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-rw-r--r--net/sunrpc/xprt.c2192
1 files changed, 2192 insertions, 0 deletions
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
new file mode 100644
index 0000000000..ab453ede54
--- /dev/null
+++ b/net/sunrpc/xprt.c
@@ -0,0 +1,2192 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/net/sunrpc/xprt.c
+ *
+ * This is a generic RPC call interface supporting congestion avoidance,
+ * and asynchronous calls.
+ *
+ * The interface works like this:
+ *
+ * - When a process places a call, it allocates a request slot if
+ * one is available. Otherwise, it sleeps on the backlog queue
+ * (xprt_reserve).
+ * - Next, the caller puts together the RPC message, stuffs it into
+ * the request struct, and calls xprt_transmit().
+ * - xprt_transmit sends the message and installs the caller on the
+ * transport's wait list. At the same time, if a reply is expected,
+ * it installs a timer that is run after the packet's timeout has
+ * expired.
+ * - When a packet arrives, the data_ready handler walks the list of
+ * pending requests for that transport. If a matching XID is found, the
+ * caller is woken up, and the timer removed.
+ * - When no reply arrives within the timeout interval, the timer is
+ * fired by the kernel and runs xprt_timer(). It either adjusts the
+ * timeout values (minor timeout) or wakes up the caller with a status
+ * of -ETIMEDOUT.
+ * - When the caller receives a notification from RPC that a reply arrived,
+ * it should release the RPC slot, and process the reply.
+ * If the call timed out, it may choose to retry the operation by
+ * adjusting the initial timeout value, and simply calling rpc_call
+ * again.
+ *
+ * Support for async RPC is done through a set of RPC-specific scheduling
+ * primitives that `transparently' work for processes as well as async
+ * tasks that rely on callbacks.
+ *
+ * Copyright (C) 1995-1997, Olaf Kirch <okir@monad.swb.de>
+ *
+ * Transport switch API copyright (C) 2005, Chuck Lever <cel@netapp.com>
+ */
+
+#include <linux/module.h>
+
+#include <linux/types.h>
+#include <linux/interrupt.h>
+#include <linux/workqueue.h>
+#include <linux/net.h>
+#include <linux/ktime.h>
+
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/metrics.h>
+#include <linux/sunrpc/bc_xprt.h>
+#include <linux/rcupdate.h>
+#include <linux/sched/mm.h>
+
+#include <trace/events/sunrpc.h>
+
+#include "sunrpc.h"
+#include "sysfs.h"
+#include "fail.h"
+
+/*
+ * Local variables
+ */
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY RPCDBG_XPRT
+#endif
+
+/*
+ * Local functions
+ */
+static void xprt_init(struct rpc_xprt *xprt, struct net *net);
+static __be32 xprt_alloc_xid(struct rpc_xprt *xprt);
+static void xprt_destroy(struct rpc_xprt *xprt);
+static void xprt_request_init(struct rpc_task *task);
+static int xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf);
+
+static DEFINE_SPINLOCK(xprt_list_lock);
+static LIST_HEAD(xprt_list);
+
+static unsigned long xprt_request_timeout(const struct rpc_rqst *req)
+{
+ unsigned long timeout = jiffies + req->rq_timeout;
+
+ if (time_before(timeout, req->rq_majortimeo))
+ return timeout;
+ return req->rq_majortimeo;
+}
+
+/**
+ * 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->ident == transport->ident)
+ goto out;
+ }
+
+ 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);
+ goto out;
+ }
+ }
+ result = -ENOENT;
+
+out:
+ spin_unlock(&xprt_list_lock);
+ return result;
+}
+EXPORT_SYMBOL_GPL(xprt_unregister_transport);
+
+static void
+xprt_class_release(const struct xprt_class *t)
+{
+ module_put(t->owner);
+}
+
+static const struct xprt_class *
+xprt_class_find_by_ident_locked(int ident)
+{
+ const struct xprt_class *t;
+
+ list_for_each_entry(t, &xprt_list, list) {
+ if (t->ident != ident)
+ continue;
+ if (!try_module_get(t->owner))
+ continue;
+ return t;
+ }
+ return NULL;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_ident(int ident)
+{
+ const struct xprt_class *t;
+
+ spin_lock(&xprt_list_lock);
+ t = xprt_class_find_by_ident_locked(ident);
+ spin_unlock(&xprt_list_lock);
+ return t;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid_locked(const char *netid)
+{
+ const struct xprt_class *t;
+ unsigned int i;
+
+ list_for_each_entry(t, &xprt_list, list) {
+ for (i = 0; t->netid[i][0] != '\0'; i++) {
+ if (strcmp(t->netid[i], netid) != 0)
+ continue;
+ if (!try_module_get(t->owner))
+ continue;
+ return t;
+ }
+ }
+ return NULL;
+}
+
+static const struct xprt_class *
+xprt_class_find_by_netid(const char *netid)
+{
+ const struct xprt_class *t;
+
+ spin_lock(&xprt_list_lock);
+ t = xprt_class_find_by_netid_locked(netid);
+ if (!t) {
+ spin_unlock(&xprt_list_lock);
+ request_module("rpc%s", netid);
+ spin_lock(&xprt_list_lock);
+ t = xprt_class_find_by_netid_locked(netid);
+ }
+ spin_unlock(&xprt_list_lock);
+ return t;
+}
+
+/**
+ * xprt_find_transport_ident - convert a netid into a transport identifier
+ * @netid: transport to load
+ *
+ * Returns:
+ * > 0: transport identifier
+ * -ENOENT: transport module not available
+ */
+int xprt_find_transport_ident(const char *netid)
+{
+ const struct xprt_class *t;
+ int ret;
+
+ t = xprt_class_find_by_netid(netid);
+ if (!t)
+ return -ENOENT;
+ ret = t->ident;
+ xprt_class_release(t);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_find_transport_ident);
+
+static void xprt_clear_locked(struct rpc_xprt *xprt)
+{
+ xprt->snd_task = NULL;
+ if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state))
+ clear_bit_unlock(XPRT_LOCKED, &xprt->state);
+ else
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+}
+
+/**
+ * xprt_reserve_xprt - serialize write access to transports
+ * @task: task that is requesting access to the transport
+ * @xprt: pointer to the target transport
+ *
+ * This prevents mixing the payload of separate requests, and prevents
+ * transport connects from colliding with writes. No congestion control
+ * is provided.
+ */
+int xprt_reserve_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
+ if (task == xprt->snd_task)
+ goto out_locked;
+ goto out_sleep;
+ }
+ if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+ goto out_unlock;
+ xprt->snd_task = task;
+
+out_locked:
+ trace_xprt_reserve_xprt(xprt, task);
+ return 1;
+
+out_unlock:
+ xprt_clear_locked(xprt);
+out_sleep:
+ task->tk_status = -EAGAIN;
+ if (RPC_IS_SOFT(task))
+ rpc_sleep_on_timeout(&xprt->sending, task, NULL,
+ xprt_request_timeout(req));
+ else
+ rpc_sleep_on(&xprt->sending, task, NULL);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xprt_reserve_xprt);
+
+static bool
+xprt_need_congestion_window_wait(struct rpc_xprt *xprt)
+{
+ return test_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+static void
+xprt_set_congestion_window_wait(struct rpc_xprt *xprt)
+{
+ if (!list_empty(&xprt->xmit_queue)) {
+ /* Peek at head of queue to see if it can make progress */
+ if (list_first_entry(&xprt->xmit_queue, struct rpc_rqst,
+ rq_xmit)->rq_cong)
+ return;
+ }
+ set_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+static void
+xprt_test_and_clear_congestion_window_wait(struct rpc_xprt *xprt)
+{
+ if (!RPCXPRT_CONGESTED(xprt))
+ clear_bit(XPRT_CWND_WAIT, &xprt->state);
+}
+
+/*
+ * xprt_reserve_xprt_cong - serialize write access to transports
+ * @task: task that is requesting access to the transport
+ *
+ * Same as xprt_reserve_xprt, but Van Jacobson congestion control is
+ * integrated into the decision of whether a request is allowed to be
+ * woken up and given access to the transport.
+ * Note that the lock is only granted if we know there are free slots.
+ */
+int xprt_reserve_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state)) {
+ if (task == xprt->snd_task)
+ goto out_locked;
+ goto out_sleep;
+ }
+ if (req == NULL) {
+ xprt->snd_task = task;
+ goto out_locked;
+ }
+ if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+ goto out_unlock;
+ if (!xprt_need_congestion_window_wait(xprt)) {
+ xprt->snd_task = task;
+ goto out_locked;
+ }
+out_unlock:
+ xprt_clear_locked(xprt);
+out_sleep:
+ task->tk_status = -EAGAIN;
+ if (RPC_IS_SOFT(task))
+ rpc_sleep_on_timeout(&xprt->sending, task, NULL,
+ xprt_request_timeout(req));
+ else
+ rpc_sleep_on(&xprt->sending, task, NULL);
+ return 0;
+out_locked:
+ trace_xprt_reserve_cong(xprt, task);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(xprt_reserve_xprt_cong);
+
+static inline int xprt_lock_write(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ int retval;
+
+ if (test_bit(XPRT_LOCKED, &xprt->state) && xprt->snd_task == task)
+ return 1;
+ spin_lock(&xprt->transport_lock);
+ retval = xprt->ops->reserve_xprt(xprt, task);
+ spin_unlock(&xprt->transport_lock);
+ return retval;
+}
+
+static bool __xprt_lock_write_func(struct rpc_task *task, void *data)
+{
+ struct rpc_xprt *xprt = data;
+
+ xprt->snd_task = task;
+ return true;
+}
+
+static void __xprt_lock_write_next(struct rpc_xprt *xprt)
+{
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+ return;
+ if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+ goto out_unlock;
+ if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
+ __xprt_lock_write_func, xprt))
+ return;
+out_unlock:
+ xprt_clear_locked(xprt);
+}
+
+static void __xprt_lock_write_next_cong(struct rpc_xprt *xprt)
+{
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+ return;
+ if (test_bit(XPRT_WRITE_SPACE, &xprt->state))
+ goto out_unlock;
+ if (xprt_need_congestion_window_wait(xprt))
+ goto out_unlock;
+ if (rpc_wake_up_first_on_wq(xprtiod_workqueue, &xprt->sending,
+ __xprt_lock_write_func, xprt))
+ return;
+out_unlock:
+ xprt_clear_locked(xprt);
+}
+
+/**
+ * xprt_release_xprt - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL. No congestion control is provided.
+ */
+void xprt_release_xprt(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ if (xprt->snd_task == task) {
+ xprt_clear_locked(xprt);
+ __xprt_lock_write_next(xprt);
+ }
+ trace_xprt_release_xprt(xprt, task);
+}
+EXPORT_SYMBOL_GPL(xprt_release_xprt);
+
+/**
+ * xprt_release_xprt_cong - allow other requests to use a transport
+ * @xprt: transport with other tasks potentially waiting
+ * @task: task that is releasing access to the transport
+ *
+ * Note that "task" can be NULL. Another task is awoken to use the
+ * transport if the transport's congestion window allows it.
+ */
+void xprt_release_xprt_cong(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ if (xprt->snd_task == task) {
+ xprt_clear_locked(xprt);
+ __xprt_lock_write_next_cong(xprt);
+ }
+ trace_xprt_release_cong(xprt, task);
+}
+EXPORT_SYMBOL_GPL(xprt_release_xprt_cong);
+
+void xprt_release_write(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ if (xprt->snd_task != task)
+ return;
+ spin_lock(&xprt->transport_lock);
+ xprt->ops->release_xprt(xprt, task);
+ spin_unlock(&xprt->transport_lock);
+}
+
+/*
+ * Van Jacobson congestion avoidance. Check if the congestion window
+ * overflowed. Put the task to sleep if this is the case.
+ */
+static int
+__xprt_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ if (req->rq_cong)
+ return 1;
+ trace_xprt_get_cong(xprt, req->rq_task);
+ if (RPCXPRT_CONGESTED(xprt)) {
+ xprt_set_congestion_window_wait(xprt);
+ return 0;
+ }
+ req->rq_cong = 1;
+ xprt->cong += RPC_CWNDSCALE;
+ return 1;
+}
+
+/*
+ * Adjust the congestion window, and wake up the next task
+ * that has been sleeping due to congestion
+ */
+static void
+__xprt_put_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ if (!req->rq_cong)
+ return;
+ req->rq_cong = 0;
+ xprt->cong -= RPC_CWNDSCALE;
+ xprt_test_and_clear_congestion_window_wait(xprt);
+ trace_xprt_put_cong(xprt, req->rq_task);
+ __xprt_lock_write_next_cong(xprt);
+}
+
+/**
+ * xprt_request_get_cong - Request congestion control credits
+ * @xprt: pointer to transport
+ * @req: pointer to RPC request
+ *
+ * Useful for transports that require congestion control.
+ */
+bool
+xprt_request_get_cong(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ bool ret = false;
+
+ if (req->rq_cong)
+ return true;
+ spin_lock(&xprt->transport_lock);
+ ret = __xprt_get_cong(xprt, req) != 0;
+ spin_unlock(&xprt->transport_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_request_get_cong);
+
+/**
+ * xprt_release_rqst_cong - housekeeping when request is complete
+ * @task: RPC request that recently completed
+ *
+ * Useful for transports that require congestion control.
+ */
+void xprt_release_rqst_cong(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ __xprt_put_cong(req->rq_xprt, req);
+}
+EXPORT_SYMBOL_GPL(xprt_release_rqst_cong);
+
+static void xprt_clear_congestion_window_wait_locked(struct rpc_xprt *xprt)
+{
+ if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state))
+ __xprt_lock_write_next_cong(xprt);
+}
+
+/*
+ * Clear the congestion window wait flag and wake up the next
+ * entry on xprt->sending
+ */
+static void
+xprt_clear_congestion_window_wait(struct rpc_xprt *xprt)
+{
+ if (test_and_clear_bit(XPRT_CWND_WAIT, &xprt->state)) {
+ spin_lock(&xprt->transport_lock);
+ __xprt_lock_write_next_cong(xprt);
+ spin_unlock(&xprt->transport_lock);
+ }
+}
+
+/**
+ * xprt_adjust_cwnd - adjust transport congestion window
+ * @xprt: pointer to xprt
+ * @task: recently completed RPC request used to adjust window
+ * @result: result code of completed RPC request
+ *
+ * The transport code maintains an estimate on the maximum number of out-
+ * standing RPC requests, using a smoothed version of the congestion
+ * avoidance implemented in 44BSD. This is basically the Van Jacobson
+ * congestion algorithm: If a retransmit occurs, the congestion window is
+ * halved; otherwise, it is incremented by 1/cwnd when
+ *
+ * - a reply is received and
+ * - a full number of requests are outstanding and
+ * - the congestion window hasn't been updated recently.
+ */
+void xprt_adjust_cwnd(struct rpc_xprt *xprt, struct rpc_task *task, int result)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ unsigned long cwnd = xprt->cwnd;
+
+ if (result >= 0 && cwnd <= xprt->cong) {
+ /* The (cwnd >> 1) term makes sure
+ * the result gets rounded properly. */
+ cwnd += (RPC_CWNDSCALE * RPC_CWNDSCALE + (cwnd >> 1)) / cwnd;
+ if (cwnd > RPC_MAXCWND(xprt))
+ cwnd = RPC_MAXCWND(xprt);
+ __xprt_lock_write_next_cong(xprt);
+ } else if (result == -ETIMEDOUT) {
+ cwnd >>= 1;
+ if (cwnd < RPC_CWNDSCALE)
+ cwnd = RPC_CWNDSCALE;
+ }
+ dprintk("RPC: cong %ld, cwnd was %ld, now %ld\n",
+ xprt->cong, xprt->cwnd, cwnd);
+ xprt->cwnd = cwnd;
+ __xprt_put_cong(xprt, req);
+}
+EXPORT_SYMBOL_GPL(xprt_adjust_cwnd);
+
+/**
+ * xprt_wake_pending_tasks - wake all tasks on a transport's pending queue
+ * @xprt: transport with waiting tasks
+ * @status: result code to plant in each task before waking it
+ *
+ */
+void xprt_wake_pending_tasks(struct rpc_xprt *xprt, int status)
+{
+ if (status < 0)
+ rpc_wake_up_status(&xprt->pending, status);
+ else
+ rpc_wake_up(&xprt->pending);
+}
+EXPORT_SYMBOL_GPL(xprt_wake_pending_tasks);
+
+/**
+ * xprt_wait_for_buffer_space - wait for transport output buffer to clear
+ * @xprt: transport
+ *
+ * Note that we only set the timer for the case of RPC_IS_SOFT(), since
+ * we don't in general want to force a socket disconnection due to
+ * an incomplete RPC call transmission.
+ */
+void xprt_wait_for_buffer_space(struct rpc_xprt *xprt)
+{
+ set_bit(XPRT_WRITE_SPACE, &xprt->state);
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_buffer_space);
+
+static bool
+xprt_clear_write_space_locked(struct rpc_xprt *xprt)
+{
+ if (test_and_clear_bit(XPRT_WRITE_SPACE, &xprt->state)) {
+ __xprt_lock_write_next(xprt);
+ dprintk("RPC: write space: waking waiting task on "
+ "xprt %p\n", xprt);
+ return true;
+ }
+ return false;
+}
+
+/**
+ * xprt_write_space - wake the task waiting for transport output buffer space
+ * @xprt: transport with waiting tasks
+ *
+ * Can be called in a soft IRQ context, so xprt_write_space never sleeps.
+ */
+bool xprt_write_space(struct rpc_xprt *xprt)
+{
+ bool ret;
+
+ if (!test_bit(XPRT_WRITE_SPACE, &xprt->state))
+ return false;
+ spin_lock(&xprt->transport_lock);
+ ret = xprt_clear_write_space_locked(xprt);
+ spin_unlock(&xprt->transport_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_write_space);
+
+static unsigned long xprt_abs_ktime_to_jiffies(ktime_t abstime)
+{
+ s64 delta = ktime_to_ns(ktime_get() - abstime);
+ return likely(delta >= 0) ?
+ jiffies - nsecs_to_jiffies(delta) :
+ jiffies + nsecs_to_jiffies(-delta);
+}
+
+static unsigned long xprt_calc_majortimeo(struct rpc_rqst *req)
+{
+ const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
+ unsigned long majortimeo = req->rq_timeout;
+
+ if (to->to_exponential)
+ majortimeo <<= to->to_retries;
+ else
+ majortimeo += to->to_increment * to->to_retries;
+ if (majortimeo > to->to_maxval || majortimeo == 0)
+ majortimeo = to->to_maxval;
+ return majortimeo;
+}
+
+static void xprt_reset_majortimeo(struct rpc_rqst *req)
+{
+ req->rq_majortimeo += xprt_calc_majortimeo(req);
+}
+
+static void xprt_reset_minortimeo(struct rpc_rqst *req)
+{
+ req->rq_minortimeo += req->rq_timeout;
+}
+
+static void xprt_init_majortimeo(struct rpc_task *task, struct rpc_rqst *req)
+{
+ unsigned long time_init;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (likely(xprt && xprt_connected(xprt)))
+ time_init = jiffies;
+ else
+ time_init = xprt_abs_ktime_to_jiffies(task->tk_start);
+ req->rq_timeout = task->tk_client->cl_timeout->to_initval;
+ req->rq_majortimeo = time_init + xprt_calc_majortimeo(req);
+ req->rq_minortimeo = time_init + req->rq_timeout;
+}
+
+/**
+ * xprt_adjust_timeout - adjust timeout values for next retransmit
+ * @req: RPC request containing parameters to use for the adjustment
+ *
+ */
+int xprt_adjust_timeout(struct rpc_rqst *req)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+ const struct rpc_timeout *to = req->rq_task->tk_client->cl_timeout;
+ int status = 0;
+
+ if (time_before(jiffies, req->rq_majortimeo)) {
+ if (time_before(jiffies, req->rq_minortimeo))
+ return status;
+ if (to->to_exponential)
+ req->rq_timeout <<= 1;
+ else
+ req->rq_timeout += to->to_increment;
+ if (to->to_maxval && req->rq_timeout >= to->to_maxval)
+ req->rq_timeout = to->to_maxval;
+ req->rq_retries++;
+ } else {
+ req->rq_timeout = to->to_initval;
+ req->rq_retries = 0;
+ xprt_reset_majortimeo(req);
+ /* Reset the RTT counters == "slow start" */
+ spin_lock(&xprt->transport_lock);
+ rpc_init_rtt(req->rq_task->tk_client->cl_rtt, to->to_initval);
+ spin_unlock(&xprt->transport_lock);
+ status = -ETIMEDOUT;
+ }
+ xprt_reset_minortimeo(req);
+
+ if (req->rq_timeout == 0) {
+ printk(KERN_WARNING "xprt_adjust_timeout: rq_timeout = 0!\n");
+ req->rq_timeout = 5 * HZ;
+ }
+ return status;
+}
+
+static void xprt_autoclose(struct work_struct *work)
+{
+ struct rpc_xprt *xprt =
+ container_of(work, struct rpc_xprt, task_cleanup);
+ unsigned int pflags = memalloc_nofs_save();
+
+ trace_xprt_disconnect_auto(xprt);
+ xprt->connect_cookie++;
+ smp_mb__before_atomic();
+ clear_bit(XPRT_CLOSE_WAIT, &xprt->state);
+ xprt->ops->close(xprt);
+ xprt_release_write(xprt, NULL);
+ wake_up_bit(&xprt->state, XPRT_LOCKED);
+ memalloc_nofs_restore(pflags);
+}
+
+/**
+ * xprt_disconnect_done - mark a transport as disconnected
+ * @xprt: transport to flag for disconnect
+ *
+ */
+void xprt_disconnect_done(struct rpc_xprt *xprt)
+{
+ trace_xprt_disconnect_done(xprt);
+ spin_lock(&xprt->transport_lock);
+ xprt_clear_connected(xprt);
+ xprt_clear_write_space_locked(xprt);
+ xprt_clear_congestion_window_wait_locked(xprt);
+ xprt_wake_pending_tasks(xprt, -ENOTCONN);
+ spin_unlock(&xprt->transport_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_disconnect_done);
+
+/**
+ * xprt_schedule_autoclose_locked - Try to schedule an autoclose RPC call
+ * @xprt: transport to disconnect
+ */
+static void xprt_schedule_autoclose_locked(struct rpc_xprt *xprt)
+{
+ if (test_and_set_bit(XPRT_CLOSE_WAIT, &xprt->state))
+ return;
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+ else if (xprt->snd_task && !test_bit(XPRT_SND_IS_COOKIE, &xprt->state))
+ rpc_wake_up_queued_task_set_status(&xprt->pending,
+ xprt->snd_task, -ENOTCONN);
+}
+
+/**
+ * xprt_force_disconnect - force a transport to disconnect
+ * @xprt: transport to disconnect
+ *
+ */
+void xprt_force_disconnect(struct rpc_xprt *xprt)
+{
+ trace_xprt_disconnect_force(xprt);
+
+ /* Don't race with the test_bit() in xprt_clear_locked() */
+ spin_lock(&xprt->transport_lock);
+ xprt_schedule_autoclose_locked(xprt);
+ spin_unlock(&xprt->transport_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_force_disconnect);
+
+static unsigned int
+xprt_connect_cookie(struct rpc_xprt *xprt)
+{
+ return READ_ONCE(xprt->connect_cookie);
+}
+
+static bool
+xprt_request_retransmit_after_disconnect(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ return req->rq_connect_cookie != xprt_connect_cookie(xprt) ||
+ !xprt_connected(xprt);
+}
+
+/**
+ * xprt_conditional_disconnect - force a transport to disconnect
+ * @xprt: transport to disconnect
+ * @cookie: 'connection cookie'
+ *
+ * This attempts to break the connection if and only if 'cookie' matches
+ * the current transport 'connection cookie'. It ensures that we don't
+ * try to break the connection more than once when we need to retransmit
+ * a batch of RPC requests.
+ *
+ */
+void xprt_conditional_disconnect(struct rpc_xprt *xprt, unsigned int cookie)
+{
+ /* Don't race with the test_bit() in xprt_clear_locked() */
+ spin_lock(&xprt->transport_lock);
+ if (cookie != xprt->connect_cookie)
+ goto out;
+ if (test_bit(XPRT_CLOSING, &xprt->state))
+ goto out;
+ xprt_schedule_autoclose_locked(xprt);
+out:
+ spin_unlock(&xprt->transport_lock);
+}
+
+static bool
+xprt_has_timer(const struct rpc_xprt *xprt)
+{
+ return xprt->idle_timeout != 0;
+}
+
+static void
+xprt_schedule_autodisconnect(struct rpc_xprt *xprt)
+ __must_hold(&xprt->transport_lock)
+{
+ xprt->last_used = jiffies;
+ if (RB_EMPTY_ROOT(&xprt->recv_queue) && xprt_has_timer(xprt))
+ mod_timer(&xprt->timer, xprt->last_used + xprt->idle_timeout);
+}
+
+static void
+xprt_init_autodisconnect(struct timer_list *t)
+{
+ struct rpc_xprt *xprt = from_timer(xprt, t, timer);
+
+ if (!RB_EMPTY_ROOT(&xprt->recv_queue))
+ return;
+ /* Reset xprt->last_used to avoid connect/autodisconnect cycling */
+ xprt->last_used = jiffies;
+ if (test_and_set_bit(XPRT_LOCKED, &xprt->state))
+ return;
+ queue_work(xprtiod_workqueue, &xprt->task_cleanup);
+}
+
+#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
+static void xprt_inject_disconnect(struct rpc_xprt *xprt)
+{
+ if (!fail_sunrpc.ignore_client_disconnect &&
+ should_fail(&fail_sunrpc.attr, 1))
+ xprt->ops->inject_disconnect(xprt);
+}
+#else
+static inline void xprt_inject_disconnect(struct rpc_xprt *xprt)
+{
+}
+#endif
+
+bool xprt_lock_connect(struct rpc_xprt *xprt,
+ struct rpc_task *task,
+ void *cookie)
+{
+ bool ret = false;
+
+ spin_lock(&xprt->transport_lock);
+ if (!test_bit(XPRT_LOCKED, &xprt->state))
+ goto out;
+ if (xprt->snd_task != task)
+ goto out;
+ set_bit(XPRT_SND_IS_COOKIE, &xprt->state);
+ xprt->snd_task = cookie;
+ ret = true;
+out:
+ spin_unlock(&xprt->transport_lock);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(xprt_lock_connect);
+
+void xprt_unlock_connect(struct rpc_xprt *xprt, void *cookie)
+{
+ spin_lock(&xprt->transport_lock);
+ if (xprt->snd_task != cookie)
+ goto out;
+ if (!test_bit(XPRT_LOCKED, &xprt->state))
+ goto out;
+ xprt->snd_task =NULL;
+ clear_bit(XPRT_SND_IS_COOKIE, &xprt->state);
+ xprt->ops->release_xprt(xprt, NULL);
+ xprt_schedule_autodisconnect(xprt);
+out:
+ spin_unlock(&xprt->transport_lock);
+ wake_up_bit(&xprt->state, XPRT_LOCKED);
+}
+EXPORT_SYMBOL_GPL(xprt_unlock_connect);
+
+/**
+ * xprt_connect - schedule a transport connect operation
+ * @task: RPC task that is requesting the connect
+ *
+ */
+void xprt_connect(struct rpc_task *task)
+{
+ struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
+
+ trace_xprt_connect(xprt);
+
+ if (!xprt_bound(xprt)) {
+ task->tk_status = -EAGAIN;
+ return;
+ }
+ if (!xprt_lock_write(xprt, task))
+ return;
+
+ if (!xprt_connected(xprt) && !test_bit(XPRT_CLOSE_WAIT, &xprt->state)) {
+ task->tk_rqstp->rq_connect_cookie = xprt->connect_cookie;
+ rpc_sleep_on_timeout(&xprt->pending, task, NULL,
+ xprt_request_timeout(task->tk_rqstp));
+
+ if (test_bit(XPRT_CLOSING, &xprt->state))
+ return;
+ if (xprt_test_and_set_connecting(xprt))
+ return;
+ /* Race breaker */
+ if (!xprt_connected(xprt)) {
+ xprt->stat.connect_start = jiffies;
+ xprt->ops->connect(xprt, task);
+ } else {
+ xprt_clear_connecting(xprt);
+ task->tk_status = 0;
+ rpc_wake_up_queued_task(&xprt->pending, task);
+ }
+ }
+ xprt_release_write(xprt, task);
+}
+
+/**
+ * xprt_reconnect_delay - compute the wait before scheduling a connect
+ * @xprt: transport instance
+ *
+ */
+unsigned long xprt_reconnect_delay(const struct rpc_xprt *xprt)
+{
+ unsigned long start, now = jiffies;
+
+ start = xprt->stat.connect_start + xprt->reestablish_timeout;
+ if (time_after(start, now))
+ return start - now;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(xprt_reconnect_delay);
+
+/**
+ * xprt_reconnect_backoff - compute the new re-establish timeout
+ * @xprt: transport instance
+ * @init_to: initial reestablish timeout
+ *
+ */
+void xprt_reconnect_backoff(struct rpc_xprt *xprt, unsigned long init_to)
+{
+ xprt->reestablish_timeout <<= 1;
+ if (xprt->reestablish_timeout > xprt->max_reconnect_timeout)
+ xprt->reestablish_timeout = xprt->max_reconnect_timeout;
+ if (xprt->reestablish_timeout < init_to)
+ xprt->reestablish_timeout = init_to;
+}
+EXPORT_SYMBOL_GPL(xprt_reconnect_backoff);
+
+enum xprt_xid_rb_cmp {
+ XID_RB_EQUAL,
+ XID_RB_LEFT,
+ XID_RB_RIGHT,
+};
+static enum xprt_xid_rb_cmp
+xprt_xid_cmp(__be32 xid1, __be32 xid2)
+{
+ if (xid1 == xid2)
+ return XID_RB_EQUAL;
+ if ((__force u32)xid1 < (__force u32)xid2)
+ return XID_RB_LEFT;
+ return XID_RB_RIGHT;
+}
+
+static struct rpc_rqst *
+xprt_request_rb_find(struct rpc_xprt *xprt, __be32 xid)
+{
+ struct rb_node *n = xprt->recv_queue.rb_node;
+ struct rpc_rqst *req;
+
+ while (n != NULL) {
+ req = rb_entry(n, struct rpc_rqst, rq_recv);
+ switch (xprt_xid_cmp(xid, req->rq_xid)) {
+ case XID_RB_LEFT:
+ n = n->rb_left;
+ break;
+ case XID_RB_RIGHT:
+ n = n->rb_right;
+ break;
+ case XID_RB_EQUAL:
+ return req;
+ }
+ }
+ return NULL;
+}
+
+static void
+xprt_request_rb_insert(struct rpc_xprt *xprt, struct rpc_rqst *new)
+{
+ struct rb_node **p = &xprt->recv_queue.rb_node;
+ struct rb_node *n = NULL;
+ struct rpc_rqst *req;
+
+ while (*p != NULL) {
+ n = *p;
+ req = rb_entry(n, struct rpc_rqst, rq_recv);
+ switch(xprt_xid_cmp(new->rq_xid, req->rq_xid)) {
+ case XID_RB_LEFT:
+ p = &n->rb_left;
+ break;
+ case XID_RB_RIGHT:
+ p = &n->rb_right;
+ break;
+ case XID_RB_EQUAL:
+ WARN_ON_ONCE(new != req);
+ return;
+ }
+ }
+ rb_link_node(&new->rq_recv, n, p);
+ rb_insert_color(&new->rq_recv, &xprt->recv_queue);
+}
+
+static void
+xprt_request_rb_remove(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ rb_erase(&req->rq_recv, &xprt->recv_queue);
+}
+
+/**
+ * xprt_lookup_rqst - find an RPC request corresponding to an XID
+ * @xprt: transport on which the original request was transmitted
+ * @xid: RPC XID of incoming reply
+ *
+ * Caller holds xprt->queue_lock.
+ */
+struct rpc_rqst *xprt_lookup_rqst(struct rpc_xprt *xprt, __be32 xid)
+{
+ struct rpc_rqst *entry;
+
+ entry = xprt_request_rb_find(xprt, xid);
+ if (entry != NULL) {
+ trace_xprt_lookup_rqst(xprt, xid, 0);
+ entry->rq_rtt = ktime_sub(ktime_get(), entry->rq_xtime);
+ return entry;
+ }
+
+ dprintk("RPC: xprt_lookup_rqst did not find xid %08x\n",
+ ntohl(xid));
+ trace_xprt_lookup_rqst(xprt, xid, -ENOENT);
+ xprt->stat.bad_xids++;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_lookup_rqst);
+
+static bool
+xprt_is_pinned_rqst(struct rpc_rqst *req)
+{
+ return atomic_read(&req->rq_pin) != 0;
+}
+
+/**
+ * xprt_pin_rqst - Pin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller must ensure this is atomic with the call to xprt_lookup_rqst()
+ * so should be holding xprt->queue_lock.
+ */
+void xprt_pin_rqst(struct rpc_rqst *req)
+{
+ atomic_inc(&req->rq_pin);
+}
+EXPORT_SYMBOL_GPL(xprt_pin_rqst);
+
+/**
+ * xprt_unpin_rqst - Unpin a request on the transport receive list
+ * @req: Request to pin
+ *
+ * Caller should be holding xprt->queue_lock.
+ */
+void xprt_unpin_rqst(struct rpc_rqst *req)
+{
+ if (!test_bit(RPC_TASK_MSG_PIN_WAIT, &req->rq_task->tk_runstate)) {
+ atomic_dec(&req->rq_pin);
+ return;
+ }
+ if (atomic_dec_and_test(&req->rq_pin))
+ wake_up_var(&req->rq_pin);
+}
+EXPORT_SYMBOL_GPL(xprt_unpin_rqst);
+
+static void xprt_wait_on_pinned_rqst(struct rpc_rqst *req)
+{
+ wait_var_event(&req->rq_pin, !xprt_is_pinned_rqst(req));
+}
+
+static bool
+xprt_request_data_received(struct rpc_task *task)
+{
+ return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
+ READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) != 0;
+}
+
+static bool
+xprt_request_need_enqueue_receive(struct rpc_task *task, struct rpc_rqst *req)
+{
+ return !test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) &&
+ READ_ONCE(task->tk_rqstp->rq_reply_bytes_recvd) == 0;
+}
+
+/**
+ * xprt_request_enqueue_receive - Add an request to the receive queue
+ * @task: RPC task
+ *
+ */
+int
+xprt_request_enqueue_receive(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+ int ret;
+
+ if (!xprt_request_need_enqueue_receive(task, req))
+ return 0;
+
+ ret = xprt_request_prepare(task->tk_rqstp, &req->rq_rcv_buf);
+ if (ret)
+ return ret;
+ spin_lock(&xprt->queue_lock);
+
+ /* Update the softirq receive buffer */
+ memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
+ sizeof(req->rq_private_buf));
+
+ /* Add request to the receive list */
+ xprt_request_rb_insert(xprt, req);
+ set_bit(RPC_TASK_NEED_RECV, &task->tk_runstate);
+ spin_unlock(&xprt->queue_lock);
+
+ /* Turn off autodisconnect */
+ del_timer_sync(&xprt->timer);
+ return 0;
+}
+
+/**
+ * xprt_request_dequeue_receive_locked - Remove a request from the receive queue
+ * @task: RPC task
+ *
+ * Caller must hold xprt->queue_lock.
+ */
+static void
+xprt_request_dequeue_receive_locked(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ if (test_and_clear_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
+ xprt_request_rb_remove(req->rq_xprt, req);
+}
+
+/**
+ * xprt_update_rtt - Update RPC RTT statistics
+ * @task: RPC request that recently completed
+ *
+ * Caller holds xprt->queue_lock.
+ */
+void xprt_update_rtt(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_rtt *rtt = task->tk_client->cl_rtt;
+ unsigned int timer = task->tk_msg.rpc_proc->p_timer;
+ long m = usecs_to_jiffies(ktime_to_us(req->rq_rtt));
+
+ if (timer) {
+ if (req->rq_ntrans == 1)
+ rpc_update_rtt(rtt, timer, m);
+ rpc_set_timeo(rtt, timer, req->rq_ntrans - 1);
+ }
+}
+EXPORT_SYMBOL_GPL(xprt_update_rtt);
+
+/**
+ * xprt_complete_rqst - called when reply processing is complete
+ * @task: RPC request that recently completed
+ * @copied: actual number of bytes received from the transport
+ *
+ * Caller holds xprt->queue_lock.
+ */
+void xprt_complete_rqst(struct rpc_task *task, int copied)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ xprt->stat.recvs++;
+
+ xdr_free_bvec(&req->rq_rcv_buf);
+ req->rq_private_buf.bvec = NULL;
+ req->rq_private_buf.len = copied;
+ /* Ensure all writes are done before we update */
+ /* req->rq_reply_bytes_recvd */
+ smp_wmb();
+ req->rq_reply_bytes_recvd = copied;
+ xprt_request_dequeue_receive_locked(task);
+ rpc_wake_up_queued_task(&xprt->pending, task);
+}
+EXPORT_SYMBOL_GPL(xprt_complete_rqst);
+
+static void xprt_timer(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (task->tk_status != -ETIMEDOUT)
+ return;
+
+ trace_xprt_timer(xprt, req->rq_xid, task->tk_status);
+ if (!req->rq_reply_bytes_recvd) {
+ if (xprt->ops->timer)
+ xprt->ops->timer(xprt, task);
+ } else
+ task->tk_status = 0;
+}
+
+/**
+ * xprt_wait_for_reply_request_def - wait for reply
+ * @task: pointer to rpc_task
+ *
+ * Set a request's retransmit timeout based on the transport's
+ * default timeout parameters. Used by transports that don't adjust
+ * the retransmit timeout based on round-trip time estimation,
+ * and put the task to sleep on the pending queue.
+ */
+void xprt_wait_for_reply_request_def(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
+ xprt_request_timeout(req));
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_def);
+
+/**
+ * xprt_wait_for_reply_request_rtt - wait for reply using RTT estimator
+ * @task: pointer to rpc_task
+ *
+ * Set a request's retransmit timeout using the RTT estimator,
+ * and put the task to sleep on the pending queue.
+ */
+void xprt_wait_for_reply_request_rtt(struct rpc_task *task)
+{
+ int timer = task->tk_msg.rpc_proc->p_timer;
+ struct rpc_clnt *clnt = task->tk_client;
+ struct rpc_rtt *rtt = clnt->cl_rtt;
+ struct rpc_rqst *req = task->tk_rqstp;
+ unsigned long max_timeout = clnt->cl_timeout->to_maxval;
+ unsigned long timeout;
+
+ timeout = rpc_calc_rto(rtt, timer);
+ timeout <<= rpc_ntimeo(rtt, timer) + req->rq_retries;
+ if (timeout > max_timeout || timeout == 0)
+ timeout = max_timeout;
+ rpc_sleep_on_timeout(&req->rq_xprt->pending, task, xprt_timer,
+ jiffies + timeout);
+}
+EXPORT_SYMBOL_GPL(xprt_wait_for_reply_request_rtt);
+
+/**
+ * xprt_request_wait_receive - wait for the reply to an RPC request
+ * @task: RPC task about to send a request
+ *
+ */
+void xprt_request_wait_receive(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (!test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate))
+ return;
+ /*
+ * Sleep on the pending queue if we're expecting a reply.
+ * The spinlock ensures atomicity between the test of
+ * req->rq_reply_bytes_recvd, and the call to rpc_sleep_on().
+ */
+ spin_lock(&xprt->queue_lock);
+ if (test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate)) {
+ xprt->ops->wait_for_reply_request(task);
+ /*
+ * Send an extra queue wakeup call if the
+ * connection was dropped in case the call to
+ * rpc_sleep_on() raced.
+ */
+ if (xprt_request_retransmit_after_disconnect(task))
+ rpc_wake_up_queued_task_set_status(&xprt->pending,
+ task, -ENOTCONN);
+ }
+ spin_unlock(&xprt->queue_lock);
+}
+
+static bool
+xprt_request_need_enqueue_transmit(struct rpc_task *task, struct rpc_rqst *req)
+{
+ return !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
+}
+
+/**
+ * xprt_request_enqueue_transmit - queue a task for transmission
+ * @task: pointer to rpc_task
+ *
+ * Add a task to the transmission queue.
+ */
+void
+xprt_request_enqueue_transmit(struct rpc_task *task)
+{
+ struct rpc_rqst *pos, *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+ int ret;
+
+ if (xprt_request_need_enqueue_transmit(task, req)) {
+ ret = xprt_request_prepare(task->tk_rqstp, &req->rq_snd_buf);
+ if (ret) {
+ task->tk_status = ret;
+ return;
+ }
+ req->rq_bytes_sent = 0;
+ spin_lock(&xprt->queue_lock);
+ /*
+ * Requests that carry congestion control credits are added
+ * to the head of the list to avoid starvation issues.
+ */
+ if (req->rq_cong) {
+ xprt_clear_congestion_window_wait(xprt);
+ list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
+ if (pos->rq_cong)
+ continue;
+ /* Note: req is added _before_ pos */
+ list_add_tail(&req->rq_xmit, &pos->rq_xmit);
+ INIT_LIST_HEAD(&req->rq_xmit2);
+ goto out;
+ }
+ } else if (!req->rq_seqno) {
+ list_for_each_entry(pos, &xprt->xmit_queue, rq_xmit) {
+ if (pos->rq_task->tk_owner != task->tk_owner)
+ continue;
+ list_add_tail(&req->rq_xmit2, &pos->rq_xmit2);
+ INIT_LIST_HEAD(&req->rq_xmit);
+ goto out;
+ }
+ }
+ list_add_tail(&req->rq_xmit, &xprt->xmit_queue);
+ INIT_LIST_HEAD(&req->rq_xmit2);
+out:
+ atomic_long_inc(&xprt->xmit_queuelen);
+ set_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate);
+ spin_unlock(&xprt->queue_lock);
+ }
+}
+
+/**
+ * xprt_request_dequeue_transmit_locked - remove a task from the transmission queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmission queue
+ * Caller must hold xprt->queue_lock
+ */
+static void
+xprt_request_dequeue_transmit_locked(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ if (!test_and_clear_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ return;
+ if (!list_empty(&req->rq_xmit)) {
+ list_del(&req->rq_xmit);
+ if (!list_empty(&req->rq_xmit2)) {
+ struct rpc_rqst *next = list_first_entry(&req->rq_xmit2,
+ struct rpc_rqst, rq_xmit2);
+ list_del(&req->rq_xmit2);
+ list_add_tail(&next->rq_xmit, &next->rq_xprt->xmit_queue);
+ }
+ } else
+ list_del(&req->rq_xmit2);
+ atomic_long_dec(&req->rq_xprt->xmit_queuelen);
+ xdr_free_bvec(&req->rq_snd_buf);
+}
+
+/**
+ * xprt_request_dequeue_transmit - remove a task from the transmission queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmission queue
+ */
+static void
+xprt_request_dequeue_transmit(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ spin_lock(&xprt->queue_lock);
+ xprt_request_dequeue_transmit_locked(task);
+ spin_unlock(&xprt->queue_lock);
+}
+
+/**
+ * xprt_request_dequeue_xprt - remove a task from the transmit+receive queue
+ * @task: pointer to rpc_task
+ *
+ * Remove a task from the transmit and receive queues, and ensure that
+ * it is not pinned by the receive work item.
+ */
+void
+xprt_request_dequeue_xprt(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate) ||
+ test_bit(RPC_TASK_NEED_RECV, &task->tk_runstate) ||
+ xprt_is_pinned_rqst(req)) {
+ spin_lock(&xprt->queue_lock);
+ while (xprt_is_pinned_rqst(req)) {
+ set_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
+ spin_unlock(&xprt->queue_lock);
+ xprt_wait_on_pinned_rqst(req);
+ spin_lock(&xprt->queue_lock);
+ clear_bit(RPC_TASK_MSG_PIN_WAIT, &task->tk_runstate);
+ }
+ xprt_request_dequeue_transmit_locked(task);
+ xprt_request_dequeue_receive_locked(task);
+ spin_unlock(&xprt->queue_lock);
+ xdr_free_bvec(&req->rq_rcv_buf);
+ }
+}
+
+/**
+ * xprt_request_prepare - prepare an encoded request for transport
+ * @req: pointer to rpc_rqst
+ * @buf: pointer to send/rcv xdr_buf
+ *
+ * Calls into the transport layer to do whatever is needed to prepare
+ * the request for transmission or receive.
+ * Returns error, or zero.
+ */
+static int
+xprt_request_prepare(struct rpc_rqst *req, struct xdr_buf *buf)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (xprt->ops->prepare_request)
+ return xprt->ops->prepare_request(req, buf);
+ return 0;
+}
+
+/**
+ * xprt_request_need_retransmit - Test if a task needs retransmission
+ * @task: pointer to rpc_task
+ *
+ * Test for whether a connection breakage requires the task to retransmit
+ */
+bool
+xprt_request_need_retransmit(struct rpc_task *task)
+{
+ return xprt_request_retransmit_after_disconnect(task);
+}
+
+/**
+ * xprt_prepare_transmit - reserve the transport before sending a request
+ * @task: RPC task about to send a request
+ *
+ */
+bool xprt_prepare_transmit(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+
+ if (!xprt_lock_write(xprt, task)) {
+ /* Race breaker: someone may have transmitted us */
+ if (!test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ rpc_wake_up_queued_task_set_status(&xprt->sending,
+ task, 0);
+ return false;
+
+ }
+ if (atomic_read(&xprt->swapper))
+ /* This will be clear in __rpc_execute */
+ current->flags |= PF_MEMALLOC;
+ return true;
+}
+
+void xprt_end_transmit(struct rpc_task *task)
+{
+ struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
+
+ xprt_inject_disconnect(xprt);
+ xprt_release_write(xprt, task);
+}
+
+/**
+ * xprt_request_transmit - send an RPC request on a transport
+ * @req: pointer to request to transmit
+ * @snd_task: RPC task that owns the transport lock
+ *
+ * This performs the transmission of a single request.
+ * Note that if the request is not the same as snd_task, then it
+ * does need to be pinned.
+ * Returns '0' on success.
+ */
+static int
+xprt_request_transmit(struct rpc_rqst *req, struct rpc_task *snd_task)
+{
+ struct rpc_xprt *xprt = req->rq_xprt;
+ struct rpc_task *task = req->rq_task;
+ unsigned int connect_cookie;
+ int is_retrans = RPC_WAS_SENT(task);
+ int status;
+
+ if (!req->rq_bytes_sent) {
+ if (xprt_request_data_received(task)) {
+ status = 0;
+ goto out_dequeue;
+ }
+ /* Verify that our message lies in the RPCSEC_GSS window */
+ if (rpcauth_xmit_need_reencode(task)) {
+ status = -EBADMSG;
+ goto out_dequeue;
+ }
+ if (RPC_SIGNALLED(task)) {
+ status = -ERESTARTSYS;
+ goto out_dequeue;
+ }
+ }
+
+ /*
+ * Update req->rq_ntrans before transmitting to avoid races with
+ * xprt_update_rtt(), which needs to know that it is recording a
+ * reply to the first transmission.
+ */
+ req->rq_ntrans++;
+
+ trace_rpc_xdr_sendto(task, &req->rq_snd_buf);
+ connect_cookie = xprt->connect_cookie;
+ status = xprt->ops->send_request(req);
+ if (status != 0) {
+ req->rq_ntrans--;
+ trace_xprt_transmit(req, status);
+ return status;
+ }
+
+ if (is_retrans) {
+ task->tk_client->cl_stats->rpcretrans++;
+ trace_xprt_retransmit(req);
+ }
+
+ xprt_inject_disconnect(xprt);
+
+ task->tk_flags |= RPC_TASK_SENT;
+ spin_lock(&xprt->transport_lock);
+
+ xprt->stat.sends++;
+ xprt->stat.req_u += xprt->stat.sends - xprt->stat.recvs;
+ xprt->stat.bklog_u += xprt->backlog.qlen;
+ xprt->stat.sending_u += xprt->sending.qlen;
+ xprt->stat.pending_u += xprt->pending.qlen;
+ spin_unlock(&xprt->transport_lock);
+
+ req->rq_connect_cookie = connect_cookie;
+out_dequeue:
+ trace_xprt_transmit(req, status);
+ xprt_request_dequeue_transmit(task);
+ rpc_wake_up_queued_task_set_status(&xprt->sending, task, status);
+ return status;
+}
+
+/**
+ * xprt_transmit - send an RPC request on a transport
+ * @task: controlling RPC task
+ *
+ * Attempts to drain the transmit queue. On exit, either the transport
+ * signalled an error that needs to be handled before transmission can
+ * resume, or @task finished transmitting, and detected that it already
+ * received a reply.
+ */
+void
+xprt_transmit(struct rpc_task *task)
+{
+ struct rpc_rqst *next, *req = task->tk_rqstp;
+ struct rpc_xprt *xprt = req->rq_xprt;
+ int status;
+
+ spin_lock(&xprt->queue_lock);
+ for (;;) {
+ next = list_first_entry_or_null(&xprt->xmit_queue,
+ struct rpc_rqst, rq_xmit);
+ if (!next)
+ break;
+ xprt_pin_rqst(next);
+ spin_unlock(&xprt->queue_lock);
+ status = xprt_request_transmit(next, task);
+ if (status == -EBADMSG && next != req)
+ status = 0;
+ spin_lock(&xprt->queue_lock);
+ xprt_unpin_rqst(next);
+ if (status < 0) {
+ if (test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ task->tk_status = status;
+ break;
+ }
+ /* Was @task transmitted, and has it received a reply? */
+ if (xprt_request_data_received(task) &&
+ !test_bit(RPC_TASK_NEED_XMIT, &task->tk_runstate))
+ break;
+ cond_resched_lock(&xprt->queue_lock);
+ }
+ spin_unlock(&xprt->queue_lock);
+}
+
+static void xprt_complete_request_init(struct rpc_task *task)
+{
+ if (task->tk_rqstp)
+ xprt_request_init(task);
+}
+
+void xprt_add_backlog(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ set_bit(XPRT_CONGESTED, &xprt->state);
+ rpc_sleep_on(&xprt->backlog, task, xprt_complete_request_init);
+}
+EXPORT_SYMBOL_GPL(xprt_add_backlog);
+
+static bool __xprt_set_rq(struct rpc_task *task, void *data)
+{
+ struct rpc_rqst *req = data;
+
+ if (task->tk_rqstp == NULL) {
+ memset(req, 0, sizeof(*req)); /* mark unused */
+ task->tk_rqstp = req;
+ return true;
+ }
+ return false;
+}
+
+bool xprt_wake_up_backlog(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ if (rpc_wake_up_first(&xprt->backlog, __xprt_set_rq, req) == NULL) {
+ clear_bit(XPRT_CONGESTED, &xprt->state);
+ return false;
+ }
+ return true;
+}
+EXPORT_SYMBOL_GPL(xprt_wake_up_backlog);
+
+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)) {
+ xprt_add_backlog(xprt, task);
+ ret = true;
+ }
+ spin_unlock(&xprt->reserve_lock);
+out:
+ return ret;
+}
+
+static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt)
+{
+ struct rpc_rqst *req = ERR_PTR(-EAGAIN);
+
+ if (xprt->num_reqs >= xprt->max_reqs)
+ goto out;
+ ++xprt->num_reqs;
+ spin_unlock(&xprt->reserve_lock);
+ req = kzalloc(sizeof(*req), rpc_task_gfp_mask());
+ spin_lock(&xprt->reserve_lock);
+ if (req != NULL)
+ goto out;
+ --xprt->num_reqs;
+ req = ERR_PTR(-ENOMEM);
+out:
+ return req;
+}
+
+static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ if (xprt->num_reqs > xprt->min_reqs) {
+ --xprt->num_reqs;
+ kfree(req);
+ return true;
+ }
+ return false;
+}
+
+void xprt_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ struct rpc_rqst *req;
+
+ spin_lock(&xprt->reserve_lock);
+ if (!list_empty(&xprt->free)) {
+ req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
+ list_del(&req->rq_list);
+ goto out_init_req;
+ }
+ req = xprt_dynamic_alloc_slot(xprt);
+ if (!IS_ERR(req))
+ goto out_init_req;
+ switch (PTR_ERR(req)) {
+ case -ENOMEM:
+ dprintk("RPC: dynamic allocation of request slot "
+ "failed! Retrying\n");
+ task->tk_status = -ENOMEM;
+ break;
+ case -EAGAIN:
+ xprt_add_backlog(xprt, task);
+ dprintk("RPC: waiting for request slot\n");
+ fallthrough;
+ default:
+ task->tk_status = -EAGAIN;
+ }
+ spin_unlock(&xprt->reserve_lock);
+ return;
+out_init_req:
+ xprt->stat.max_slots = max_t(unsigned int, xprt->stat.max_slots,
+ xprt->num_reqs);
+ spin_unlock(&xprt->reserve_lock);
+
+ task->tk_status = 0;
+ task->tk_rqstp = req;
+}
+EXPORT_SYMBOL_GPL(xprt_alloc_slot);
+
+void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ spin_lock(&xprt->reserve_lock);
+ if (!xprt_wake_up_backlog(xprt, req) &&
+ !xprt_dynamic_free_slot(xprt, req)) {
+ memset(req, 0, sizeof(*req)); /* mark unused */
+ list_add(&req->rq_list, &xprt->free);
+ }
+ spin_unlock(&xprt->reserve_lock);
+}
+EXPORT_SYMBOL_GPL(xprt_free_slot);
+
+static void xprt_free_all_slots(struct rpc_xprt *xprt)
+{
+ struct rpc_rqst *req;
+ while (!list_empty(&xprt->free)) {
+ req = list_first_entry(&xprt->free, struct rpc_rqst, rq_list);
+ list_del(&req->rq_list);
+ kfree(req);
+ }
+}
+
+static DEFINE_IDA(rpc_xprt_ids);
+
+void xprt_cleanup_ids(void)
+{
+ ida_destroy(&rpc_xprt_ids);
+}
+
+static int xprt_alloc_id(struct rpc_xprt *xprt)
+{
+ int id;
+
+ id = ida_alloc(&rpc_xprt_ids, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ xprt->id = id;
+ return 0;
+}
+
+static void xprt_free_id(struct rpc_xprt *xprt)
+{
+ ida_free(&rpc_xprt_ids, xprt->id);
+}
+
+struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
+ unsigned int num_prealloc,
+ unsigned int max_alloc)
+{
+ struct rpc_xprt *xprt;
+ struct rpc_rqst *req;
+ int i;
+
+ xprt = kzalloc(size, GFP_KERNEL);
+ if (xprt == NULL)
+ goto out;
+
+ xprt_alloc_id(xprt);
+ xprt_init(xprt, net);
+
+ for (i = 0; i < num_prealloc; i++) {
+ req = kzalloc(sizeof(struct rpc_rqst), GFP_KERNEL);
+ if (!req)
+ goto out_free;
+ list_add(&req->rq_list, &xprt->free);
+ }
+ xprt->max_reqs = max_t(unsigned int, max_alloc, num_prealloc);
+ xprt->min_reqs = num_prealloc;
+ xprt->num_reqs = num_prealloc;
+
+ return xprt;
+
+out_free:
+ xprt_free(xprt);
+out:
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_alloc);
+
+void xprt_free(struct rpc_xprt *xprt)
+{
+ put_net_track(xprt->xprt_net, &xprt->ns_tracker);
+ xprt_free_all_slots(xprt);
+ xprt_free_id(xprt);
+ rpc_sysfs_xprt_destroy(xprt);
+ kfree_rcu(xprt, rcu);
+}
+EXPORT_SYMBOL_GPL(xprt_free);
+
+static void
+xprt_init_connect_cookie(struct rpc_rqst *req, struct rpc_xprt *xprt)
+{
+ req->rq_connect_cookie = xprt_connect_cookie(xprt) - 1;
+}
+
+static __be32
+xprt_alloc_xid(struct rpc_xprt *xprt)
+{
+ __be32 xid;
+
+ spin_lock(&xprt->reserve_lock);
+ xid = (__force __be32)xprt->xid++;
+ spin_unlock(&xprt->reserve_lock);
+ return xid;
+}
+
+static void
+xprt_init_xid(struct rpc_xprt *xprt)
+{
+ xprt->xid = get_random_u32();
+}
+
+static void
+xprt_request_init(struct rpc_task *task)
+{
+ struct rpc_xprt *xprt = task->tk_xprt;
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ req->rq_task = task;
+ req->rq_xprt = xprt;
+ req->rq_buffer = NULL;
+ req->rq_xid = xprt_alloc_xid(xprt);
+ xprt_init_connect_cookie(req, xprt);
+ req->rq_snd_buf.len = 0;
+ req->rq_snd_buf.buflen = 0;
+ req->rq_rcv_buf.len = 0;
+ req->rq_rcv_buf.buflen = 0;
+ req->rq_snd_buf.bvec = NULL;
+ req->rq_rcv_buf.bvec = NULL;
+ req->rq_release_snd_buf = NULL;
+ xprt_init_majortimeo(task, req);
+
+ trace_xprt_reserve(req);
+}
+
+static void
+xprt_do_reserve(struct rpc_xprt *xprt, struct rpc_task *task)
+{
+ xprt->ops->alloc_slot(xprt, task);
+ if (task->tk_rqstp != NULL)
+ xprt_request_init(task);
+}
+
+/**
+ * xprt_reserve - allocate an RPC request slot
+ * @task: RPC task requesting a slot allocation
+ *
+ * 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)
+{
+ struct rpc_xprt *xprt = task->tk_xprt;
+
+ task->tk_status = 0;
+ if (task->tk_rqstp != NULL)
+ return;
+
+ task->tk_status = -EAGAIN;
+ if (!xprt_throttle_congested(xprt, task))
+ xprt_do_reserve(xprt, task);
+}
+
+/**
+ * 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_xprt;
+
+ task->tk_status = 0;
+ if (task->tk_rqstp != NULL)
+ return;
+
+ task->tk_status = -EAGAIN;
+ xprt_do_reserve(xprt, task);
+}
+
+/**
+ * xprt_release - release an RPC request slot
+ * @task: task which is finished with the slot
+ *
+ */
+void xprt_release(struct rpc_task *task)
+{
+ struct rpc_xprt *xprt;
+ struct rpc_rqst *req = task->tk_rqstp;
+
+ if (req == NULL) {
+ if (task->tk_client) {
+ xprt = task->tk_xprt;
+ xprt_release_write(xprt, task);
+ }
+ return;
+ }
+
+ xprt = req->rq_xprt;
+ xprt_request_dequeue_xprt(task);
+ spin_lock(&xprt->transport_lock);
+ xprt->ops->release_xprt(xprt, task);
+ if (xprt->ops->release_request)
+ xprt->ops->release_request(task);
+ xprt_schedule_autodisconnect(xprt);
+ spin_unlock(&xprt->transport_lock);
+ if (req->rq_buffer)
+ xprt->ops->buf_free(task);
+ if (req->rq_cred != NULL)
+ put_rpccred(req->rq_cred);
+ if (req->rq_release_snd_buf)
+ req->rq_release_snd_buf(req);
+
+ task->tk_rqstp = NULL;
+ if (likely(!bc_prealloc(req)))
+ xprt->ops->free_slot(xprt, req);
+ else
+ xprt_free_bc_request(req);
+}
+
+#ifdef CONFIG_SUNRPC_BACKCHANNEL
+void
+xprt_init_bc_request(struct rpc_rqst *req, struct rpc_task *task)
+{
+ struct xdr_buf *xbufp = &req->rq_snd_buf;
+
+ task->tk_rqstp = req;
+ req->rq_task = task;
+ xprt_init_connect_cookie(req, req->rq_xprt);
+ /*
+ * Set up the xdr_buf length.
+ * This also indicates that the buffer is XDR encoded already.
+ */
+ xbufp->len = xbufp->head[0].iov_len + xbufp->page_len +
+ xbufp->tail[0].iov_len;
+}
+#endif
+
+static void xprt_init(struct rpc_xprt *xprt, struct net *net)
+{
+ kref_init(&xprt->kref);
+
+ spin_lock_init(&xprt->transport_lock);
+ spin_lock_init(&xprt->reserve_lock);
+ spin_lock_init(&xprt->queue_lock);
+
+ INIT_LIST_HEAD(&xprt->free);
+ xprt->recv_queue = RB_ROOT;
+ INIT_LIST_HEAD(&xprt->xmit_queue);
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+ spin_lock_init(&xprt->bc_pa_lock);
+ INIT_LIST_HEAD(&xprt->bc_pa_list);
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+ INIT_LIST_HEAD(&xprt->xprt_switch);
+
+ xprt->last_used = jiffies;
+ xprt->cwnd = RPC_INITCWND;
+ xprt->bind_index = 0;
+
+ rpc_init_wait_queue(&xprt->binding, "xprt_binding");
+ rpc_init_wait_queue(&xprt->pending, "xprt_pending");
+ rpc_init_wait_queue(&xprt->sending, "xprt_sending");
+ rpc_init_priority_wait_queue(&xprt->backlog, "xprt_backlog");
+
+ xprt_init_xid(xprt);
+
+ xprt->xprt_net = get_net_track(net, &xprt->ns_tracker, GFP_KERNEL);
+}
+
+/**
+ * xprt_create_transport - create an RPC transport
+ * @args: rpc transport creation arguments
+ *
+ */
+struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
+{
+ struct rpc_xprt *xprt;
+ const struct xprt_class *t;
+
+ t = xprt_class_find_by_ident(args->ident);
+ if (!t) {
+ dprintk("RPC: transport (%d) not supported\n", args->ident);
+ return ERR_PTR(-EIO);
+ }
+
+ xprt = t->setup(args);
+ xprt_class_release(t);
+
+ if (IS_ERR(xprt))
+ goto out;
+ if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)
+ xprt->idle_timeout = 0;
+ INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
+ if (xprt_has_timer(xprt))
+ timer_setup(&xprt->timer, xprt_init_autodisconnect, 0);
+ else
+ timer_setup(&xprt->timer, NULL, 0);
+
+ if (strlen(args->servername) > RPC_MAXNETNAMELEN) {
+ xprt_destroy(xprt);
+ return ERR_PTR(-EINVAL);
+ }
+ xprt->servername = kstrdup(args->servername, GFP_KERNEL);
+ if (xprt->servername == NULL) {
+ xprt_destroy(xprt);
+ return ERR_PTR(-ENOMEM);
+ }
+
+ rpc_xprt_debugfs_register(xprt);
+
+ trace_xprt_create(xprt);
+out:
+ return xprt;
+}
+
+static void xprt_destroy_cb(struct work_struct *work)
+{
+ struct rpc_xprt *xprt =
+ container_of(work, struct rpc_xprt, task_cleanup);
+
+ trace_xprt_destroy(xprt);
+
+ rpc_xprt_debugfs_unregister(xprt);
+ rpc_destroy_wait_queue(&xprt->binding);
+ rpc_destroy_wait_queue(&xprt->pending);
+ rpc_destroy_wait_queue(&xprt->sending);
+ rpc_destroy_wait_queue(&xprt->backlog);
+ kfree(xprt->servername);
+ /*
+ * Destroy any existing back channel
+ */
+ xprt_destroy_backchannel(xprt, UINT_MAX);
+
+ /*
+ * Tear down transport state and free the rpc_xprt
+ */
+ xprt->ops->destroy(xprt);
+}
+
+/**
+ * xprt_destroy - destroy an RPC transport, killing off all requests.
+ * @xprt: transport to destroy
+ *
+ */
+static void xprt_destroy(struct rpc_xprt *xprt)
+{
+ /*
+ * Exclude transport connect/disconnect handlers and autoclose
+ */
+ wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE);
+
+ /*
+ * xprt_schedule_autodisconnect() can run after XPRT_LOCKED
+ * is cleared. We use ->transport_lock to ensure the mod_timer()
+ * can only run *before* del_time_sync(), never after.
+ */
+ spin_lock(&xprt->transport_lock);
+ del_timer_sync(&xprt->timer);
+ spin_unlock(&xprt->transport_lock);
+
+ /*
+ * Destroy sockets etc from the system workqueue so they can
+ * safely flush receive work running on rpciod.
+ */
+ INIT_WORK(&xprt->task_cleanup, xprt_destroy_cb);
+ schedule_work(&xprt->task_cleanup);
+}
+
+static void xprt_destroy_kref(struct kref *kref)
+{
+ xprt_destroy(container_of(kref, struct rpc_xprt, kref));
+}
+
+/**
+ * xprt_get - return a reference to an RPC transport.
+ * @xprt: pointer to the transport
+ *
+ */
+struct rpc_xprt *xprt_get(struct rpc_xprt *xprt)
+{
+ if (xprt != NULL && kref_get_unless_zero(&xprt->kref))
+ return xprt;
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(xprt_get);
+
+/**
+ * xprt_put - release a reference to an RPC transport.
+ * @xprt: pointer to the transport
+ *
+ */
+void xprt_put(struct rpc_xprt *xprt)
+{
+ if (xprt != NULL)
+ kref_put(&xprt->kref, xprt_destroy_kref);
+}
+EXPORT_SYMBOL_GPL(xprt_put);
+
+void xprt_set_offline_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+ if (!test_and_set_bit(XPRT_OFFLINE, &xprt->state)) {
+ spin_lock(&xps->xps_lock);
+ xps->xps_nactive--;
+ spin_unlock(&xps->xps_lock);
+ }
+}
+
+void xprt_set_online_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+ if (test_and_clear_bit(XPRT_OFFLINE, &xprt->state)) {
+ spin_lock(&xps->xps_lock);
+ xps->xps_nactive++;
+ spin_unlock(&xps->xps_lock);
+ }
+}
+
+void xprt_delete_locked(struct rpc_xprt *xprt, struct rpc_xprt_switch *xps)
+{
+ if (test_and_set_bit(XPRT_REMOVE, &xprt->state))
+ return;
+
+ xprt_force_disconnect(xprt);
+ if (!test_bit(XPRT_CONNECTED, &xprt->state))
+ return;
+
+ if (!xprt->sending.qlen && !xprt->pending.qlen &&
+ !xprt->backlog.qlen && !atomic_long_read(&xprt->queuelen))
+ rpc_xprt_switch_remove_xprt(xps, xprt, true);
+}