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Diffstat (limited to '')
| -rw-r--r-- | net/sunrpc/xprt.c | 2077 |
1 files changed, 2077 insertions, 0 deletions
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c new file mode 100644 index 000000000..13d5323f8 --- /dev/null +++ b/net/sunrpc/xprt.c @@ -0,0 +1,2077 @@ +// 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" + +/* + * 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 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_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_load_transport - load a transport implementation + * @netid: transport to load + * + * Returns: + * 0: transport successfully loaded + * -ENOENT: transport module not available + */ +int xprt_load_transport(const char *netid) +{ + const struct xprt_class *t; + + t = xprt_class_find_by_netid(netid); + if (!t) + return -ENOENT; + xprt_class_release(t); + return 0; +} +EXPORT_SYMBOL_GPL(xprt_load_transport); + +static void xprt_clear_locked(struct rpc_xprt *xprt) +{ + xprt->snd_task = NULL; + if (!test_bit(XPRT_CLOSE_WAIT, &xprt->state)) { + smp_mb__before_atomic(); + clear_bit(XPRT_LOCKED, &xprt->state); + smp_mb__after_atomic(); + } 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); + +static inline 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); + 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); +} + +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 + * + */ +void +xprt_request_enqueue_receive(struct rpc_task *task) +{ + struct rpc_rqst *req = task->tk_rqstp; + struct rpc_xprt *xprt = req->rq_xprt; + + if (!xprt_request_need_enqueue_receive(task, req)) + return; + + xprt_request_prepare(task->tk_rqstp); + 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_singleshot_timer_sync(&xprt->timer); +} + +/** + * 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++; + + 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; + + if (xprt_request_need_enqueue_transmit(task, req)) { + 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: + 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); +} + +/** + * 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); + xprt_request_dequeue_transmit_locked(task); + xprt_request_dequeue_receive_locked(task); + 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); + } + spin_unlock(&xprt->queue_lock); + } +} + +/** + * xprt_request_prepare - prepare an encoded request for transport + * @req: pointer to rpc_rqst + * + * Calls into the transport layer to do whatever is needed to prepare + * the request for transmission or receive. + */ +void +xprt_request_prepare(struct rpc_rqst *req) +{ + struct rpc_xprt *xprt = req->rq_xprt; + + if (xprt->ops->prepare_request) + xprt->ops->prepare_request(req); +} + +/** + * 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; + + } + 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++; + + 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); + gfp_t gfp_mask = GFP_KERNEL; + + if (xprt->num_reqs >= xprt->max_reqs) + goto out; + ++xprt->num_reqs; + spin_unlock(&xprt->reserve_lock); + if (current->flags & PF_WQ_WORKER) + gfp_mask |= __GFP_NORETRY | __GFP_NOWARN; + req = kzalloc(sizeof(*req), 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); + } +} + +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_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); + } + if (max_alloc > num_prealloc) + xprt->max_reqs = max_alloc; + else + xprt->max_reqs = 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(xprt->xprt_net); + xprt_free_all_slots(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 = prandom_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); + xdr_free_bvec(&req->rq_rcv_buf); + xdr_free_bvec(&req->rq_snd_buf); + 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(net); +} + +/** + * 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; + struct xprt_class *t; + + spin_lock(&xprt_list_lock); + list_for_each_entry(t, &xprt_list, list) { + if (t->ident == args->ident) { + spin_unlock(&xprt_list_lock); + goto found; + } + } + spin_unlock(&xprt_list_lock); + dprintk("RPC: transport (%d) not supported\n", args->ident); + return ERR_PTR(-EIO); + +found: + xprt = t->setup(args); + 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); |