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

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