SUNRPC,RPCSEC_GSS: fix krb5 sequence numbers.

Use a spinlock to ensure unique sequence numbers when creating krb5 gss tokens.

Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/auth_gss/gss_krb5_wrap.c b/net/sunrpc/auth_gss/gss_krb5_wrap.c
index 346133e..89d1f3e 100644
--- a/net/sunrpc/auth_gss/gss_krb5_wrap.c
+++ b/net/sunrpc/auth_gss/gss_krb5_wrap.c
@@ -128,6 +128,7 @@
 	s32			now;
 	int			headlen;
 	struct page		**tmp_pages;
+	u32			seq_send;
 
 	dprintk("RPC:     gss_wrap_kerberos\n");
 
@@ -206,18 +207,20 @@
 		BUG();
 	}
 
+	spin_lock(&krb5_seq_lock);
+	seq_send = kctx->seq_send++;
+	spin_unlock(&krb5_seq_lock);
+
 	/* XXX would probably be more efficient to compute checksum
 	 * and encrypt at the same time: */
 	if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff,
-			       kctx->seq_send, krb5_hdr + 16, krb5_hdr + 8)))
+			       seq_send, krb5_hdr + 16, krb5_hdr + 8)))
 		goto out_err;
 
 	if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize,
 									pages))
 		goto out_err;
 
-	kctx->seq_send++;
-
 	return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE);
 out_err:
 	return GSS_S_FAILURE;