xref: /linux/net/sunrpc/svc_xprt.c (revision 2a2c74b2efcb1a0ca3fdcb5fbb96ad8de6a29177)
1 /*
2  * linux/net/sunrpc/svc_xprt.c
3  *
4  * Author: Tom Tucker <tom@opengridcomputing.com>
5  */
6 
7 #include <linux/sched.h>
8 #include <linux/errno.h>
9 #include <linux/freezer.h>
10 #include <linux/kthread.h>
11 #include <linux/slab.h>
12 #include <net/sock.h>
13 #include <linux/sunrpc/stats.h>
14 #include <linux/sunrpc/svc_xprt.h>
15 #include <linux/sunrpc/svcsock.h>
16 #include <linux/sunrpc/xprt.h>
17 #include <linux/module.h>
18 
19 #define RPCDBG_FACILITY	RPCDBG_SVCXPRT
20 
21 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
22 static int svc_deferred_recv(struct svc_rqst *rqstp);
23 static struct cache_deferred_req *svc_defer(struct cache_req *req);
24 static void svc_age_temp_xprts(unsigned long closure);
25 static void svc_delete_xprt(struct svc_xprt *xprt);
26 
27 /* apparently the "standard" is that clients close
28  * idle connections after 5 minutes, servers after
29  * 6 minutes
30  *   http://www.connectathon.org/talks96/nfstcp.pdf
31  */
32 static int svc_conn_age_period = 6*60;
33 
34 /* List of registered transport classes */
35 static DEFINE_SPINLOCK(svc_xprt_class_lock);
36 static LIST_HEAD(svc_xprt_class_list);
37 
38 /* SMP locking strategy:
39  *
40  *	svc_pool->sp_lock protects most of the fields of that pool.
41  *	svc_serv->sv_lock protects sv_tempsocks, sv_permsocks, sv_tmpcnt.
42  *	when both need to be taken (rare), svc_serv->sv_lock is first.
43  *	BKL protects svc_serv->sv_nrthread.
44  *	svc_sock->sk_lock protects the svc_sock->sk_deferred list
45  *             and the ->sk_info_authunix cache.
46  *
47  *	The XPT_BUSY bit in xprt->xpt_flags prevents a transport being
48  *	enqueued multiply. During normal transport processing this bit
49  *	is set by svc_xprt_enqueue and cleared by svc_xprt_received.
50  *	Providers should not manipulate this bit directly.
51  *
52  *	Some flags can be set to certain values at any time
53  *	providing that certain rules are followed:
54  *
55  *	XPT_CONN, XPT_DATA:
56  *		- Can be set or cleared at any time.
57  *		- After a set, svc_xprt_enqueue must be called to enqueue
58  *		  the transport for processing.
59  *		- After a clear, the transport must be read/accepted.
60  *		  If this succeeds, it must be set again.
61  *	XPT_CLOSE:
62  *		- Can set at any time. It is never cleared.
63  *      XPT_DEAD:
64  *		- Can only be set while XPT_BUSY is held which ensures
65  *		  that no other thread will be using the transport or will
66  *		  try to set XPT_DEAD.
67  */
68 
69 int svc_reg_xprt_class(struct svc_xprt_class *xcl)
70 {
71 	struct svc_xprt_class *cl;
72 	int res = -EEXIST;
73 
74 	dprintk("svc: Adding svc transport class '%s'\n", xcl->xcl_name);
75 
76 	INIT_LIST_HEAD(&xcl->xcl_list);
77 	spin_lock(&svc_xprt_class_lock);
78 	/* Make sure there isn't already a class with the same name */
79 	list_for_each_entry(cl, &svc_xprt_class_list, xcl_list) {
80 		if (strcmp(xcl->xcl_name, cl->xcl_name) == 0)
81 			goto out;
82 	}
83 	list_add_tail(&xcl->xcl_list, &svc_xprt_class_list);
84 	res = 0;
85 out:
86 	spin_unlock(&svc_xprt_class_lock);
87 	return res;
88 }
89 EXPORT_SYMBOL_GPL(svc_reg_xprt_class);
90 
91 void svc_unreg_xprt_class(struct svc_xprt_class *xcl)
92 {
93 	dprintk("svc: Removing svc transport class '%s'\n", xcl->xcl_name);
94 	spin_lock(&svc_xprt_class_lock);
95 	list_del_init(&xcl->xcl_list);
96 	spin_unlock(&svc_xprt_class_lock);
97 }
98 EXPORT_SYMBOL_GPL(svc_unreg_xprt_class);
99 
100 /*
101  * Format the transport list for printing
102  */
103 int svc_print_xprts(char *buf, int maxlen)
104 {
105 	struct svc_xprt_class *xcl;
106 	char tmpstr[80];
107 	int len = 0;
108 	buf[0] = '\0';
109 
110 	spin_lock(&svc_xprt_class_lock);
111 	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
112 		int slen;
113 
114 		sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
115 		slen = strlen(tmpstr);
116 		if (len + slen > maxlen)
117 			break;
118 		len += slen;
119 		strcat(buf, tmpstr);
120 	}
121 	spin_unlock(&svc_xprt_class_lock);
122 
123 	return len;
124 }
125 
126 static void svc_xprt_free(struct kref *kref)
127 {
128 	struct svc_xprt *xprt =
129 		container_of(kref, struct svc_xprt, xpt_ref);
130 	struct module *owner = xprt->xpt_class->xcl_owner;
131 	if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags))
132 		svcauth_unix_info_release(xprt);
133 	put_net(xprt->xpt_net);
134 	/* See comment on corresponding get in xs_setup_bc_tcp(): */
135 	if (xprt->xpt_bc_xprt)
136 		xprt_put(xprt->xpt_bc_xprt);
137 	xprt->xpt_ops->xpo_free(xprt);
138 	module_put(owner);
139 }
140 
141 void svc_xprt_put(struct svc_xprt *xprt)
142 {
143 	kref_put(&xprt->xpt_ref, svc_xprt_free);
144 }
145 EXPORT_SYMBOL_GPL(svc_xprt_put);
146 
147 /*
148  * Called by transport drivers to initialize the transport independent
149  * portion of the transport instance.
150  */
151 void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl,
152 		   struct svc_xprt *xprt, struct svc_serv *serv)
153 {
154 	memset(xprt, 0, sizeof(*xprt));
155 	xprt->xpt_class = xcl;
156 	xprt->xpt_ops = xcl->xcl_ops;
157 	kref_init(&xprt->xpt_ref);
158 	xprt->xpt_server = serv;
159 	INIT_LIST_HEAD(&xprt->xpt_list);
160 	INIT_LIST_HEAD(&xprt->xpt_ready);
161 	INIT_LIST_HEAD(&xprt->xpt_deferred);
162 	INIT_LIST_HEAD(&xprt->xpt_users);
163 	mutex_init(&xprt->xpt_mutex);
164 	spin_lock_init(&xprt->xpt_lock);
165 	set_bit(XPT_BUSY, &xprt->xpt_flags);
166 	rpc_init_wait_queue(&xprt->xpt_bc_pending, "xpt_bc_pending");
167 	xprt->xpt_net = get_net(net);
168 }
169 EXPORT_SYMBOL_GPL(svc_xprt_init);
170 
171 static struct svc_xprt *__svc_xpo_create(struct svc_xprt_class *xcl,
172 					 struct svc_serv *serv,
173 					 struct net *net,
174 					 const int family,
175 					 const unsigned short port,
176 					 int flags)
177 {
178 	struct sockaddr_in sin = {
179 		.sin_family		= AF_INET,
180 		.sin_addr.s_addr	= htonl(INADDR_ANY),
181 		.sin_port		= htons(port),
182 	};
183 #if IS_ENABLED(CONFIG_IPV6)
184 	struct sockaddr_in6 sin6 = {
185 		.sin6_family		= AF_INET6,
186 		.sin6_addr		= IN6ADDR_ANY_INIT,
187 		.sin6_port		= htons(port),
188 	};
189 #endif
190 	struct sockaddr *sap;
191 	size_t len;
192 
193 	switch (family) {
194 	case PF_INET:
195 		sap = (struct sockaddr *)&sin;
196 		len = sizeof(sin);
197 		break;
198 #if IS_ENABLED(CONFIG_IPV6)
199 	case PF_INET6:
200 		sap = (struct sockaddr *)&sin6;
201 		len = sizeof(sin6);
202 		break;
203 #endif
204 	default:
205 		return ERR_PTR(-EAFNOSUPPORT);
206 	}
207 
208 	return xcl->xcl_ops->xpo_create(serv, net, sap, len, flags);
209 }
210 
211 /*
212  * svc_xprt_received conditionally queues the transport for processing
213  * by another thread. The caller must hold the XPT_BUSY bit and must
214  * not thereafter touch transport data.
215  *
216  * Note: XPT_DATA only gets cleared when a read-attempt finds no (or
217  * insufficient) data.
218  */
219 static void svc_xprt_received(struct svc_xprt *xprt)
220 {
221 	WARN_ON_ONCE(!test_bit(XPT_BUSY, &xprt->xpt_flags));
222 	if (!test_bit(XPT_BUSY, &xprt->xpt_flags))
223 		return;
224 	/* As soon as we clear busy, the xprt could be closed and
225 	 * 'put', so we need a reference to call svc_xprt_enqueue with:
226 	 */
227 	svc_xprt_get(xprt);
228 	clear_bit(XPT_BUSY, &xprt->xpt_flags);
229 	svc_xprt_enqueue(xprt);
230 	svc_xprt_put(xprt);
231 }
232 
233 void svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *new)
234 {
235 	clear_bit(XPT_TEMP, &new->xpt_flags);
236 	spin_lock_bh(&serv->sv_lock);
237 	list_add(&new->xpt_list, &serv->sv_permsocks);
238 	spin_unlock_bh(&serv->sv_lock);
239 	svc_xprt_received(new);
240 }
241 
242 int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
243 		    struct net *net, const int family,
244 		    const unsigned short port, int flags)
245 {
246 	struct svc_xprt_class *xcl;
247 
248 	dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
249 	spin_lock(&svc_xprt_class_lock);
250 	list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
251 		struct svc_xprt *newxprt;
252 		unsigned short newport;
253 
254 		if (strcmp(xprt_name, xcl->xcl_name))
255 			continue;
256 
257 		if (!try_module_get(xcl->xcl_owner))
258 			goto err;
259 
260 		spin_unlock(&svc_xprt_class_lock);
261 		newxprt = __svc_xpo_create(xcl, serv, net, family, port, flags);
262 		if (IS_ERR(newxprt)) {
263 			module_put(xcl->xcl_owner);
264 			return PTR_ERR(newxprt);
265 		}
266 		svc_add_new_perm_xprt(serv, newxprt);
267 		newport = svc_xprt_local_port(newxprt);
268 		return newport;
269 	}
270  err:
271 	spin_unlock(&svc_xprt_class_lock);
272 	dprintk("svc: transport %s not found\n", xprt_name);
273 
274 	/* This errno is exposed to user space.  Provide a reasonable
275 	 * perror msg for a bad transport. */
276 	return -EPROTONOSUPPORT;
277 }
278 EXPORT_SYMBOL_GPL(svc_create_xprt);
279 
280 /*
281  * Copy the local and remote xprt addresses to the rqstp structure
282  */
283 void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt)
284 {
285 	memcpy(&rqstp->rq_addr, &xprt->xpt_remote, xprt->xpt_remotelen);
286 	rqstp->rq_addrlen = xprt->xpt_remotelen;
287 
288 	/*
289 	 * Destination address in request is needed for binding the
290 	 * source address in RPC replies/callbacks later.
291 	 */
292 	memcpy(&rqstp->rq_daddr, &xprt->xpt_local, xprt->xpt_locallen);
293 	rqstp->rq_daddrlen = xprt->xpt_locallen;
294 }
295 EXPORT_SYMBOL_GPL(svc_xprt_copy_addrs);
296 
297 /**
298  * svc_print_addr - Format rq_addr field for printing
299  * @rqstp: svc_rqst struct containing address to print
300  * @buf: target buffer for formatted address
301  * @len: length of target buffer
302  *
303  */
304 char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
305 {
306 	return __svc_print_addr(svc_addr(rqstp), buf, len);
307 }
308 EXPORT_SYMBOL_GPL(svc_print_addr);
309 
310 /*
311  * Queue up an idle server thread.  Must have pool->sp_lock held.
312  * Note: this is really a stack rather than a queue, so that we only
313  * use as many different threads as we need, and the rest don't pollute
314  * the cache.
315  */
316 static void svc_thread_enqueue(struct svc_pool *pool, struct svc_rqst *rqstp)
317 {
318 	list_add(&rqstp->rq_list, &pool->sp_threads);
319 }
320 
321 /*
322  * Dequeue an nfsd thread.  Must have pool->sp_lock held.
323  */
324 static void svc_thread_dequeue(struct svc_pool *pool, struct svc_rqst *rqstp)
325 {
326 	list_del(&rqstp->rq_list);
327 }
328 
329 static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
330 {
331 	if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
332 		return true;
333 	if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED)))
334 		return xprt->xpt_ops->xpo_has_wspace(xprt);
335 	return false;
336 }
337 
338 /*
339  * Queue up a transport with data pending. If there are idle nfsd
340  * processes, wake 'em up.
341  *
342  */
343 void svc_xprt_enqueue(struct svc_xprt *xprt)
344 {
345 	struct svc_pool *pool;
346 	struct svc_rqst	*rqstp;
347 	int cpu;
348 
349 	if (!svc_xprt_has_something_to_do(xprt))
350 		return;
351 
352 	cpu = get_cpu();
353 	pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
354 	put_cpu();
355 
356 	spin_lock_bh(&pool->sp_lock);
357 
358 	if (!list_empty(&pool->sp_threads) &&
359 	    !list_empty(&pool->sp_sockets))
360 		printk(KERN_ERR
361 		       "svc_xprt_enqueue: "
362 		       "threads and transports both waiting??\n");
363 
364 	pool->sp_stats.packets++;
365 
366 	/* Mark transport as busy. It will remain in this state until
367 	 * the provider calls svc_xprt_received. We update XPT_BUSY
368 	 * atomically because it also guards against trying to enqueue
369 	 * the transport twice.
370 	 */
371 	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) {
372 		/* Don't enqueue transport while already enqueued */
373 		dprintk("svc: transport %p busy, not enqueued\n", xprt);
374 		goto out_unlock;
375 	}
376 
377 	if (!list_empty(&pool->sp_threads)) {
378 		rqstp = list_entry(pool->sp_threads.next,
379 				   struct svc_rqst,
380 				   rq_list);
381 		dprintk("svc: transport %p served by daemon %p\n",
382 			xprt, rqstp);
383 		svc_thread_dequeue(pool, rqstp);
384 		if (rqstp->rq_xprt)
385 			printk(KERN_ERR
386 				"svc_xprt_enqueue: server %p, rq_xprt=%p!\n",
387 				rqstp, rqstp->rq_xprt);
388 		rqstp->rq_xprt = xprt;
389 		svc_xprt_get(xprt);
390 		pool->sp_stats.threads_woken++;
391 		wake_up(&rqstp->rq_wait);
392 	} else {
393 		dprintk("svc: transport %p put into queue\n", xprt);
394 		list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
395 		pool->sp_stats.sockets_queued++;
396 	}
397 
398 out_unlock:
399 	spin_unlock_bh(&pool->sp_lock);
400 }
401 EXPORT_SYMBOL_GPL(svc_xprt_enqueue);
402 
403 /*
404  * Dequeue the first transport.  Must be called with the pool->sp_lock held.
405  */
406 static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
407 {
408 	struct svc_xprt	*xprt;
409 
410 	if (list_empty(&pool->sp_sockets))
411 		return NULL;
412 
413 	xprt = list_entry(pool->sp_sockets.next,
414 			  struct svc_xprt, xpt_ready);
415 	list_del_init(&xprt->xpt_ready);
416 
417 	dprintk("svc: transport %p dequeued, inuse=%d\n",
418 		xprt, atomic_read(&xprt->xpt_ref.refcount));
419 
420 	return xprt;
421 }
422 
423 /**
424  * svc_reserve - change the space reserved for the reply to a request.
425  * @rqstp:  The request in question
426  * @space: new max space to reserve
427  *
428  * Each request reserves some space on the output queue of the transport
429  * to make sure the reply fits.  This function reduces that reserved
430  * space to be the amount of space used already, plus @space.
431  *
432  */
433 void svc_reserve(struct svc_rqst *rqstp, int space)
434 {
435 	space += rqstp->rq_res.head[0].iov_len;
436 
437 	if (space < rqstp->rq_reserved) {
438 		struct svc_xprt *xprt = rqstp->rq_xprt;
439 		atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved);
440 		rqstp->rq_reserved = space;
441 
442 		svc_xprt_enqueue(xprt);
443 	}
444 }
445 EXPORT_SYMBOL_GPL(svc_reserve);
446 
447 static void svc_xprt_release(struct svc_rqst *rqstp)
448 {
449 	struct svc_xprt	*xprt = rqstp->rq_xprt;
450 
451 	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
452 
453 	kfree(rqstp->rq_deferred);
454 	rqstp->rq_deferred = NULL;
455 
456 	svc_free_res_pages(rqstp);
457 	rqstp->rq_res.page_len = 0;
458 	rqstp->rq_res.page_base = 0;
459 
460 	/* Reset response buffer and release
461 	 * the reservation.
462 	 * But first, check that enough space was reserved
463 	 * for the reply, otherwise we have a bug!
464 	 */
465 	if ((rqstp->rq_res.len) >  rqstp->rq_reserved)
466 		printk(KERN_ERR "RPC request reserved %d but used %d\n",
467 		       rqstp->rq_reserved,
468 		       rqstp->rq_res.len);
469 
470 	rqstp->rq_res.head[0].iov_len = 0;
471 	svc_reserve(rqstp, 0);
472 	rqstp->rq_xprt = NULL;
473 
474 	svc_xprt_put(xprt);
475 }
476 
477 /*
478  * External function to wake up a server waiting for data
479  * This really only makes sense for services like lockd
480  * which have exactly one thread anyway.
481  */
482 void svc_wake_up(struct svc_serv *serv)
483 {
484 	struct svc_rqst	*rqstp;
485 	unsigned int i;
486 	struct svc_pool *pool;
487 
488 	for (i = 0; i < serv->sv_nrpools; i++) {
489 		pool = &serv->sv_pools[i];
490 
491 		spin_lock_bh(&pool->sp_lock);
492 		if (!list_empty(&pool->sp_threads)) {
493 			rqstp = list_entry(pool->sp_threads.next,
494 					   struct svc_rqst,
495 					   rq_list);
496 			dprintk("svc: daemon %p woken up.\n", rqstp);
497 			/*
498 			svc_thread_dequeue(pool, rqstp);
499 			rqstp->rq_xprt = NULL;
500 			 */
501 			wake_up(&rqstp->rq_wait);
502 		} else
503 			pool->sp_task_pending = 1;
504 		spin_unlock_bh(&pool->sp_lock);
505 	}
506 }
507 EXPORT_SYMBOL_GPL(svc_wake_up);
508 
509 int svc_port_is_privileged(struct sockaddr *sin)
510 {
511 	switch (sin->sa_family) {
512 	case AF_INET:
513 		return ntohs(((struct sockaddr_in *)sin)->sin_port)
514 			< PROT_SOCK;
515 	case AF_INET6:
516 		return ntohs(((struct sockaddr_in6 *)sin)->sin6_port)
517 			< PROT_SOCK;
518 	default:
519 		return 0;
520 	}
521 }
522 
523 /*
524  * Make sure that we don't have too many active connections. If we have,
525  * something must be dropped. It's not clear what will happen if we allow
526  * "too many" connections, but when dealing with network-facing software,
527  * we have to code defensively. Here we do that by imposing hard limits.
528  *
529  * There's no point in trying to do random drop here for DoS
530  * prevention. The NFS clients does 1 reconnect in 15 seconds. An
531  * attacker can easily beat that.
532  *
533  * The only somewhat efficient mechanism would be if drop old
534  * connections from the same IP first. But right now we don't even
535  * record the client IP in svc_sock.
536  *
537  * single-threaded services that expect a lot of clients will probably
538  * need to set sv_maxconn to override the default value which is based
539  * on the number of threads
540  */
541 static void svc_check_conn_limits(struct svc_serv *serv)
542 {
543 	unsigned int limit = serv->sv_maxconn ? serv->sv_maxconn :
544 				(serv->sv_nrthreads+3) * 20;
545 
546 	if (serv->sv_tmpcnt > limit) {
547 		struct svc_xprt *xprt = NULL;
548 		spin_lock_bh(&serv->sv_lock);
549 		if (!list_empty(&serv->sv_tempsocks)) {
550 			/* Try to help the admin */
551 			net_notice_ratelimited("%s: too many open connections, consider increasing the %s\n",
552 					       serv->sv_name, serv->sv_maxconn ?
553 					       "max number of connections" :
554 					       "number of threads");
555 			/*
556 			 * Always select the oldest connection. It's not fair,
557 			 * but so is life
558 			 */
559 			xprt = list_entry(serv->sv_tempsocks.prev,
560 					  struct svc_xprt,
561 					  xpt_list);
562 			set_bit(XPT_CLOSE, &xprt->xpt_flags);
563 			svc_xprt_get(xprt);
564 		}
565 		spin_unlock_bh(&serv->sv_lock);
566 
567 		if (xprt) {
568 			svc_xprt_enqueue(xprt);
569 			svc_xprt_put(xprt);
570 		}
571 	}
572 }
573 
574 static int svc_alloc_arg(struct svc_rqst *rqstp)
575 {
576 	struct svc_serv *serv = rqstp->rq_server;
577 	struct xdr_buf *arg;
578 	int pages;
579 	int i;
580 
581 	/* now allocate needed pages.  If we get a failure, sleep briefly */
582 	pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
583 	WARN_ON_ONCE(pages >= RPCSVC_MAXPAGES);
584 	if (pages >= RPCSVC_MAXPAGES)
585 		/* use as many pages as possible */
586 		pages = RPCSVC_MAXPAGES - 1;
587 	for (i = 0; i < pages ; i++)
588 		while (rqstp->rq_pages[i] == NULL) {
589 			struct page *p = alloc_page(GFP_KERNEL);
590 			if (!p) {
591 				set_current_state(TASK_INTERRUPTIBLE);
592 				if (signalled() || kthread_should_stop()) {
593 					set_current_state(TASK_RUNNING);
594 					return -EINTR;
595 				}
596 				schedule_timeout(msecs_to_jiffies(500));
597 			}
598 			rqstp->rq_pages[i] = p;
599 		}
600 	rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
601 
602 	/* Make arg->head point to first page and arg->pages point to rest */
603 	arg = &rqstp->rq_arg;
604 	arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
605 	arg->head[0].iov_len = PAGE_SIZE;
606 	arg->pages = rqstp->rq_pages + 1;
607 	arg->page_base = 0;
608 	/* save at least one page for response */
609 	arg->page_len = (pages-2)*PAGE_SIZE;
610 	arg->len = (pages-1)*PAGE_SIZE;
611 	arg->tail[0].iov_len = 0;
612 	return 0;
613 }
614 
615 static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
616 {
617 	struct svc_xprt *xprt;
618 	struct svc_pool		*pool = rqstp->rq_pool;
619 	DECLARE_WAITQUEUE(wait, current);
620 	long			time_left;
621 
622 	/* Normally we will wait up to 5 seconds for any required
623 	 * cache information to be provided.
624 	 */
625 	rqstp->rq_chandle.thread_wait = 5*HZ;
626 
627 	spin_lock_bh(&pool->sp_lock);
628 	xprt = svc_xprt_dequeue(pool);
629 	if (xprt) {
630 		rqstp->rq_xprt = xprt;
631 		svc_xprt_get(xprt);
632 
633 		/* As there is a shortage of threads and this request
634 		 * had to be queued, don't allow the thread to wait so
635 		 * long for cache updates.
636 		 */
637 		rqstp->rq_chandle.thread_wait = 1*HZ;
638 		pool->sp_task_pending = 0;
639 	} else {
640 		if (pool->sp_task_pending) {
641 			pool->sp_task_pending = 0;
642 			spin_unlock_bh(&pool->sp_lock);
643 			return ERR_PTR(-EAGAIN);
644 		}
645 		/* No data pending. Go to sleep */
646 		svc_thread_enqueue(pool, rqstp);
647 
648 		/*
649 		 * We have to be able to interrupt this wait
650 		 * to bring down the daemons ...
651 		 */
652 		set_current_state(TASK_INTERRUPTIBLE);
653 
654 		/*
655 		 * checking kthread_should_stop() here allows us to avoid
656 		 * locking and signalling when stopping kthreads that call
657 		 * svc_recv. If the thread has already been woken up, then
658 		 * we can exit here without sleeping. If not, then it
659 		 * it'll be woken up quickly during the schedule_timeout
660 		 */
661 		if (kthread_should_stop()) {
662 			set_current_state(TASK_RUNNING);
663 			spin_unlock_bh(&pool->sp_lock);
664 			return ERR_PTR(-EINTR);
665 		}
666 
667 		add_wait_queue(&rqstp->rq_wait, &wait);
668 		spin_unlock_bh(&pool->sp_lock);
669 
670 		time_left = schedule_timeout(timeout);
671 
672 		try_to_freeze();
673 
674 		spin_lock_bh(&pool->sp_lock);
675 		remove_wait_queue(&rqstp->rq_wait, &wait);
676 		if (!time_left)
677 			pool->sp_stats.threads_timedout++;
678 
679 		xprt = rqstp->rq_xprt;
680 		if (!xprt) {
681 			svc_thread_dequeue(pool, rqstp);
682 			spin_unlock_bh(&pool->sp_lock);
683 			dprintk("svc: server %p, no data yet\n", rqstp);
684 			if (signalled() || kthread_should_stop())
685 				return ERR_PTR(-EINTR);
686 			else
687 				return ERR_PTR(-EAGAIN);
688 		}
689 	}
690 	spin_unlock_bh(&pool->sp_lock);
691 	return xprt;
692 }
693 
694 static void svc_add_new_temp_xprt(struct svc_serv *serv, struct svc_xprt *newxpt)
695 {
696 	spin_lock_bh(&serv->sv_lock);
697 	set_bit(XPT_TEMP, &newxpt->xpt_flags);
698 	list_add(&newxpt->xpt_list, &serv->sv_tempsocks);
699 	serv->sv_tmpcnt++;
700 	if (serv->sv_temptimer.function == NULL) {
701 		/* setup timer to age temp transports */
702 		setup_timer(&serv->sv_temptimer, svc_age_temp_xprts,
703 			    (unsigned long)serv);
704 		mod_timer(&serv->sv_temptimer,
705 			  jiffies + svc_conn_age_period * HZ);
706 	}
707 	spin_unlock_bh(&serv->sv_lock);
708 	svc_xprt_received(newxpt);
709 }
710 
711 static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
712 {
713 	struct svc_serv *serv = rqstp->rq_server;
714 	int len = 0;
715 
716 	if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
717 		dprintk("svc_recv: found XPT_CLOSE\n");
718 		svc_delete_xprt(xprt);
719 		/* Leave XPT_BUSY set on the dead xprt: */
720 		return 0;
721 	}
722 	if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
723 		struct svc_xprt *newxpt;
724 		/*
725 		 * We know this module_get will succeed because the
726 		 * listener holds a reference too
727 		 */
728 		__module_get(xprt->xpt_class->xcl_owner);
729 		svc_check_conn_limits(xprt->xpt_server);
730 		newxpt = xprt->xpt_ops->xpo_accept(xprt);
731 		if (newxpt)
732 			svc_add_new_temp_xprt(serv, newxpt);
733 	} else if (xprt->xpt_ops->xpo_has_wspace(xprt)) {
734 		/* XPT_DATA|XPT_DEFERRED case: */
735 		dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
736 			rqstp, rqstp->rq_pool->sp_id, xprt,
737 			atomic_read(&xprt->xpt_ref.refcount));
738 		rqstp->rq_deferred = svc_deferred_dequeue(xprt);
739 		if (rqstp->rq_deferred)
740 			len = svc_deferred_recv(rqstp);
741 		else
742 			len = xprt->xpt_ops->xpo_recvfrom(rqstp);
743 		dprintk("svc: got len=%d\n", len);
744 		rqstp->rq_reserved = serv->sv_max_mesg;
745 		atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
746 	}
747 	/* clear XPT_BUSY: */
748 	svc_xprt_received(xprt);
749 	return len;
750 }
751 
752 /*
753  * Receive the next request on any transport.  This code is carefully
754  * organised not to touch any cachelines in the shared svc_serv
755  * structure, only cachelines in the local svc_pool.
756  */
757 int svc_recv(struct svc_rqst *rqstp, long timeout)
758 {
759 	struct svc_xprt		*xprt = NULL;
760 	struct svc_serv		*serv = rqstp->rq_server;
761 	int			len, err;
762 
763 	dprintk("svc: server %p waiting for data (to = %ld)\n",
764 		rqstp, timeout);
765 
766 	if (rqstp->rq_xprt)
767 		printk(KERN_ERR
768 			"svc_recv: service %p, transport not NULL!\n",
769 			 rqstp);
770 	if (waitqueue_active(&rqstp->rq_wait))
771 		printk(KERN_ERR
772 			"svc_recv: service %p, wait queue active!\n",
773 			 rqstp);
774 
775 	err = svc_alloc_arg(rqstp);
776 	if (err)
777 		return err;
778 
779 	try_to_freeze();
780 	cond_resched();
781 	if (signalled() || kthread_should_stop())
782 		return -EINTR;
783 
784 	xprt = svc_get_next_xprt(rqstp, timeout);
785 	if (IS_ERR(xprt))
786 		return PTR_ERR(xprt);
787 
788 	len = svc_handle_xprt(rqstp, xprt);
789 
790 	/* No data, incomplete (TCP) read, or accept() */
791 	if (len <= 0)
792 		goto out;
793 
794 	clear_bit(XPT_OLD, &xprt->xpt_flags);
795 
796 	rqstp->rq_secure = svc_port_is_privileged(svc_addr(rqstp));
797 	rqstp->rq_chandle.defer = svc_defer;
798 
799 	if (serv->sv_stats)
800 		serv->sv_stats->netcnt++;
801 	return len;
802 out:
803 	rqstp->rq_res.len = 0;
804 	svc_xprt_release(rqstp);
805 	return -EAGAIN;
806 }
807 EXPORT_SYMBOL_GPL(svc_recv);
808 
809 /*
810  * Drop request
811  */
812 void svc_drop(struct svc_rqst *rqstp)
813 {
814 	dprintk("svc: xprt %p dropped request\n", rqstp->rq_xprt);
815 	svc_xprt_release(rqstp);
816 }
817 EXPORT_SYMBOL_GPL(svc_drop);
818 
819 /*
820  * Return reply to client.
821  */
822 int svc_send(struct svc_rqst *rqstp)
823 {
824 	struct svc_xprt	*xprt;
825 	int		len;
826 	struct xdr_buf	*xb;
827 
828 	xprt = rqstp->rq_xprt;
829 	if (!xprt)
830 		return -EFAULT;
831 
832 	/* release the receive skb before sending the reply */
833 	rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
834 
835 	/* calculate over-all length */
836 	xb = &rqstp->rq_res;
837 	xb->len = xb->head[0].iov_len +
838 		xb->page_len +
839 		xb->tail[0].iov_len;
840 
841 	/* Grab mutex to serialize outgoing data. */
842 	mutex_lock(&xprt->xpt_mutex);
843 	if (test_bit(XPT_DEAD, &xprt->xpt_flags)
844 			|| test_bit(XPT_CLOSE, &xprt->xpt_flags))
845 		len = -ENOTCONN;
846 	else
847 		len = xprt->xpt_ops->xpo_sendto(rqstp);
848 	mutex_unlock(&xprt->xpt_mutex);
849 	rpc_wake_up(&xprt->xpt_bc_pending);
850 	svc_xprt_release(rqstp);
851 
852 	if (len == -ECONNREFUSED || len == -ENOTCONN || len == -EAGAIN)
853 		return 0;
854 	return len;
855 }
856 
857 /*
858  * Timer function to close old temporary transports, using
859  * a mark-and-sweep algorithm.
860  */
861 static void svc_age_temp_xprts(unsigned long closure)
862 {
863 	struct svc_serv *serv = (struct svc_serv *)closure;
864 	struct svc_xprt *xprt;
865 	struct list_head *le, *next;
866 
867 	dprintk("svc_age_temp_xprts\n");
868 
869 	if (!spin_trylock_bh(&serv->sv_lock)) {
870 		/* busy, try again 1 sec later */
871 		dprintk("svc_age_temp_xprts: busy\n");
872 		mod_timer(&serv->sv_temptimer, jiffies + HZ);
873 		return;
874 	}
875 
876 	list_for_each_safe(le, next, &serv->sv_tempsocks) {
877 		xprt = list_entry(le, struct svc_xprt, xpt_list);
878 
879 		/* First time through, just mark it OLD. Second time
880 		 * through, close it. */
881 		if (!test_and_set_bit(XPT_OLD, &xprt->xpt_flags))
882 			continue;
883 		if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
884 		    test_bit(XPT_BUSY, &xprt->xpt_flags))
885 			continue;
886 		list_del_init(le);
887 		set_bit(XPT_CLOSE, &xprt->xpt_flags);
888 		set_bit(XPT_DETACHED, &xprt->xpt_flags);
889 		dprintk("queuing xprt %p for closing\n", xprt);
890 
891 		/* a thread will dequeue and close it soon */
892 		svc_xprt_enqueue(xprt);
893 	}
894 	spin_unlock_bh(&serv->sv_lock);
895 
896 	mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
897 }
898 
899 static void call_xpt_users(struct svc_xprt *xprt)
900 {
901 	struct svc_xpt_user *u;
902 
903 	spin_lock(&xprt->xpt_lock);
904 	while (!list_empty(&xprt->xpt_users)) {
905 		u = list_first_entry(&xprt->xpt_users, struct svc_xpt_user, list);
906 		list_del(&u->list);
907 		u->callback(u);
908 	}
909 	spin_unlock(&xprt->xpt_lock);
910 }
911 
912 /*
913  * Remove a dead transport
914  */
915 static void svc_delete_xprt(struct svc_xprt *xprt)
916 {
917 	struct svc_serv	*serv = xprt->xpt_server;
918 	struct svc_deferred_req *dr;
919 
920 	/* Only do this once */
921 	if (test_and_set_bit(XPT_DEAD, &xprt->xpt_flags))
922 		BUG();
923 
924 	dprintk("svc: svc_delete_xprt(%p)\n", xprt);
925 	xprt->xpt_ops->xpo_detach(xprt);
926 
927 	spin_lock_bh(&serv->sv_lock);
928 	if (!test_and_set_bit(XPT_DETACHED, &xprt->xpt_flags))
929 		list_del_init(&xprt->xpt_list);
930 	WARN_ON_ONCE(!list_empty(&xprt->xpt_ready));
931 	if (test_bit(XPT_TEMP, &xprt->xpt_flags))
932 		serv->sv_tmpcnt--;
933 	spin_unlock_bh(&serv->sv_lock);
934 
935 	while ((dr = svc_deferred_dequeue(xprt)) != NULL)
936 		kfree(dr);
937 
938 	call_xpt_users(xprt);
939 	svc_xprt_put(xprt);
940 }
941 
942 void svc_close_xprt(struct svc_xprt *xprt)
943 {
944 	set_bit(XPT_CLOSE, &xprt->xpt_flags);
945 	if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
946 		/* someone else will have to effect the close */
947 		return;
948 	/*
949 	 * We expect svc_close_xprt() to work even when no threads are
950 	 * running (e.g., while configuring the server before starting
951 	 * any threads), so if the transport isn't busy, we delete
952 	 * it ourself:
953 	 */
954 	svc_delete_xprt(xprt);
955 }
956 EXPORT_SYMBOL_GPL(svc_close_xprt);
957 
958 static int svc_close_list(struct svc_serv *serv, struct list_head *xprt_list, struct net *net)
959 {
960 	struct svc_xprt *xprt;
961 	int ret = 0;
962 
963 	spin_lock(&serv->sv_lock);
964 	list_for_each_entry(xprt, xprt_list, xpt_list) {
965 		if (xprt->xpt_net != net)
966 			continue;
967 		ret++;
968 		set_bit(XPT_CLOSE, &xprt->xpt_flags);
969 		svc_xprt_enqueue(xprt);
970 	}
971 	spin_unlock(&serv->sv_lock);
972 	return ret;
973 }
974 
975 static struct svc_xprt *svc_dequeue_net(struct svc_serv *serv, struct net *net)
976 {
977 	struct svc_pool *pool;
978 	struct svc_xprt *xprt;
979 	struct svc_xprt *tmp;
980 	int i;
981 
982 	for (i = 0; i < serv->sv_nrpools; i++) {
983 		pool = &serv->sv_pools[i];
984 
985 		spin_lock_bh(&pool->sp_lock);
986 		list_for_each_entry_safe(xprt, tmp, &pool->sp_sockets, xpt_ready) {
987 			if (xprt->xpt_net != net)
988 				continue;
989 			list_del_init(&xprt->xpt_ready);
990 			spin_unlock_bh(&pool->sp_lock);
991 			return xprt;
992 		}
993 		spin_unlock_bh(&pool->sp_lock);
994 	}
995 	return NULL;
996 }
997 
998 static void svc_clean_up_xprts(struct svc_serv *serv, struct net *net)
999 {
1000 	struct svc_xprt *xprt;
1001 
1002 	while ((xprt = svc_dequeue_net(serv, net))) {
1003 		set_bit(XPT_CLOSE, &xprt->xpt_flags);
1004 		svc_delete_xprt(xprt);
1005 	}
1006 }
1007 
1008 /*
1009  * Server threads may still be running (especially in the case where the
1010  * service is still running in other network namespaces).
1011  *
1012  * So we shut down sockets the same way we would on a running server, by
1013  * setting XPT_CLOSE, enqueuing, and letting a thread pick it up to do
1014  * the close.  In the case there are no such other threads,
1015  * threads running, svc_clean_up_xprts() does a simple version of a
1016  * server's main event loop, and in the case where there are other
1017  * threads, we may need to wait a little while and then check again to
1018  * see if they're done.
1019  */
1020 void svc_close_net(struct svc_serv *serv, struct net *net)
1021 {
1022 	int delay = 0;
1023 
1024 	while (svc_close_list(serv, &serv->sv_permsocks, net) +
1025 	       svc_close_list(serv, &serv->sv_tempsocks, net)) {
1026 
1027 		svc_clean_up_xprts(serv, net);
1028 		msleep(delay++);
1029 	}
1030 }
1031 
1032 /*
1033  * Handle defer and revisit of requests
1034  */
1035 
1036 static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
1037 {
1038 	struct svc_deferred_req *dr =
1039 		container_of(dreq, struct svc_deferred_req, handle);
1040 	struct svc_xprt *xprt = dr->xprt;
1041 
1042 	spin_lock(&xprt->xpt_lock);
1043 	set_bit(XPT_DEFERRED, &xprt->xpt_flags);
1044 	if (too_many || test_bit(XPT_DEAD, &xprt->xpt_flags)) {
1045 		spin_unlock(&xprt->xpt_lock);
1046 		dprintk("revisit canceled\n");
1047 		svc_xprt_put(xprt);
1048 		kfree(dr);
1049 		return;
1050 	}
1051 	dprintk("revisit queued\n");
1052 	dr->xprt = NULL;
1053 	list_add(&dr->handle.recent, &xprt->xpt_deferred);
1054 	spin_unlock(&xprt->xpt_lock);
1055 	svc_xprt_enqueue(xprt);
1056 	svc_xprt_put(xprt);
1057 }
1058 
1059 /*
1060  * Save the request off for later processing. The request buffer looks
1061  * like this:
1062  *
1063  * <xprt-header><rpc-header><rpc-pagelist><rpc-tail>
1064  *
1065  * This code can only handle requests that consist of an xprt-header
1066  * and rpc-header.
1067  */
1068 static struct cache_deferred_req *svc_defer(struct cache_req *req)
1069 {
1070 	struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
1071 	struct svc_deferred_req *dr;
1072 
1073 	if (rqstp->rq_arg.page_len || !rqstp->rq_usedeferral)
1074 		return NULL; /* if more than a page, give up FIXME */
1075 	if (rqstp->rq_deferred) {
1076 		dr = rqstp->rq_deferred;
1077 		rqstp->rq_deferred = NULL;
1078 	} else {
1079 		size_t skip;
1080 		size_t size;
1081 		/* FIXME maybe discard if size too large */
1082 		size = sizeof(struct svc_deferred_req) + rqstp->rq_arg.len;
1083 		dr = kmalloc(size, GFP_KERNEL);
1084 		if (dr == NULL)
1085 			return NULL;
1086 
1087 		dr->handle.owner = rqstp->rq_server;
1088 		dr->prot = rqstp->rq_prot;
1089 		memcpy(&dr->addr, &rqstp->rq_addr, rqstp->rq_addrlen);
1090 		dr->addrlen = rqstp->rq_addrlen;
1091 		dr->daddr = rqstp->rq_daddr;
1092 		dr->argslen = rqstp->rq_arg.len >> 2;
1093 		dr->xprt_hlen = rqstp->rq_xprt_hlen;
1094 
1095 		/* back up head to the start of the buffer and copy */
1096 		skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;
1097 		memcpy(dr->args, rqstp->rq_arg.head[0].iov_base - skip,
1098 		       dr->argslen << 2);
1099 	}
1100 	svc_xprt_get(rqstp->rq_xprt);
1101 	dr->xprt = rqstp->rq_xprt;
1102 	rqstp->rq_dropme = true;
1103 
1104 	dr->handle.revisit = svc_revisit;
1105 	return &dr->handle;
1106 }
1107 
1108 /*
1109  * recv data from a deferred request into an active one
1110  */
1111 static int svc_deferred_recv(struct svc_rqst *rqstp)
1112 {
1113 	struct svc_deferred_req *dr = rqstp->rq_deferred;
1114 
1115 	/* setup iov_base past transport header */
1116 	rqstp->rq_arg.head[0].iov_base = dr->args + (dr->xprt_hlen>>2);
1117 	/* The iov_len does not include the transport header bytes */
1118 	rqstp->rq_arg.head[0].iov_len = (dr->argslen<<2) - dr->xprt_hlen;
1119 	rqstp->rq_arg.page_len = 0;
1120 	/* The rq_arg.len includes the transport header bytes */
1121 	rqstp->rq_arg.len     = dr->argslen<<2;
1122 	rqstp->rq_prot        = dr->prot;
1123 	memcpy(&rqstp->rq_addr, &dr->addr, dr->addrlen);
1124 	rqstp->rq_addrlen     = dr->addrlen;
1125 	/* Save off transport header len in case we get deferred again */
1126 	rqstp->rq_xprt_hlen   = dr->xprt_hlen;
1127 	rqstp->rq_daddr       = dr->daddr;
1128 	rqstp->rq_respages    = rqstp->rq_pages;
1129 	return (dr->argslen<<2) - dr->xprt_hlen;
1130 }
1131 
1132 
1133 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt)
1134 {
1135 	struct svc_deferred_req *dr = NULL;
1136 
1137 	if (!test_bit(XPT_DEFERRED, &xprt->xpt_flags))
1138 		return NULL;
1139 	spin_lock(&xprt->xpt_lock);
1140 	if (!list_empty(&xprt->xpt_deferred)) {
1141 		dr = list_entry(xprt->xpt_deferred.next,
1142 				struct svc_deferred_req,
1143 				handle.recent);
1144 		list_del_init(&dr->handle.recent);
1145 	} else
1146 		clear_bit(XPT_DEFERRED, &xprt->xpt_flags);
1147 	spin_unlock(&xprt->xpt_lock);
1148 	return dr;
1149 }
1150 
1151 /**
1152  * svc_find_xprt - find an RPC transport instance
1153  * @serv: pointer to svc_serv to search
1154  * @xcl_name: C string containing transport's class name
1155  * @net: owner net pointer
1156  * @af: Address family of transport's local address
1157  * @port: transport's IP port number
1158  *
1159  * Return the transport instance pointer for the endpoint accepting
1160  * connections/peer traffic from the specified transport class,
1161  * address family and port.
1162  *
1163  * Specifying 0 for the address family or port is effectively a
1164  * wild-card, and will result in matching the first transport in the
1165  * service's list that has a matching class name.
1166  */
1167 struct svc_xprt *svc_find_xprt(struct svc_serv *serv, const char *xcl_name,
1168 			       struct net *net, const sa_family_t af,
1169 			       const unsigned short port)
1170 {
1171 	struct svc_xprt *xprt;
1172 	struct svc_xprt *found = NULL;
1173 
1174 	/* Sanity check the args */
1175 	if (serv == NULL || xcl_name == NULL)
1176 		return found;
1177 
1178 	spin_lock_bh(&serv->sv_lock);
1179 	list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
1180 		if (xprt->xpt_net != net)
1181 			continue;
1182 		if (strcmp(xprt->xpt_class->xcl_name, xcl_name))
1183 			continue;
1184 		if (af != AF_UNSPEC && af != xprt->xpt_local.ss_family)
1185 			continue;
1186 		if (port != 0 && port != svc_xprt_local_port(xprt))
1187 			continue;
1188 		found = xprt;
1189 		svc_xprt_get(xprt);
1190 		break;
1191 	}
1192 	spin_unlock_bh(&serv->sv_lock);
1193 	return found;
1194 }
1195 EXPORT_SYMBOL_GPL(svc_find_xprt);
1196 
1197 static int svc_one_xprt_name(const struct svc_xprt *xprt,
1198 			     char *pos, int remaining)
1199 {
1200 	int len;
1201 
1202 	len = snprintf(pos, remaining, "%s %u\n",
1203 			xprt->xpt_class->xcl_name,
1204 			svc_xprt_local_port(xprt));
1205 	if (len >= remaining)
1206 		return -ENAMETOOLONG;
1207 	return len;
1208 }
1209 
1210 /**
1211  * svc_xprt_names - format a buffer with a list of transport names
1212  * @serv: pointer to an RPC service
1213  * @buf: pointer to a buffer to be filled in
1214  * @buflen: length of buffer to be filled in
1215  *
1216  * Fills in @buf with a string containing a list of transport names,
1217  * each name terminated with '\n'.
1218  *
1219  * Returns positive length of the filled-in string on success; otherwise
1220  * a negative errno value is returned if an error occurs.
1221  */
1222 int svc_xprt_names(struct svc_serv *serv, char *buf, const int buflen)
1223 {
1224 	struct svc_xprt *xprt;
1225 	int len, totlen;
1226 	char *pos;
1227 
1228 	/* Sanity check args */
1229 	if (!serv)
1230 		return 0;
1231 
1232 	spin_lock_bh(&serv->sv_lock);
1233 
1234 	pos = buf;
1235 	totlen = 0;
1236 	list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
1237 		len = svc_one_xprt_name(xprt, pos, buflen - totlen);
1238 		if (len < 0) {
1239 			*buf = '\0';
1240 			totlen = len;
1241 		}
1242 		if (len <= 0)
1243 			break;
1244 
1245 		pos += len;
1246 		totlen += len;
1247 	}
1248 
1249 	spin_unlock_bh(&serv->sv_lock);
1250 	return totlen;
1251 }
1252 EXPORT_SYMBOL_GPL(svc_xprt_names);
1253 
1254 
1255 /*----------------------------------------------------------------------------*/
1256 
1257 static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
1258 {
1259 	unsigned int pidx = (unsigned int)*pos;
1260 	struct svc_serv *serv = m->private;
1261 
1262 	dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
1263 
1264 	if (!pidx)
1265 		return SEQ_START_TOKEN;
1266 	return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]);
1267 }
1268 
1269 static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
1270 {
1271 	struct svc_pool *pool = p;
1272 	struct svc_serv *serv = m->private;
1273 
1274 	dprintk("svc_pool_stats_next, *pos=%llu\n", *pos);
1275 
1276 	if (p == SEQ_START_TOKEN) {
1277 		pool = &serv->sv_pools[0];
1278 	} else {
1279 		unsigned int pidx = (pool - &serv->sv_pools[0]);
1280 		if (pidx < serv->sv_nrpools-1)
1281 			pool = &serv->sv_pools[pidx+1];
1282 		else
1283 			pool = NULL;
1284 	}
1285 	++*pos;
1286 	return pool;
1287 }
1288 
1289 static void svc_pool_stats_stop(struct seq_file *m, void *p)
1290 {
1291 }
1292 
1293 static int svc_pool_stats_show(struct seq_file *m, void *p)
1294 {
1295 	struct svc_pool *pool = p;
1296 
1297 	if (p == SEQ_START_TOKEN) {
1298 		seq_puts(m, "# pool packets-arrived sockets-enqueued threads-woken threads-timedout\n");
1299 		return 0;
1300 	}
1301 
1302 	seq_printf(m, "%u %lu %lu %lu %lu\n",
1303 		pool->sp_id,
1304 		pool->sp_stats.packets,
1305 		pool->sp_stats.sockets_queued,
1306 		pool->sp_stats.threads_woken,
1307 		pool->sp_stats.threads_timedout);
1308 
1309 	return 0;
1310 }
1311 
1312 static const struct seq_operations svc_pool_stats_seq_ops = {
1313 	.start	= svc_pool_stats_start,
1314 	.next	= svc_pool_stats_next,
1315 	.stop	= svc_pool_stats_stop,
1316 	.show	= svc_pool_stats_show,
1317 };
1318 
1319 int svc_pool_stats_open(struct svc_serv *serv, struct file *file)
1320 {
1321 	int err;
1322 
1323 	err = seq_open(file, &svc_pool_stats_seq_ops);
1324 	if (!err)
1325 		((struct seq_file *) file->private_data)->private = serv;
1326 	return err;
1327 }
1328 EXPORT_SYMBOL(svc_pool_stats_open);
1329 
1330 /*----------------------------------------------------------------------------*/
1331