[bug report] cifs: avoid use of global locks for high contention data

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Shyam Prasad N,

The patch fe67bd563ec2: "cifs: avoid use of global locks for high
contention data" from Jul 27, 2022, leads to the following Smatch
static checker warning:

fs/cifs/connect.c:4641 cifs_tree_connect()
warn: inconsistent returns '&tcon->tc_lock'.
  Locked on  : 4587
  Unlocked on: 4641

fs/cifs/connect.c
  4570  int cifs_tree_connect(const unsigned int xid, struct cifs_tcon *tcon, const struct nls_table *nlsc)
  4571  {
  4572          int rc;
  4573          struct TCP_Server_Info *server = tcon->ses->server;
  4574          const struct smb_version_operations *ops = server->ops;
  4575          struct super_block *sb = NULL;
  4576          struct cifs_sb_info *cifs_sb;
  4577          struct dfs_cache_tgt_list tl = DFS_CACHE_TGT_LIST_INIT(tl);
  4578          char *tree;
  4579          struct dfs_info3_param ref = {0};
  4580  
  4581          /* only send once per connect */
  4582          spin_lock(&tcon->tc_lock);
                           ^^^^^^^^^^^^^

  4583          if (tcon->ses->ses_status != SES_GOOD ||
  4584              (tcon->status != TID_NEW &&
  4585              tcon->status != TID_NEED_TCON)) {
  4586                  spin_unlock(&tcon->ses->ses_lock);
                                     ^^^^^^^^^^^^^^^^^^^
Originally this used to take a lock and then unlock it again but now it
unlocks a different lock.

  4587                  return 0;
  4588          }
  4589          tcon->status = TID_IN_TCON;
  4590          spin_unlock(&tcon->tc_lock);
  4591  

regards,
dan carpenter