SUNRPC: Provide a new API for registering transport implementations
To allow transport capabilities to be loaded dynamically, provide an API
for registering and unregistering the transports with the RPC client.
Eventually xprt_create_transport() will be changed to search the list of
registered transports when initializing a fresh transport.
Signed-off-by: Chuck Lever <[email protected]>
Signed-off-by: Tom Talpey <[email protected]>
---
include/linux/sunrpc/xprt.h | 11 ++++++
net/sunrpc/xprt.c | 75 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+)
Index: kernel/include/linux/sunrpc/xprt.h
===================================================================
--- kernel.orig/include/linux/sunrpc/xprt.h
+++ kernel/include/linux/sunrpc/xprt.h
@@ -208,6 +208,15 @@ struct rpc_xprtsock_create {
struct rpc_timeout * timeout; /* optional timeout parameters */
};
+struct xprt_class {
+ struct list_head list;
+ unsigned short family;
+ int protocol;
+ struct rpc_xprt * (*setup)(struct rpc_xprtsock_create *);
+ struct module *owner;
+ char name[32];
+};
+
/*
* Transport operations used by ULPs
*/
@@ -239,6 +248,8 @@ static inline __be32 *xprt_skip_transpor
/*
* Transport switch helper functions
*/
+int xprt_register_transport(struct xprt_class *type);
+int xprt_unregister_transport(struct xprt_class *type);
void xprt_set_retrans_timeout_def(struct rpc_task *task);
void xprt_set_retrans_timeout_rtt(struct rpc_task *task);
void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status);
Index: kernel/net/sunrpc/xprt.c
===================================================================
--- kernel.orig/net/sunrpc/xprt.c
+++ kernel/net/sunrpc/xprt.c
@@ -62,6 +62,9 @@ static inline void do_xprt_reserve(struc
static void xprt_connect_status(struct rpc_task *task);
static int __xprt_get_cong(struct rpc_xprt *, struct rpc_task *);
+static spinlock_t xprt_list_lock = SPIN_LOCK_UNLOCKED;
+static LIST_HEAD(xprt_list);
+
/*
* The transport code maintains an estimate on the maximum number of out-
* standing RPC requests, using a smoothed version of the congestion
@@ -81,6 +84,78 @@ static int __xprt_get_cong(struct r
#define RPCXPRT_CONGESTED(xprt) ((xprt)->cong >= (xprt)->cwnd)
/**
+ * xprt_register_transport - register a transport implementation
+ * @transport: transport to register
+ *
+ * If a transport implementation is loaded as a kernel module, it can
+ * call this interface to make itself known to the RPC client.
+ *
+ * Returns:
+ * 0: transport successfully registered
+ * -EEXIST: transport already registered
+ * -EINVAL: transport module being unloaded
+ */
+int xprt_register_transport(struct xprt_class *transport)
+{
+ struct xprt_class *t;
+ int result;
+
+ result = -EEXIST;
+ spin_lock(&xprt_list_lock);
+ list_for_each_entry(t, &xprt_list, list) {
+ /* don't register the same transport class twice */
+ if (t == transport)
+ goto out;
+ }
+
+ result = -EINVAL;
+ if (try_module_get(THIS_MODULE)) {
+ list_add_tail(&transport->list, &xprt_list);
+ printk(KERN_INFO "RPC: Registered %s transport module.\n",
+ transport->name);
+ result = 0;
+ }
+
+out:
+ spin_unlock(&xprt_list_lock);
+ return result;
+}
+EXPORT_SYMBOL_GPL(xprt_register_transport);
+
+/**
+ * xprt_unregister_transport - unregister a transport implementation
+ * transport: transport to unregister
+ *
+ * Returns:
+ * 0: transport successfully unregistered
+ * -ENOENT: transport never registered
+ */
+int xprt_unregister_transport(struct xprt_class *transport)
+{
+ struct xprt_class *t;
+ int result;
+
+ result = 0;
+ spin_lock(&xprt_list_lock);
+ list_for_each_entry(t, &xprt_list, list) {
+ if (t == transport) {
+ printk(KERN_INFO
+ "RPC: Unregistered %s transport module.\n",
+ transport->name);
+ list_del_init(&transport->list);
+ module_put(THIS_MODULE);
+ goto out;
+ }
+ }
+ result = -ENOENT;
+
+out:
+ spin_unlock(&xprt_list_lock);
+ return result;
+}
+EXPORT_SYMBOL_GPL(xprt_unregister_transport);
+
+/**
* xprt_reserve_xprt - serialize write access to transports
* @task: task that is requesting access to the transport
*
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