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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.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 == 0)
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 /*
706  * Create or destroy enough new threads to make the number
707  * of threads the given number.  If `pool' is non-NULL, applies
708  * only to threads in that pool, otherwise round-robins between
709  * all pools.  Caller must ensure that mutual exclusion between this and
710  * server startup or shutdown.
711  *
712  * Destroying threads relies on the service threads filling in
713  * rqstp->rq_task, which only the nfs ones do.  Assumes the serv
714  * has been created using svc_create_pooled().
715  *
716  * Based on code that used to be in nfsd_svc() but tweaked
717  * to be pool-aware.
718  */
719 int
720 svc_set_num_threads(struct svc_serv *serv, struct svc_pool *pool, int nrservs)
721 {
722         struct svc_rqst *rqstp;
723         struct task_struct *task;
724         struct svc_pool *chosen_pool;
725         int error = 0;
726         unsigned int state = serv->sv_nrthreads-1;
727         int node;
728 
729         if (pool == NULL) {
730                 /* The -1 assumes caller has done a svc_get() */
731                 nrservs -= (serv->sv_nrthreads-1);
732         } else {
733                 spin_lock_bh(&pool->sp_lock);
734                 nrservs -= pool->sp_nrthreads;
735                 spin_unlock_bh(&pool->sp_lock);
736         }
737 
738         /* create new threads */
739         while (nrservs > 0) {
740                 nrservs--;
741                 chosen_pool = choose_pool(serv, pool, &state);
742 
743                 node = svc_pool_map_get_node(chosen_pool->sp_id);
744                 rqstp = svc_prepare_thread(serv, chosen_pool, node);
745                 if (IS_ERR(rqstp)) {
746                         error = PTR_ERR(rqstp);
747                         break;
748                 }
749 
750                 __module_get(serv->sv_ops->svo_module);
751                 task = kthread_create_on_node(serv->sv_ops->svo_function, rqstp,
752                                               node, "%s", serv->sv_name);
753                 if (IS_ERR(task)) {
754                         error = PTR_ERR(task);
755                         module_put(serv->sv_ops->svo_module);
756                         svc_exit_thread(rqstp);
757                         break;
758                 }
759 
760                 rqstp->rq_task = task;
761                 if (serv->sv_nrpools > 1)
762                         svc_pool_map_set_cpumask(task, chosen_pool->sp_id);
763 
764                 svc_sock_update_bufs(serv);
765                 wake_up_process(task);
766         }
767         /* destroy old threads */
768         while (nrservs < 0 &&
769                (task = choose_victim(serv, pool, &state)) != NULL) {
770                 send_sig(SIGINT, task, 1);
771                 nrservs++;
772         }
773 
774         return error;
775 }
776 EXPORT_SYMBOL_GPL(svc_set_num_threads);
777 
778 /*
779  * Called from a server thread as it's exiting. Caller must hold the "service
780  * mutex" for the service.
781  */
782 void
783 svc_rqst_free(struct svc_rqst *rqstp)
784 {
785         svc_release_buffer(rqstp);
786         kfree(rqstp->rq_resp);
787         kfree(rqstp->rq_argp);
788         kfree(rqstp->rq_auth_data);
789         kfree_rcu(rqstp, rq_rcu_head);
790 }
791 EXPORT_SYMBOL_GPL(svc_rqst_free);
792 
793 void
794 svc_exit_thread(struct svc_rqst *rqstp)
795 {
796         struct svc_serv *serv = rqstp->rq_server;
797         struct svc_pool *pool = rqstp->rq_pool;
798 
799         spin_lock_bh(&pool->sp_lock);
800         pool->sp_nrthreads--;
801         if (!test_and_set_bit(RQ_VICTIM, &rqstp->rq_flags))
802                 list_del_rcu(&rqstp->rq_all);
803         spin_unlock_bh(&pool->sp_lock);
804 
805         svc_rqst_free(rqstp);
806 
807         /* Release the server */
808         if (serv)
809                 svc_destroy(serv);
810 }
811 EXPORT_SYMBOL_GPL(svc_exit_thread);
812 
813 /*
814  * Register an "inet" protocol family netid with the local
815  * rpcbind daemon via an rpcbind v4 SET request.
816  *
817  * No netconfig infrastructure is available in the kernel, so
818  * we map IP_ protocol numbers to netids by hand.
819  *
820  * Returns zero on success; a negative errno value is returned
821  * if any error occurs.
822  */
823 static int __svc_rpcb_register4(struct net *net, const u32 program,
824                                 const u32 version,
825                                 const unsigned short protocol,
826                                 const unsigned short port)
827 {
828         const struct sockaddr_in sin = {
829                 .sin_family             = AF_INET,
830                 .sin_addr.s_addr        = htonl(INADDR_ANY),
831                 .sin_port               = htons(port),
832         };
833         const char *netid;
834         int error;
835 
836         switch (protocol) {
837         case IPPROTO_UDP:
838                 netid = RPCBIND_NETID_UDP;
839                 break;
840         case IPPROTO_TCP:
841                 netid = RPCBIND_NETID_TCP;
842                 break;
843         default:
844                 return -ENOPROTOOPT;
845         }
846 
847         error = rpcb_v4_register(net, program, version,
848                                         (const struct sockaddr *)&sin, netid);
849 
850         /*
851          * User space didn't support rpcbind v4, so retry this
852          * registration request with the legacy rpcbind v2 protocol.
853          */
854         if (error == -EPROTONOSUPPORT)
855                 error = rpcb_register(net, program, version, protocol, port);
856 
857         return error;
858 }
859 
860 #if IS_ENABLED(CONFIG_IPV6)
861 /*
862  * Register an "inet6" protocol family netid with the local
863  * rpcbind daemon via an rpcbind v4 SET request.
864  *
865  * No netconfig infrastructure is available in the kernel, so
866  * we map IP_ protocol numbers to netids by hand.
867  *
868  * Returns zero on success; a negative errno value is returned
869  * if any error occurs.
870  */
871 static int __svc_rpcb_register6(struct net *net, const u32 program,
872                                 const u32 version,
873                                 const unsigned short protocol,
874                                 const unsigned short port)
875 {
876         const struct sockaddr_in6 sin6 = {
877                 .sin6_family            = AF_INET6,
878                 .sin6_addr              = IN6ADDR_ANY_INIT,
879                 .sin6_port              = htons(port),
880         };
881         const char *netid;
882         int error;
883 
884         switch (protocol) {
885         case IPPROTO_UDP:
886                 netid = RPCBIND_NETID_UDP6;
887                 break;
888         case IPPROTO_TCP:
889                 netid = RPCBIND_NETID_TCP6;
890                 break;
891         default:
892                 return -ENOPROTOOPT;
893         }
894 
895         error = rpcb_v4_register(net, program, version,
896                                         (const struct sockaddr *)&sin6, netid);
897 
898         /*
899          * User space didn't support rpcbind version 4, so we won't
900          * use a PF_INET6 listener.
901          */
902         if (error == -EPROTONOSUPPORT)
903                 error = -EAFNOSUPPORT;
904 
905         return error;
906 }
907 #endif  /* IS_ENABLED(CONFIG_IPV6) */
908 
909 /*
910  * Register a kernel RPC service via rpcbind version 4.
911  *
912  * Returns zero on success; a negative errno value is returned
913  * if any error occurs.
914  */
915 static int __svc_register(struct net *net, const char *progname,
916                           const u32 program, const u32 version,
917                           const int family,
918                           const unsigned short protocol,
919                           const unsigned short port)
920 {
921         int error = -EAFNOSUPPORT;
922 
923         switch (family) {
924         case PF_INET:
925                 error = __svc_rpcb_register4(net, program, version,
926                                                 protocol, port);
927                 break;
928 #if IS_ENABLED(CONFIG_IPV6)
929         case PF_INET6:
930                 error = __svc_rpcb_register6(net, program, version,
931                                                 protocol, port);
932 #endif
933         }
934 
935         return error;
936 }
937 
938 /**
939  * svc_register - register an RPC service with the local portmapper
940  * @serv: svc_serv struct for the service to register
941  * @net: net namespace for the service to register
942  * @family: protocol family of service's listener socket
943  * @proto: transport protocol number to advertise
944  * @port: port to advertise
945  *
946  * Service is registered for any address in the passed-in protocol family
947  */
948 int svc_register(const struct svc_serv *serv, struct net *net,
949                  const int family, const unsigned short proto,
950                  const unsigned short port)
951 {
952         struct svc_program      *progp;
953         struct svc_version      *vers;
954         unsigned int            i;
955         int                     error = 0;
956 
957         WARN_ON_ONCE(proto == 0 && port == 0);
958         if (proto == 0 && port == 0)
959                 return -EINVAL;
960 
961         for (progp = serv->sv_program; progp; progp = progp->pg_next) {
962                 for (i = 0; i < progp->pg_nvers; i++) {
963                         vers = progp->pg_vers[i];
964                         if (vers == NULL)
965                                 continue;
966 
967                         dprintk("svc: svc_register(%sv%d, %s, %u, %u)%s\n",
968                                         progp->pg_name,
969                                         i,
970                                         proto == IPPROTO_UDP?  "udp" : "tcp",
971                                         port,
972                                         family,
973                                         vers->vs_hidden ?
974                                         " (but not telling portmap)" : "");
975 
976                         if (vers->vs_hidden)
977                                 continue;
978 
979                         error = __svc_register(net, progp->pg_name, progp->pg_prog,
980                                                 i, family, proto, port);
981 
982                         if (vers->vs_rpcb_optnl) {
983                                 error = 0;
984                                 continue;
985                         }
986 
987                         if (error < 0) {
988                                 printk(KERN_WARNING "svc: failed to register "
989                                         "%sv%u RPC service (errno %d).\n",
990                                         progp->pg_name, i, -error);
991                                 break;
992                         }
993                 }
994         }
995 
996         return error;
997 }
998 
999 /*
1000  * If user space is running rpcbind, it should take the v4 UNSET
1001  * and clear everything for this [program, version].  If user space
1002  * is running portmap, it will reject the v4 UNSET, but won't have
1003  * any "inet6" entries anyway.  So a PMAP_UNSET should be sufficient
1004  * in this case to clear all existing entries for [program, version].
1005  */
1006 static void __svc_unregister(struct net *net, const u32 program, const u32 version,
1007                              const char *progname)
1008 {
1009         int error;
1010 
1011         error = rpcb_v4_register(net, program, version, NULL, "");
1012 
1013         /*
1014          * User space didn't support rpcbind v4, so retry this
1015          * request with the legacy rpcbind v2 protocol.
1016          */
1017         if (error == -EPROTONOSUPPORT)
1018                 error = rpcb_register(net, program, version, 0, 0);
1019 
1020         dprintk("svc: %s(%sv%u), error %d\n",
1021                         __func__, progname, version, error);
1022 }
1023 
1024 /*
1025  * All netids, bind addresses and ports registered for [program, version]
1026  * are removed from the local rpcbind database (if the service is not
1027  * hidden) to make way for a new instance of the service.
1028  *
1029  * The result of unregistration is reported via dprintk for those who want
1030  * verification of the result, but is otherwise not important.
1031  */
1032 static void svc_unregister(const struct svc_serv *serv, struct net *net)
1033 {
1034         struct svc_program *progp;
1035         unsigned long flags;
1036         unsigned int i;
1037 
1038         clear_thread_flag(TIF_SIGPENDING);
1039 
1040         for (progp = serv->sv_program; progp; progp = progp->pg_next) {
1041                 for (i = 0; i < progp->pg_nvers; i++) {
1042                         if (progp->pg_vers[i] == NULL)
1043                                 continue;
1044                         if (progp->pg_vers[i]->vs_hidden)
1045                                 continue;
1046 
1047                         dprintk("svc: attempting to unregister %sv%u\n",
1048                                 progp->pg_name, i);
1049                         __svc_unregister(net, progp->pg_prog, i, progp->pg_name);
1050                 }
1051         }
1052 
1053         spin_lock_irqsave(&current->sighand->siglock, flags);
1054         recalc_sigpending();
1055         spin_unlock_irqrestore(&current->sighand->siglock, flags);
1056 }
1057 
1058 /*
1059  * dprintk the given error with the address of the client that caused it.
1060  */
1061 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
1062 static __printf(2, 3)
1063 void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...)
1064 {
1065         struct va_format vaf;
1066         va_list args;
1067         char    buf[RPC_MAX_ADDRBUFLEN];
1068 
1069         va_start(args, fmt);
1070 
1071         vaf.fmt = fmt;
1072         vaf.va = &args;
1073 
1074         dprintk("svc: %s: %pV", svc_print_addr(rqstp, buf, sizeof(buf)), &vaf);
1075 
1076         va_end(args);
1077 }
1078 #else
1079 static __printf(2,3) void svc_printk(struct svc_rqst *rqstp, const char *fmt, ...) {}
1080 #endif
1081 
1082 /*
1083  * Common routine for processing the RPC request.
1084  */
1085 static int
1086 svc_process_common(struct svc_rqst *rqstp, struct kvec *argv, struct kvec *resv)
1087 {
1088         struct svc_program      *progp;
1089         struct svc_version      *versp = NULL;  /* compiler food */
1090         struct svc_procedure    *procp = NULL;
1091         struct svc_serv         *serv = rqstp->rq_server;
1092         kxdrproc_t              xdr;
1093         __be32                  *statp;
1094         u32                     prog, vers, proc;
1095         __be32                  auth_stat, rpc_stat;
1096         int                     auth_res;
1097         __be32                  *reply_statp;
1098 
1099         rpc_stat = rpc_success;
1100 
1101         if (argv->iov_len < 6*4)
1102                 goto err_short_len;
1103 
1104         /* Will be turned off only in gss privacy case: */
1105         set_bit(RQ_SPLICE_OK, &rqstp->rq_flags);
1106         /* Will be turned off only when NFSv4 Sessions are used */
1107         set_bit(RQ_USEDEFERRAL, &rqstp->rq_flags);
1108         clear_bit(RQ_DROPME, &rqstp->rq_flags);
1109 
1110         /* Setup reply header */
1111         rqstp->rq_xprt->xpt_ops->xpo_prep_reply_hdr(rqstp);
1112 
1113         svc_putu32(resv, rqstp->rq_xid);
1114 
1115         vers = svc_getnl(argv);
1116 
1117         /* First words of reply: */
1118         svc_putnl(resv, 1);             /* REPLY */
1119 
1120         if (vers != 2)          /* RPC version number */
1121                 goto err_bad_rpc;
1122 
1123         /* Save position in case we later decide to reject: */
1124         reply_statp = resv->iov_base + resv->iov_len;
1125 
1126         svc_putnl(resv, 0);             /* ACCEPT */
1127 
1128         rqstp->rq_prog = prog = svc_getnl(argv);        /* program number */
1129         rqstp->rq_vers = vers = svc_getnl(argv);        /* version number */
1130         rqstp->rq_proc = proc = svc_getnl(argv);        /* procedure number */
1131 
1132         for (progp = serv->sv_program; progp; progp = progp->pg_next)
1133                 if (prog == progp->pg_prog)
1134                         break;
1135 
1136         /*
1137          * Decode auth data, and add verifier to reply buffer.
1138          * We do this before anything else in order to get a decent
1139          * auth verifier.
1140          */
1141         auth_res = svc_authenticate(rqstp, &auth_stat);
1142         /* Also give the program a chance to reject this call: */
1143         if (auth_res == SVC_OK && progp) {
1144                 auth_stat = rpc_autherr_badcred;
1145                 auth_res = progp->pg_authenticate(rqstp);
1146         }
1147         switch (auth_res) {
1148         case SVC_OK:
1149                 break;
1150         case SVC_GARBAGE:
1151                 goto err_garbage;
1152         case SVC_SYSERR:
1153                 rpc_stat = rpc_system_err;
1154                 goto err_bad;
1155         case SVC_DENIED:
1156                 goto err_bad_auth;
1157         case SVC_CLOSE:
1158                 goto close;
1159         case SVC_DROP:
1160                 goto dropit;
1161         case SVC_COMPLETE:
1162                 goto sendit;
1163         }
1164 
1165         if (progp == NULL)
1166                 goto err_bad_prog;
1167 
1168         if (vers >= progp->pg_nvers ||
1169           !(versp = progp->pg_vers[vers]))
1170                 goto err_bad_vers;
1171 
1172         procp = versp->vs_proc + proc;
1173         if (proc >= versp->vs_nproc || !procp->pc_func)
1174                 goto err_bad_proc;
1175         rqstp->rq_procinfo = procp;
1176 
1177         /* Syntactic check complete */
1178         serv->sv_stats->rpccnt++;
1179 
1180         /* Build the reply header. */
1181         statp = resv->iov_base +resv->iov_len;
1182         svc_putnl(resv, RPC_SUCCESS);
1183 
1184         /* Bump per-procedure stats counter */
1185         procp->pc_count++;
1186 
1187         /* Initialize storage for argp and resp */
1188         memset(rqstp->rq_argp, 0, procp->pc_argsize);
1189         memset(rqstp->rq_resp, 0, procp->pc_ressize);
1190 
1191         /* un-reserve some of the out-queue now that we have a
1192          * better idea of reply size
1193          */
1194         if (procp->pc_xdrressize)
1195                 svc_reserve_auth(rqstp, procp->pc_xdrressize<<2);
1196 
1197         /* Call the function that processes the request. */
1198         if (!versp->vs_dispatch) {
1199                 /* Decode arguments */
1200                 xdr = procp->pc_decode;
1201                 if (xdr && !xdr(rqstp, argv->iov_base, rqstp->rq_argp))
1202                         goto err_garbage;
1203 
1204                 *statp = procp->pc_func(rqstp, rqstp->rq_argp, rqstp->rq_resp);
1205 
1206                 /* Encode reply */
1207                 if (*statp == rpc_drop_reply ||
1208                     test_bit(RQ_DROPME, &rqstp->rq_flags)) {
1209                         if (procp->pc_release)
1210                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1211                         goto dropit;
1212                 }
1213                 if (*statp == rpc_autherr_badcred) {
1214                         if (procp->pc_release)
1215                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1216                         goto err_bad_auth;
1217                 }
1218                 if (*statp == rpc_success &&
1219                     (xdr = procp->pc_encode) &&
1220                     !xdr(rqstp, resv->iov_base+resv->iov_len, rqstp->rq_resp)) {
1221                         dprintk("svc: failed to encode reply\n");
1222                         /* serv->sv_stats->rpcsystemerr++; */
1223                         *statp = rpc_system_err;
1224                 }
1225         } else {
1226                 dprintk("svc: calling dispatcher\n");
1227                 if (!versp->vs_dispatch(rqstp, statp)) {
1228                         /* Release reply info */
1229                         if (procp->pc_release)
1230                                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1231                         goto dropit;
1232                 }
1233         }
1234 
1235         /* Check RPC status result */
1236         if (*statp != rpc_success)
1237                 resv->iov_len = ((void*)statp)  - resv->iov_base + 4;
1238 
1239         /* Release reply info */
1240         if (procp->pc_release)
1241                 procp->pc_release(rqstp, NULL, rqstp->rq_resp);
1242 
1243         if (procp->pc_encode == NULL)
1244                 goto dropit;
1245 
1246  sendit:
1247         if (svc_authorise(rqstp))
1248                 goto close;
1249         return 1;               /* Caller can now send it */
1250 
1251  dropit:
1252         svc_authorise(rqstp);   /* doesn't hurt to call this twice */
1253         dprintk("svc: svc_process dropit\n");
1254         return 0;
1255 
1256  close:
1257         if (test_bit(XPT_TEMP, &rqstp->rq_xprt->xpt_flags))
1258                 svc_close_xprt(rqstp->rq_xprt);
1259         dprintk("svc: svc_process close\n");
1260         return 0;
1261 
1262 err_short_len:
1263         svc_printk(rqstp, "short len %Zd, dropping request\n",
1264                         argv->iov_len);
1265         goto close;
1266 
1267 err_bad_rpc:
1268         serv->sv_stats->rpcbadfmt++;
1269         svc_putnl(resv, 1);     /* REJECT */
1270         svc_putnl(resv, 0);     /* RPC_MISMATCH */
1271         svc_putnl(resv, 2);     /* Only RPCv2 supported */
1272         svc_putnl(resv, 2);
1273         goto sendit;
1274 
1275 err_bad_auth:
1276         dprintk("svc: authentication failed (%d)\n", ntohl(auth_stat));
1277         serv->sv_stats->rpcbadauth++;
1278         /* Restore write pointer to location of accept status: */
1279         xdr_ressize_check(rqstp, reply_statp);
1280         svc_putnl(resv, 1);     /* REJECT */
1281         svc_putnl(resv, 1);     /* AUTH_ERROR */
1282         svc_putnl(resv, ntohl(auth_stat));      /* status */
1283         goto sendit;
1284 
1285 err_bad_prog:
1286         dprintk("svc: unknown program %d\n", prog);
1287         serv->sv_stats->rpcbadfmt++;
1288         svc_putnl(resv, RPC_PROG_UNAVAIL);
1289         goto sendit;
1290 
1291 err_bad_vers:
1292         svc_printk(rqstp, "unknown version (%d for prog %d, %s)\n",
1293                        vers, prog, progp->pg_name);
1294 
1295         serv->sv_stats->rpcbadfmt++;
1296         svc_putnl(resv, RPC_PROG_MISMATCH);
1297         svc_putnl(resv, progp->pg_lovers);
1298         svc_putnl(resv, progp->pg_hivers);
1299         goto sendit;
1300 
1301 err_bad_proc:
1302         svc_printk(rqstp, "unknown procedure (%d)\n", proc);
1303 
1304         serv->sv_stats->rpcbadfmt++;
1305         svc_putnl(resv, RPC_PROC_UNAVAIL);
1306         goto sendit;
1307 
1308 err_garbage:
1309         svc_printk(rqstp, "failed to decode args\n");
1310 
1311         rpc_stat = rpc_garbage_args;
1312 err_bad:
1313         serv->sv_stats->rpcbadfmt++;
1314         svc_putnl(resv, ntohl(rpc_stat));
1315         goto sendit;
1316 }
1317 
1318 /*
1319  * Process the RPC request.
1320  */
1321 int
1322 svc_process(struct svc_rqst *rqstp)
1323 {
1324         struct kvec             *argv = &rqstp->rq_arg.head[0];
1325         struct kvec             *resv = &rqstp->rq_res.head[0];
1326         struct svc_serv         *serv = rqstp->rq_server;
1327         u32                     dir;
1328 
1329         /*
1330          * Setup response xdr_buf.
1331          * Initially it has just one page
1332          */
1333         rqstp->rq_next_page = &rqstp->rq_respages[1];
1334         resv->iov_base = page_address(rqstp->rq_respages[0]);
1335         resv->iov_len = 0;
1336         rqstp->rq_res.pages = rqstp->rq_respages + 1;
1337         rqstp->rq_res.len = 0;
1338         rqstp->rq_res.page_base = 0;
1339         rqstp->rq_res.page_len = 0;
1340         rqstp->rq_res.buflen = PAGE_SIZE;
1341         rqstp->rq_res.tail[0].iov_base = NULL;
1342         rqstp->rq_res.tail[0].iov_len = 0;
1343 
1344         dir  = svc_getnl(argv);
1345         if (dir != 0) {
1346                 /* direction != CALL */
1347                 svc_printk(rqstp, "bad direction %d, dropping request\n", dir);
1348                 serv->sv_stats->rpcbadfmt++;
1349                 goto out_drop;
1350         }
1351 
1352         /* Returns 1 for send, 0 for drop */
1353         if (likely(svc_process_common(rqstp, argv, resv))) {
1354                 int ret = svc_send(rqstp);
1355 
1356                 trace_svc_process(rqstp, ret);
1357                 return ret;
1358         }
1359 out_drop:
1360         trace_svc_process(rqstp, 0);
1361         svc_drop(rqstp);
1362         return 0;
1363 }
1364 EXPORT_SYMBOL_GPL(svc_process);
1365 
1366 #if defined(CONFIG_SUNRPC_BACKCHANNEL)
1367 /*
1368  * Process a backchannel RPC request that arrived over an existing
1369  * outbound connection
1370  */
1371 int
1372 bc_svc_process(struct svc_serv *serv, struct rpc_rqst *req,
1373                struct svc_rqst *rqstp)
1374 {
1375         struct kvec     *argv = &rqstp->rq_arg.head[0];
1376         struct kvec     *resv = &rqstp->rq_res.head[0];
1377         struct rpc_task *task;
1378         int proc_error;
1379         int error;
1380 
1381         dprintk("svc: %s(%p)\n", __func__, req);
1382 
1383         /* Build the svc_rqst used by the common processing routine */
1384         rqstp->rq_xprt = serv->sv_bc_xprt;
1385         rqstp->rq_xid = req->rq_xid;
1386         rqstp->rq_prot = req->rq_xprt->prot;
1387         rqstp->rq_server = serv;
1388 
1389         rqstp->rq_addrlen = sizeof(req->rq_xprt->addr);
1390         memcpy(&rqstp->rq_addr, &req->rq_xprt->addr, rqstp->rq_addrlen);
1391         memcpy(&rqstp->rq_arg, &req->rq_rcv_buf, sizeof(rqstp->rq_arg));
1392         memcpy(&rqstp->rq_res, &req->rq_snd_buf, sizeof(rqstp->rq_res));
1393 
1394         /* Adjust the argument buffer length */
1395         rqstp->rq_arg.len = req->rq_private_buf.len;
1396         if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len) {
1397                 rqstp->rq_arg.head[0].iov_len = rqstp->rq_arg.len;
1398                 rqstp->rq_arg.page_len = 0;
1399         } else if (rqstp->rq_arg.len <= rqstp->rq_arg.head[0].iov_len +
1400                         rqstp->rq_arg.page_len)
1401                 rqstp->rq_arg.page_len = rqstp->rq_arg.len -
1402                         rqstp->rq_arg.head[0].iov_len;
1403         else
1404                 rqstp->rq_arg.len = rqstp->rq_arg.head[0].iov_len +
1405                         rqstp->rq_arg.page_len;
1406 
1407         /* reset result send buffer "put" position */
1408         resv->iov_len = 0;
1409 
1410         /*
1411          * Skip the next two words because they've already been
1412          * processed in the transport
1413          */
1414         svc_getu32(argv);       /* XID */
1415         svc_getnl(argv);        /* CALLDIR */
1416 
1417         /* Parse and execute the bc call */
1418         proc_error = svc_process_common(rqstp, argv, resv);
1419 
1420         atomic_inc(&req->rq_xprt->bc_free_slots);
1421         if (!proc_error) {
1422                 /* Processing error: drop the request */
1423                 xprt_free_bc_request(req);
1424                 return 0;
1425         }
1426 
1427         /* Finally, send the reply synchronously */
1428         memcpy(&req->rq_snd_buf, &rqstp->rq_res, sizeof(req->rq_snd_buf));
1429         task = rpc_run_bc_task(req);
1430         if (IS_ERR(task)) {
1431                 error = PTR_ERR(task);
1432                 goto out;
1433         }
1434 
1435         WARN_ON_ONCE(atomic_read(&task->tk_count) != 1);
1436         error = task->tk_status;
1437         rpc_put_task(task);
1438 
1439 out:
1440         dprintk("svc: %s(), error=%d\n", __func__, error);
1441         return error;
1442 }
1443 EXPORT_SYMBOL_GPL(bc_svc_process);
1444 #endif /* CONFIG_SUNRPC_BACKCHANNEL */
1445 
1446 /*
1447  * Return (transport-specific) limit on the rpc payload.
1448  */
1449 u32 svc_max_payload(const struct svc_rqst *rqstp)
1450 {
1451         u32 max = rqstp->rq_xprt->xpt_class->xcl_max_payload;
1452 
1453         if (rqstp->rq_server->sv_max_payload < max)
1454                 max = rqstp->rq_server->sv_max_payload;
1455         return max;
1456 }
1457 EXPORT_SYMBOL_GPL(svc_max_payload);
1458 

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