
          rtnetlink_init();
  #endif
  #ifdef CONFIG_NETLINK_DEV
          init_netlink();
  #endif
  #ifdef CONFIG_NETFILTER
          netfilter_init();
  #endif
  
  #ifdef CONFIG_BLUEZ
          bluez_init();
  #endif
  }
  
  int socket_get_info(char *buffer, char **start, off_t offset, int length)
  {
          int len, cpu;
          int counter = 0;
  
          for (cpu=0; cpu<smp_num_cpus; cpu++)
                  counter += sockets_in_use[cpu_logical_map(cpu)].counter;
  
          /* It can be negative, by the way. 8) */
          if (counter < 0)
                  counter = 0;
  
          len = sprintf(buffer, "sockets: used %d\n", counter);
          if (offset >= len)
          {
                  *start = buffer;
                  return 0;
          }
          *start = buffer + offset;
          len -= offset;
          if (len > length)
                  len = length;
          if (len < 0)
                  len = 0;
          return len;
  }

Cache object: 825e28c0e53a6c9a01d0dccfccb8b62e