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

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