re: CIFS: Move readpage code to ops struct

[Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

Hello Pavel Shilovsky,

This is a semi-automatic email about new static checker warnings.

The patch f9c6e234c3ca: "CIFS: Move readpage code to ops struct" from 
Sep 18, 2012, leads to the following Smatch complaint:

fs/cifs/file.c:2954 cifs_read()
	 warn: variable dereferenced before check 'tcon->ses' (see line 2932)

fs/cifs/file.c
  2931		tcon = tlink_tcon(open_file->tlink);
  2932		server = tcon->ses->server;
                         ^^^^^^^^^^^
New dereference.

  2933	
  2934		if (!server->ops->sync_read) {
  2935			free_xid(xid);
  2936			return -ENOSYS;
  2937		}
  2938	
  2939		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_RWPIDFORWARD)
  2940			pid = open_file->pid;
  2941		else
  2942			pid = current->tgid;
  2943	
  2944		if ((file->f_flags & O_ACCMODE) == O_WRONLY)
  2945			cFYI(1, "attempting read on write only file instance");
  2946	
  2947		for (total_read = 0, cur_offset = read_data; read_size > total_read;
  2948		     total_read += bytes_read, cur_offset += bytes_read) {
  2949			current_read_size = min_t(uint, read_size - total_read, rsize);
  2950			/*
  2951			 * For windows me and 9x we do not want to request more than it
  2952			 * negotiated since it will refuse the read then.
  2953			 */
  2954			if ((tcon->ses) && !(tcon->ses->capabilities &
                             ^^^^^^^^^
Old check.

  2955					tcon->ses->server->vals->cap_large_files)) {
  2956				current_read_size = min_t(uint, current_read_size,

regards,
dan carpenter