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-rw-r--r--include/linux/sunrpc/xprt.h2
-rw-r--r--net/sunrpc/clnt.c17
-rw-r--r--net/sunrpc/xprt.c61
3 files changed, 76 insertions, 4 deletions
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 30834be..12815f6 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -279,6 +279,7 @@ struct xprt_class {
struct rpc_xprt *xprt_create_transport(struct xprt_create *args);
void xprt_connect(struct rpc_task *task);
void xprt_reserve(struct rpc_task *task);
+void xprt_retry_reserve(struct rpc_task *task);
int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task);
int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task);
void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task);
@@ -334,6 +335,7 @@ int xs_swapper(struct rpc_xprt *xprt, int enable);
#define XPRT_CLOSING (6)
#define XPRT_CONNECTION_ABORT (7)
#define XPRT_CONNECTION_CLOSE (8)
+#define XPRT_CONGESTED (9)
static inline void xprt_set_connected(struct rpc_xprt *xprt)
{
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index b95a0a2..a80ee9b 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1306,6 +1306,8 @@ call_reserve(struct rpc_task *task)
xprt_reserve(task);
}
+static void call_retry_reserve(struct rpc_task *task);
+
/*
* 1b. Grok the result of xprt_reserve()
*/
@@ -1347,7 +1349,7 @@ call_reserveresult(struct rpc_task *task)
case -ENOMEM:
rpc_delay(task, HZ >> 2);
case -EAGAIN: /* woken up; retry */
- task->tk_action = call_reserve;
+ task->tk_action = call_retry_reserve;
return;
case -EIO: /* probably a shutdown */
break;
@@ -1360,6 +1362,19 @@ call_reserveresult(struct rpc_task *task)
}
/*
+ * 1c. Retry reserving an RPC call slot
+ */
+static void
+call_retry_reserve(struct rpc_task *task)
+{
+ dprint_status(task);
+
+ task->tk_status = 0;
+ task->tk_action = call_reserveresult;
+ xprt_retry_reserve(task);
+}
+
+/*
* 2. Bind and/or refresh the credentials
*/
static void
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index b7478d5..745fca3 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -948,6 +948,34 @@ void xprt_transmit(struct rpc_task *task)
spin_unlock_bh(&xprt->transport_lock);
}
+static void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ set_bit(XPRT_CONGESTED, &xprt->state);
+ rpc_sleep_on(&xprt->backlog, task, NULL);
+}
+
+static void xprt_wake_up_backlog(struct rpc_xprt *xprt)
+{
+ if (rpc_wake_up_next(&xprt->backlog) == NULL)
+ clear_bit(XPRT_CONGESTED, &xprt->state);
+}
+
+static bool xprt_throttle_congested(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ bool ret = false;
+
+ if (!test_bit(XPRT_CONGESTED, &xprt->state))
+ goto out;
+ spin_lock(&xprt->reserve_lock);
+ if (test_bit(XPRT_CONGESTED, &xprt->state)) {
+ rpc_sleep_on(&xprt->backlog, task, NULL);
+ ret = true;
+ }
+ spin_unlock(&xprt->reserve_lock);
+out:
+ return ret;
+}
+
static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
{
struct rpc_rqst *req = ERR_PTR(-EAGAIN);
@@ -992,7 +1020,7 @@ void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
task->tk_status = -ENOMEM;
break;
case -EAGAIN:
- rpc_sleep_on(&xprt->backlog, task, NULL);
+ xprt_add_backlog(xprt, task);
dprintk("RPC: waiting for request slot\n");
default:
task->tk_status = -EAGAIN;
@@ -1028,7 +1056,7 @@ static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
memset(req, 0, sizeof(*req)); /* mark unused */
list_add(&req->rq_list, &xprt->free);
}
- rpc_wake_up_next(&xprt->backlog);
+ xprt_wake_up_backlog(xprt);
spin_unlock(&xprt->reserve_lock);
}
@@ -1092,7 +1120,8 @@ EXPORT_SYMBOL_GPL(xprt_free);
* xprt_reserve - allocate an RPC request slot
* @task: RPC task requesting a slot allocation
*
- * If no more slots are available, place the task on the transport's
+ * If the transport is marked as being congested, or if no more
+ * slots are available, place the task on the transport's
* backlog queue.
*/
void xprt_reserve(struct rpc_task *task)
@@ -1107,6 +1136,32 @@ void xprt_reserve(struct rpc_task *task)
task->tk_status = -EAGAIN;
rcu_read_lock();
xprt = rcu_dereference(task->tk_client->cl_xprt);
+ if (!xprt_throttle_congested(xprt, task))
+ xprt->ops->alloc_slot(xprt, task);
+ rcu_read_unlock();
+}
+
+/**
+ * xprt_retry_reserve - allocate an RPC request slot
+ * @task: RPC task requesting a slot allocation
+ *
+ * If no more slots are available, place the task on the transport's
+ * backlog queue.
+ * Note that the only difference with xprt_reserve is that we now
+ * ignore the value of the XPRT_CONGESTED flag.
+ */
+void xprt_retry_reserve(struct rpc_task *task)
+{
+ struct rpc_xprt *xprt;
+
+ task->tk_status = 0;
+ if (task->tk_rqstp != NULL)
+ return;
+
+ task->tk_timeout = 0;
+ task->tk_status = -EAGAIN;
+ rcu_read_lock();
+ xprt = rcu_dereference(task->tk_client->cl_xprt);
xprt->ops->alloc_slot(xprt, task);
rcu_read_unlock();
}
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