cifs: throw a warning if negotiate or sess_setup ops are passed NULL server or session pointers

These look pretty cargo-culty to me, but let's be certain. Leave
them in place for now. Pop a WARN if it ever does happen. Also,
move to a more standard idiom for setting the "server" pointer.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>

3 files changed, 16 insertions, 19 deletions

diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index a58dc77cc443..c1c2006376a1 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -375,16 +375,15 @@ CIFSSMBNegotiate(const unsigned int xid, struct cifs_ses *ses)
         int rc = 0;
         int bytes_returned;
         int i;
-        struct TCP_Server_Info *server;
+        struct TCP_Server_Info *server = ses->server;
         u16 count;
         unsigned int secFlags;
 
-        if (ses->server)
-                server = ses->server;
-        else {
-                rc = -EIO;
-                return rc;
+        if (!server) {
+                WARN(1, "%s: server is NULL!\n", __func__);
+                return -EIO;
         }
+
         rc = smb_init(SMB_COM_NEGOTIATE, 0, NULL /* no tcon yet */ ,
                       (void **) &pSMB, (void **) &pSMBr);
         if (rc)
diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c
index 838e2240fc55..e8c5dc9f3386 100644
--- a/fs/cifs/sess.c
+++ b/fs/cifs/sess.c
@@ -576,8 +576,10 @@ CIFS_SessSetup(const unsigned int xid, struct cifs_ses *ses,
         u16 blob_len;
         char *ntlmsspblob = NULL;
 
-        if (ses == NULL)
+        if (ses == NULL) {
+                WARN(1, "%s: ses == NULL!", __func__);
                 return -EINVAL;
+        }
 
         type = ses->server->secType;
         cifs_dbg(FYI, "sess setup type %d\n", type);
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 2b95ce2b54e8..3af66aa18d3b 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -328,7 +328,7 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
         struct kvec iov[1];
         int rc = 0;
         int resp_buftype;
-        struct TCP_Server_Info *server;
+        struct TCP_Server_Info *server = ses->server;
         unsigned int sec_flags;
         u16 temp = 0;
         int blob_offset, blob_length;
@@ -337,11 +337,9 @@ SMB2_negotiate(const unsigned int xid, struct cifs_ses *ses)
 
         cifs_dbg(FYI, "Negotiate protocol\n");
 
-        if (ses->server)
-                server = ses->server;
-        else {
-                rc = -EIO;
-                return rc;
+        if (!server) {
+                WARN(1, "%s: server is NULL!\n", __func__);
+                return -EIO;
         }
 
         rc = small_smb2_init(SMB2_NEGOTIATE, NULL, (void **) &req);
@@ -480,7 +478,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
         int rc = 0;
         int resp_buftype;
         __le32 phase = NtLmNegotiate; /* NTLMSSP, if needed, is multistage */
-        struct TCP_Server_Info *server;
+        struct TCP_Server_Info *server = ses->server;
         unsigned int sec_flags;
         u8 temp = 0;
         u16 blob_length = 0;
@@ -490,11 +488,9 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 
         cifs_dbg(FYI, "Session Setup\n");
 
-        if (ses->server)
-                server = ses->server;
-        else {
-                rc = -EIO;
-                return rc;
+        if (!server) {
+                WARN(1, "%s: server is NULL!\n", __func__);
+                return -EIO;
         }
 
         /*