diff --git a/include/linux/ceph/auth.h b/include/linux/ceph/auth.h
index c9c3b3a..5f33868 100644
--- a/include/linux/ceph/auth.h
+++ b/include/linux/ceph/auth.h
@@ -78,6 +78,8 @@ struct ceph_auth_client {
 	u64 global_id;          /* our unique id in system */
 	const struct ceph_crypto_key *key;     /* our secret key */
 	unsigned want_keys;     /* which services we want */
+
+	struct mutex mutex;
 };
 
 extern struct ceph_auth_client *ceph_auth_init(const char *name,
diff --git a/net/ceph/auth.c b/net/ceph/auth.c
index a22de54..6b923bc 100644
--- a/net/ceph/auth.c
+++ b/net/ceph/auth.c
@@ -47,6 +47,7 @@ struct ceph_auth_client *ceph_auth_init(const char *name, const struct ceph_cryp
 	if (!ac)
 		goto out;
 
+	mutex_init(&ac->mutex);
 	ac->negotiating = true;
 	if (name)
 		ac->name = name;
@@ -73,10 +74,12 @@ void ceph_auth_destroy(struct ceph_auth_client *ac)
  */
 void ceph_auth_reset(struct ceph_auth_client *ac)
 {
+	mutex_lock(&ac->mutex);
 	dout("auth_reset %p\n", ac);
 	if (ac->ops && !ac->negotiating)
 		ac->ops->reset(ac);
 	ac->negotiating = true;
+	mutex_unlock(&ac->mutex);
 }
 
 int ceph_entity_name_encode(const char *name, void **p, void *end)
@@ -102,6 +105,7 @@ int ceph_auth_build_hello(struct ceph_auth_client *ac, void *buf, size_t len)
 	int i, num;
 	int ret;
 
+	mutex_lock(&ac->mutex);
 	dout("auth_build_hello\n");
 	monhdr->have_version = 0;
 	monhdr->session_mon = cpu_to_le16(-1);
@@ -122,15 +126,19 @@ int ceph_auth_build_hello(struct ceph_auth_client *ac, void *buf, size_t len)
 
 	ret = ceph_entity_name_encode(ac->name, &p, end);
 	if (ret < 0)
-		return ret;
+		goto out;
 	ceph_decode_need(&p, end, sizeof(u64), bad);
 	ceph_encode_64(&p, ac->global_id);
 
 	ceph_encode_32(&lenp, p - lenp - sizeof(u32));
-	return p - buf;
+	ret = p - buf;
+out:
+	mutex_unlock(&ac->mutex);
+	return ret;
 
 bad:
-	return -ERANGE;
+	ret = -ERANGE;
+	goto out;
 }
 
 static int ceph_build_auth_request(struct ceph_auth_client *ac,
@@ -151,11 +159,13 @@ static int ceph_build_auth_request(struct ceph_auth_client *ac,
 	if (ret < 0) {
 		pr_err("error %d building auth method %s request\n", ret,
 		       ac->ops->name);
-		return ret;
+		goto out;
 	}
 	dout(" built request %d bytes\n", ret);
 	ceph_encode_32(&p, ret);
-	return p + ret - msg_buf;
+	ret = p + ret - msg_buf;
+out:
+	return ret;
 }
 
 /*
@@ -176,6 +186,7 @@ int ceph_handle_auth_reply(struct ceph_auth_client *ac,
 	int result_msg_len;
 	int ret = -EINVAL;
 
+	mutex_lock(&ac->mutex);
 	dout("handle_auth_reply %p %p\n", p, end);
 	ceph_decode_need(&p, end, sizeof(u32) * 3 + sizeof(u64), bad);
 	protocol = ceph_decode_32(&p);
@@ -227,35 +238,44 @@ int ceph_handle_auth_reply(struct ceph_auth_client *ac,
 
 	ret = ac->ops->handle_reply(ac, result, payload, payload_end);
 	if (ret == -EAGAIN) {
-		return ceph_build_auth_request(ac, reply_buf, reply_len);
+		ret = ceph_build_auth_request(ac, reply_buf, reply_len);
 	} else if (ret) {
 		pr_err("auth method '%s' error %d\n", ac->ops->name, ret);
-		return ret;
 	}
-	return 0;
 
-bad:
-	pr_err("failed to decode auth msg\n");
 out:
+	mutex_unlock(&ac->mutex);
 	return ret;
+
+bad:
+	pr_err("failed to decode auth msg\n");
+	ret = -EINVAL;
+	goto out;
 }
 
 int ceph_build_auth(struct ceph_auth_client *ac,
 		    void *msg_buf, size_t msg_len)
 {
+	int ret = 0;
+
+	mutex_lock(&ac->mutex);
 	if (!ac->protocol)
-		return ceph_auth_build_hello(ac, msg_buf, msg_len);
-	BUG_ON(!ac->ops);
-	if (ac->ops->should_authenticate(ac))
-		return ceph_build_auth_request(ac, msg_buf, msg_len);
-	return 0;
+		ret = ceph_auth_build_hello(ac, msg_buf, msg_len);
+	else if (ac->ops->should_authenticate(ac))
+		ret = ceph_build_auth_request(ac, msg_buf, msg_len);
+	mutex_unlock(&ac->mutex);
+	return ret;
 }
 
 int ceph_auth_is_authenticated(struct ceph_auth_client *ac)
 {
-	if (!ac->ops)
-		return 0;
-	return ac->ops->is_authenticated(ac);
+	int ret = 0;
+
+	mutex_lock(&ac->mutex);
+	if (ac->ops)
+		ret = ac->ops->is_authenticated(ac);
+	mutex_unlock(&ac->mutex);
+	return ret;
 }
 EXPORT_SYMBOL(ceph_auth_is_authenticated);
 
@@ -263,17 +283,23 @@ int ceph_auth_create_authorizer(struct ceph_auth_client *ac,
 				int peer_type,
 				struct ceph_auth_handshake *auth)
 {
+	int ret = 0;
+
+	mutex_lock(&ac->mutex);
 	if (ac->ops && ac->ops->create_authorizer)
-		return ac->ops->create_authorizer(ac, peer_type, auth);
-	return 0;
+		ret = ac->ops->create_authorizer(ac, peer_type, auth);
+	mutex_unlock(&ac->mutex);
+	return ret;
 }
 EXPORT_SYMBOL(ceph_auth_create_authorizer);
 
 void ceph_auth_destroy_authorizer(struct ceph_auth_client *ac,
 				  struct ceph_authorizer *a)
 {
+	mutex_lock(&ac->mutex);
 	if (ac->ops && ac->ops->destroy_authorizer)
 		ac->ops->destroy_authorizer(ac, a);
+	mutex_unlock(&ac->mutex);
 }
 EXPORT_SYMBOL(ceph_auth_destroy_authorizer);
 
@@ -283,8 +309,10 @@ int ceph_auth_update_authorizer(struct ceph_auth_client *ac,
 {
 	int ret = 0;
 
+	mutex_lock(&ac->mutex);
 	if (ac->ops && ac->ops->update_authorizer)
 		ret = ac->ops->update_authorizer(ac, peer_type, a);
+	mutex_unlock(&ac->mutex);
 	return ret;
 }
 EXPORT_SYMBOL(ceph_auth_update_authorizer);
@@ -292,15 +320,21 @@ EXPORT_SYMBOL(ceph_auth_update_authorizer);
 int ceph_auth_verify_authorizer_reply(struct ceph_auth_client *ac,
 				      struct ceph_authorizer *a, size_t len)
 {
+	int ret = 0;
+
+	mutex_lock(&ac->mutex);
 	if (ac->ops && ac->ops->verify_authorizer_reply)
-		return ac->ops->verify_authorizer_reply(ac, a, len);
-	return 0;
+		ret = ac->ops->verify_authorizer_reply(ac, a, len);
+	mutex_unlock(&ac->mutex);
+	return ret;
 }
 EXPORT_SYMBOL(ceph_auth_verify_authorizer_reply);
 
 void ceph_auth_invalidate_authorizer(struct ceph_auth_client *ac, int peer_type)
 {
+	mutex_lock(&ac->mutex);
 	if (ac->ops && ac->ops->invalidate_authorizer)
 		ac->ops->invalidate_authorizer(ac, peer_type);
+	mutex_unlock(&ac->mutex);
 }
 EXPORT_SYMBOL(ceph_auth_invalidate_authorizer);
