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TOMOYO Linux Cross Reference
Linux/net/sunrpc/svc_xprt.c

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  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/addr.h>
 14 #include <linux/sunrpc/stats.h>
 15 #include <linux/sunrpc/svc_xprt.h>
 16 #include <linux/sunrpc/svcsock.h>
 17 #include <linux/sunrpc/xprt.h>
 18 #include <linux/module.h>
 19 #include <linux/netdevice.h>
 20 #include <trace/events/sunrpc.h>
 21 
 22 #define RPCDBG_FACILITY RPCDBG_SVCXPRT
 23 
 24 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt);
 25 static int svc_deferred_recv(struct svc_rqst *rqstp);
 26 static struct cache_deferred_req *svc_defer(struct cache_req *req);
 27 static void svc_age_temp_xprts(unsigned long closure);
 28 static void svc_delete_xprt(struct svc_xprt *xprt);
 29 
 30 /* apparently the "standard" is that clients close
 31  * idle connections after 5 minutes, servers after
 32  * 6 minutes
 33  *   http://www.connectathon.org/talks96/nfstcp.pdf
 34  */
 35 static int svc_conn_age_period = 6*60;
 36 
 37 /* List of registered transport classes */
 38 static DEFINE_SPINLOCK(svc_xprt_class_lock);
 39 static LIST_HEAD(svc_xprt_class_list);
 40 
 41 /* SMP locking strategy:
 42  *
 43  *      svc_pool->sp_lock protects most of the fields of that pool.
 44  *      svc_serv->sv_lock protects sv_tempsocks, sv_permsocks, sv_tmpcnt.
 45  *      when both need to be taken (rare), svc_serv->sv_lock is first.
 46  *      The "service mutex" protects svc_serv->sv_nrthread.
 47  *      svc_sock->sk_lock protects the svc_sock->sk_deferred list
 48  *             and the ->sk_info_authunix cache.
 49  *
 50  *      The XPT_BUSY bit in xprt->xpt_flags prevents a transport being
 51  *      enqueued multiply. During normal transport processing this bit
 52  *      is set by svc_xprt_enqueue and cleared by svc_xprt_received.
 53  *      Providers should not manipulate this bit directly.
 54  *
 55  *      Some flags can be set to certain values at any time
 56  *      providing that certain rules are followed:
 57  *
 58  *      XPT_CONN, XPT_DATA:
 59  *              - Can be set or cleared at any time.
 60  *              - After a set, svc_xprt_enqueue must be called to enqueue
 61  *                the transport for processing.
 62  *              - After a clear, the transport must be read/accepted.
 63  *                If this succeeds, it must be set again.
 64  *      XPT_CLOSE:
 65  *              - Can set at any time. It is never cleared.
 66  *      XPT_DEAD:
 67  *              - Can only be set while XPT_BUSY is held which ensures
 68  *                that no other thread will be using the transport or will
 69  *                try to set XPT_DEAD.
 70  */
 71 int svc_reg_xprt_class(struct svc_xprt_class *xcl)
 72 {
 73         struct svc_xprt_class *cl;
 74         int res = -EEXIST;
 75 
 76         dprintk("svc: Adding svc transport class '%s'\n", xcl->xcl_name);
 77 
 78         INIT_LIST_HEAD(&xcl->xcl_list);
 79         spin_lock(&svc_xprt_class_lock);
 80         /* Make sure there isn't already a class with the same name */
 81         list_for_each_entry(cl, &svc_xprt_class_list, xcl_list) {
 82                 if (strcmp(xcl->xcl_name, cl->xcl_name) == 0)
 83                         goto out;
 84         }
 85         list_add_tail(&xcl->xcl_list, &svc_xprt_class_list);
 86         res = 0;
 87 out:
 88         spin_unlock(&svc_xprt_class_lock);
 89         return res;
 90 }
 91 EXPORT_SYMBOL_GPL(svc_reg_xprt_class);
 92 
 93 void svc_unreg_xprt_class(struct svc_xprt_class *xcl)
 94 {
 95         dprintk("svc: Removing svc transport class '%s'\n", xcl->xcl_name);
 96         spin_lock(&svc_xprt_class_lock);
 97         list_del_init(&xcl->xcl_list);
 98         spin_unlock(&svc_xprt_class_lock);
 99 }
100 EXPORT_SYMBOL_GPL(svc_unreg_xprt_class);
101 
102 /*
103  * Format the transport list for printing
104  */
105 int svc_print_xprts(char *buf, int maxlen)
106 {
107         struct svc_xprt_class *xcl;
108         char tmpstr[80];
109         int len = 0;
110         buf[0] = '\0';
111 
112         spin_lock(&svc_xprt_class_lock);
113         list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
114                 int slen;
115 
116                 sprintf(tmpstr, "%s %d\n", xcl->xcl_name, xcl->xcl_max_payload);
117                 slen = strlen(tmpstr);
118                 if (len + slen > maxlen)
119                         break;
120                 len += slen;
121                 strcat(buf, tmpstr);
122         }
123         spin_unlock(&svc_xprt_class_lock);
124 
125         return len;
126 }
127 
128 static void svc_xprt_free(struct kref *kref)
129 {
130         struct svc_xprt *xprt =
131                 container_of(kref, struct svc_xprt, xpt_ref);
132         struct module *owner = xprt->xpt_class->xcl_owner;
133         if (test_bit(XPT_CACHE_AUTH, &xprt->xpt_flags))
134                 svcauth_unix_info_release(xprt);
135         put_net(xprt->xpt_net);
136         /* See comment on corresponding get in xs_setup_bc_tcp(): */
137         if (xprt->xpt_bc_xprt)
138                 xprt_put(xprt->xpt_bc_xprt);
139         if (xprt->xpt_bc_xps)
140                 xprt_switch_put(xprt->xpt_bc_xps);
141         xprt->xpt_ops->xpo_free(xprt);
142         module_put(owner);
143 }
144 
145 void svc_xprt_put(struct svc_xprt *xprt)
146 {
147         kref_put(&xprt->xpt_ref, svc_xprt_free);
148 }
149 EXPORT_SYMBOL_GPL(svc_xprt_put);
150 
151 /*
152  * Called by transport drivers to initialize the transport independent
153  * portion of the transport instance.
154  */
155 void svc_xprt_init(struct net *net, struct svc_xprt_class *xcl,
156                    struct svc_xprt *xprt, struct svc_serv *serv)
157 {
158         memset(xprt, 0, sizeof(*xprt));
159         xprt->xpt_class = xcl;
160         xprt->xpt_ops = xcl->xcl_ops;
161         kref_init(&xprt->xpt_ref);
162         xprt->xpt_server = serv;
163         INIT_LIST_HEAD(&xprt->xpt_list);
164         INIT_LIST_HEAD(&xprt->xpt_ready);
165         INIT_LIST_HEAD(&xprt->xpt_deferred);
166         INIT_LIST_HEAD(&xprt->xpt_users);
167         mutex_init(&xprt->xpt_mutex);
168         spin_lock_init(&xprt->xpt_lock);
169         set_bit(XPT_BUSY, &xprt->xpt_flags);
170         rpc_init_wait_queue(&xprt->xpt_bc_pending, "xpt_bc_pending");
171         xprt->xpt_net = get_net(net);
172 }
173 EXPORT_SYMBOL_GPL(svc_xprt_init);
174 
175 static struct svc_xprt *__svc_xpo_create(struct svc_xprt_class *xcl,
176                                          struct svc_serv *serv,
177                                          struct net *net,
178                                          const int family,
179                                          const unsigned short port,
180                                          int flags)
181 {
182         struct sockaddr_in sin = {
183                 .sin_family             = AF_INET,
184                 .sin_addr.s_addr        = htonl(INADDR_ANY),
185                 .sin_port               = htons(port),
186         };
187 #if IS_ENABLED(CONFIG_IPV6)
188         struct sockaddr_in6 sin6 = {
189                 .sin6_family            = AF_INET6,
190                 .sin6_addr              = IN6ADDR_ANY_INIT,
191                 .sin6_port              = htons(port),
192         };
193 #endif
194         struct sockaddr *sap;
195         size_t len;
196 
197         switch (family) {
198         case PF_INET:
199                 sap = (struct sockaddr *)&sin;
200                 len = sizeof(sin);
201                 break;
202 #if IS_ENABLED(CONFIG_IPV6)
203         case PF_INET6:
204                 sap = (struct sockaddr *)&sin6;
205                 len = sizeof(sin6);
206                 break;
207 #endif
208         default:
209                 return ERR_PTR(-EAFNOSUPPORT);
210         }
211 
212         return xcl->xcl_ops->xpo_create(serv, net, sap, len, flags);
213 }
214 
215 /*
216  * svc_xprt_received conditionally queues the transport for processing
217  * by another thread. The caller must hold the XPT_BUSY bit and must
218  * not thereafter touch transport data.
219  *
220  * Note: XPT_DATA only gets cleared when a read-attempt finds no (or
221  * insufficient) data.
222  */
223 static void svc_xprt_received(struct svc_xprt *xprt)
224 {
225         if (!test_bit(XPT_BUSY, &xprt->xpt_flags)) {
226                 WARN_ONCE(1, "xprt=0x%p already busy!", xprt);
227                 return;
228         }
229 
230         /* As soon as we clear busy, the xprt could be closed and
231          * 'put', so we need a reference to call svc_enqueue_xprt with:
232          */
233         svc_xprt_get(xprt);
234         smp_mb__before_atomic();
235         clear_bit(XPT_BUSY, &xprt->xpt_flags);
236         xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt);
237         svc_xprt_put(xprt);
238 }
239 
240 void svc_add_new_perm_xprt(struct svc_serv *serv, struct svc_xprt *new)
241 {
242         clear_bit(XPT_TEMP, &new->xpt_flags);
243         spin_lock_bh(&serv->sv_lock);
244         list_add(&new->xpt_list, &serv->sv_permsocks);
245         spin_unlock_bh(&serv->sv_lock);
246         svc_xprt_received(new);
247 }
248 
249 int _svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
250                     struct net *net, const int family,
251                     const unsigned short port, int flags)
252 {
253         struct svc_xprt_class *xcl;
254 
255         spin_lock(&svc_xprt_class_lock);
256         list_for_each_entry(xcl, &svc_xprt_class_list, xcl_list) {
257                 struct svc_xprt *newxprt;
258                 unsigned short newport;
259 
260                 if (strcmp(xprt_name, xcl->xcl_name))
261                         continue;
262 
263                 if (!try_module_get(xcl->xcl_owner))
264                         goto err;
265 
266                 spin_unlock(&svc_xprt_class_lock);
267                 newxprt = __svc_xpo_create(xcl, serv, net, family, port, flags);
268                 if (IS_ERR(newxprt)) {
269                         module_put(xcl->xcl_owner);
270                         return PTR_ERR(newxprt);
271                 }
272                 svc_add_new_perm_xprt(serv, newxprt);
273                 newport = svc_xprt_local_port(newxprt);
274                 return newport;
275         }
276  err:
277         spin_unlock(&svc_xprt_class_lock);
278         /* This errno is exposed to user space.  Provide a reasonable
279          * perror msg for a bad transport. */
280         return -EPROTONOSUPPORT;
281 }
282 
283 int svc_create_xprt(struct svc_serv *serv, const char *xprt_name,
284                     struct net *net, const int family,
285                     const unsigned short port, int flags)
286 {
287         int err;
288 
289         dprintk("svc: creating transport %s[%d]\n", xprt_name, port);
290         err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
291         if (err == -EPROTONOSUPPORT) {
292                 request_module("svc%s", xprt_name);
293                 err = _svc_create_xprt(serv, xprt_name, net, family, port, flags);
294         }
295         if (err)
296                 dprintk("svc: transport %s not found, err %d\n",
297                         xprt_name, err);
298         return err;
299 }
300 EXPORT_SYMBOL_GPL(svc_create_xprt);
301 
302 /*
303  * Copy the local and remote xprt addresses to the rqstp structure
304  */
305 void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt)
306 {
307         memcpy(&rqstp->rq_addr, &xprt->xpt_remote, xprt->xpt_remotelen);
308         rqstp->rq_addrlen = xprt->xpt_remotelen;
309 
310         /*
311          * Destination address in request is needed for binding the
312          * source address in RPC replies/callbacks later.
313          */
314         memcpy(&rqstp->rq_daddr, &xprt->xpt_local, xprt->xpt_locallen);
315         rqstp->rq_daddrlen = xprt->xpt_locallen;
316 }
317 EXPORT_SYMBOL_GPL(svc_xprt_copy_addrs);
318 
319 /**
320  * svc_print_addr - Format rq_addr field for printing
321  * @rqstp: svc_rqst struct containing address to print
322  * @buf: target buffer for formatted address
323  * @len: length of target buffer
324  *
325  */
326 char *svc_print_addr(struct svc_rqst *rqstp, char *buf, size_t len)
327 {
328         return __svc_print_addr(svc_addr(rqstp), buf, len);
329 }
330 EXPORT_SYMBOL_GPL(svc_print_addr);
331 
332 static bool svc_xprt_has_something_to_do(struct svc_xprt *xprt)
333 {
334         if (xprt->xpt_flags & ((1<<XPT_CONN)|(1<<XPT_CLOSE)))
335                 return true;
336         if (xprt->xpt_flags & ((1<<XPT_DATA)|(1<<XPT_DEFERRED)))
337                 return xprt->xpt_ops->xpo_has_wspace(xprt);
338         return false;
339 }
340 
341 void svc_xprt_do_enqueue(struct svc_xprt *xprt)
342 {
343         struct svc_pool *pool;
344         struct svc_rqst *rqstp = NULL;
345         int cpu;
346         bool queued = false;
347 
348         if (!svc_xprt_has_something_to_do(xprt))
349                 goto out;
350 
351         /* Mark transport as busy. It will remain in this state until
352          * the provider calls svc_xprt_received. We update XPT_BUSY
353          * atomically because it also guards against trying to enqueue
354          * the transport twice.
355          */
356         if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags)) {
357                 /* Don't enqueue transport while already enqueued */
358                 dprintk("svc: transport %p busy, not enqueued\n", xprt);
359                 goto out;
360         }
361 
362         cpu = get_cpu();
363         pool = svc_pool_for_cpu(xprt->xpt_server, cpu);
364 
365         atomic_long_inc(&pool->sp_stats.packets);
366 
367 redo_search:
368         /* find a thread for this xprt */
369         rcu_read_lock();
370         list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
371                 /* Do a lockless check first */
372                 if (test_bit(RQ_BUSY, &rqstp->rq_flags))
373                         continue;
374 
375                 /*
376                  * Once the xprt has been queued, it can only be dequeued by
377                  * the task that intends to service it. All we can do at that
378                  * point is to try to wake this thread back up so that it can
379                  * do so.
380                  */
381                 if (!queued) {
382                         spin_lock_bh(&rqstp->rq_lock);
383                         if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags)) {
384                                 /* already busy, move on... */
385                                 spin_unlock_bh(&rqstp->rq_lock);
386                                 continue;
387                         }
388 
389                         /* this one will do */
390                         rqstp->rq_xprt = xprt;
391                         svc_xprt_get(xprt);
392                         spin_unlock_bh(&rqstp->rq_lock);
393                 }
394                 rcu_read_unlock();
395 
396                 atomic_long_inc(&pool->sp_stats.threads_woken);
397                 wake_up_process(rqstp->rq_task);
398                 put_cpu();
399                 goto out;
400         }
401         rcu_read_unlock();
402 
403         /*
404          * We didn't find an idle thread to use, so we need to queue the xprt.
405          * Do so and then search again. If we find one, we can't hook this one
406          * up to it directly but we can wake the thread up in the hopes that it
407          * will pick it up once it searches for a xprt to service.
408          */
409         if (!queued) {
410                 queued = true;
411                 dprintk("svc: transport %p put into queue\n", xprt);
412                 spin_lock_bh(&pool->sp_lock);
413                 list_add_tail(&xprt->xpt_ready, &pool->sp_sockets);
414                 pool->sp_stats.sockets_queued++;
415                 spin_unlock_bh(&pool->sp_lock);
416                 goto redo_search;
417         }
418         rqstp = NULL;
419         put_cpu();
420 out:
421         trace_svc_xprt_do_enqueue(xprt, rqstp);
422 }
423 EXPORT_SYMBOL_GPL(svc_xprt_do_enqueue);
424 
425 /*
426  * Queue up a transport with data pending. If there are idle nfsd
427  * processes, wake 'em up.
428  *
429  */
430 void svc_xprt_enqueue(struct svc_xprt *xprt)
431 {
432         if (test_bit(XPT_BUSY, &xprt->xpt_flags))
433                 return;
434         xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt);
435 }
436 EXPORT_SYMBOL_GPL(svc_xprt_enqueue);
437 
438 /*
439  * Dequeue the first transport, if there is one.
440  */
441 static struct svc_xprt *svc_xprt_dequeue(struct svc_pool *pool)
442 {
443         struct svc_xprt *xprt = NULL;
444 
445         if (list_empty(&pool->sp_sockets))
446                 goto out;
447 
448         spin_lock_bh(&pool->sp_lock);
449         if (likely(!list_empty(&pool->sp_sockets))) {
450                 xprt = list_first_entry(&pool->sp_sockets,
451                                         struct svc_xprt, xpt_ready);
452                 list_del_init(&xprt->xpt_ready);
453                 svc_xprt_get(xprt);
454 
455                 dprintk("svc: transport %p dequeued, inuse=%d\n",
456                         xprt, atomic_read(&xprt->xpt_ref.refcount));
457         }
458         spin_unlock_bh(&pool->sp_lock);
459 out:
460         trace_svc_xprt_dequeue(xprt);
461         return xprt;
462 }
463 
464 /**
465  * svc_reserve - change the space reserved for the reply to a request.
466  * @rqstp:  The request in question
467  * @space: new max space to reserve
468  *
469  * Each request reserves some space on the output queue of the transport
470  * to make sure the reply fits.  This function reduces that reserved
471  * space to be the amount of space used already, plus @space.
472  *
473  */
474 void svc_reserve(struct svc_rqst *rqstp, int space)
475 {
476         space += rqstp->rq_res.head[0].iov_len;
477 
478         if (space < rqstp->rq_reserved) {
479                 struct svc_xprt *xprt = rqstp->rq_xprt;
480                 atomic_sub((rqstp->rq_reserved - space), &xprt->xpt_reserved);
481                 rqstp->rq_reserved = space;
482 
483                 if (xprt->xpt_ops->xpo_adjust_wspace)
484                         xprt->xpt_ops->xpo_adjust_wspace(xprt);
485                 svc_xprt_enqueue(xprt);
486         }
487 }
488 EXPORT_SYMBOL_GPL(svc_reserve);
489 
490 static void svc_xprt_release(struct svc_rqst *rqstp)
491 {
492         struct svc_xprt *xprt = rqstp->rq_xprt;
493 
494         rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
495 
496         kfree(rqstp->rq_deferred);
497         rqstp->rq_deferred = NULL;
498 
499         svc_free_res_pages(rqstp);
500         rqstp->rq_res.page_len = 0;
501         rqstp->rq_res.page_base = 0;
502 
503         /* Reset response buffer and release
504          * the reservation.
505          * But first, check that enough space was reserved
506          * for the reply, otherwise we have a bug!
507          */
508         if ((rqstp->rq_res.len) >  rqstp->rq_reserved)
509                 printk(KERN_ERR "RPC request reserved %d but used %d\n",
510                        rqstp->rq_reserved,
511                        rqstp->rq_res.len);
512 
513         rqstp->rq_res.head[0].iov_len = 0;
514         svc_reserve(rqstp, 0);
515         rqstp->rq_xprt = NULL;
516 
517         svc_xprt_put(xprt);
518 }
519 
520 /*
521  * Some svc_serv's will have occasional work to do, even when a xprt is not
522  * waiting to be serviced. This function is there to "kick" a task in one of
523  * those services so that it can wake up and do that work. Note that we only
524  * bother with pool 0 as we don't need to wake up more than one thread for
525  * this purpose.
526  */
527 void svc_wake_up(struct svc_serv *serv)
528 {
529         struct svc_rqst *rqstp;
530         struct svc_pool *pool;
531 
532         pool = &serv->sv_pools[0];
533 
534         rcu_read_lock();
535         list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
536                 /* skip any that aren't queued */
537                 if (test_bit(RQ_BUSY, &rqstp->rq_flags))
538                         continue;
539                 rcu_read_unlock();
540                 dprintk("svc: daemon %p woken up.\n", rqstp);
541                 wake_up_process(rqstp->rq_task);
542                 trace_svc_wake_up(rqstp->rq_task->pid);
543                 return;
544         }
545         rcu_read_unlock();
546 
547         /* No free entries available */
548         set_bit(SP_TASK_PENDING, &pool->sp_flags);
549         smp_wmb();
550         trace_svc_wake_up(0);
551 }
552 EXPORT_SYMBOL_GPL(svc_wake_up);
553 
554 int svc_port_is_privileged(struct sockaddr *sin)
555 {
556         switch (sin->sa_family) {
557         case AF_INET:
558                 return ntohs(((struct sockaddr_in *)sin)->sin_port)
559                         < PROT_SOCK;
560         case AF_INET6:
561                 return ntohs(((struct sockaddr_in6 *)sin)->sin6_port)
562                         < PROT_SOCK;
563         default:
564                 return 0;
565         }
566 }
567 
568 /*
569  * Make sure that we don't have too many active connections. If we have,
570  * something must be dropped. It's not clear what will happen if we allow
571  * "too many" connections, but when dealing with network-facing software,
572  * we have to code defensively. Here we do that by imposing hard limits.
573  *
574  * There's no point in trying to do random drop here for DoS
575  * prevention. The NFS clients does 1 reconnect in 15 seconds. An
576  * attacker can easily beat that.
577  *
578  * The only somewhat efficient mechanism would be if drop old
579  * connections from the same IP first. But right now we don't even
580  * record the client IP in svc_sock.
581  *
582  * single-threaded services that expect a lot of clients will probably
583  * need to set sv_maxconn to override the default value which is based
584  * on the number of threads
585  */
586 static void svc_check_conn_limits(struct svc_serv *serv)
587 {
588         unsigned int limit = serv->sv_maxconn ? serv->sv_maxconn :
589                                 (serv->sv_nrthreads+3) * 20;
590 
591         if (serv->sv_tmpcnt > limit) {
592                 struct svc_xprt *xprt = NULL;
593                 spin_lock_bh(&serv->sv_lock);
594                 if (!list_empty(&serv->sv_tempsocks)) {
595                         /* Try to help the admin */
596                         net_notice_ratelimited("%s: too many open connections, consider increasing the %s\n",
597                                                serv->sv_name, serv->sv_maxconn ?
598                                                "max number of connections" :
599                                                "number of threads");
600                         /*
601                          * Always select the oldest connection. It's not fair,
602                          * but so is life
603                          */
604                         xprt = list_entry(serv->sv_tempsocks.prev,
605                                           struct svc_xprt,
606                                           xpt_list);
607                         set_bit(XPT_CLOSE, &xprt->xpt_flags);
608                         svc_xprt_get(xprt);
609                 }
610                 spin_unlock_bh(&serv->sv_lock);
611 
612                 if (xprt) {
613                         svc_xprt_enqueue(xprt);
614                         svc_xprt_put(xprt);
615                 }
616         }
617 }
618 
619 static int svc_alloc_arg(struct svc_rqst *rqstp)
620 {
621         struct svc_serv *serv = rqstp->rq_server;
622         struct xdr_buf *arg;
623         int pages;
624         int i;
625 
626         /* now allocate needed pages.  If we get a failure, sleep briefly */
627         pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
628         WARN_ON_ONCE(pages >= RPCSVC_MAXPAGES);
629         if (pages >= RPCSVC_MAXPAGES)
630                 /* use as many pages as possible */
631                 pages = RPCSVC_MAXPAGES - 1;
632         for (i = 0; i < pages ; i++)
633                 while (rqstp->rq_pages[i] == NULL) {
634                         struct page *p = alloc_page(GFP_KERNEL);
635                         if (!p) {
636                                 set_current_state(TASK_INTERRUPTIBLE);
637                                 if (signalled() || kthread_should_stop()) {
638                                         set_current_state(TASK_RUNNING);
639                                         return -EINTR;
640                                 }
641                                 schedule_timeout(msecs_to_jiffies(500));
642                         }
643                         rqstp->rq_pages[i] = p;
644                 }
645         rqstp->rq_page_end = &rqstp->rq_pages[i];
646         rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
647 
648         /* Make arg->head point to first page and arg->pages point to rest */
649         arg = &rqstp->rq_arg;
650         arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
651         arg->head[0].iov_len = PAGE_SIZE;
652         arg->pages = rqstp->rq_pages + 1;
653         arg->page_base = 0;
654         /* save at least one page for response */
655         arg->page_len = (pages-2)*PAGE_SIZE;
656         arg->len = (pages-1)*PAGE_SIZE;
657         arg->tail[0].iov_len = 0;
658         return 0;
659 }
660 
661 static bool
662 rqst_should_sleep(struct svc_rqst *rqstp)
663 {
664         struct svc_pool         *pool = rqstp->rq_pool;
665 
666         /* did someone call svc_wake_up? */
667         if (test_and_clear_bit(SP_TASK_PENDING, &pool->sp_flags))
668                 return false;
669 
670         /* was a socket queued? */
671         if (!list_empty(&pool->sp_sockets))
672                 return false;
673 
674         /* are we shutting down? */
675         if (signalled() || kthread_should_stop())
676                 return false;
677 
678         /* are we freezing? */
679         if (freezing(current))
680                 return false;
681 
682         return true;
683 }
684 
685 static struct svc_xprt *svc_get_next_xprt(struct svc_rqst *rqstp, long timeout)
686 {
687         struct svc_xprt *xprt;
688         struct svc_pool         *pool = rqstp->rq_pool;
689         long                    time_left = 0;
690 
691         /* rq_xprt should be clear on entry */
692         WARN_ON_ONCE(rqstp->rq_xprt);
693 
694         /* Normally we will wait up to 5 seconds for any required
695          * cache information to be provided.
696          */
697         rqstp->rq_chandle.thread_wait = 5*HZ;
698 
699         xprt = svc_xprt_dequeue(pool);
700         if (xprt) {
701                 rqstp->rq_xprt = xprt;
702 
703                 /* As there is a shortage of threads and this request
704                  * had to be queued, don't allow the thread to wait so
705                  * long for cache updates.
706                  */
707                 rqstp->rq_chandle.thread_wait = 1*HZ;
708                 clear_bit(SP_TASK_PENDING, &pool->sp_flags);
709                 return xprt;
710         }
711 
712         /*
713          * We have to be able to interrupt this wait
714          * to bring down the daemons ...
715          */
716         set_current_state(TASK_INTERRUPTIBLE);
717         clear_bit(RQ_BUSY, &rqstp->rq_flags);
718         smp_mb();
719 
720         if (likely(rqst_should_sleep(rqstp)))
721                 time_left = schedule_timeout(timeout);
722         else
723                 __set_current_state(TASK_RUNNING);
724 
725         try_to_freeze();
726 
727         spin_lock_bh(&rqstp->rq_lock);
728         set_bit(RQ_BUSY, &rqstp->rq_flags);
729         spin_unlock_bh(&rqstp->rq_lock);
730 
731         xprt = rqstp->rq_xprt;
732         if (xprt != NULL)
733                 return xprt;
734 
735         if (!time_left)
736                 atomic_long_inc(&pool->sp_stats.threads_timedout);
737 
738         if (signalled() || kthread_should_stop())
739                 return ERR_PTR(-EINTR);
740         return ERR_PTR(-EAGAIN);
741 }
742 
743 static void svc_add_new_temp_xprt(struct svc_serv *serv, struct svc_xprt *newxpt)
744 {
745         spin_lock_bh(&serv->sv_lock);
746         set_bit(XPT_TEMP, &newxpt->xpt_flags);
747         list_add(&newxpt->xpt_list, &serv->sv_tempsocks);
748         serv->sv_tmpcnt++;
749         if (serv->sv_temptimer.function == NULL) {
750                 /* setup timer to age temp transports */
751                 setup_timer(&serv->sv_temptimer, svc_age_temp_xprts,
752                             (unsigned long)serv);
753                 mod_timer(&serv->sv_temptimer,
754                           jiffies + svc_conn_age_period * HZ);
755         }
756         spin_unlock_bh(&serv->sv_lock);
757         svc_xprt_received(newxpt);
758 }
759 
760 static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
761 {
762         struct svc_serv *serv = rqstp->rq_server;
763         int len = 0;
764 
765         if (test_bit(XPT_CLOSE, &xprt->xpt_flags)) {
766                 dprintk("svc_recv: found XPT_CLOSE\n");
767                 svc_delete_xprt(xprt);
768                 /* Leave XPT_BUSY set on the dead xprt: */
769                 goto out;
770         }
771         if (test_bit(XPT_LISTENER, &xprt->xpt_flags)) {
772                 struct svc_xprt *newxpt;
773                 /*
774                  * We know this module_get will succeed because the
775                  * listener holds a reference too
776                  */
777                 __module_get(xprt->xpt_class->xcl_owner);
778                 svc_check_conn_limits(xprt->xpt_server);
779                 newxpt = xprt->xpt_ops->xpo_accept(xprt);
780                 if (newxpt)
781                         svc_add_new_temp_xprt(serv, newxpt);
782                 else
783                         module_put(xprt->xpt_class->xcl_owner);
784         } else {
785                 /* XPT_DATA|XPT_DEFERRED case: */
786                 dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
787                         rqstp, rqstp->rq_pool->sp_id, xprt,
788                         atomic_read(&xprt->xpt_ref.refcount));
789                 rqstp->rq_deferred = svc_deferred_dequeue(xprt);
790                 if (rqstp->rq_deferred)
791                         len = svc_deferred_recv(rqstp);
792                 else
793                         len = xprt->xpt_ops->xpo_recvfrom(rqstp);
794                 dprintk("svc: got len=%d\n", len);
795                 rqstp->rq_reserved = serv->sv_max_mesg;
796                 atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
797         }
798         /* clear XPT_BUSY: */
799         svc_xprt_received(xprt);
800 out:
801         trace_svc_handle_xprt(xprt, len);
802         return len;
803 }
804 
805 /*
806  * Receive the next request on any transport.  This code is carefully
807  * organised not to touch any cachelines in the shared svc_serv
808  * structure, only cachelines in the local svc_pool.
809  */
810 int svc_recv(struct svc_rqst *rqstp, long timeout)
811 {
812         struct svc_xprt         *xprt = NULL;
813         struct svc_serv         *serv = rqstp->rq_server;
814         int                     len, err;
815 
816         dprintk("svc: server %p waiting for data (to = %ld)\n",
817                 rqstp, timeout);
818 
819         if (rqstp->rq_xprt)
820                 printk(KERN_ERR
821                         "svc_recv: service %p, transport not NULL!\n",
822                          rqstp);
823 
824         err = svc_alloc_arg(rqstp);
825         if (err)
826                 goto out;
827 
828         try_to_freeze();
829         cond_resched();
830         err = -EINTR;
831         if (signalled() || kthread_should_stop())
832                 goto out;
833 
834         xprt = svc_get_next_xprt(rqstp, timeout);
835         if (IS_ERR(xprt)) {
836                 err = PTR_ERR(xprt);
837                 goto out;
838         }
839 
840         len = svc_handle_xprt(rqstp, xprt);
841 
842         /* No data, incomplete (TCP) read, or accept() */
843         err = -EAGAIN;
844         if (len <= 0)
845                 goto out_release;
846 
847         clear_bit(XPT_OLD, &xprt->xpt_flags);
848 
849         if (xprt->xpt_ops->xpo_secure_port(rqstp))
850                 set_bit(RQ_SECURE, &rqstp->rq_flags);
851         else
852                 clear_bit(RQ_SECURE, &rqstp->rq_flags);
853         rqstp->rq_chandle.defer = svc_defer;
854         rqstp->rq_xid = svc_getu32(&rqstp->rq_arg.head[0]);
855 
856         if (serv->sv_stats)
857                 serv->sv_stats->netcnt++;
858         trace_svc_recv(rqstp, len);
859         return len;
860 out_release:
861         rqstp->rq_res.len = 0;
862         svc_xprt_release(rqstp);
863 out:
864         trace_svc_recv(rqstp, err);
865         return err;
866 }
867 EXPORT_SYMBOL_GPL(svc_recv);
868 
869 /*
870  * Drop request
871  */
872 void svc_drop(struct svc_rqst *rqstp)
873 {
874         dprintk("svc: xprt %p dropped request\n", rqstp->rq_xprt);
875         svc_xprt_release(rqstp);
876 }
877 EXPORT_SYMBOL_GPL(svc_drop);
878 
879 /*
880  * Return reply to client.
881  */
882 int svc_send(struct svc_rqst *rqstp)
883 {
884         struct svc_xprt *xprt;
885         int             len = -EFAULT;
886         struct xdr_buf  *xb;
887 
888         xprt = rqstp->rq_xprt;
889         if (!xprt)
890                 goto out;
891 
892         /* release the receive skb before sending the reply */
893         rqstp->rq_xprt->xpt_ops->xpo_release_rqst(rqstp);
894 
895         /* calculate over-all length */
896         xb = &rqstp->rq_res;
897         xb->len = xb->head[0].iov_len +
898                 xb->page_len +
899                 xb->tail[0].iov_len;
900 
901         /* Grab mutex to serialize outgoing data. */
902         mutex_lock(&xprt->xpt_mutex);
903         if (test_bit(XPT_DEAD, &xprt->xpt_flags)
904                         || test_bit(XPT_CLOSE, &xprt->xpt_flags))
905                 len = -ENOTCONN;
906         else
907                 len = xprt->xpt_ops->xpo_sendto(rqstp);
908         mutex_unlock(&xprt->xpt_mutex);
909         rpc_wake_up(&xprt->xpt_bc_pending);
910         svc_xprt_release(rqstp);
911 
912         if (len == -ECONNREFUSED || len == -ENOTCONN || len == -EAGAIN)
913                 len = 0;
914 out:
915         trace_svc_send(rqstp, len);
916         return len;
917 }
918 
919 /*
920  * Timer function to close old temporary transports, using
921  * a mark-and-sweep algorithm.
922  */
923 static void svc_age_temp_xprts(unsigned long closure)
924 {
925         struct svc_serv *serv = (struct svc_serv *)closure;
926         struct svc_xprt *xprt;
927         struct list_head *le, *next;
928 
929         dprintk("svc_age_temp_xprts\n");
930 
931         if (!spin_trylock_bh(&serv->sv_lock)) {
932                 /* busy, try again 1 sec later */
933                 dprintk("svc_age_temp_xprts: busy\n");
934                 mod_timer(&serv->sv_temptimer, jiffies + HZ);
935                 return;
936         }
937 
938         list_for_each_safe(le, next, &serv->sv_tempsocks) {
939                 xprt = list_entry(le, struct svc_xprt, xpt_list);
940 
941                 /* First time through, just mark it OLD. Second time
942                  * through, close it. */
943                 if (!test_and_set_bit(XPT_OLD, &xprt->xpt_flags))
944                         continue;
945                 if (atomic_read(&xprt->xpt_ref.refcount) > 1 ||
946                     test_bit(XPT_BUSY, &xprt->xpt_flags))
947                         continue;
948                 list_del_init(le);
949                 set_bit(XPT_CLOSE, &xprt->xpt_flags);
950                 dprintk("queuing xprt %p for closing\n", xprt);
951 
952                 /* a thread will dequeue and close it soon */
953                 svc_xprt_enqueue(xprt);
954         }
955         spin_unlock_bh(&serv->sv_lock);
956 
957         mod_timer(&serv->sv_temptimer, jiffies + svc_conn_age_period * HZ);
958 }
959 
960 /* Close temporary transports whose xpt_local matches server_addr immediately
961  * instead of waiting for them to be picked up by the timer.
962  *
963  * This is meant to be called from a notifier_block that runs when an ip
964  * address is deleted.
965  */
966 void svc_age_temp_xprts_now(struct svc_serv *serv, struct sockaddr *server_addr)
967 {
968         struct svc_xprt *xprt;
969         struct svc_sock *svsk;
970         struct socket *sock;
971         struct list_head *le, *next;
972         LIST_HEAD(to_be_closed);
973         struct linger no_linger = {
974                 .l_onoff = 1,
975                 .l_linger = 0,
976         };
977 
978         spin_lock_bh(&serv->sv_lock);
979         list_for_each_safe(le, next, &serv->sv_tempsocks) {
980                 xprt = list_entry(le, struct svc_xprt, xpt_list);
981                 if (rpc_cmp_addr(server_addr, (struct sockaddr *)
982                                 &xprt->xpt_local)) {
983                         dprintk("svc_age_temp_xprts_now: found %p\n", xprt);
984                         list_move(le, &to_be_closed);
985                 }
986         }
987         spin_unlock_bh(&serv->sv_lock);
988 
989         while (!list_empty(&to_be_closed)) {
990                 le = to_be_closed.next;
991                 list_del_init(le);
992                 xprt = list_entry(le, struct svc_xprt, xpt_list);
993                 dprintk("svc_age_temp_xprts_now: closing %p\n", xprt);
994                 svsk = container_of(xprt, struct svc_sock, sk_xprt);
995                 sock = svsk->sk_sock;
996                 kernel_setsockopt(sock, SOL_SOCKET, SO_LINGER,
997                                   (char *)&no_linger, sizeof(no_linger));
998                 svc_close_xprt(xprt);
999         }
1000 }
1001 EXPORT_SYMBOL_GPL(svc_age_temp_xprts_now);
1002 
1003 static void call_xpt_users(struct svc_xprt *xprt)
1004 {
1005         struct svc_xpt_user *u;
1006 
1007         spin_lock(&xprt->xpt_lock);
1008         while (!list_empty(&xprt->xpt_users)) {
1009                 u = list_first_entry(&xprt->xpt_users, struct svc_xpt_user, list);
1010                 list_del(&u->list);
1011                 u->callback(u);
1012         }
1013         spin_unlock(&xprt->xpt_lock);
1014 }
1015 
1016 /*
1017  * Remove a dead transport
1018  */
1019 static void svc_delete_xprt(struct svc_xprt *xprt)
1020 {
1021         struct svc_serv *serv = xprt->xpt_server;
1022         struct svc_deferred_req *dr;
1023 
1024         /* Only do this once */
1025         if (test_and_set_bit(XPT_DEAD, &xprt->xpt_flags))
1026                 BUG();
1027 
1028         dprintk("svc: svc_delete_xprt(%p)\n", xprt);
1029         xprt->xpt_ops->xpo_detach(xprt);
1030 
1031         spin_lock_bh(&serv->sv_lock);
1032         list_del_init(&xprt->xpt_list);
1033         WARN_ON_ONCE(!list_empty(&xprt->xpt_ready));
1034         if (test_bit(XPT_TEMP, &xprt->xpt_flags))
1035                 serv->sv_tmpcnt--;
1036         spin_unlock_bh(&serv->sv_lock);
1037 
1038         while ((dr = svc_deferred_dequeue(xprt)) != NULL)
1039                 kfree(dr);
1040 
1041         call_xpt_users(xprt);
1042         svc_xprt_put(xprt);
1043 }
1044 
1045 void svc_close_xprt(struct svc_xprt *xprt)
1046 {
1047         set_bit(XPT_CLOSE, &xprt->xpt_flags);
1048         if (test_and_set_bit(XPT_BUSY, &xprt->xpt_flags))
1049                 /* someone else will have to effect the close */
1050                 return;
1051         /*
1052          * We expect svc_close_xprt() to work even when no threads are
1053          * running (e.g., while configuring the server before starting
1054          * any threads), so if the transport isn't busy, we delete
1055          * it ourself:
1056          */
1057         svc_delete_xprt(xprt);
1058 }
1059 EXPORT_SYMBOL_GPL(svc_close_xprt);
1060 
1061 static int svc_close_list(struct svc_serv *serv, struct list_head *xprt_list, struct net *net)
1062 {
1063         struct svc_xprt *xprt;
1064         int ret = 0;
1065 
1066         spin_lock(&serv->sv_lock);
1067         list_for_each_entry(xprt, xprt_list, xpt_list) {
1068                 if (xprt->xpt_net != net)
1069                         continue;
1070                 ret++;
1071                 set_bit(XPT_CLOSE, &xprt->xpt_flags);
1072                 svc_xprt_enqueue(xprt);
1073         }
1074         spin_unlock(&serv->sv_lock);
1075         return ret;
1076 }
1077 
1078 static struct svc_xprt *svc_dequeue_net(struct svc_serv *serv, struct net *net)
1079 {
1080         struct svc_pool *pool;
1081         struct svc_xprt *xprt;
1082         struct svc_xprt *tmp;
1083         int i;
1084 
1085         for (i = 0; i < serv->sv_nrpools; i++) {
1086                 pool = &serv->sv_pools[i];
1087 
1088                 spin_lock_bh(&pool->sp_lock);
1089                 list_for_each_entry_safe(xprt, tmp, &pool->sp_sockets, xpt_ready) {
1090                         if (xprt->xpt_net != net)
1091                                 continue;
1092                         list_del_init(&xprt->xpt_ready);
1093                         spin_unlock_bh(&pool->sp_lock);
1094                         return xprt;
1095                 }
1096                 spin_unlock_bh(&pool->sp_lock);
1097         }
1098         return NULL;
1099 }
1100 
1101 static void svc_clean_up_xprts(struct svc_serv *serv, struct net *net)
1102 {
1103         struct svc_xprt *xprt;
1104 
1105         while ((xprt = svc_dequeue_net(serv, net))) {
1106                 set_bit(XPT_CLOSE, &xprt->xpt_flags);
1107                 svc_delete_xprt(xprt);
1108         }
1109 }
1110 
1111 /*
1112  * Server threads may still be running (especially in the case where the
1113  * service is still running in other network namespaces).
1114  *
1115  * So we shut down sockets the same way we would on a running server, by
1116  * setting XPT_CLOSE, enqueuing, and letting a thread pick it up to do
1117  * the close.  In the case there are no such other threads,
1118  * threads running, svc_clean_up_xprts() does a simple version of a
1119  * server's main event loop, and in the case where there are other
1120  * threads, we may need to wait a little while and then check again to
1121  * see if they're done.
1122  */
1123 void svc_close_net(struct svc_serv *serv, struct net *net)
1124 {
1125         int delay = 0;
1126 
1127         while (svc_close_list(serv, &serv->sv_permsocks, net) +
1128                svc_close_list(serv, &serv->sv_tempsocks, net)) {
1129 
1130                 svc_clean_up_xprts(serv, net);
1131                 msleep(delay++);
1132         }
1133 }
1134 
1135 /*
1136  * Handle defer and revisit of requests
1137  */
1138 
1139 static void svc_revisit(struct cache_deferred_req *dreq, int too_many)
1140 {
1141         struct svc_deferred_req *dr =
1142                 container_of(dreq, struct svc_deferred_req, handle);
1143         struct svc_xprt *xprt = dr->xprt;
1144 
1145         spin_lock(&xprt->xpt_lock);
1146         set_bit(XPT_DEFERRED, &xprt->xpt_flags);
1147         if (too_many || test_bit(XPT_DEAD, &xprt->xpt_flags)) {
1148                 spin_unlock(&xprt->xpt_lock);
1149                 dprintk("revisit canceled\n");
1150                 svc_xprt_put(xprt);
1151                 kfree(dr);
1152                 return;
1153         }
1154         dprintk("revisit queued\n");
1155         dr->xprt = NULL;
1156         list_add(&dr->handle.recent, &xprt->xpt_deferred);
1157         spin_unlock(&xprt->xpt_lock);
1158         svc_xprt_enqueue(xprt);
1159         svc_xprt_put(xprt);
1160 }
1161 
1162 /*
1163  * Save the request off for later processing. The request buffer looks
1164  * like this:
1165  *
1166  * <xprt-header><rpc-header><rpc-pagelist><rpc-tail>
1167  *
1168  * This code can only handle requests that consist of an xprt-header
1169  * and rpc-header.
1170  */
1171 static struct cache_deferred_req *svc_defer(struct cache_req *req)
1172 {
1173         struct svc_rqst *rqstp = container_of(req, struct svc_rqst, rq_chandle);
1174         struct svc_deferred_req *dr;
1175 
1176         if (rqstp->rq_arg.page_len || !test_bit(RQ_USEDEFERRAL, &rqstp->rq_flags))
1177                 return NULL; /* if more than a page, give up FIXME */
1178         if (rqstp->rq_deferred) {
1179                 dr = rqstp->rq_deferred;
1180                 rqstp->rq_deferred = NULL;
1181         } else {
1182                 size_t skip;
1183                 size_t size;
1184                 /* FIXME maybe discard if size too large */
1185                 size = sizeof(struct svc_deferred_req) + rqstp->rq_arg.len;
1186                 dr = kmalloc(size, GFP_KERNEL);
1187                 if (dr == NULL)
1188                         return NULL;
1189 
1190                 dr->handle.owner = rqstp->rq_server;
1191                 dr->prot = rqstp->rq_prot;
1192                 memcpy(&dr->addr, &rqstp->rq_addr, rqstp->rq_addrlen);
1193                 dr->addrlen = rqstp->rq_addrlen;
1194                 dr->daddr = rqstp->rq_daddr;
1195                 dr->argslen = rqstp->rq_arg.len >> 2;
1196                 dr->xprt_hlen = rqstp->rq_xprt_hlen;
1197 
1198                 /* back up head to the start of the buffer and copy */
1199                 skip = rqstp->rq_arg.len - rqstp->rq_arg.head[0].iov_len;
1200                 memcpy(dr->args, rqstp->rq_arg.head[0].iov_base - skip,
1201                        dr->argslen << 2);
1202         }
1203         svc_xprt_get(rqstp->rq_xprt);
1204         dr->xprt = rqstp->rq_xprt;
1205         set_bit(RQ_DROPME, &rqstp->rq_flags);
1206 
1207         dr->handle.revisit = svc_revisit;
1208         return &dr->handle;
1209 }
1210 
1211 /*
1212  * recv data from a deferred request into an active one
1213  */
1214 static int svc_deferred_recv(struct svc_rqst *rqstp)
1215 {
1216         struct svc_deferred_req *dr = rqstp->rq_deferred;
1217 
1218         /* setup iov_base past transport header */
1219         rqstp->rq_arg.head[0].iov_base = dr->args + (dr->xprt_hlen>>2);
1220         /* The iov_len does not include the transport header bytes */
1221         rqstp->rq_arg.head[0].iov_len = (dr->argslen<<2) - dr->xprt_hlen;
1222         rqstp->rq_arg.page_len = 0;
1223         /* The rq_arg.len includes the transport header bytes */
1224         rqstp->rq_arg.len     = dr->argslen<<2;
1225         rqstp->rq_prot        = dr->prot;
1226         memcpy(&rqstp->rq_addr, &dr->addr, dr->addrlen);
1227         rqstp->rq_addrlen     = dr->addrlen;
1228         /* Save off transport header len in case we get deferred again */
1229         rqstp->rq_xprt_hlen   = dr->xprt_hlen;
1230         rqstp->rq_daddr       = dr->daddr;
1231         rqstp->rq_respages    = rqstp->rq_pages;
1232         return (dr->argslen<<2) - dr->xprt_hlen;
1233 }
1234 
1235 
1236 static struct svc_deferred_req *svc_deferred_dequeue(struct svc_xprt *xprt)
1237 {
1238         struct svc_deferred_req *dr = NULL;
1239 
1240         if (!test_bit(XPT_DEFERRED, &xprt->xpt_flags))
1241                 return NULL;
1242         spin_lock(&xprt->xpt_lock);
1243         if (!list_empty(&xprt->xpt_deferred)) {
1244                 dr = list_entry(xprt->xpt_deferred.next,
1245                                 struct svc_deferred_req,
1246                                 handle.recent);
1247                 list_del_init(&dr->handle.recent);
1248         } else
1249                 clear_bit(XPT_DEFERRED, &xprt->xpt_flags);
1250         spin_unlock(&xprt->xpt_lock);
1251         return dr;
1252 }
1253 
1254 /**
1255  * svc_find_xprt - find an RPC transport instance
1256  * @serv: pointer to svc_serv to search
1257  * @xcl_name: C string containing transport's class name
1258  * @net: owner net pointer
1259  * @af: Address family of transport's local address
1260  * @port: transport's IP port number
1261  *
1262  * Return the transport instance pointer for the endpoint accepting
1263  * connections/peer traffic from the specified transport class,
1264  * address family and port.
1265  *
1266  * Specifying 0 for the address family or port is effectively a
1267  * wild-card, and will result in matching the first transport in the
1268  * service's list that has a matching class name.
1269  */
1270 struct svc_xprt *svc_find_xprt(struct svc_serv *serv, const char *xcl_name,
1271                                struct net *net, const sa_family_t af,
1272                                const unsigned short port)
1273 {
1274         struct svc_xprt *xprt;
1275         struct svc_xprt *found = NULL;
1276 
1277         /* Sanity check the args */
1278         if (serv == NULL || xcl_name == NULL)
1279                 return found;
1280 
1281         spin_lock_bh(&serv->sv_lock);
1282         list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
1283                 if (xprt->xpt_net != net)
1284                         continue;
1285                 if (strcmp(xprt->xpt_class->xcl_name, xcl_name))
1286                         continue;
1287                 if (af != AF_UNSPEC && af != xprt->xpt_local.ss_family)
1288                         continue;
1289                 if (port != 0 && port != svc_xprt_local_port(xprt))
1290                         continue;
1291                 found = xprt;
1292                 svc_xprt_get(xprt);
1293                 break;
1294         }
1295         spin_unlock_bh(&serv->sv_lock);
1296         return found;
1297 }
1298 EXPORT_SYMBOL_GPL(svc_find_xprt);
1299 
1300 static int svc_one_xprt_name(const struct svc_xprt *xprt,
1301                              char *pos, int remaining)
1302 {
1303         int len;
1304 
1305         len = snprintf(pos, remaining, "%s %u\n",
1306                         xprt->xpt_class->xcl_name,
1307                         svc_xprt_local_port(xprt));
1308         if (len >= remaining)
1309                 return -ENAMETOOLONG;
1310         return len;
1311 }
1312 
1313 /**
1314  * svc_xprt_names - format a buffer with a list of transport names
1315  * @serv: pointer to an RPC service
1316  * @buf: pointer to a buffer to be filled in
1317  * @buflen: length of buffer to be filled in
1318  *
1319  * Fills in @buf with a string containing a list of transport names,
1320  * each name terminated with '\n'.
1321  *
1322  * Returns positive length of the filled-in string on success; otherwise
1323  * a negative errno value is returned if an error occurs.
1324  */
1325 int svc_xprt_names(struct svc_serv *serv, char *buf, const int buflen)
1326 {
1327         struct svc_xprt *xprt;
1328         int len, totlen;
1329         char *pos;
1330 
1331         /* Sanity check args */
1332         if (!serv)
1333                 return 0;
1334 
1335         spin_lock_bh(&serv->sv_lock);
1336 
1337         pos = buf;
1338         totlen = 0;
1339         list_for_each_entry(xprt, &serv->sv_permsocks, xpt_list) {
1340                 len = svc_one_xprt_name(xprt, pos, buflen - totlen);
1341                 if (len < 0) {
1342                         *buf = '\0';
1343                         totlen = len;
1344                 }
1345                 if (len <= 0)
1346                         break;
1347 
1348                 pos += len;
1349                 totlen += len;
1350         }
1351 
1352         spin_unlock_bh(&serv->sv_lock);
1353         return totlen;
1354 }
1355 EXPORT_SYMBOL_GPL(svc_xprt_names);
1356 
1357 
1358 /*----------------------------------------------------------------------------*/
1359 
1360 static void *svc_pool_stats_start(struct seq_file *m, loff_t *pos)
1361 {
1362         unsigned int pidx = (unsigned int)*pos;
1363         struct svc_serv *serv = m->private;
1364 
1365         dprintk("svc_pool_stats_start, *pidx=%u\n", pidx);
1366 
1367         if (!pidx)
1368                 return SEQ_START_TOKEN;
1369         return (pidx > serv->sv_nrpools ? NULL : &serv->sv_pools[pidx-1]);
1370 }
1371 
1372 static void *svc_pool_stats_next(struct seq_file *m, void *p, loff_t *pos)
1373 {
1374         struct svc_pool *pool = p;
1375         struct svc_serv *serv = m->private;
1376 
1377         dprintk("svc_pool_stats_next, *pos=%llu\n", *pos);
1378 
1379         if (p == SEQ_START_TOKEN) {
1380                 pool = &serv->sv_pools[0];
1381         } else {
1382                 unsigned int pidx = (pool - &serv->sv_pools[0]);
1383                 if (pidx < serv->sv_nrpools-1)
1384                         pool = &serv->sv_pools[pidx+1];
1385                 else
1386                         pool = NULL;
1387         }
1388         ++*pos;
1389         return pool;
1390 }
1391 
1392 static void svc_pool_stats_stop(struct seq_file *m, void *p)
1393 {
1394 }
1395 
1396 static int svc_pool_stats_show(struct seq_file *m, void *p)
1397 {
1398         struct svc_pool *pool = p;
1399 
1400         if (p == SEQ_START_TOKEN) {
1401                 seq_puts(m, "# pool packets-arrived sockets-enqueued threads-woken threads-timedout\n");
1402                 return 0;
1403         }
1404 
1405         seq_printf(m, "%u %lu %lu %lu %lu\n",
1406                 pool->sp_id,
1407                 (unsigned long)atomic_long_read(&pool->sp_stats.packets),
1408                 pool->sp_stats.sockets_queued,
1409                 (unsigned long)atomic_long_read(&pool->sp_stats.threads_woken),
1410                 (unsigned long)atomic_long_read(&pool->sp_stats.threads_timedout));
1411 
1412         return 0;
1413 }
1414 
1415 static const struct seq_operations svc_pool_stats_seq_ops = {
1416         .start  = svc_pool_stats_start,
1417         .next   = svc_pool_stats_next,
1418         .stop   = svc_pool_stats_stop,
1419         .show   = svc_pool_stats_show,
1420 };
1421 
1422 int svc_pool_stats_open(struct svc_serv *serv, struct file *file)
1423 {
1424         int err;
1425 
1426         err = seq_open(file, &svc_pool_stats_seq_ops);
1427         if (!err)
1428                 ((struct seq_file *) file->private_data)->private = serv;
1429         return err;
1430 }
1431 EXPORT_SYMBOL(svc_pool_stats_open);
1432 
1433 /*----------------------------------------------------------------------------*/
1434 

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