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

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