cifs: added WARN_ON for all the count decrements

We have a few ref counters srv_count, ses_count and
tc_count which we use for ref counting. Added a WARN_ON
during the decrement of each of these counters to make
sure that they don't go below their minimum values.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index a1e8702..6b6c3e3 100644 (file)
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -1295,6 +1295,9 @@ cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
                return;
        }
 
+       /* srv_count can never go negative */
+       WARN_ON(server->srv_count < 0);
+
        put_net(cifs_net_ns(server));
 
        list_del_init(&server->tcp_ses_list);
@@ -1654,6 +1657,9 @@ void cifs_put_smb_ses(struct cifs_ses *ses)
        }
        spin_unlock(&cifs_tcp_ses_lock);
 
+       /* ses_count can never go negative */
+       WARN_ON(ses->ses_count < 0);
+
        spin_lock(&GlobalMid_Lock);
        if (ses->status == CifsGood)
                ses->status = CifsExiting;
@@ -2021,6 +2027,9 @@ cifs_put_tcon(struct cifs_tcon *tcon)
                return;
        }
 
+       /* tc_count can never go negative */
+       WARN_ON(tcon->tc_count < 0);
+
        if (tcon->use_witness) {
                int rc;
 

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 232d528..ba3c58e 100644 (file)
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -2910,6 +2910,8 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses,
                /* ipc tcons are not refcounted */
                spin_lock(&cifs_tcp_ses_lock);
                tcon->tc_count--;
+               /* tc_count can never go negative */
+               WARN_ON(tcon->tc_count < 0);
                spin_unlock(&cifs_tcp_ses_lock);
        }
        kfree(utf16_path);