net/sunrpc/clnt.c

   1 /*
   2  *  linux/net/sunrpc/clnt.c
   3  *
   4  *  This file contains the high-level RPC interface.
   5  *  It is modeled as a finite state machine to support both synchronous
   6  *  and asynchronous requests.
   7  *
   8  *  -   RPC header generation and argument serialization.
   9  *  -   Credential refresh.
  10  *  -   TCP connect handling.
  11  *  -   Retry of operation when it is suspected the operation failed because
  12  *      of uid squashing on the server, or when the credentials were stale
  13  *      and need to be refreshed, or when a packet was damaged in transit.
  14  *      This may be have to be moved to the VFS layer.
  15  *
  16  *  NB: BSD uses a more intelligent approach to guessing when a request
  17  *  or reply has been lost by keeping the RTO estimate for each procedure.
  18  *  We currently make do with a constant timeout value.
  19  *
  20  *  Copyright (C) 1992,1993 Rick Sladkey <jrs@world.std.com>
  21  *  Copyright (C) 1995,1996 Olaf Kirch <okir@monad.swb.de>
  22  */
  23
  24 #include <asm/system.h>
  25
  26 #include <linux/module.h>
  27 #include <linux/types.h>
  28 #include <linux/mm.h>
  29 #include <linux/slab.h>
  30 #include <linux/utsname.h>
  31 #include <linux/workqueue.h>
  32
  33 #include <linux/sunrpc/clnt.h>
  34 #include <linux/sunrpc/rpc_pipe_fs.h>
  35 #include <linux/sunrpc/metrics.h>
  36
  37
  38 #define RPC_SLACK_SPACE         (1024)  /* total overkill */
  39
  40 #ifdef RPC_DEBUG
  41 # define RPCDBG_FACILITY        RPCDBG_CALL
  42 #endif
  43
  44 static DECLARE_WAIT_QUEUE_HEAD(destroy_wait);
  45
  46
  47 static void     call_start(struct rpc_task *task);
  48 static void     call_reserve(struct rpc_task *task);
  49 static void     call_reserveresult(struct rpc_task *task);
  50 static void     call_allocate(struct rpc_task *task);
  51 static void     call_encode(struct rpc_task *task);
  52 static void     call_decode(struct rpc_task *task);
  53 static void     call_bind(struct rpc_task *task);
  54 static void     call_bind_status(struct rpc_task *task);
  55 static void     call_transmit(struct rpc_task *task);
  56 static void     call_status(struct rpc_task *task);
  57 static void     call_transmit_status(struct rpc_task *task);
  58 static void     call_refresh(struct rpc_task *task);
  59 static void     call_refreshresult(struct rpc_task *task);
  60 static void     call_timeout(struct rpc_task *task);
  61 static void     call_connect(struct rpc_task *task);
  62 static void     call_connect_status(struct rpc_task *task);
  63 static u32 *    call_header(struct rpc_task *task);
  64 static u32 *    call_verify(struct rpc_task *task);
  65
  66
  67 static int
  68 rpc_setup_pipedir(struct rpc_clnt *clnt, char *dir_name)
  69 {
  70         static uint32_t clntid;
  71         int error;
  72
  73         clnt->cl_vfsmnt = ERR_PTR(-ENOENT);
  74         clnt->cl_dentry = ERR_PTR(-ENOENT);
  75         if (dir_name == NULL)
  76                 return 0;
  77
  78         clnt->cl_vfsmnt = rpc_get_mount();
  79         if (IS_ERR(clnt->cl_vfsmnt))
  80                 return PTR_ERR(clnt->cl_vfsmnt);
  81
  82         for (;;) {
  83                 snprintf(clnt->cl_pathname, sizeof(clnt->cl_pathname),
  84                                 "%s/clnt%x", dir_name,
  85                                 (unsigned int)clntid++);
  86                 clnt->cl_pathname[sizeof(clnt->cl_pathname) - 1] = '\0';
  87                 clnt->cl_dentry = rpc_mkdir(clnt->cl_pathname, clnt);
  88                 if (!IS_ERR(clnt->cl_dentry))
  89                         return 0;
  90                 error = PTR_ERR(clnt->cl_dentry);
  91                 if (error != -EEXIST) {
  92                         printk(KERN_INFO "RPC: Couldn't create pipefs entry %s, error %d\n",
  93                                         clnt->cl_pathname, error);
  94                         rpc_put_mount();
  95                         return error;
  96                 }
  97         }
  98 }
  99
 100 /*
 101  * Create an RPC client
 102  * FIXME: This should also take a flags argument (as in task->tk_flags).
 103  * It's called (among others) from pmap_create_client, which may in
 104  * turn be called by an async task. In this case, rpciod should not be
 105  * made to sleep too long.
 106  */
 107 struct rpc_clnt *
 108 rpc_new_client(struct rpc_xprt *xprt, char *servname,
 109                   struct rpc_program *program, u32 vers,
 110                   rpc_authflavor_t flavor)
 111 {
 112         struct rpc_version      *version;
 113         struct rpc_clnt         *clnt = NULL;
 114         struct rpc_auth         *auth;
 115         int err;
 116         int len;
 117
 118         dprintk("RPC: creating %s client for %s (xprt %p)\n",
 119                 program->name, servname, xprt);
 120
 121         err = -EINVAL;
 122         if (!xprt)
 123                 goto out_no_xprt;
 124         if (vers >= program->nrvers || !(version = program->version[vers]))
 125                 goto out_err;
 126
 127         err = -ENOMEM;
 128         clnt = kzalloc(sizeof(*clnt), GFP_KERNEL);
 129         if (!clnt)
 130                 goto out_err;
 131         atomic_set(&clnt->cl_users, 0);
 132         atomic_set(&clnt->cl_count, 1);
 133         clnt->cl_parent = clnt;
 134
 135         clnt->cl_server = clnt->cl_inline_name;
 136         len = strlen(servname) + 1;
 137         if (len > sizeof(clnt->cl_inline_name)) {
 138                 char *buf = kmalloc(len, GFP_KERNEL);
 139                 if (buf != 0)
 140                         clnt->cl_server = buf;
 141                 else
 142                         len = sizeof(clnt->cl_inline_name);
 143         }
 144         strlcpy(clnt->cl_server, servname, len);
 145
 146         clnt->cl_xprt     = xprt;
 147         clnt->cl_procinfo = version->procs;
 148         clnt->cl_maxproc  = version->nrprocs;
 149         clnt->cl_protname = program->name;
 150         clnt->cl_pmap     = &clnt->cl_pmap_default;
 151         clnt->cl_port     = xprt->addr.sin_port;
 152         clnt->cl_prog     = program->number;
 153         clnt->cl_vers     = version->number;
 154         clnt->cl_prot     = xprt->prot;
 155         clnt->cl_stats    = program->stats;
 156         clnt->cl_metrics  = rpc_alloc_iostats(clnt);
 157         rpc_init_wait_queue(&clnt->cl_pmap_default.pm_bindwait, "bindwait");
 158
 159         if (!clnt->cl_port)
 160                 clnt->cl_autobind = 1;
 161
 162         clnt->cl_rtt = &clnt->cl_rtt_default;
 163         rpc_init_rtt(&clnt->cl_rtt_default, xprt->timeout.to_initval);
 164
 165         err = rpc_setup_pipedir(clnt, program->pipe_dir_name);
 166         if (err < 0)
 167                 goto out_no_path;
 168
 169         auth = rpcauth_create(flavor, clnt);
 170         if (IS_ERR(auth)) {
 171                 printk(KERN_INFO "RPC: Couldn't create auth handle (flavor %u)\n",
 172                                 flavor);
 173                 err = PTR_ERR(auth);
 174                 goto out_no_auth;
 175         }
 176
 177         /* save the nodename */
 178         clnt->cl_nodelen = strlen(system_utsname.nodename);
 179         if (clnt->cl_nodelen > UNX_MAXNODENAME)
 180                 clnt->cl_nodelen = UNX_MAXNODENAME;
 181         memcpy(clnt->cl_nodename, system_utsname.nodename, clnt->cl_nodelen);
 182         return clnt;
 183
 184 out_no_auth:
 185         if (!IS_ERR(clnt->cl_dentry)) {
 186                 rpc_rmdir(clnt->cl_dentry);
 187                 rpc_put_mount();
 188         }
 189 out_no_path:
 190         if (clnt->cl_server != clnt->cl_inline_name)
 191                 kfree(clnt->cl_server);
 192         kfree(clnt);
 193 out_err:
 194         xprt_destroy(xprt);
 195 out_no_xprt:
 196         return ERR_PTR(err);
 197 }
 198
 199 /**
 200  * Create an RPC client
 201  * @xprt - pointer to xprt struct
 202  * @servname - name of server
 203  * @info - rpc_program
 204  * @version - rpc_program version
 205  * @authflavor - rpc_auth flavour to use
 206  *
 207  * Creates an RPC client structure, then pings the server in order to
 208  * determine if it is up, and if it supports this program and version.
 209  *
 210  * This function should never be called by asynchronous tasks such as
 211  * the portmapper.
 212  */
 213 struct rpc_clnt *rpc_create_client(struct rpc_xprt *xprt, char *servname,
 214                 struct rpc_program *info, u32 version, rpc_authflavor_t authflavor)
 215 {
 216         struct rpc_clnt *clnt;
 217         int err;
 218
 219         clnt = rpc_new_client(xprt, servname, info, version, authflavor);
 220         if (IS_ERR(clnt))
 221                 return clnt;
 222         err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 223         if (err == 0)
 224                 return clnt;
 225         rpc_shutdown_client(clnt);
 226         return ERR_PTR(err);
 227 }
 228
 229 /*
 230  * This function clones the RPC client structure. It allows us to share the
 231  * same transport while varying parameters such as the authentication
 232  * flavour.
 233  */
 234 struct rpc_clnt *
 235 rpc_clone_client(struct rpc_clnt *clnt)
 236 {
 237         struct rpc_clnt *new;
 238
 239         new = kmalloc(sizeof(*new), GFP_KERNEL);
 240         if (!new)
 241                 goto out_no_clnt;
 242         memcpy(new, clnt, sizeof(*new));
 243         atomic_set(&new->cl_count, 1);
 244         atomic_set(&new->cl_users, 0);
 245         new->cl_parent = clnt;
 246         atomic_inc(&clnt->cl_count);
 247         /* Duplicate portmapper */
 248         rpc_init_wait_queue(&new->cl_pmap_default.pm_bindwait, "bindwait");
 249         /* Turn off autobind on clones */
 250         new->cl_autobind = 0;
 251         new->cl_oneshot = 0;
 252         new->cl_dead = 0;
 253         if (!IS_ERR(new->cl_dentry))
 254                 dget(new->cl_dentry);
 255         rpc_init_rtt(&new->cl_rtt_default, clnt->cl_xprt->timeout.to_initval);
 256         if (new->cl_auth)
 257                 atomic_inc(&new->cl_auth->au_count);
 258         new->cl_pmap            = &new->cl_pmap_default;
 259         new->cl_metrics         = rpc_alloc_iostats(clnt);
 260         return new;
 261 out_no_clnt:
 262         printk(KERN_INFO "RPC: out of memory in %s\n", __FUNCTION__);
 263         return ERR_PTR(-ENOMEM);
 264 }
 265
 266 /*
 267  * Properly shut down an RPC client, terminating all outstanding
 268  * requests. Note that we must be certain that cl_oneshot and
 269  * cl_dead are cleared, or else the client would be destroyed
 270  * when the last task releases it.
 271  */
 272 int
 273 rpc_shutdown_client(struct rpc_clnt *clnt)
 274 {
 275         dprintk("RPC: shutting down %s client for %s, tasks=%d\n",
 276                         clnt->cl_protname, clnt->cl_server,
 277                         atomic_read(&clnt->cl_users));
 278
 279         while (atomic_read(&clnt->cl_users) > 0) {
 280                 /* Don't let rpc_release_client destroy us */
 281                 clnt->cl_oneshot = 0;
 282                 clnt->cl_dead = 0;
 283                 rpc_killall_tasks(clnt);
 284                 wait_event_timeout(destroy_wait,
 285                         !atomic_read(&clnt->cl_users), 1*HZ);
 286         }
 287
 288         if (atomic_read(&clnt->cl_users) < 0) {
 289                 printk(KERN_ERR "RPC: rpc_shutdown_client clnt %p tasks=%d\n",
 290                                 clnt, atomic_read(&clnt->cl_users));
 291 #ifdef RPC_DEBUG
 292                 rpc_show_tasks();
 293 #endif
 294                 BUG();
 295         }
 296
 297         return rpc_destroy_client(clnt);
 298 }
 299
 300 /*
 301  * Delete an RPC client
 302  */
 303 int
 304 rpc_destroy_client(struct rpc_clnt *clnt)
 305 {
 306         if (!atomic_dec_and_test(&clnt->cl_count))
 307                 return 1;
 308         BUG_ON(atomic_read(&clnt->cl_users) != 0);
 309
 310         dprintk("RPC: destroying %s client for %s\n",
 311                         clnt->cl_protname, clnt->cl_server);
 312         if (clnt->cl_auth) {
 313                 rpcauth_destroy(clnt->cl_auth);
 314                 clnt->cl_auth = NULL;
 315         }
 316         if (clnt->cl_parent != clnt) {
 317                 if (!IS_ERR(clnt->cl_dentry))
 318                         dput(clnt->cl_dentry);
 319                 rpc_destroy_client(clnt->cl_parent);
 320                 goto out_free;
 321         }
 322         if (!IS_ERR(clnt->cl_dentry)) {
 323                 rpc_rmdir(clnt->cl_dentry);
 324                 rpc_put_mount();
 325         }
 326         if (clnt->cl_xprt) {
 327                 xprt_destroy(clnt->cl_xprt);
 328                 clnt->cl_xprt = NULL;
 329         }
 330         if (clnt->cl_server != clnt->cl_inline_name)
 331                 kfree(clnt->cl_server);
 332 out_free:
 333         rpc_free_iostats(clnt->cl_metrics);
 334         clnt->cl_metrics = NULL;
 335         kfree(clnt);
 336         return 0;
 337 }
 338
 339 /*
 340  * Release an RPC client
 341  */
 342 void
 343 rpc_release_client(struct rpc_clnt *clnt)
 344 {
 345         dprintk("RPC:      rpc_release_client(%p, %d)\n",
 346                                 clnt, atomic_read(&clnt->cl_users));
 347
 348         if (!atomic_dec_and_test(&clnt->cl_users))
 349                 return;
 350         wake_up(&destroy_wait);
 351         if (clnt->cl_oneshot || clnt->cl_dead)
 352                 rpc_destroy_client(clnt);
 353 }
 354
 355 /**
 356  * rpc_bind_new_program - bind a new RPC program to an existing client
 357  * @old - old rpc_client
 358  * @program - rpc program to set
 359  * @vers - rpc program version
 360  *
 361  * Clones the rpc client and sets up a new RPC program. This is mainly
 362  * of use for enabling different RPC programs to share the same transport.
 363  * The Sun NFSv2/v3 ACL protocol can do this.
 364  */
 365 struct rpc_clnt *rpc_bind_new_program(struct rpc_clnt *old,
 366                                       struct rpc_program *program,
 367                                       int vers)
 368 {
 369         struct rpc_clnt *clnt;
 370         struct rpc_version *version;
 371         int err;
 372
 373         BUG_ON(vers >= program->nrvers || !program->version[vers]);
 374         version = program->version[vers];
 375         clnt = rpc_clone_client(old);
 376         if (IS_ERR(clnt))
 377                 goto out;
 378         clnt->cl_procinfo = version->procs;
 379         clnt->cl_maxproc  = version->nrprocs;
 380         clnt->cl_protname = program->name;
 381         clnt->cl_prog     = program->number;
 382         clnt->cl_vers     = version->number;
 383         clnt->cl_stats    = program->stats;
 384         err = rpc_ping(clnt, RPC_TASK_SOFT|RPC_TASK_NOINTR);
 385         if (err != 0) {
 386                 rpc_shutdown_client(clnt);
 387                 clnt = ERR_PTR(err);
 388         }
 389 out:
 390         return clnt;
 391 }
 392
 393 /*
 394  * Default callback for async RPC calls
 395  */
 396 static void
 397 rpc_default_callback(struct rpc_task *task, void *data)
 398 {
 399 }
 400
 401 static const struct rpc_call_ops rpc_default_ops = {
 402         .rpc_call_done = rpc_default_callback,
 403 };
 404
 405 /*
 406  *      Export the signal mask handling for synchronous code that
 407  *      sleeps on RPC calls
 408  */
 409 #define RPC_INTR_SIGNALS (sigmask(SIGHUP) | sigmask(SIGINT) | sigmask(SIGQUIT) | sigmask(SIGTERM))
 410
 411 static void rpc_save_sigmask(sigset_t *oldset, int intr)
 412 {
 413         unsigned long   sigallow = sigmask(SIGKILL);
 414         sigset_t sigmask;
 415
 416         /* Block all signals except those listed in sigallow */
 417         if (intr)
 418                 sigallow |= RPC_INTR_SIGNALS;
 419         siginitsetinv(&sigmask, sigallow);
 420         sigprocmask(SIG_BLOCK, &sigmask, oldset);
 421 }
 422
 423 static inline void rpc_task_sigmask(struct rpc_task *task, sigset_t *oldset)
 424 {
 425         rpc_save_sigmask(oldset, !RPC_TASK_UNINTERRUPTIBLE(task));
 426 }
 427
 428 static inline void rpc_restore_sigmask(sigset_t *oldset)
 429 {
 430         sigprocmask(SIG_SETMASK, oldset, NULL);
 431 }
 432
 433 void rpc_clnt_sigmask(struct rpc_clnt *clnt, sigset_t *oldset)
 434 {
 435         rpc_save_sigmask(oldset, clnt->cl_intr);
 436 }
 437
 438 void rpc_clnt_sigunmask(struct rpc_clnt *clnt, sigset_t *oldset)
 439 {
 440         rpc_restore_sigmask(oldset);
 441 }
 442
 443 /*
 444  * New rpc_call implementation
 445  */
 446 int rpc_call_sync(struct rpc_clnt *clnt, struct rpc_message *msg, int flags)
 447 {
 448         struct rpc_task *task;
 449         sigset_t        oldset;
 450         int             status;
 451
 452         /* If this client is slain all further I/O fails */
 453         if (clnt->cl_dead)
 454                 return -EIO;
 455
 456         BUG_ON(flags & RPC_TASK_ASYNC);
 457
 458         status = -ENOMEM;
 459         task = rpc_new_task(clnt, flags, &rpc_default_ops, NULL);
 460         if (task == NULL)
 461                 goto out;
 462
 463         /* Mask signals on RPC calls _and_ GSS_AUTH upcalls */
 464         rpc_task_sigmask(task, &oldset);
 465
 466         rpc_call_setup(task, msg, 0);
 467
 468         /* Set up the call info struct and execute the task */
 469         status = task->tk_status;
 470         if (status == 0) {
 471                 atomic_inc(&task->tk_count);
 472                 status = rpc_execute(task);
 473                 if (status == 0)
 474                         status = task->tk_status;
 475         }
 476         rpc_restore_sigmask(&oldset);
 477         rpc_release_task(task);
 478 out:
 479         return status;
 480 }
 481
 482 /*
 483  * New rpc_call implementation
 484  */
 485 int
 486 rpc_call_async(struct rpc_clnt *clnt, struct rpc_message *msg, int flags,
 487                const struct rpc_call_ops *tk_ops, void *data)
 488 {
 489         struct rpc_task *task;
 490         sigset_t        oldset;
 491         int             status;
 492
 493         /* If this client is slain all further I/O fails */
 494         status = -EIO;
 495         if (clnt->cl_dead)
 496                 goto out_release;
 497
 498         flags |= RPC_TASK_ASYNC;
 499
 500         /* Create/initialize a new RPC task */
 501         status = -ENOMEM;
 502         if (!(task = rpc_new_task(clnt, flags, tk_ops, data)))
 503                 goto out_release;
 504
 505         /* Mask signals on GSS_AUTH upcalls */
 506         rpc_task_sigmask(task, &oldset);
 507
 508         rpc_call_setup(task, msg, 0);
 509
 510         /* Set up the call info struct and execute the task */
 511         status = task->tk_status;
 512         if (status == 0)
 513                 rpc_execute(task);
 514         else
 515                 rpc_release_task(task);
 516
 517         rpc_restore_sigmask(&oldset);
 518         return status;
 519 out_release:
 520         if (tk_ops->rpc_release != NULL)
 521                 tk_ops->rpc_release(data);
 522         return status;
 523 }
 524
 525
 526 void
 527 rpc_call_setup(struct rpc_task *task, struct rpc_message *msg, int flags)
 528 {
 529         task->tk_msg   = *msg;
 530         task->tk_flags |= flags;
 531         /* Bind the user cred */
 532         if (task->tk_msg.rpc_cred != NULL)
 533                 rpcauth_holdcred(task);
 534         else
 535                 rpcauth_bindcred(task);
 536
 537         if (task->tk_status == 0)
 538                 task->tk_action = call_start;
 539         else
 540                 task->tk_action = rpc_exit_task;
 541 }
 542
 543 void
 544 rpc_setbufsize(struct rpc_clnt *clnt, unsigned int sndsize, unsigned int rcvsize)
 545 {
 546         struct rpc_xprt *xprt = clnt->cl_xprt;
 547         if (xprt->ops->set_buffer_size)
 548                 xprt->ops->set_buffer_size(xprt, sndsize, rcvsize);
 549 }
 550
 551 /*
 552  * Return size of largest payload RPC client can support, in bytes
 553  *
 554  * For stream transports, this is one RPC record fragment (see RFC
 555  * 1831), as we don't support multi-record requests yet.  For datagram
 556  * transports, this is the size of an IP packet minus the IP, UDP, and
 557  * RPC header sizes.
 558  */
 559 size_t rpc_max_payload(struct rpc_clnt *clnt)
 560 {
 561         return clnt->cl_xprt->max_payload;
 562 }
 563 EXPORT_SYMBOL(rpc_max_payload);
 564
 565 /**
 566  * rpc_force_rebind - force transport to check that remote port is unchanged
 567  * @clnt: client to rebind
 568  *
 569  */
 570 void rpc_force_rebind(struct rpc_clnt *clnt)
 571 {
 572         if (clnt->cl_autobind)
 573                 clnt->cl_port = 0;
 574 }
 575 EXPORT_SYMBOL(rpc_force_rebind);
 576
 577 /*
 578  * Restart an (async) RPC call. Usually called from within the
 579  * exit handler.
 580  */
 581 void
 582 rpc_restart_call(struct rpc_task *task)
 583 {
 584         if (RPC_ASSASSINATED(task))
 585                 return;
 586
 587         task->tk_action = call_start;
 588 }
 589
 590 /*
 591  * 0.  Initial state
 592  *
 593  *     Other FSM states can be visited zero or more times, but
 594  *     this state is visited exactly once for each RPC.
 595  */
 596 static void
 597 call_start(struct rpc_task *task)
 598 {
 599         struct rpc_clnt *clnt = task->tk_client;
 600
 601         dprintk("RPC: %4d call_start %s%d proc %d (%s)\n", task->tk_pid,
 602                 clnt->cl_protname, clnt->cl_vers, task->tk_msg.rpc_proc->p_proc,
 603                 (RPC_IS_ASYNC(task) ? "async" : "sync"));
 604
 605         /* Increment call count */
 606         task->tk_msg.rpc_proc->p_count++;
 607         clnt->cl_stats->rpccnt++;
 608         task->tk_action = call_reserve;
 609 }
 610
 611 /*
 612  * 1.   Reserve an RPC call slot
 613  */
 614 static void
 615 call_reserve(struct rpc_task *task)
 616 {
 617         dprintk("RPC: %4d call_reserve\n", task->tk_pid);
 618
 619         if (!rpcauth_uptodatecred(task)) {
 620                 task->tk_action = call_refresh;
 621                 return;
 622         }
 623
 624         task->tk_status  = 0;
 625         task->tk_action  = call_reserveresult;
 626         xprt_reserve(task);
 627 }
 628
 629 /*
 630  * 1b.  Grok the result of xprt_reserve()
 631  */
 632 static void
 633 call_reserveresult(struct rpc_task *task)
 634 {
 635         int status = task->tk_status;
 636
 637         dprintk("RPC: %4d call_reserveresult (status %d)\n",
 638                                 task->tk_pid, task->tk_status);
 639
 640         /*
 641          * After a call to xprt_reserve(), we must have either
 642          * a request slot or else an error status.
 643          */
 644         task->tk_status = 0;
 645         if (status >= 0) {
 646                 if (task->tk_rqstp) {
 647                         task->tk_action = call_allocate;
 648                         return;
 649                 }
 650
 651                 printk(KERN_ERR "%s: status=%d, but no request slot, exiting\n",
 652                                 __FUNCTION__, status);
 653                 rpc_exit(task, -EIO);
 654                 return;
 655         }
 656
 657         /*
 658          * Even though there was an error, we may have acquired
 659          * a request slot somehow.  Make sure not to leak it.
 660          */
 661         if (task->tk_rqstp) {
 662                 printk(KERN_ERR "%s: status=%d, request allocated anyway\n",
 663                                 __FUNCTION__, status);
 664                 xprt_release(task);
 665         }
 666
 667         switch (status) {
 668         case -EAGAIN:   /* woken up; retry */
 669                 task->tk_action = call_reserve;
 670                 return;
 671         case -EIO:      /* probably a shutdown */
 672                 break;
 673         default:
 674                 printk(KERN_ERR "%s: unrecognized error %d, exiting\n",
 675                                 __FUNCTION__, status);
 676                 break;
 677         }
 678         rpc_exit(task, status);
 679 }
 680
 681 /*
 682  * 2.   Allocate the buffer. For details, see sched.c:rpc_malloc.
 683  *      (Note: buffer memory is freed in xprt_release).
 684  */
 685 static void
 686 call_allocate(struct rpc_task *task)
 687 {
 688         struct rpc_rqst *req = task->tk_rqstp;
 689         struct rpc_xprt *xprt = task->tk_xprt;
 690         unsigned int    bufsiz;
 691
 692         dprintk("RPC: %4d call_allocate (status %d)\n",
 693                                 task->tk_pid, task->tk_status);
 694         task->tk_action = call_bind;
 695         if (req->rq_buffer)
 696                 return;
 697
 698         /* FIXME: compute buffer requirements more exactly using
 699          * auth->au_wslack */
 700         bufsiz = task->tk_msg.rpc_proc->p_bufsiz + RPC_SLACK_SPACE;
 701
 702         if (xprt->ops->buf_alloc(task, bufsiz << 1) != NULL)
 703                 return;
 704         printk(KERN_INFO "RPC: buffer allocation failed for task %p\n", task);
 705
 706         if (RPC_IS_ASYNC(task) || !signalled()) {
 707                 xprt_release(task);
 708                 task->tk_action = call_reserve;
 709                 rpc_delay(task, HZ>>4);
 710                 return;
 711         }
 712
 713         rpc_exit(task, -ERESTARTSYS);
 714 }
 715
 716 static inline int
 717 rpc_task_need_encode(struct rpc_task *task)
 718 {
 719         return task->tk_rqstp->rq_snd_buf.len == 0;
 720 }
 721
 722 static inline void
 723 rpc_task_force_reencode(struct rpc_task *task)
 724 {
 725         task->tk_rqstp->rq_snd_buf.len = 0;
 726 }
 727
 728 /*
 729  * 3.   Encode arguments of an RPC call
 730  */
 731 static void
 732 call_encode(struct rpc_task *task)
 733 {
 734         struct rpc_rqst *req = task->tk_rqstp;
 735         struct xdr_buf *sndbuf = &req->rq_snd_buf;
 736         struct xdr_buf *rcvbuf = &req->rq_rcv_buf;
 737         unsigned int    bufsiz;
 738         kxdrproc_t      encode;
 739         u32             *p;
 740
 741         dprintk("RPC: %4d call_encode (status %d)\n",
 742                                 task->tk_pid, task->tk_status);
 743
 744         /* Default buffer setup */
 745         bufsiz = req->rq_bufsize >> 1;
 746         sndbuf->head[0].iov_base = (void *)req->rq_buffer;
 747         sndbuf->head[0].iov_len  = bufsiz;
 748         sndbuf->tail[0].iov_len  = 0;
 749         sndbuf->page_len         = 0;
 750         sndbuf->len              = 0;
 751         sndbuf->buflen           = bufsiz;
 752         rcvbuf->head[0].iov_base = (void *)((char *)req->rq_buffer + bufsiz);
 753         rcvbuf->head[0].iov_len  = bufsiz;
 754         rcvbuf->tail[0].iov_len  = 0;
 755         rcvbuf->page_len         = 0;
 756         rcvbuf->len              = 0;
 757         rcvbuf->buflen           = bufsiz;
 758
 759         /* Encode header and provided arguments */
 760         encode = task->tk_msg.rpc_proc->p_encode;
 761         if (!(p = call_header(task))) {
 762                 printk(KERN_INFO "RPC: call_header failed, exit EIO\n");
 763                 rpc_exit(task, -EIO);
 764                 return;
 765         }
 766         if (encode == NULL)
 767                 return;
 768
 769         task->tk_status = rpcauth_wrap_req(task, encode, req, p,
 770                         task->tk_msg.rpc_argp);
 771         if (task->tk_status == -ENOMEM) {
 772                 /* XXX: Is this sane? */
 773                 rpc_delay(task, 3*HZ);
 774                 task->tk_status = -EAGAIN;
 775         }
 776 }
 777
 778 /*
 779  * 4.   Get the server port number if not yet set
 780  */
 781 static void
 782 call_bind(struct rpc_task *task)
 783 {
 784         struct rpc_clnt *clnt = task->tk_client;
 785
 786         dprintk("RPC: %4d call_bind (status %d)\n",
 787                                 task->tk_pid, task->tk_status);
 788
 789         task->tk_action = call_connect;
 790         if (!clnt->cl_port) {
 791                 task->tk_action = call_bind_status;
 792                 task->tk_timeout = task->tk_xprt->bind_timeout;
 793                 rpc_getport(task, clnt);
 794         }
 795 }
 796
 797 /*
 798  * 4a.  Sort out bind result
 799  */
 800 static void
 801 call_bind_status(struct rpc_task *task)
 802 {
 803         int status = -EACCES;
 804
 805         if (task->tk_status >= 0) {
 806                 dprintk("RPC: %4d call_bind_status (status %d)\n",
 807                                         task->tk_pid, task->tk_status);
 808                 task->tk_status = 0;
 809                 task->tk_action = call_connect;
 810                 return;
 811         }
 812
 813         switch (task->tk_status) {
 814         case -EACCES:
 815                 dprintk("RPC: %4d remote rpcbind: RPC program/version unavailable\n",
 816                                 task->tk_pid);
 817                 rpc_delay(task, 3*HZ);
 818                 goto retry_bind;
 819         case -ETIMEDOUT:
 820                 dprintk("RPC: %4d rpcbind request timed out\n",
 821                                 task->tk_pid);
 822                 if (RPC_IS_SOFT(task)) {
 823                         status = -EIO;
 824                         break;
 825                 }
 826                 goto retry_bind;
 827         case -EPFNOSUPPORT:
 828                 dprintk("RPC: %4d remote rpcbind service unavailable\n",
 829                                 task->tk_pid);
 830                 break;
 831         case -EPROTONOSUPPORT:
 832                 dprintk("RPC: %4d remote rpcbind version 2 unavailable\n",
 833                                 task->tk_pid);
 834                 break;
 835         default:
 836                 dprintk("RPC: %4d unrecognized rpcbind error (%d)\n",
 837                                 task->tk_pid, -task->tk_status);
 838                 status = -EIO;
 839                 break;
 840         }
 841
 842         rpc_exit(task, status);
 843         return;
 844
 845 retry_bind:
 846         task->tk_status = 0;
 847         task->tk_action = call_bind;
 848         return;
 849 }
 850
 851 /*
 852  * 4b.  Connect to the RPC server
 853  */
 854 static void
 855 call_connect(struct rpc_task *task)
 856 {
 857         struct rpc_xprt *xprt = task->tk_xprt;
 858
 859         dprintk("RPC: %4d call_connect xprt %p %s connected\n",
 860                         task->tk_pid, xprt,
 861                         (xprt_connected(xprt) ? "is" : "is not"));
 862
 863         task->tk_action = call_transmit;
 864         if (!xprt_connected(xprt)) {
 865                 task->tk_action = call_connect_status;
 866                 if (task->tk_status < 0)
 867                         return;
 868                 xprt_connect(task);
 869         }
 870 }
 871
 872 /*
 873  * 4c.  Sort out connect result
 874  */
 875 static void
 876 call_connect_status(struct rpc_task *task)
 877 {
 878         struct rpc_clnt *clnt = task->tk_client;
 879         int status = task->tk_status;
 880
 881         dprintk("RPC: %5u call_connect_status (status %d)\n",
 882                                 task->tk_pid, task->tk_status);
 883
 884         task->tk_status = 0;
 885         if (status >= 0) {
 886                 clnt->cl_stats->netreconn++;
 887                 task->tk_action = call_transmit;
 888                 return;
 889         }
 890
 891         /* Something failed: remote service port may have changed */
 892         rpc_force_rebind(clnt);
 893
 894         switch (status) {
 895         case -ENOTCONN:
 896         case -ETIMEDOUT:
 897         case -EAGAIN:
 898                 task->tk_action = call_bind;
 899                 break;
 900         default:
 901                 rpc_exit(task, -EIO);
 902                 break;
 903         }
 904 }
 905
 906 /*
 907  * 5.   Transmit the RPC request, and wait for reply
 908  */
 909 static void
 910 call_transmit(struct rpc_task *task)
 911 {
 912         dprintk("RPC: %4d call_transmit (status %d)\n",
 913                                 task->tk_pid, task->tk_status);
 914
 915         task->tk_action = call_status;
 916         if (task->tk_status < 0)
 917                 return;
 918         task->tk_status = xprt_prepare_transmit(task);
 919         if (task->tk_status != 0)
 920                 return;
 921         task->tk_action = call_transmit_status;
 922         /* Encode here so that rpcsec_gss can use correct sequence number. */
 923         if (rpc_task_need_encode(task)) {
 924                 BUG_ON(task->tk_rqstp->rq_bytes_sent != 0);
 925                 call_encode(task);
 926                 /* Did the encode result in an error condition? */
 927                 if (task->tk_status != 0)
 928                         return;
 929         }
 930         xprt_transmit(task);
 931         if (task->tk_status < 0)
 932                 return;
 933         /*
 934          * On success, ensure that we call xprt_end_transmit() before sleeping
 935          * in order to allow access to the socket to other RPC requests.
 936          */
 937         call_transmit_status(task);
 938         if (task->tk_msg.rpc_proc->p_decode != NULL)
 939                 return;
 940         task->tk_action = rpc_exit_task;
 941         rpc_wake_up_task(task);
 942 }
 943
 944 /*
 945  * 5a.  Handle cleanup after a transmission
 946  */
 947 static void
 948 call_transmit_status(struct rpc_task *task)
 949 {
 950         task->tk_action = call_status;
 951         /*
 952          * Special case: if we've been waiting on the socket's write_space()
 953          * callback, then don't call xprt_end_transmit().
 954          */
 955         if (task->tk_status == -EAGAIN)
 956                 return;
 957         xprt_end_transmit(task);
 958         rpc_task_force_reencode(task);
 959 }
 960
 961 /*
 962  * 6.   Sort out the RPC call status
 963  */
 964 static void
 965 call_status(struct rpc_task *task)
 966 {
 967         struct rpc_clnt *clnt = task->tk_client;
 968         struct rpc_rqst *req = task->tk_rqstp;
 969         int             status;
 970
 971         if (req->rq_received > 0 && !req->rq_bytes_sent)
 972                 task->tk_status = req->rq_received;
 973
 974         dprintk("RPC: %4d call_status (status %d)\n",
 975                                 task->tk_pid, task->tk_status);
 976
 977         status = task->tk_status;
 978         if (status >= 0) {
 979                 task->tk_action = call_decode;
 980                 return;
 981         }
 982
 983         task->tk_status = 0;
 984         switch(status) {
 985         case -ETIMEDOUT:
 986                 task->tk_action = call_timeout;
 987                 break;
 988         case -ECONNREFUSED:
 989         case -ENOTCONN:
 990                 rpc_force_rebind(clnt);
 991                 task->tk_action = call_bind;
 992                 break;
 993         case -EAGAIN:
 994                 task->tk_action = call_transmit;
 995                 break;
 996         case -EIO:
 997                 /* shutdown or soft timeout */
 998                 rpc_exit(task, status);
 999                 break;
1000         default:
1001                 printk("%s: RPC call returned error %d\n",
1002                                clnt->cl_protname, -status);
1003                 rpc_exit(task, status);
1004                 break;
1005         }
1006 }
1007
1008 /*
1009  * 6a.  Handle RPC timeout
1010  *      We do not release the request slot, so we keep using the
1011  *      same XID for all retransmits.
1012  */
1013 static void
1014 call_timeout(struct rpc_task *task)
1015 {
1016         struct rpc_clnt *clnt = task->tk_client;
1017
1018         if (xprt_adjust_timeout(task->tk_rqstp) == 0) {
1019                 dprintk("RPC: %4d call_timeout (minor)\n", task->tk_pid);
1020                 goto retry;
1021         }
1022
1023         dprintk("RPC: %4d call_timeout (major)\n", task->tk_pid);
1024         task->tk_timeouts++;
1025
1026         if (RPC_IS_SOFT(task)) {
1027                 printk(KERN_NOTICE "%s: server %s not responding, timed out\n",
1028                                 clnt->cl_protname, clnt->cl_server);
1029                 rpc_exit(task, -EIO);
1030                 return;
1031         }
1032
1033         if (!(task->tk_flags & RPC_CALL_MAJORSEEN)) {
1034                 task->tk_flags |= RPC_CALL_MAJORSEEN;
1035                 printk(KERN_NOTICE "%s: server %s not responding, still trying\n",
1036                         clnt->cl_protname, clnt->cl_server);
1037         }
1038         rpc_force_rebind(clnt);
1039
1040 retry:
1041         clnt->cl_stats->rpcretrans++;
1042         task->tk_action = call_bind;
1043         task->tk_status = 0;
1044 }
1045
1046 /*
1047  * 7.   Decode the RPC reply
1048  */
1049 static void
1050 call_decode(struct rpc_task *task)
1051 {
1052         struct rpc_clnt *clnt = task->tk_client;
1053         struct rpc_rqst *req = task->tk_rqstp;
1054         kxdrproc_t      decode = task->tk_msg.rpc_proc->p_decode;
1055         u32             *p;
1056
1057         dprintk("RPC: %4d call_decode (status %d)\n",
1058                                 task->tk_pid, task->tk_status);
1059
1060         if (task->tk_flags & RPC_CALL_MAJORSEEN) {
1061                 printk(KERN_NOTICE "%s: server %s OK\n",
1062                         clnt->cl_protname, clnt->cl_server);
1063                 task->tk_flags &= ~RPC_CALL_MAJORSEEN;
1064         }
1065
1066         if (task->tk_status < 12) {
1067                 if (!RPC_IS_SOFT(task)) {
1068                         task->tk_action = call_bind;
1069                         clnt->cl_stats->rpcretrans++;
1070                         goto out_retry;
1071                 }
1072                 printk(KERN_WARNING "%s: too small RPC reply size (%d bytes)\n",
1073                         clnt->cl_protname, task->tk_status);
1074                 rpc_exit(task, -EIO);
1075                 return;
1076         }
1077
1078         /*
1079          * Ensure that we see all writes made by xprt_complete_rqst()
1080          * before it changed req->rq_received.
1081          */
1082         smp_rmb();
1083         req->rq_rcv_buf.len = req->rq_private_buf.len;
1084
1085         /* Check that the softirq receive buffer is valid */
1086         WARN_ON(memcmp(&req->rq_rcv_buf, &req->rq_private_buf,
1087                                 sizeof(req->rq_rcv_buf)) != 0);
1088
1089         /* Verify the RPC header */
1090         p = call_verify(task);
1091         if (IS_ERR(p)) {
1092                 if (p == ERR_PTR(-EAGAIN))
1093                         goto out_retry;
1094                 return;
1095         }
1096
1097         task->tk_action = rpc_exit_task;
1098
1099         if (decode)
1100                 task->tk_status = rpcauth_unwrap_resp(task, decode, req, p,
1101                                                       task->tk_msg.rpc_resp);
1102         dprintk("RPC: %4d call_decode result %d\n", task->tk_pid,
1103                                         task->tk_status);
1104         return;
1105 out_retry:
1106         req->rq_received = req->rq_private_buf.len = 0;
1107         task->tk_status = 0;
1108 }
1109
1110 /*
1111  * 8.   Refresh the credentials if rejected by the server
1112  */
1113 static void
1114 call_refresh(struct rpc_task *task)
1115 {
1116         dprintk("RPC: %4d call_refresh\n", task->tk_pid);
1117
1118         xprt_release(task);     /* Must do to obtain new XID */
1119         task->tk_action = call_refreshresult;
1120         task->tk_status = 0;
1121         task->tk_client->cl_stats->rpcauthrefresh++;
1122         rpcauth_refreshcred(task);
1123 }
1124
1125 /*
1126  * 8a.  Process the results of a credential refresh
1127  */
1128 static void
1129 call_refreshresult(struct rpc_task *task)
1130 {
1131         int status = task->tk_status;
1132         dprintk("RPC: %4d call_refreshresult (status %d)\n",
1133                                 task->tk_pid, task->tk_status);
1134
1135         task->tk_status = 0;
1136         task->tk_action = call_reserve;
1137         if (status >= 0 && rpcauth_uptodatecred(task))
1138                 return;
1139         if (status == -EACCES) {
1140                 rpc_exit(task, -EACCES);
1141                 return;
1142         }
1143         task->tk_action = call_refresh;
1144         if (status != -ETIMEDOUT)
1145                 rpc_delay(task, 3*HZ);
1146         return;
1147 }
1148
1149 /*
1150  * Call header serialization
1151  */
1152 static u32 *
1153 call_header(struct rpc_task *task)
1154 {
1155         struct rpc_clnt *clnt = task->tk_client;
1156         struct rpc_rqst *req = task->tk_rqstp;
1157         u32             *p = req->rq_svec[0].iov_base;
1158
1159         /* FIXME: check buffer size? */
1160
1161         p = xprt_skip_transport_header(task->tk_xprt, p);
1162         *p++ = req->rq_xid;             /* XID */
1163         *p++ = htonl(RPC_CALL);         /* CALL */
1164         *p++ = htonl(RPC_VERSION);      /* RPC version */
1165         *p++ = htonl(clnt->cl_prog);    /* program number */
1166         *p++ = htonl(clnt->cl_vers);    /* program version */
1167         *p++ = htonl(task->tk_msg.rpc_proc->p_proc);    /* procedure */
1168         p = rpcauth_marshcred(task, p);
1169         req->rq_slen = xdr_adjust_iovec(&req->rq_svec[0], p);
1170         return p;
1171 }
1172
1173 /*
1174  * Reply header verification
1175  */
1176 static u32 *
1177 call_verify(struct rpc_task *task)
1178 {
1179         struct kvec *iov = &task->tk_rqstp->rq_rcv_buf.head[0];
1180         int len = task->tk_rqstp->rq_rcv_buf.len >> 2;
1181         u32     *p = iov->iov_base, n;
1182         int error = -EACCES;
1183
1184         if ((task->tk_rqstp->rq_rcv_buf.len & 3) != 0) {
1185                 /* RFC-1014 says that the representation of XDR data must be a
1186                  * multiple of four bytes
1187                  * - if it isn't pointer subtraction in the NFS client may give
1188                  *   undefined results
1189                  */
1190                 printk(KERN_WARNING
1191                        "call_verify: XDR representation not a multiple of"
1192                        " 4 bytes: 0x%x\n", task->tk_rqstp->rq_rcv_buf.len);
1193                 goto out_eio;
1194         }
1195         if ((len -= 3) < 0)
1196                 goto out_overflow;
1197         p += 1; /* skip XID */
1198
1199         if ((n = ntohl(*p++)) != RPC_REPLY) {
1200                 printk(KERN_WARNING "call_verify: not an RPC reply: %x\n", n);
1201                 goto out_garbage;
1202         }
1203         if ((n = ntohl(*p++)) != RPC_MSG_ACCEPTED) {
1204                 if (--len < 0)
1205                         goto out_overflow;
1206                 switch ((n = ntohl(*p++))) {
1207                         case RPC_AUTH_ERROR:
1208                                 break;
1209                         case RPC_MISMATCH:
1210                                 dprintk("%s: RPC call version mismatch!\n", __FUNCTION__);
1211                                 error = -EPROTONOSUPPORT;
1212                                 goto out_err;
1213                         default:
1214                                 dprintk("%s: RPC call rejected, unknown error: %x\n", __FUNCTION__, n);
1215                                 goto out_eio;
1216                 }
1217                 if (--len < 0)
1218                         goto out_overflow;
1219                 switch ((n = ntohl(*p++))) {
1220                 case RPC_AUTH_REJECTEDCRED:
1221                 case RPC_AUTH_REJECTEDVERF:
1222                 case RPCSEC_GSS_CREDPROBLEM:
1223                 case RPCSEC_GSS_CTXPROBLEM:
1224                         if (!task->tk_cred_retry)
1225                                 break;
1226                         task->tk_cred_retry--;
1227                         dprintk("RPC: %4d call_verify: retry stale creds\n",
1228                                                         task->tk_pid);
1229                         rpcauth_invalcred(task);
1230                         task->tk_action = call_refresh;
1231                         goto out_retry;
1232                 case RPC_AUTH_BADCRED:
1233                 case RPC_AUTH_BADVERF:
1234                         /* possibly garbled cred/verf? */
1235                         if (!task->tk_garb_retry)
1236                                 break;
1237                         task->tk_garb_retry--;
1238                         dprintk("RPC: %4d call_verify: retry garbled creds\n",
1239                                                         task->tk_pid);
1240                         task->tk_action = call_bind;
1241                         goto out_retry;
1242                 case RPC_AUTH_TOOWEAK:
1243                         printk(KERN_NOTICE "call_verify: server %s requires stronger "
1244                                "authentication.\n", task->tk_client->cl_server);
1245                         break;
1246                 default:
1247                         printk(KERN_WARNING "call_verify: unknown auth error: %x\n", n);
1248                         error = -EIO;
1249                 }
1250                 dprintk("RPC: %4d call_verify: call rejected %d\n",
1251                                                 task->tk_pid, n);
1252                 goto out_err;
1253         }
1254         if (!(p = rpcauth_checkverf(task, p))) {
1255                 printk(KERN_WARNING "call_verify: auth check failed\n");
1256                 goto out_garbage;               /* bad verifier, retry */
1257         }
1258         len = p - (u32 *)iov->iov_base - 1;
1259         if (len < 0)
1260                 goto out_overflow;
1261         switch ((n = ntohl(*p++))) {
1262         case RPC_SUCCESS:
1263                 return p;
1264         case RPC_PROG_UNAVAIL:
1265                 dprintk("RPC: call_verify: program %u is unsupported by server %s\n",
1266                                 (unsigned int)task->tk_client->cl_prog,
1267                                 task->tk_client->cl_server);
1268                 error = -EPFNOSUPPORT;
1269                 goto out_err;
1270         case RPC_PROG_MISMATCH:
1271                 dprintk("RPC: call_verify: program %u, version %u unsupported by server %s\n",
1272                                 (unsigned int)task->tk_client->cl_prog,
1273                                 (unsigned int)task->tk_client->cl_vers,
1274                                 task->tk_client->cl_server);
1275                 error = -EPROTONOSUPPORT;
1276                 goto out_err;
1277         case RPC_PROC_UNAVAIL:
1278                 dprintk("RPC: call_verify: proc %p unsupported by program %u, version %u on server %s\n",
1279                                 task->tk_msg.rpc_proc,
1280                                 task->tk_client->cl_prog,
1281                                 task->tk_client->cl_vers,
1282                                 task->tk_client->cl_server);
1283                 error = -EOPNOTSUPP;
1284                 goto out_err;
1285         case RPC_GARBAGE_ARGS:
1286                 dprintk("RPC: %4d %s: server saw garbage\n", task->tk_pid, __FUNCTION__);
1287                 break;                  /* retry */
1288         default:
1289                 printk(KERN_WARNING "call_verify: server accept status: %x\n", n);
1290                 /* Also retry */
1291         }
1292
1293 out_garbage:
1294         task->tk_client->cl_stats->rpcgarbage++;
1295         if (task->tk_garb_retry) {
1296                 task->tk_garb_retry--;
1297                 dprintk("RPC %s: retrying %4d\n", __FUNCTION__, task->tk_pid);
1298                 task->tk_action = call_bind;
1299 out_retry:
1300                 return ERR_PTR(-EAGAIN);
1301         }
1302         printk(KERN_WARNING "RPC %s: retry failed, exit EIO\n", __FUNCTION__);
1303 out_eio:
1304         error = -EIO;
1305 out_err:
1306         rpc_exit(task, error);
1307         return ERR_PTR(error);
1308 out_overflow:
1309         printk(KERN_WARNING "RPC %s: server reply was truncated.\n", __FUNCTION__);
1310         goto out_garbage;
1311 }
1312
1313 static int rpcproc_encode_null(void *rqstp, u32 *data, void *obj)
1314 {
1315         return 0;
1316 }
1317
1318 static int rpcproc_decode_null(void *rqstp, u32 *data, void *obj)
1319 {
1320         return 0;
1321 }
1322
1323 static struct rpc_procinfo rpcproc_null = {
1324         .p_encode = rpcproc_encode_null,
1325         .p_decode = rpcproc_decode_null,
1326 };
1327
1328 int rpc_ping(struct rpc_clnt *clnt, int flags)
1329 {
1330         struct rpc_message msg = {
1331                 .rpc_proc = &rpcproc_null,
1332         };
1333         int err;
1334         msg.rpc_cred = authnull_ops.lookup_cred(NULL, NULL, 0);
1335         err = rpc_call_sync(clnt, &msg, flags);
1336         put_rpccred(msg.rpc_cred);
1337         return err;
1338 }