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

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  1 /*
  2  * linux/net/sunrpc/svc.c
  3  *
  4  * High-level RPC service routines
  5  *
  6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
  7  *
  8  * Multiple threads pools and NUMAisation
  9  * Copyright (c) 2006 Silicon Graphics, Inc.
 10  * by Greg Banks <gnb@melbourne.sgi.com>
 11  */
 12 
 13 #include <linux/linkage.h>
 14 #include <linux/sched/signal.h>
 15 #include <linux/errno.h>
 16 #include <linux/net.h>
 17 #include <linux/in.h>
 18 #include <linux/mm.h>
 19 #include <linux/interrupt.h>
 20 #include <linux/module.h>
 21 #include <linux/kthread.h>
 22 #include <linux/slab.h>
 23 
 24 #include <linux/sunrpc/types.h>
 25 #include <linux/sunrpc/xdr.h>
 26 #include <linux/sunrpc/stats.h>
 27 #include <linux/sunrpc/svcsock.h>
 28 #include <linux/sunrpc/clnt.h>
 29 #include <linux/sunrpc/bc_xprt.h>
 30 
 31 #include <trace/events/sunrpc.h>
 32 
 33 #define RPCDBG_FACILITY RPCDBG_SVCDSP
 34 
 35 static void svc_unregister(const struct svc_serv *serv, struct net *net);
 36 
 37 #define svc_serv_is_pooled(serv)    ((serv)->sv_ops->svo_function)
 38 
 39 #define SVC_POOL_DEFAULT        SVC_POOL_GLOBAL
 40 
 41 /*
 42  * Structure for mapping cpus to pools and vice versa.
 43  * Setup once during sunrpc initialisation.
 44  */
 45 struct svc_pool_map svc_pool_map = {
 46         .mode = SVC_POOL_DEFAULT
 47 };
 48 EXPORT_SYMBOL_GPL(svc_pool_map);
 49 
 50 static DEFINE_MUTEX(svc_pool_map_mutex);/* protects svc_pool_map.count only */
 51 
 52 static int
 53 param_set_pool_mode(const char *val, struct kernel_param *kp)
 54 {
 55         int *ip = (int *)kp->arg;
 56         struct svc_pool_map *m = &svc_pool_map;
 57         int err;
 58 
 59         mutex_lock(&svc_pool_map_mutex);
 60 
 61         err = -EBUSY;
 62         if (m->count)
 63                 goto out;
 64 
 65         err = 0;
 66         if (!strncmp(val, "auto", 4))
 67                 *ip = SVC_POOL_AUTO;
 68         else if (!strncmp(val, "global", 6))
 69                 *ip = SVC_POOL_GLOBAL;
 70         else if (!strncmp(val, "percpu", 6))
 71                 *ip = SVC_POOL_PERCPU;
 72         else if (!strncmp(val, "pernode", 7))
 73                 *ip = SVC_POOL_PERNODE;
 74         else
 75                 err = -EINVAL;
 76 
 77 out:
 78         mutex_unlock(&svc_pool_map_mutex);
 79         return err;
 80 }
 81 
 82 static int
 83 param_get_pool_mode(char *buf, struct kernel_param *kp)
 84 {
 85         int *ip = (int *)kp->arg;
 86 
 87         switch (*ip)
 88         {
 89         case SVC_POOL_AUTO:
 90                 return strlcpy(buf, "auto", 20);
 91         case SVC_POOL_GLOBAL:
 92                 return strlcpy(buf, "global", 20);
 93         case SVC_POOL_PERCPU:
 94                 return strlcpy(buf, "percpu", 20);
 95         case SVC_POOL_PERNODE:
 96                 return strlcpy(buf, "pernode", 20);
 97         default:
 98                 return sprintf(buf, "%d", *ip);
 99         }
100 }
101 
102 module_param_call(pool_mode, param_set_pool_mode, param_get_pool_mode,
103                  &svc_pool_map.mode, 0644);
104 
105 /*
106  * Detect best pool mapping mode heuristically,
107  * according to the machine's topology.
108  */
109 static int
110 svc_pool_map_choose_mode(void)
111 {
112         unsigned int node;
113 
114         if (nr_online_nodes > 1) {
115                 /*
116                  * Actually have multiple NUMA nodes,
117                  * so split pools on NUMA node boundaries
118                  */
119                 return SVC_POOL_PERNODE;
120         }
121 
122         node = first_online_node;
123         if (nr_cpus_node(node) > 2) {
124                 /*
125                  * Non-trivial SMP, or CONFIG_NUMA on
126                  * non-NUMA hardware, e.g. with a generic
127                  * x86_64 kernel on Xeons.  In this case we
128                  * want to divide the pools on cpu boundaries.
129                  */
130                 return SVC_POOL_PERCPU;
131         }
132 
133         /* default: one global pool */
134         return SVC_POOL_GLOBAL;
135 }
136 
137 /*
138  * Allocate the to_pool[] and pool_to[] arrays.
139  * Returns 0 on success or an errno.
140  */
141 static int
142 svc_pool_map_alloc_arrays(struct svc_pool_map *m, unsigned int maxpools)
143 {
144         m->to_pool = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL);
145         if (!m->to_pool)
146                 goto fail;
147         m->pool_to = kcalloc(maxpools, sizeof(unsigned int), GFP_KERNEL);
148         if (!m->pool_to)
149                 goto fail_free;
150 
151         return 0;
152 
153 fail_free:
154         kfree(m->to_pool);
155         m->to_pool = NULL;
156 fail:
157         return -ENOMEM;
158 }
159 
160 /*
161  * Initialise the pool map for SVC_POOL_PERCPU mode.
162  * Returns number of pools or <0 on error.
163  */
164 static int
165 svc_pool_map_init_percpu(struct svc_pool_map *m)
166 {
167         unsigned int maxpools = nr_cpu_ids;
168         unsigned int pidx = 0;
169         unsigned int cpu;
170         int err;
171 
172         err = svc_pool_map_alloc_arrays(m, maxpools);
173         if (err)
174                 return err;
175 
176         for_each_online_cpu(cpu) {
177                 BUG_ON(pidx >= maxpools);
178                 m->to_pool[cpu] = pidx;
179                 m->pool_to[pidx] = cpu;
180                 pidx++;
181         }
182         /* cpus brought online later all get mapped to pool0, sorry */
183 
184         return pidx;
185 };
186 
187 
188 /*
189  * Initialise the pool map for SVC_POOL_PERNODE mode.
190  * Returns number of pools or <0 on error.
191  */
192 static int
193 svc_pool_map_init_pernode(struct svc_pool_map *m)
194 {
195         unsigned int maxpools = nr_node_ids;
196         unsigned int pidx = 0;
197         unsigned int node;
198         int err;
199 
200         err = svc_pool_map_alloc_arrays(m, maxpools);
201         if (err)
202                 return err;
203 
204         for_each_node_with_cpus(node) {
205                 /* some architectures (e.g. SN2) have cpuless nodes */
206                 BUG_ON(pidx > maxpools);
207                 m->to_pool[node] = pidx;
208                 m->pool_to[pidx] = node;
209                 pidx++;
210         }
211         /* nodes brought online later all get mapped to pool0, sorry */
212 
213         return pidx;
214 }
215 
216 
217 /*
218  * Add a reference to the global map of cpus to pools (and
219  * vice versa).  Initialise the map if we're the first user.
220  * Returns the number of pools.
221  */
222 unsigned int
223 svc_pool_map_get(void)
224 {
225         struct svc_pool_map *m = &svc_pool_map;
226         int npools = -1;
227 
228         mutex_lock(&svc_pool_map_mutex);
229 
230         if (m->count++) {
231                 mutex_unlock(&svc_pool_map_mutex);
232                 return m->npools;
233         }
234 
235         if (m->mode == SVC_POOL_AUTO)
236                 m->mode = svc_pool_map_choose_mode();
237 
238         switch (m->mode) {
239         case SVC_POOL_PERCPU:
240                 npools = svc_pool_map_init_percpu(m);
241                 break;
242         case SVC_POOL_PERNODE:
243                 npools = svc_pool_map_init_pernode(m);
244                 break;
245         }
246 
247         if (npools < 0) {
248                 /* default, or memory allocation failure */
249                 npools = 1;
250                 m->mode = SVC_POOL_GLOBAL;
251         }
252         m->npools = npools;
253 
254         mutex_unlock(&svc_pool_map_mutex);
255         return m->npools;
256 }
257 EXPORT_SYMBOL_GPL(svc_pool_map_get);
258 
259 /*
260  * Drop a reference to the global map of cpus to pools.
261  * When the last reference is dropped, the map data is
262  * freed; this allows the sysadmin to change the pool
263  * mode using the pool_mode module option without
264  * rebooting or re-loading sunrpc.ko.
265  */
266 void
267 svc_pool_map_put(void)
268 {
269         struct svc_pool_map *m = &svc_pool_map;
270 
271         mutex_lock(&svc_pool_map_mutex);
272 
273         if (!--m->count) {
274                 kfree(m->to_pool);
275                 m->to_pool = NULL;
276                 kfree(m->pool_to);
277                 m->pool_to = NULL;
278                 m->npools = 0;
279         }
280 
281         mutex_unlock(&svc_pool_map_mutex);
282 }
283 EXPORT_SYMBOL_GPL(svc_pool_map_put);
284 
285 static int svc_pool_map_get_node(unsigned int pidx)
286 {
287         const struct svc_pool_map *m = &svc_pool_map;
288 
289         if (m->count) {
290                 if (m->mode == SVC_POOL_PERCPU)
291                         return cpu_to_node(m->pool_to[pidx]);
292                 if (m->mode == SVC_POOL_PERNODE)
293                         return m->pool_to[pidx];
294         }
295         return NUMA_NO_NODE;
296 }
297 /*
298  * Set the given thread's cpus_allowed mask so that it
299  * will only run on cpus in the given pool.
300  */
301 static inline void
302 svc_pool_map_set_cpumask(struct task_struct *task, unsigned int pidx)
303 {
304         struct svc_pool_map *m = &svc_pool_map;
305         unsigned int node = m->pool_to[pidx];
306 
307         /*
308          * The caller checks for sv_nrpools > 1, which
309          * implies that we've been initialized.
310          */
311         WARN_ON_ONCE(m->count == 0);
312         if (m->count == 0)
313                 return;
314 
315         switch (m->mode) {
316         case SVC_POOL_PERCPU:
317         {
318                 set_cpus_allowed_ptr(task, cpumask_of(node));
319                 break;
320         }
321         case SVC_POOL_PERNODE:
322         {
323                 set_cpus_allowed_ptr(task, cpumask_of_node(node));
324                 break;
325         }
326         }
327 }
328 
329 /*
330  * Use the mapping mode to choose a pool for a given CPU.
331  * Used when enqueueing an incoming RPC.  Always returns
332  * a non-NULL pool pointer.
333  */
334 struct svc_pool *
335 svc_pool_for_cpu(struct svc_serv *serv, int cpu)
336 {
337         struct svc_pool_map *m = &svc_pool_map;
338         unsigned int pidx = 0;
339 
340         /*
341          * An uninitialised map happens in a pure client when
342          * lockd is brought up, so silently treat it the
343          * same as SVC_POOL_GLOBAL.
344          */
345         if (svc_serv_is_pooled(serv)) {
346                 switch (m->mode) {
347                 case SVC_POOL_PERCPU:
348                         pidx = m->to_pool[cpu];
349                         break;
350                 case SVC_POOL_PERNODE:
351                         pidx = m->to_pool[cpu_to_node(cpu)];
352                         break;
353                 }
354         }
355         return &serv->sv_pools[pidx % serv->sv_nrpools];
356 }
357 
358 int svc_rpcb_setup(struct svc_serv *serv, struct net *net)
359 {
360         int err;
361 
362         err = rpcb_create_local(net);
363         if (err)
364                 return err;
365 
366         /* Remove any stale portmap registrations */
367         svc_unregister(serv, net);
368         return 0;
369 }
370 EXPORT_SYMBOL_GPL(svc_rpcb_setup);
371 
372 void svc_rpcb_cleanup(struct svc_serv *serv, struct net *net)
373 {
374         svc_unregister(serv, net);
375         rpcb_put_local(net);
376 }
377 EXPORT_SYMBOL_GPL(svc_rpcb_cleanup);
378 
379 static int svc_uses_rpcbind(struct svc_serv *serv)
380 {
381         struct svc_program      *progp;
382         unsigned int            i;
383 
384         for (progp = serv->sv_program; progp; progp = progp->pg_next) {
385                 for (i = 0; i < progp->pg_nvers; i++) {
386                         if (progp->pg_vers[i] == NULL)
387                                 continue;
388                         if (!progp->pg_vers[i]->vs_hidden)
389                                 return 1;
390                 }
391         }
392 
393         return 0;
394 }
395 
396 int svc_bind(struct svc_serv *serv, struct net *net)
397 {
398         if (!svc_uses_rpcbind(serv))
399                 return 0;
400         return svc_rpcb_setup(serv, net);
401 }
402 EXPORT_SYMBOL_GPL(svc_bind);
403 
404 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
405 static void
406 __svc_init_bc(struct svc_serv *serv)
407 {
408         INIT_LIST_HEAD(&serv->sv_cb_list);
409         spin_lock_init(&serv->sv_cb_lock);
410         init_waitqueue_head(&serv->sv_cb_waitq);
411 }
412 #else
413 static void
414 __svc_init_bc(struct svc_serv *serv)
415 {
416 }
417 #endif
418 
419 /*
420  * Create an RPC service
421  */
422 static struct svc_serv *
423 __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
424              struct svc_serv_ops *ops)
425 {
426         struct svc_serv *serv;
427         unsigned int vers;
428         unsigned int xdrsize;
429         unsigned int i;
430 
431         if (!(serv = kzalloc(sizeof(*serv), GFP_KERNEL)))
432                 return NULL;
433         serv->sv_name      = prog->pg_name;
434         serv->sv_program   = prog;
435         serv->sv_nrthreads = 1;
436         serv->sv_stats     = prog->pg_stats;
437         if (bufsize > RPCSVC_MAXPAYLOAD)
438                 bufsize = RPCSVC_MAXPAYLOAD;
439         serv->sv_max_payload = bufsize? bufsize : 4096;
440         serv->sv_max_mesg  = roundup(serv->sv_max_payload + PAGE_SIZE, PAGE_SIZE);
441         serv->sv_ops = ops;
442         xdrsize = 0;
443         while (prog) {
444                 prog->pg_lovers = prog->pg_nvers-1;
445                 for (vers=0; vers<prog->pg_nvers ; vers++)
446                         if (prog->pg_vers[vers]) {
447                                 prog->pg_hivers = vers;
448                                 if (prog->pg_lovers > vers)
449                                         prog->pg_lovers = vers;
450                                 if (prog->pg_vers[vers]->vs_xdrsize > xdrsize)
451                                         xdrsize = prog->pg_vers[vers]->vs_xdrsize;
452                         }
453                 prog = prog->pg_next;
454         }
455         serv->sv_xdrsize   = xdrsize;
456         INIT_LIST_HEAD(&serv->sv_tempsocks);
457         INIT_LIST_HEAD(&serv->sv_permsocks);
458         init_timer(&serv->sv_temptimer);
459         spin_lock_init(&serv->sv_lock);
460 
461         __svc_init_bc(serv);
462 
463         serv->sv_nrpools = npools;
464         serv->sv_pools =
465                 kcalloc(serv->sv_nrpools, sizeof(struct svc_pool),
466                         GFP_KERNEL);
467         if (!serv->sv_pools) {
468                 kfree(serv);
469                 return NULL;
470         }
471 
472         for (i = 0; i < serv->sv_nrpools; i++) {
473                 struct svc_pool *pool = &serv->sv_pools[i];
474 
475                 dprintk("svc: initialising pool %u for %s\n",
476                                 i, serv->sv_name);
477 
478                 pool->sp_id = i;
479                 INIT_LIST_HEAD(&pool->sp_sockets);
480                 INIT_LIST_HEAD(&pool->sp_all_threads);
481                 spin_lock_init(&pool->sp_lock);
482         }
483 
484         return serv;
485 }
486 
487 struct svc_serv *
488 svc_create(struct svc_program *prog, unsigned int bufsize,
489            struct svc_serv_ops *ops)
490 {
491         return __svc_create(prog, bufsize, /*npools*/1, ops);
492 }
493 EXPORT_SYMBOL_GPL(svc_create);
494 
495 struct svc_serv *
496 svc_create_pooled(struct svc_program *prog, unsigned int bufsize,
497                   struct svc_serv_ops *ops)
498 {
499         struct svc_serv *serv;
500         unsigned int npools = svc_pool_map_get();
501 
502         serv = __svc_create(prog, bufsize, npools, ops);
503         if (!serv)
504                 goto out_err;
505         return serv;
506 out_err:
507         svc_pool_map_put();
508         return NULL;
509 }
510 EXPORT_SYMBOL_GPL(svc_create_pooled);
511 
512 void svc_shutdown_net(struct svc_serv *serv, struct net *net)
513 {
514         svc_close_net(serv, net);
515 
516         if (serv->sv_ops->svo_shutdown)
517                 serv->sv_ops->svo_shutdown(serv, net);
518 }
519 EXPORT_SYMBOL_GPL(svc_shutdown_net);
520 
521 /*
522  * Destroy an RPC service. Should be called with appropriate locking to
523  * protect the sv_nrthreads, sv_permsocks and sv_tempsocks.
524  */
525 void
526 svc_destroy(struct svc_serv *serv)
527 {
528         dprintk("svc: svc_destroy(%s, %d)\n",
529                                 serv->sv_program->pg_name,
530                                 serv->sv_nrthreads);
531 
532         if (serv->sv_nrthreads) {
533                 if (--(serv->sv_nrthreads) != 0) {
534                         svc_sock_update_bufs(serv);
535                         return;
536                 }
537         } else
538                 printk("svc_destroy: no threads for serv=%p!\n", serv);
539 
540         del_timer_sync(&serv->sv_temptimer);
541 
542         /*
543          * The last user is gone and thus all sockets have to be destroyed to
544          * the point. Check this.
545          */
546         BUG_ON(!list_empty(&serv->sv_permsocks));
547         BUG_ON(!list_empty(&serv->sv_tempsocks));
548 
549         cache_clean_deferred(serv);
550 
551         if (svc_serv_is_pooled(serv))
552                 svc_pool_map_put();
553 
554         kfree(serv->sv_pools);
555         kfree(serv);
556 }
557 EXPORT_SYMBOL_GPL(svc_destroy);
558 
559 /*
560  * Allocate an RPC server's buffer space.
561  * We allocate pages and place them in rq_argpages.
562  */
563 static int
564 svc_init_buffer(struct svc_rqst *rqstp, unsigned int size, int node)
565 {
566         unsigned int pages, arghi;
567 
568         /* bc_xprt uses fore channel allocated buffers */
569         if (svc_is_backchannel(rqstp))
570                 return 1;
571 
572         pages = size / PAGE_SIZE + 1; /* extra page as we hold both request and reply.
573                                        * We assume one is at most one page
574                                        */
575         arghi = 0;
576         WARN_ON_ONCE(pages > RPCSVC_MAXPAGES);
577         if (pages > RPCSVC_MAXPAGES)
578                 pages = RPCSVC_MAXPAGES;
579         while (pages) {
580                 struct page *p = alloc_pages_node(node, GFP_KERNEL, 0);
581                 if (!p)
582                         break;
583                 rqstp->rq_pages[arghi++] = p;
584                 pages--;
585         }
586         return pages == 0;
587 }
588 
589 /*
590  * Release an RPC server buffer
591  */
592 static void
593 svc_release_buffer(struct svc_rqst *rqstp)
594 {
595         unsigned int i;
596 
597         for (i = 0; i < ARRAY_SIZE(rqstp->rq_pages); i++)
598                 if (rqstp->rq_pages[i])
599                         put_page(rqstp->rq_pages[i]);
600 }
601 
602 struct svc_rqst *
603 svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node)
604 {
605         struct svc_rqst *rqstp;
606 
607         rqstp = kzalloc_node(sizeof(*rqstp), GFP_KERNEL, node);
608         if (!rqstp)
609                 return rqstp;
610 
611         __set_bit(RQ_BUSY, &rqstp->rq_flags);
612         spin_lock_init(&rqstp->rq_lock);
613         rqstp->rq_server = serv;
614         rqstp->rq_pool = pool;
615 
616         rqstp->rq_argp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node);
617         if (!rqstp->rq_argp)
618                 goto out_enomem;
619 
620         rqstp->rq_resp = kmalloc_node(serv->sv_xdrsize, GFP_KERNEL, node);
621         if (!rqstp->rq_resp)
622                 goto out_enomem;
623 
624         if (!svc_init_buffer(rqstp, serv->sv_max_mesg, node))
625                 goto out_enomem;
626 
627         return rqstp;
628 out_enomem:
629         svc_rqst_free(rqstp);
630         return NULL;
631 }
632 EXPORT_SYMBOL_GPL(svc_rqst_alloc);
633 
634 struct svc_rqst *
635 svc_prepare_thread(struct svc_serv *serv, struct svc_pool *pool, int node)
636 {
637         struct svc_rqst *rqstp;
638 
639         rqstp = svc_rqst_alloc(serv, pool, node);
640         if (!rqstp)
641                 return ERR_PTR(-ENOMEM);
642 
643         serv->sv_nrthreads++;
644         spin_lock_bh(&pool->sp_lock);
645         pool->sp_nrthreads++;
646         list_add_rcu(&rqstp->rq_all, &pool->sp_all_threads);
647         spin_unlock_bh(&pool->sp_lock);
648         return rqstp;
649 }
650 EXPORT_SYMBOL_GPL(svc_prepare_thread);
651 
652 /*
653  * Choose a pool in which to create a new thread, for svc_set_num_threads
654  */
655 static inline struct svc_pool *
656 choose_pool(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
657 {
658         if (pool != NULL)
659                 return pool;
660 
661         return &serv->sv_pools[(*state)++ % serv->sv_nrpools];
662 }
663 
664 /*
665  * Choose a thread to kill, for svc_set_num_threads
666  */
667 static inline struct task_struct *
668 choose_victim(struct svc_serv *serv, struct svc_pool *pool, unsigned int *state)
669 {
670         unsigned int i;
671         struct task_struct *task = NULL;
672 
673         if (pool != NULL) {
674                 spin_lock_bh(&pool->sp_lock);
675         } else {
676                 /* choose a pool in round-robin fashion */
677                 for (i = 0; i < serv->sv_nrpools; i++) {
678                         pool = &serv->sv_pools[--(*state) % serv->sv_nrpools];
679                         spin_lock_bh(&pool->sp_lock);
680                         if (!list_empty(&pool->sp_all_threads))
681                                 goto found_pool;
682                         spin_unlock_bh(&pool->sp_lock);
683                 }
684                 return NULL;
685         }
686 
687 found_pool:
688         if (!list_empty(&pool->sp_all_threads)) {
689                 struct svc_rqst *rqstp;
690 
691                 /*
692                  * Remove from the pool->sp_all_threads list
693                  * so we don't try to kill it again.
694                  */
695                 rqstp = list_entry(pool->sp_all_threads.next, struct svc_rqst, rq_all);
696                 set_bit(RQ_VICTIM, &rqstp->rq_flags);
697                 list_del_rcu(&rqstp->rq_all);
698                 task = rqstp->rq_task;
699         }
700         spin_unlock_bh(&pool->sp_lock);
701 
702         return task;
703 }
704 
705 /* create new threads */
706 static int
707 svc_start_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
708 {
709         struct svc_rqst *rqstp;
710         struct task_struct *task;
711         struct svc_pool *chosen_pool;
712         unsigned int state = serv->sv_nrthreads-1;
713         int node;
714 
715         do {
716                 nrservs--;
717                 chosen_pool = choose_pool(serv, pool, &state);
718 
719                 node = svc_pool_map_get_node(chosen_pool->sp_id);
720                 rqstp = svc_prepare_thread(serv, chosen_pool, node);
721                 if (IS_ERR(rqstp))
722                         return PTR_ERR(rqstp);
723 
724                 __module_get(serv->sv_ops->svo_module);
725                 task = kthread_create_on_node(serv->sv_ops->svo_function, rqstp,
726                                               node, "%s", serv->sv_name);
727                 if (IS_ERR(task)) {
728                         module_put(serv->sv_ops->svo_module);
729                         svc_exit_thread(rqstp);
730                         return PTR_ERR(task);
731                 }
732 
733                 rqstp->rq_task = task;
734                 if (serv->sv_nrpools > 1)
735                         svc_pool_map_set_cpumask(task, chosen_pool->sp_id);
736 
737                 svc_sock_update_bufs(serv);
738                 wake_up_process(task);
739         } while (nrservs > 0);
740 
741         return 0;
742 }
743 
744 
745 /* destroy old threads */
746 static int
747 svc_signal_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
748 {
749         struct task_struct *task;
750         unsigned int state = serv->sv_nrthreads-1;
751 
752         /* destroy old threads */
753         do {
754                 task = choose_victim(serv, pool, &state);
755                 if (task == NULL)
756                         break;
757                 send_sig(SIGINT, task, 1);
758                 nrservs++;
759         } while (nrservs < 0);
760 
761         return 0;
762 }
763 
764 /*
765  * Create or destroy enough new threads to make the number
766  * of threads the given number.  If `pool' is non-NULL, applies
767  * only to threads in that pool, otherwise round-robins between
768  * all pools.  Caller must ensure that mutual exclusion between this and
769  * server startup or shutdown.
770  *
771  * Destroying threads relies on the service threads filling in
772  * rqstp->rq_task, which only the nfs ones do.  Assumes the serv
773  * has been created using svc_create_pooled().
774  *
775  * Based on code that used to be in nfsd_svc() but tweaked
776  * to be pool-aware.
777  */
778 int
779 svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
780 {
781         if (pool == NULL) {
782                 /* The -1 assumes caller has done a svc_get() */
783                 nrservs -= (serv->sv_nrthreads-1);
784         } else {
785                 spin_lock_bh(&pool->sp_lock);
786                 nrservs -= pool->sp_nrthreads;
787                 spin_unlock_bh(&pool->sp_lock);
788         }
789 
790         if (nrservs > 0)
791                 return svc_start_kthreads(serv, pool, nrservs);
792         if (nrservs < 0)
793                 return svc_signal_kthreads(serv, pool, nrservs);
794         return 0;
795 }
796 EXPORT_SYMBOL_GPL(svc_set_num_threads);
797 
798 /* destroy old threads */
799 static int
800 svc_stop_kthreads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
801 {
802         struct task_struct *task;
803         unsigned int state = serv->sv_nrthreads-1;
804 
805         /* destroy old threads */
806         do {
807                 task = choose_victim(serv, pool, &state);
808                 if (task == NULL)
809                         break;
810                 kthread_stop(task);
811                 nrservs++;
812         } while (nrservs < 0);
813         return 0;
814 }
815 
816 int
817 svc_set_num_threads_sync(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
818 {
819         if (pool == NULL) {
820                 /* The -1 assumes caller has done a svc_get() */
821                 nrservs -= (serv->sv_nrthreads-1);
822         } else {
823                 spin_lock_bh(&pool->sp_lock);
824                 nrservs -= pool->sp_nrthreads;
825                 spin_unlock_bh(&pool->sp_lock);
826         }
827 
828         if (nrservs > 0)
829                 return svc_start_kthreads(serv, pool, nrservs);
830         if (nrservs < 0)
831                 return svc_stop_kthreads(serv, pool, nrservs);
832         return 0;
833 }
834 EXPORT_SYMBOL_GPL(svc_set_num_threads_sync);
835 
836 /*
837  * Called from a server thread as it's exiting. Caller must hold the "service
838  * mutex" for the service.
839  */
840 void
841 svc_rqst_free(struct svc_rqst *rqstp)
842 {
843         svc_release_buffer(rqstp);
844         kfree(rqstp->rq_resp);
845         kfree(rqstp->rq_argp);
846         kfree(rqstp->rq_auth_data);
847         kfree_rcu(rqstp, rq_rcu_head);
848 }
849 EXPORT_SYMBOL_GPL(svc_rqst_free);
850 
851 void
852 svc_exit_thread(struct svc_rqst *rqstp)
853 {
854         struct svc_serv *serv = rqstp->rq_server;
855         struct svc_pool *pool = rqstp->rq_pool;
856 
857         spin_lock_bh(&pool->sp_lock);
858         pool->sp_nrthreads--;
859         if (!test_and_set_bit(RQ_VICTIM, &rqstp->rq_flags))
860                 list_del_rcu(&rqstp->rq_all);
861         spin_unlock_bh(&pool->sp_lock);
862 
863         svc_rqst_free(rqstp);
864 
865         /* Release the server */
866         if (serv)
867                 svc_destroy(serv);
868 }
869 EXPORT_SYMBOL_GPL(svc_exit_thread);
870 
871 /*
872  * Register an "inet" protocol family netid with the local
873  * rpcbind daemon via an rpcbind v4 SET request.
874  *
875  * No netconfig infrastructure is available in the kernel, so
876  * we map IP_ protocol numbers to netids by hand.
877  *
878  * Returns zero on success; a negative errno value is returned
879  * if any error occurs.
880  */
881 static int __svc_rpcb_register4(struct net *net, const u32 program,
882                                 const u32 version,
883                                 const unsigned short protocol,
884                                 const unsigned short port)
885 {
886         const struct sockaddr_in sin = {
887                 .sin_family             = AF_INET,
888                 .sin_addr.s_addr        = htonl(INADDR_ANY),
889                 .sin_port               = htons(port),
890         };
891         const char *netid;
892         int error;
893 
894         switch (protocol) {
895         case IPPROTO_UDP:
896                 netid = RPCBIND_NETID_UDP;
897                 break;
898         case IPPROTO_TCP:
899                 netid = RPCBIND_NETID_TCP;
900                 break;
901         default:
902                 return -ENOPROTOOPT;
903         }
904 
905         error = rpcb_v4_register(net, program, version,
906                                         (const struct sockaddr *)&sin, netid);
907 
908         /*
909          * User space didn't support rpcbind v4, so retry this
910          * registration request with the legacy rpcbind v2 protocol.
911          */
912         if (error == -EPROTONOSUPPORT)
913                 error = rpcb_register(net, program, version, protocol, port);
914 
915         return error;
916 }
917 
918 #if IS_ENABLED(CONFIG_IPV6)
919 /*
920  * Register an "inet6" protocol family netid with the local
921  * rpcbind daemon via an rpcbind v4 SET request.
922  *
923  * No netconfig infrastructure is available in the kernel, so
924  * we map IP_ protocol numbers to netids by hand.
925  *
926  * Returns zero on success; a negative errno value is returned
927  * if any error occurs.
928  */
929 static int __svc_rpcb_register6(struct net *net, const u32 program,
930                                 const u32 version,
931                                 const unsigned short protocol,
932                                 const unsigned short port)
933 {
934         const struct sockaddr_in6 sin6 = {
935                 .sin6_family            = AF_INET6,
936                 .sin6_addr              = IN6ADDR_ANY_INIT,
937                 .sin6_port              = htons(port),
938         };
939         const char *netid;
940         int error;
941 
942         switch (protocol) {
943         case IPPROTO_UDP:
944                 netid = RPCBIND_NETID_UDP6;
945                 break;
946         case IPPROTO_TCP:
947                 netid = RPCBIND_NETID_TCP6;
948                 break;
949         default:
950                 return -ENOPROTOOPT;
951         }
952 
953         error = rpcb_v4_register(net, program, version,
954                                         (const struct sockaddr *)&sin6, netid);
955 
956         /*
957          * User space didn't support rpcbind version 4, so we won't
958          * use a PF_INET6 listener.
959          */
960         if (error == -EPROTONOSUPPORT)
961                 error = -EAFNOSUPPORT;
962 
963         return error;
964 }
965 #endif  /* IS_ENABLED(CONFIG_IPV6) */
966 
967 /*
968  * Register a kernel RPC service via rpcbind version 4.
969  *
970  * Returns zero on success; a negative errno value is returned
971  * if any error occurs.
972  */
973 static int __svc_register(struct net *net, const char *progname,
974                           const u32 program, const u32 version,
975                           const int family,
976                           const unsigned short protocol,
977                           const unsigned short port)
978 {
979         int error = -EAFNOSUPPORT;
980 
981         switch (family) {
982         case PF_INET:
983                 error = __svc_rpcb_register4(net, program, version,
984                                                 protocol, port);
985                 break;
986 #if IS_ENABLED(CONFIG_IPV6)
987         case PF_INET6:
988                 error = __svc_rpcb_register6(net, program, version,
989                                                 protocol, port);
990 #endif
991         }
992 
993         return error;
994 }
995 
996 /**
997  * svc_register - register an RPC service with the local portmapper
998  * @serv: svc_serv struct for the service to register
999  * @net: net namespace for the service to register
1000  * @family: protocol family of service's listener socket
1001  * @proto: transport protocol number to advertise
1002  * @port: port to advertise
1003  *
1004  * Service is registered for any address in the passed-in protocol family
1005  */
1006 int svc_register(const struct svc_serv *serv, struct net *net,
1007                  const int family, const unsigned short proto,
1008                  const unsigned short port)
1009 {
1010         struct svc_program      *progp;
1011         struct svc_version      *vers;
1012         unsigned int            i;
1013         int                     error = 0;
1014 
1015         WARN_ON_ONCE(proto == 0 && port == 0);
1016         if (proto == 0 && port == 0)
1017                 return -EINVAL;
1018 
1019         for (progp = serv->sv_program; progp; progp = progp->pg_next) {
1020                 for (i = 0; i < progp->pg_nvers; i++) {
1021                         vers = progp->pg_vers[i];
1022                         if (vers == NULL)
1023                                 continue;
1024 
1025                         dprintk("svc: svc_register(%sv%d, %s, %u, %u)%s\n",
1026                                         progp->pg_name,
1027                                         i,
1028                                         proto == IPPROTO_UDP?  "udp" : "tcp",
1029                                         port,
1030                                         family,
1031                                         vers->vs_hidden ?
1032                                         " (but not telling portmap)" : "");
1033 
1034                         if (vers->vs_hidden)
1035                                 continue;
1036 
1037                         /*
1038                          * Don't register a UDP port if we need congestion
1039                          * control.
1040                          */
1041                         if (vers->vs_need_cong_ctrl && proto == IPPROTO_UDP)
1042                                 continue;
1043 
1044                         error = __svc_register(net, progp->pg_name, progp->pg_prog,
1045                                                 i, family, proto, port);
1046 
1047                         if (vers->vs_rpcb_optnl) {
1048                                 error = 0;
1049                                 continue;
1050                         }
1051 
1052                         if (error < 0) {
1053                                 printk(KERN_WARNING "svc: failed to register "
1054                                         "%sv%u RPC service (errno %d).\n",
1055                                         progp->pg_name, i, -error);
1056                                 break;
1057                         }
1058                 }
1059         }
1060 
1061         return error;
1062 }
1063 
1064 /*
1065  * If user space is running rpcbind, it should take the v4 UNSET
1066  * and clear everything for this [program, version].  If user space
1067  * is running portmap, it will reject the v4 UNSET, but won't have
1068  * any "inet6" entries anyway.  So a PMAP_UNSET should be sufficient
1069  * in this case to clear all existing entries for [program, version].
1070  */
1071 static void __svc_unregister(struct net *net, const u32 program, const u32 version,
1072                              const char *progname)
1073 {
1074         int error;
1075 
1076         error = rpcb_v4_register(net, program, version, NULL, "");
1077 
1078         /*
1079          * User space didn't support rpcbind v4, so retry this
1080          * request with the legacy rpcbind v2 protocol.
1081          */
1082         if (error == -EPROTONOSUPPORT)
1083                 error = rpcb_register(net, program, version, 0, 0);
1084 
1085         dprintk("svc: %s(%sv%u), error %d\n",
1086                         __func__, progname, version, error);
1087 }
1088 
1089 /*
1090  * All netids, bind addresses and ports registered for [program, version]
1091  * are removed from the local rpcbind database (if the service is not
1092  * hidden) to make way for a new instance of the service.
1093  *
1094  * The result of unregistration is reported via dprintk for those who want
1095  * verification of the result, but is otherwise not important.
1096  */
1097 static void svc_unregister(const struct svc_serv *serv, struct net *net)
1098 {
1099         struct svc_program *progp;
1100         unsigned long flags;
1101         unsigned int i;
1102 
1103         clear_thread_flag(TIF_SIGPENDING);
1104 
1105         for (progp = serv->sv_program; progp; progp = progp->pg_next) {
1106                 for (i = 0; i < progp->pg_nvers; i++) {
1107                         if (progp->pg_vers[i] == NULL)
1108                                 continue;
1109                         if (progp->pg_vers[i]->vs_hidden)
1110                                 continue;
1111 
1112                         dprintk("svc: attempting to unregister %sv%u\n",
1113                                 progp->pg_name, i);
1114                         __svc_unregister(net, progp->pg_prog, i, progp->pg_name);
1115                 }
1116         }
1117 
1118         spin_lock_irqsave(&current->sighand->siglock, flags);
1119         recalc_sigpending();
1120         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1121 }
1122 
1123 /*
1124  * dprintk the given error with the address of the client that caused it.
1125  */
1126 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
1127 static __printf(2, 3)
1128 void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...)
1129 {
1130         struct va_format vaf;
1131         va_list args;
1132         char    buf[RPC_MAX_ADDRBUFLEN];
1133 
1134         va_start(args, fmt);
1135 
1136         vaf.fmt = fmt;
1137         vaf.va = &args;
1138 
1139         dprintk("svc: %s: %pV", svc_print_addr(rqstp, buf, sizeof(buf)), &vaf);
1140 
1141         va_end(args);
1142 }
1143 #else
1144 static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {}
1145 #endif
1146 
1147 /*
1148  * Common routine for processing the RPC request.
1149  */
1150 static int
1151 svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
1152 {
1153         struct svc_program      *progp;
1154         struct svc_version      *versp = NULL;  /* compiler food */
1155         struct svc_procedure    *procp = NULL;
1156         struct svc_serv         *serv = rqstp->rq_server;
1157         kxdrproc_t              xdr;
1158         __be32                  *statp;
1159         u32                     prog, vers, proc;
1160         __be32                  auth_stat, rpc_stat;
1161         int                     auth_res;
1162         __be32                  *reply_statp;
1163 
1164         rpc_stat = rpc_success;
1165 
1166         if (argv->iov_len < 6*4)
1167                 goto err_short_len;
1168 
1169         /* Will be turned off only in gss privacy case: */
1170         set_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
1171         /* Will be turned off only when NFSv4 Sessions are used */
1172         set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
1173         clear_bit(RQ_DROPME, &rqstp->rq_flags);
1174 
1175         /* Setup reply header */
1176         rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(rqstp);
1177 
1178         svc_putu32(resv, rqstp->rq_xid);
1179 
1180         vers = svc_getnl(argv);
1181 
1182         /* First words of reply: */
1183         svc_putnl(resv, 1);             /* REPLY */
1184 
1185         if (vers != 2)          /* RPC version number */
1186                 goto err_bad_rpc;
1187 
1188         /* Save position in case we later decide to reject: */
1189         reply_statp = resv->iov_base + resv->iov_len;
1190 
1191         svc_putnl(resv, 0);             /* ACCEPT */
1192 
1193         rqstp->rq_prog = prog = svc_getnl(argv);        /* program number */
1194         rqstp->rq_vers = vers = svc_getnl(argv);        /* version number */
1195         rqstp->rq_proc = proc = svc_getnl(argv);        /* procedure number */
1196 
1197         for (progp = serv->sv_program; progp; progp = progp->pg_next)
1198                 if (prog == progp->pg_prog)
1199                         break;
1200 
1201         /*
1202          * Decode auth data, and add verifier to reply buffer.
1203          * We do this before anything else in order to get a decent
1204          * auth verifier.
1205          */
1206         auth_res = svc_authenticate(rqstp, &auth_stat);
1207         /* Also give the program a chance to reject this call: */
1208         if (auth_res == SVC_OK && progp) {
1209                 auth_stat = rpc_autherr_badcred;
1210                 auth_res = progp->pg_authenticate(rqstp);
1211         }
1212         switch (auth_res) {
1213         case SVC_OK:
1214                 break;
1215         case SVC_GARBAGE:
1216                 goto err_garbage;
1217         case SVC_SYSERR:
1218                 rpc_stat = rpc_system_err;
1219                 goto err_bad;
1220         case SVC_DENIED:
1221                 goto err_bad_auth;
1222         case SVC_CLOSE:
1223                 goto close;
1224         case SVC_DROP:
1225                 goto dropit;
1226         case SVC_COMPLETE:
1227                 goto sendit;
1228         }
1229 
1230         if (progp == NULL)
1231                 goto err_bad_prog;
1232 
1233         if (vers >= progp->pg_nvers ||
1234           !(versp = progp->pg_vers[vers]))
1235                 goto err_bad_vers;
1236 
1237         /*
1238          * Some protocol versions (namely NFSv4) require some form of
1239          * congestion control.  (See RFC 7530 section 3.1 paragraph 2)
1240          * In other words, UDP is not allowed. We mark those when setting
1241          * up the svc_xprt, and verify that here.
1242          *
1243          * The spec is not very clear about what error should be returned
1244          * when someone tries to access a server that is listening on UDP
1245          * for lower versions. RPC_PROG_MISMATCH seems to be the closest
1246          * fit.
1247          */
1248         if (versp->vs_need_cong_ctrl &&
1249             !test_bit(XPT_CONG_CTRL, &rqstp->rq_xprt->xpt_flags))
1250                 goto err_bad_vers;
1251 
1252         procp = versp->vs_proc + proc;
1253         if (proc >= versp->vs_nproc || !procp->pc_func)
1254                 goto err_bad_proc;
1255         rqstp->rq_procinfo = procp;
1256 
1257         /* Syntactic check complete */
1258         serv->sv_stats->rpccnt++;
1259 
1260         /* Build the reply header. */
1261         statp = resv->iov_base +resv->iov_len;
1262         svc_putnl(resv, RPC_SUCCESS);
1263 
1264         /* Bump per-procedure stats counter */
1265         procp->pc_count++;
1266 
1267         /* Initialize storage for argp and resp */
1268         memset(rqstp->rq_argp, 0, procp->pc_argsize);
1269         memset(rqstp->rq_resp, 0, procp->pc_ressize);
1270 
1271         /* un-reserve some of the out-queue now that we have a
1272          * better idea of reply size
1273          */
1274         if (procp->pc_xdrressize)
1275                 svc_reserve_auth(rqstp, procp->pc_xdrressize<<2);
1276 
1277         /* Call the function that processes the request. */
1278         if (!versp->vs_dispatch) {
1279                 /* Decode arguments */
1280                 xdr = procp->pc_decode;
1281                 if (xdr && !xdr(rqstp, argv->iov_base, rqstp->rq_argp))
1282                         goto err_garbage;
1283 
1284                 *statp = procp->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
1285 
1286                 /* Encode reply */
1287                 if (*statp == rpc_drop_reply ||
1288                     test_bit(RQ_DROPME, &rqstp->rq_flags)) {
1289                         if (procp->pc_release)
1290                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1291                         goto dropit;
1292                 }
1293                 if (*statp == rpc_autherr_badcred) {
1294                         if (procp->pc_release)
1295                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1296                         goto err_bad_auth;
1297                 }
1298                 if (*statp == rpc_success &&
1299                     (xdr = procp->pc_encode) &&
1300                     !xdr(rqstp, resv->iov_base+resv->iov_len, rqstp->rq_resp)) {
1301                         dprintk("svc: failed to encode reply\n");
1302                         /* serv->sv_stats->rpcsystemerr++; */
1303                         *statp = rpc_system_err;
1304                 }
1305         } else {
1306                 dprintk("svc: calling dispatcher\n");
1307                 if (!versp->vs_dispatch(rqstp, statp)) {
1308                         /* Release reply info */
1309                         if (procp->pc_release)
1310                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1311                         goto dropit;
1312                 }
1313         }
1314 
1315         /* Check RPC status result */
1316         if (*statp != rpc_success)
1317                 resv->iov_len = ((void*)statp)  - resv->iov_base + 4;
1318 
1319         /* Release reply info */
1320         if (procp->pc_release)
1321                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1322 
1323         if (procp->pc_encode == NULL)
1324                 goto dropit;
1325 
1326  sendit:
1327         if (svc_authorise(rqstp))
1328                 goto close;
1329         return 1;               /* Caller can now send it */
1330 
1331  dropit:
1332         svc_authorise(rqstp);   /* doesn't hurt to call this twice */
1333         dprintk("svc: svc_process dropit\n");
1334         return 0;
1335 
1336  close:
1337         if (test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
1338                 svc_close_xprt(rqstp->rq_xprt);
1339         dprintk("svc: svc_process close\n");
1340         return 0;
1341 
1342 err_short_len:
1343         svc_printk(rqstp, "short len %zd, dropping request\n",
1344                         argv->iov_len);
1345         goto close;
1346 
1347 err_bad_rpc:
1348         serv->sv_stats->rpcbadfmt++;
1349         svc_putnl(resv, 1);     /* REJECT */
1350         svc_putnl(resv, 0);     /* RPC_MISMATCH */
1351         svc_putnl(resv, 2);     /* Only RPCv2 supported */
1352         svc_putnl(resv, 2);
1353         goto sendit;
1354 
1355 err_bad_auth:
1356         dprintk("svc: authentication failed (%d)\n", ntohl(auth_stat));
1357         serv->sv_stats->rpcbadauth++;
1358         /* Restore write pointer to location of accept status: */
1359         xdr_ressize_check(rqstp, reply_statp);
1360         svc_putnl(resv, 1);     /* REJECT */
1361         svc_putnl(resv, 1);     /* AUTH_ERROR */
1362         svc_putnl(resv, ntohl(auth_stat));      /* status */
1363         goto sendit;
1364 
1365 err_bad_prog:
1366         dprintk("svc: unknown program %d\n", prog);
1367         serv->sv_stats->rpcbadfmt++;
1368         svc_putnl(resv, RPC_PROG_UNAVAIL);
1369         goto sendit;
1370 
1371 err_bad_vers:
1372         svc_printk(rqstp, "unknown version (%d for prog %d, %s)\n",
1373                        vers, prog, progp->pg_name);
1374 
1375         serv->sv_stats->rpcbadfmt++;
1376         svc_putnl(resv, RPC_PROG_MISMATCH);
1377         svc_putnl(resv, progp->pg_lovers);
1378         svc_putnl(resv, progp->pg_hivers);
1379         goto sendit;
1380 
1381 err_bad_proc:
1382         svc_printk(rqstp, "unknown procedure (%d)\n", proc);
1383 
1384         serv->sv_stats->rpcbadfmt++;
1385         svc_putnl(resv, RPC_PROC_UNAVAIL);
1386         goto sendit;
1387 
1388 err_garbage:
1389         svc_printk(rqstp, "failed to decode args\n");
1390 
1391         rpc_stat = rpc_garbage_args;
1392 err_bad:
1393         serv->sv_stats->rpcbadfmt++;
1394         svc_putnl(resv, ntohl(rpc_stat));
1395         goto sendit;
1396 }
1397 
1398 /*
1399  * Process the RPC request.
1400  */
1401 int
1402 svc_process(struct svc_rqst *rqstp)
1403 {
1404         struct kvec             *argv = &rqstp->rq_arg.head[0];
1405         struct kvec             *resv = &rqstp->rq_res.head[0];
1406         struct svc_serv         *serv = rqstp->rq_server;
1407         u32                     dir;
1408 
1409         /*
1410          * Setup response xdr_buf.
1411          * Initially it has just one page
1412          */
1413         rqstp->rq_next_page = &rqstp->rq_respages[1];
1414         resv->iov_base = page_address(rqstp->rq_respages[0]);
1415         resv->iov_len = 0;
1416         rqstp->rq_res.pages = rqstp->rq_respages + 1;
1417         rqstp->rq_res.len = 0;
1418         rqstp->rq_res.page_base = 0;
1419         rqstp->rq_res.page_len = 0;
1420         rqstp->rq_res.buflen = PAGE_SIZE;
1421         rqstp->rq_res.tail[0].iov_base = NULL;
1422         rqstp->rq_res.tail[0].iov_len = 0;
1423 
1424         dir  = svc_getnl(argv);
1425         if (dir != 0) {
1426                 /* direction != CALL */
1427                 svc_printk(rqstp, "bad direction %d, dropping request\n", dir);
1428                 serv->sv_stats->rpcbadfmt++;
1429                 goto out_drop;
1430         }
1431 
1432         /* Returns 1 for send, 0 for drop */
1433         if (likely(svc_process_common(rqstp, argv, resv))) {
1434                 int ret = svc_send(rqstp);
1435 
1436                 trace_svc_process(rqstp, ret);
1437                 return ret;
1438         }
1439 out_drop:
1440         trace_svc_process(rqstp, 0);
1441         svc_drop(rqstp);
1442         return 0;
1443 }
1444 EXPORT_SYMBOL_GPL(svc_process);
1445 
1446 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1447 /*
1448  * Process a backchannel RPC request that arrived over an existing
1449  * outbound connection
1450  */
1451 int
1452 bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
1453                struct svc_rqst *rqstp)
1454 {
1455         struct kvec     *argv = &rqstp->rq_arg.head[0];
1456         struct kvec     *resv = &rqstp->rq_res.head[0];
1457         struct rpc_task *task;
1458         int proc_error;
1459         int error;
1460 
1461         dprintk("svc: %s(%p)\n", __func__, req);
1462 
1463         /* Build the svc_rqst used by the common processing routine */
1464         rqstp->rq_xprt = serv->sv_bc_xprt;
1465         rqstp->rq_xid = req->rq_xid;
1466         rqstp->rq_prot = req->rq_xprt->prot;
1467         rqstp->rq_server = serv;
1468 
1469         rqstp->rq_addrlen = sizeof(req->rq_xprt->addr);
1470         memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);
1471         memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg));
1472         memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res));
1473 
1474         /* Adjust the argument buffer length */
1475         rqstp->rq_arg.len = req->rq_private_buf.len;
1476         if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {
1477                 rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;
1478                 rqstp->rq_arg.page_len = 0;
1479         } else if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len +
1480                         rqstp->rq_arg.page_len)
1481                 rqstp->rq_arg.page_len = rqstp->rq_arg.len -
1482                         rqstp->rq_arg.head[0].iov_len;
1483         else
1484                 rqstp->rq_arg.len = rqstp->rq_arg.head[0].iov_len +
1485                         rqstp->rq_arg.page_len;
1486 
1487         /* reset result send buffer "put" position */
1488         resv->iov_len = 0;
1489 
1490         /*
1491          * Skip the next two words because they've already been
1492          * processed in the transport
1493          */
1494         svc_getu32(argv);       /* XID */
1495         svc_getnl(argv);        /* CALLDIR */
1496 
1497         /* Parse and execute the bc call */
1498         proc_error = svc_process_common(rqstp, argv, resv);
1499 
1500         atomic_inc(&req->rq_xprt->bc_free_slots);
1501         if (!proc_error) {
1502                 /* Processing error: drop the request */
1503                 xprt_free_bc_request(req);
1504                 return 0;
1505         }
1506 
1507         /* Finally, send the reply synchronously */
1508         memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf));
1509         task = rpc_run_bc_task(req);
1510         if (IS_ERR(task)) {
1511                 error = PTR_ERR(task);
1512                 goto out;
1513         }
1514 
1515         WARN_ON_ONCE(atomic_read(&task->tk_count) != 1);
1516         error = task->tk_status;
1517         rpc_put_task(task);
1518 
1519 out:
1520         dprintk("svc: %s(), error=%d\n", __func__, error);
1521         return error;
1522 }
1523 EXPORT_SYMBOL_GPL(bc_svc_process);
1524 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1525 
1526 /*
1527  * Return (transport-specific) limit on the rpc payload.
1528  */
1529 u32 svc_max_payload(const struct svc_rqst *rqstp)
1530 {
1531         u32 max = rqstp->rq_xprt->xpt_class->xcl_max_payload;
1532 
1533         if (rqstp->rq_server->sv_max_payload < max)
1534                 max = rqstp->rq_server->sv_max_payload;
1535         return max;
1536 }
1537 EXPORT_SYMBOL_GPL(svc_max_payload);
1538 

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