1 files changed, 61 insertions, 3 deletions

diff --git a/net/sunrpc/auth_gss/auth_gss.c b/net/sunrpc/auth_gss/auth_gss.c
index 51aa27d32b5a..e451d104a434 100644
--- a/net/sunrpc/auth_gss/auth_gss.c
+++ b/net/sunrpc/auth_gss/auth_gss.c
@@ -75,7 +75,12 @@ struct gss_auth {
 	struct dentry *dentry;
 };
 
+/* pipe_version >= 0 if and only if someone has a pipe open. */
+static int pipe_version = -1;
 static atomic_t pipe_users = ATOMIC_INIT(0);
+static DEFINE_SPINLOCK(pipe_version_lock);
+static struct rpc_wait_queue pipe_version_rpc_waitqueue;
+static DECLARE_WAIT_QUEUE_HEAD(pipe_version_waitqueue);
 
 static void gss_free_ctx(struct gss_cl_ctx *);
 static struct rpc_pipe_ops gss_upcall_ops;
@@ -234,12 +239,34 @@ struct gss_upcall_msg {
 	struct gss_cl_ctx *ctx;
 };
 
+static int get_pipe_version(void)
+{
+	int ret;
+
+	spin_lock(&pipe_version_lock);
+	if (pipe_version >= 0) {
+		atomic_inc(&pipe_users);
+		ret = 0;
+	} else
+		ret = -EAGAIN;
+	spin_unlock(&pipe_version_lock);
+	return ret;
+}
+
+static void put_pipe_version(void)
+{
+	if (atomic_dec_and_lock(&pipe_users, &pipe_version_lock)) {
+		pipe_version = -1;
+		spin_unlock(&pipe_version_lock);
+	}
+}
+
 static void
 gss_release_msg(struct gss_upcall_msg *gss_msg)
 {
 	if (!atomic_dec_and_test(&gss_msg->count))
 		return;
-	atomic_dec(&pipe_users);
+	put_pipe_version();
 	BUG_ON(!list_empty(&gss_msg->list));
 	if (gss_msg->ctx != NULL)
 		gss_put_ctx(gss_msg->ctx);
@@ -330,11 +357,16 @@ static inline struct gss_upcall_msg *
 gss_alloc_msg(struct gss_auth *gss_auth, uid_t uid)
 {
 	struct gss_upcall_msg *gss_msg;
+	int vers;
 
 	gss_msg = kzalloc(sizeof(*gss_msg), GFP_NOFS);
 	if (gss_msg == NULL)
 		return ERR_PTR(-ENOMEM);
-	atomic_inc(&pipe_users);
+	vers = get_pipe_version();
+	if (vers < 0) {
+		kfree(gss_msg);
+		return ERR_PTR(vers);
+	}
 	INIT_LIST_HEAD(&gss_msg->list);
 	rpc_init_wait_queue(&gss_msg->rpc_waitqueue, "RPCSEC_GSS upcall waitq");
 	init_waitqueue_head(&gss_msg->waitqueue);
@@ -400,6 +432,14 @@ gss_refresh_upcall(struct rpc_task *task)
 	dprintk("RPC: %5u gss_refresh_upcall for uid %u\n", task->tk_pid,
 								cred->cr_uid);
 	gss_msg = gss_setup_upcall(task->tk_client, gss_auth, cred);
+	if (IS_ERR(gss_msg) == -EAGAIN) {
+		/* XXX: warning on the first, under the assumption we
+		 * shouldn't normally hit this case on a refresh. */
+		warn_gssd();
+		task->tk_timeout = 15*HZ;
+		rpc_sleep_on(&pipe_version_rpc_waitqueue, task, NULL);
+		return 0;
+	}
 	if (IS_ERR(gss_msg)) {
 		err = PTR_ERR(gss_msg);
 		goto out;
@@ -437,7 +477,17 @@ gss_create_upcall(struct gss_auth *gss_auth, struct gss_cred *gss_cred)
 	int err = 0;
 
 	dprintk("RPC:       gss_upcall for uid %u\n", cred->cr_uid);
+retry:
 	gss_msg = gss_setup_upcall(gss_auth->client, gss_auth, cred);
+	if (PTR_ERR(gss_msg) == -EAGAIN) {
+		err = wait_event_interruptible_timeout(pipe_version_waitqueue,
+				pipe_version >= 0, 15*HZ);
+		if (err)
+			goto out;
+		if (pipe_version < 0)
+			warn_gssd();
+		goto retry;
+	}
 	if (IS_ERR(gss_msg)) {
 		err = PTR_ERR(gss_msg);
 		goto out;
@@ -562,7 +612,14 @@ out:
 static int
 gss_pipe_open(struct inode *inode)
 {
+	spin_lock(&pipe_version_lock);
+	if (pipe_version < 0) {
+		pipe_version = 0;
+		rpc_wake_up(&pipe_version_rpc_waitqueue);
+		wake_up(&pipe_version_waitqueue);
+	}
 	atomic_inc(&pipe_users);
+	spin_unlock(&pipe_version_lock);
 	return 0;
 }
 
@@ -586,7 +643,7 @@ gss_pipe_release(struct inode *inode)
 	}
 	spin_unlock(&inode->i_lock);
 
-	atomic_dec(&pipe_users);
+	put_pipe_version();
 }
 
 static void
@@ -1379,6 +1436,7 @@ static int __init init_rpcsec_gss(void)
 	err = gss_svc_init();
 	if (err)
 		goto out_unregister;
+	rpc_init_wait_queue(&pipe_version_rpc_waitqueue, "gss pipe version");
 	return 0;
 out_unregister:
 	rpcauth_unregister(&authgss_ops);