fs/9p/mux.c

   1 /*
   2  * linux/fs/9p/mux.c
   3  *
   4  * Protocol Multiplexer
   5  *
   6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #include <linux/config.h>
  27 #include <linux/module.h>
  28 #include <linux/errno.h>
  29 #include <linux/fs.h>
  30 #include <linux/poll.h>
  31 #include <linux/kthread.h>
  32 #include <linux/idr.h>
  33 #include <linux/mutex.h>
  34
  35 #include "debug.h"
  36 #include "v9fs.h"
  37 #include "9p.h"
  38 #include "conv.h"
  39 #include "transport.h"
  40 #include "mux.h"
  41
  42 #define ERREQFLUSH      1
  43 #define SCHED_TIMEOUT   10
  44 #define MAXPOLLWADDR    2
  45
  46 enum {
  47         Rworksched = 1,         /* read work scheduled or running */
  48         Rpending = 2,           /* can read */
  49         Wworksched = 4,         /* write work scheduled or running */
  50         Wpending = 8,           /* can write */
  51 };
  52
  53 struct v9fs_mux_poll_task;
  54
  55 struct v9fs_req {
  56         int tag;
  57         struct v9fs_fcall *tcall;
  58         struct v9fs_fcall *rcall;
  59         int err;
  60         v9fs_mux_req_callback cb;
  61         void *cba;
  62         struct list_head req_list;
  63 };
  64
  65 struct v9fs_mux_data {
  66         spinlock_t lock;
  67         struct list_head mux_list;
  68         struct v9fs_mux_poll_task *poll_task;
  69         int msize;
  70         unsigned char *extended;
  71         struct v9fs_transport *trans;
  72         struct v9fs_idpool tagpool;
  73         int err;
  74         wait_queue_head_t equeue;
  75         struct list_head req_list;
  76         struct list_head unsent_req_list;
  77         struct v9fs_fcall *rcall;
  78         int rpos;
  79         char *rbuf;
  80         int wpos;
  81         int wsize;
  82         char *wbuf;
  83         wait_queue_t poll_wait[MAXPOLLWADDR];
  84         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  85         poll_table pt;
  86         struct work_struct rq;
  87         struct work_struct wq;
  88         unsigned long wsched;
  89 };
  90
  91 struct v9fs_mux_poll_task {
  92         struct task_struct *task;
  93         struct list_head mux_list;
  94         int muxnum;
  95 };
  96
  97 struct v9fs_mux_rpc {
  98         struct v9fs_mux_data *m;
  99         struct v9fs_req *req;
 100         int err;
 101         struct v9fs_fcall *rcall;
 102         wait_queue_head_t wqueue;
 103 };
 104
 105 static int v9fs_poll_proc(void *);
 106 static void v9fs_read_work(void *);
 107 static void v9fs_write_work(void *);
 108 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 109                           poll_table * p);
 110 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
 111 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
 112
 113 static DEFINE_MUTEX(v9fs_mux_task_lock);
 114 static struct workqueue_struct *v9fs_mux_wq;
 115
 116 static int v9fs_mux_num;
 117 static int v9fs_mux_poll_task_num;
 118 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
 119
 120 int v9fs_mux_global_init(void)
 121 {
 122         int i;
 123
 124         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
 125                 v9fs_mux_poll_tasks[i].task = NULL;
 126
 127         v9fs_mux_wq = create_workqueue("v9fs");
 128         if (!v9fs_mux_wq)
 129                 return -ENOMEM;
 130
 131         return 0;
 132 }
 133
 134 void v9fs_mux_global_exit(void)
 135 {
 136         destroy_workqueue(v9fs_mux_wq);
 137 }
 138
 139 /**
 140  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 141  * based on the number of mounted v9fs filesystems.
 142  *
 143  * The current implementation returns sqrt of the number of mounts.
 144  */
 145 static int v9fs_mux_calc_poll_procs(int muxnum)
 146 {
 147         int n;
 148
 149         if (v9fs_mux_poll_task_num)
 150                 n = muxnum / v9fs_mux_poll_task_num +
 151                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
 152         else
 153                 n = 1;
 154
 155         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
 156                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
 157
 158         return n;
 159 }
 160
 161 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
 162 {
 163         int i, n;
 164         struct v9fs_mux_poll_task *vpt, *vptlast;
 165         struct task_struct *pproc;
 166
 167         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
 168                 v9fs_mux_poll_task_num);
 169         mutex_lock(&v9fs_mux_task_lock);
 170
 171         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
 172         if (n > v9fs_mux_poll_task_num) {
 173                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 174                         if (v9fs_mux_poll_tasks[i].task == NULL) {
 175                                 vpt = &v9fs_mux_poll_tasks[i];
 176                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
 177                                 pproc = kthread_create(v9fs_poll_proc, vpt,
 178                                                    "v9fs-poll");
 179
 180                                 if (!IS_ERR(pproc)) {
 181                                         vpt->task = pproc;
 182                                         INIT_LIST_HEAD(&vpt->mux_list);
 183                                         vpt->muxnum = 0;
 184                                         v9fs_mux_poll_task_num++;
 185                                         wake_up_process(vpt->task);
 186                                 }
 187                                 break;
 188                         }
 189                 }
 190
 191                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
 192                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
 193         }
 194
 195         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
 196             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
 197
 198         vptlast = NULL;
 199         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 200                 vpt = &v9fs_mux_poll_tasks[i];
 201                 if (vpt->task != NULL) {
 202                         vptlast = vpt;
 203                         if (vpt->muxnum < n) {
 204                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 205                                 list_add(&m->mux_list, &vpt->mux_list);
 206                                 vpt->muxnum++;
 207                                 m->poll_task = vpt;
 208                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 209                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 210                                 break;
 211                         }
 212                 }
 213         }
 214
 215         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
 216                 if (vptlast == NULL)
 217                         return -ENOMEM;
 218
 219                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 220                 list_add(&m->mux_list, &vptlast->mux_list);
 221                 vptlast->muxnum++;
 222                 m->poll_task = vptlast;
 223                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 224                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 225         }
 226
 227         v9fs_mux_num++;
 228         mutex_unlock(&v9fs_mux_task_lock);
 229
 230         return 0;
 231 }
 232
 233 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
 234 {
 235         int i;
 236         struct v9fs_mux_poll_task *vpt;
 237
 238         mutex_lock(&v9fs_mux_task_lock);
 239         vpt = m->poll_task;
 240         list_del(&m->mux_list);
 241         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 242                 if (m->poll_waddr[i] != NULL) {
 243                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 244                         m->poll_waddr[i] = NULL;
 245                 }
 246         }
 247         vpt->muxnum--;
 248         if (!vpt->muxnum) {
 249                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
 250                 send_sig(SIGKILL, vpt->task, 1);
 251                 vpt->task = NULL;
 252                 v9fs_mux_poll_task_num--;
 253         }
 254         v9fs_mux_num--;
 255         mutex_unlock(&v9fs_mux_task_lock);
 256 }
 257
 258 /**
 259  * v9fs_mux_init - allocate and initialize the per-session mux data
 260  * Creates the polling task if this is the first session.
 261  *
 262  * @trans - transport structure
 263  * @msize - maximum message size
 264  * @extended - pointer to the extended flag
 265  */
 266 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
 267                                     unsigned char *extended)
 268 {
 269         int i, n;
 270         struct v9fs_mux_data *m, *mtmp;
 271
 272         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 273         m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
 274         if (!m)
 275                 return ERR_PTR(-ENOMEM);
 276
 277         spin_lock_init(&m->lock);
 278         INIT_LIST_HEAD(&m->mux_list);
 279         m->msize = msize;
 280         m->extended = extended;
 281         m->trans = trans;
 282         idr_init(&m->tagpool.pool);
 283         init_MUTEX(&m->tagpool.lock);
 284         m->err = 0;
 285         init_waitqueue_head(&m->equeue);
 286         INIT_LIST_HEAD(&m->req_list);
 287         INIT_LIST_HEAD(&m->unsent_req_list);
 288         m->rcall = NULL;
 289         m->rpos = 0;
 290         m->rbuf = NULL;
 291         m->wpos = m->wsize = 0;
 292         m->wbuf = NULL;
 293         INIT_WORK(&m->rq, v9fs_read_work, m);
 294         INIT_WORK(&m->wq, v9fs_write_work, m);
 295         m->wsched = 0;
 296         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 297         m->poll_task = NULL;
 298         n = v9fs_mux_poll_start(m);
 299         if (n)
 300                 return ERR_PTR(n);
 301
 302         n = trans->poll(trans, &m->pt);
 303         if (n & POLLIN) {
 304                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 305                 set_bit(Rpending, &m->wsched);
 306         }
 307
 308         if (n & POLLOUT) {
 309                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 310                 set_bit(Wpending, &m->wsched);
 311         }
 312
 313         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 314                 if (IS_ERR(m->poll_waddr[i])) {
 315                         v9fs_mux_poll_stop(m);
 316                         mtmp = (void *)m->poll_waddr;   /* the error code */
 317                         kfree(m);
 318                         m = mtmp;
 319                         break;
 320                 }
 321         }
 322
 323         return m;
 324 }
 325
 326 /**
 327  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
 328  */
 329 void v9fs_mux_destroy(struct v9fs_mux_data *m)
 330 {
 331         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
 332                 m->mux_list.prev, m->mux_list.next);
 333         v9fs_mux_cancel(m, -ECONNRESET);
 334
 335         if (!list_empty(&m->req_list)) {
 336                 /* wait until all processes waiting on this session exit */
 337                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
 338                         m);
 339                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 340                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 341                         list_empty(&m->req_list));
 342         }
 343
 344         v9fs_mux_poll_stop(m);
 345         m->trans = NULL;
 346
 347         kfree(m);
 348 }
 349
 350 /**
 351  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
 352  *      to files wait queue
 353  */
 354 static void
 355 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 356               poll_table * p)
 357 {
 358         int i;
 359         struct v9fs_mux_data *m;
 360
 361         m = container_of(p, struct v9fs_mux_data, pt);
 362         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 363                 if (m->poll_waddr[i] == NULL)
 364                         break;
 365
 366         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 367                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
 368                 return;
 369         }
 370
 371         m->poll_waddr[i] = wait_address;
 372
 373         if (!wait_address) {
 374                 dprintk(DEBUG_ERROR, "no wait_address\n");
 375                 m->poll_waddr[i] = ERR_PTR(-EIO);
 376                 return;
 377         }
 378
 379         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 380         add_wait_queue(wait_address, &m->poll_wait[i]);
 381 }
 382
 383 /**
 384  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
 385  */
 386 static void v9fs_poll_mux(struct v9fs_mux_data *m)
 387 {
 388         int n;
 389
 390         if (m->err < 0)
 391                 return;
 392
 393         n = m->trans->poll(m->trans, NULL);
 394         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 395                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
 396                 if (n >= 0)
 397                         n = -ECONNRESET;
 398                 v9fs_mux_cancel(m, n);
 399         }
 400
 401         if (n & POLLIN) {
 402                 set_bit(Rpending, &m->wsched);
 403                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 404                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 405                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 406                         queue_work(v9fs_mux_wq, &m->rq);
 407                 }
 408         }
 409
 410         if (n & POLLOUT) {
 411                 set_bit(Wpending, &m->wsched);
 412                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 413                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 414                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 415                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 416                         queue_work(v9fs_mux_wq, &m->wq);
 417                 }
 418         }
 419 }
 420
 421 /**
 422  * v9fs_poll_proc - polls all v9fs transports for new events and queues
 423  *      the appropriate work to the work queue
 424  */
 425 static int v9fs_poll_proc(void *a)
 426 {
 427         struct v9fs_mux_data *m, *mtmp;
 428         struct v9fs_mux_poll_task *vpt;
 429
 430         vpt = a;
 431         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
 432         allow_signal(SIGKILL);
 433         while (!kthread_should_stop()) {
 434                 set_current_state(TASK_INTERRUPTIBLE);
 435                 if (signal_pending(current))
 436                         break;
 437
 438                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 439                         v9fs_poll_mux(m);
 440                 }
 441
 442                 dprintk(DEBUG_MUX, "sleeping...\n");
 443                 schedule_timeout(SCHED_TIMEOUT * HZ);
 444         }
 445
 446         __set_current_state(TASK_RUNNING);
 447         dprintk(DEBUG_MUX, "finish\n");
 448         return 0;
 449 }
 450
 451 /**
 452  * v9fs_write_work - called when a transport can send some data
 453  */
 454 static void v9fs_write_work(void *a)
 455 {
 456         int n, err;
 457         struct v9fs_mux_data *m;
 458         struct v9fs_req *req;
 459
 460         m = a;
 461
 462         if (m->err < 0) {
 463                 clear_bit(Wworksched, &m->wsched);
 464                 return;
 465         }
 466
 467         if (!m->wsize) {
 468                 if (list_empty(&m->unsent_req_list)) {
 469                         clear_bit(Wworksched, &m->wsched);
 470                         return;
 471                 }
 472
 473                 spin_lock(&m->lock);
 474 again:
 475                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
 476                                req_list);
 477                 list_move_tail(&req->req_list, &m->req_list);
 478                 if (req->err == ERREQFLUSH)
 479                         goto again;
 480
 481                 m->wbuf = req->tcall->sdata;
 482                 m->wsize = req->tcall->size;
 483                 m->wpos = 0;
 484                 dump_data(m->wbuf, m->wsize);
 485                 spin_unlock(&m->lock);
 486         }
 487
 488         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 489         clear_bit(Wpending, &m->wsched);
 490         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 491         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 492         if (err == -EAGAIN) {
 493                 clear_bit(Wworksched, &m->wsched);
 494                 return;
 495         }
 496
 497         if (err <= 0)
 498                 goto error;
 499
 500         m->wpos += err;
 501         if (m->wpos == m->wsize)
 502                 m->wpos = m->wsize = 0;
 503
 504         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 505                 if (test_and_clear_bit(Wpending, &m->wsched))
 506                         n = POLLOUT;
 507                 else
 508                         n = m->trans->poll(m->trans, NULL);
 509
 510                 if (n & POLLOUT) {
 511                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 512                         queue_work(v9fs_mux_wq, &m->wq);
 513                 } else
 514                         clear_bit(Wworksched, &m->wsched);
 515         } else
 516                 clear_bit(Wworksched, &m->wsched);
 517
 518         return;
 519
 520       error:
 521         v9fs_mux_cancel(m, err);
 522         clear_bit(Wworksched, &m->wsched);
 523 }
 524
 525 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 526 {
 527         int ecode, tag;
 528         struct v9fs_str *ename;
 529
 530         tag = req->tag;
 531         if (!req->err && req->rcall->id == RERROR) {
 532                 ecode = req->rcall->params.rerror.errno;
 533                 ename = &req->rcall->params.rerror.error;
 534
 535                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 536
 537                 if (*m->extended)
 538                         req->err = -ecode;
 539
 540                 if (!req->err) {
 541                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 542
 543                         if (!req->err) {        /* string match failed */
 544                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 545                         }
 546
 547                         if (!req->err)
 548                                 req->err = -ESERVERFAULT;
 549                 }
 550         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 551                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 552                         req->tcall->id + 1, req->rcall->id);
 553                 if (!req->err)
 554                         req->err = -EIO;
 555         }
 556
 557         if (req->err == ERREQFLUSH)
 558                 return;
 559
 560         if (req->cb) {
 561                 dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
 562                         req->tcall, req->rcall);
 563
 564                 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 565                 req->cb = NULL;
 566         } else
 567                 kfree(req->rcall);
 568
 569         v9fs_mux_put_tag(m, tag);
 570
 571         wake_up(&m->equeue);
 572         kfree(req);
 573 }
 574
 575 /**
 576  * v9fs_read_work - called when there is some data to be read from a transport
 577  */
 578 static void v9fs_read_work(void *a)
 579 {
 580         int n, err;
 581         struct v9fs_mux_data *m;
 582         struct v9fs_req *req, *rptr, *rreq;
 583         struct v9fs_fcall *rcall;
 584         char *rbuf;
 585
 586         m = a;
 587
 588         if (m->err < 0)
 589                 return;
 590
 591         rcall = NULL;
 592         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 593
 594         if (!m->rcall) {
 595                 m->rcall =
 596                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 597                 if (!m->rcall) {
 598                         err = -ENOMEM;
 599                         goto error;
 600                 }
 601
 602                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 603                 m->rpos = 0;
 604         }
 605
 606         clear_bit(Rpending, &m->wsched);
 607         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 608         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 609         if (err == -EAGAIN) {
 610                 clear_bit(Rworksched, &m->wsched);
 611                 return;
 612         }
 613
 614         if (err <= 0)
 615                 goto error;
 616
 617         m->rpos += err;
 618         while (m->rpos > 4) {
 619                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 620                 if (n >= m->msize) {
 621                         dprintk(DEBUG_ERROR,
 622                                 "requested packet size too big: %d\n", n);
 623                         err = -EIO;
 624                         goto error;
 625                 }
 626
 627                 if (m->rpos < n)
 628                         break;
 629
 630                 dump_data(m->rbuf, n);
 631                 err =
 632                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 633                 if (err < 0) {
 634                         goto error;
 635                 }
 636
 637                 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 638                         char buf[150];
 639
 640                         v9fs_printfcall(buf, sizeof(buf), m->rcall,
 641                                 *m->extended);
 642                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 643                 }
 644
 645                 rcall = m->rcall;
 646                 rbuf = m->rbuf;
 647                 if (m->rpos > n) {
 648                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 649                                            GFP_KERNEL);
 650                         if (!m->rcall) {
 651                                 err = -ENOMEM;
 652                                 goto error;
 653                         }
 654
 655                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 656                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 657                         m->rpos -= n;
 658                 } else {
 659                         m->rcall = NULL;
 660                         m->rbuf = NULL;
 661                         m->rpos = 0;
 662                 }
 663
 664                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 665                         rcall->tag);
 666
 667                 req = NULL;
 668                 spin_lock(&m->lock);
 669                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 670                         if (rreq->tag == rcall->tag) {
 671                                 req = rreq;
 672                                 req->rcall = rcall;
 673                                 list_del(&req->req_list);
 674                                 spin_unlock(&m->lock);
 675                                 process_request(m, req);
 676                                 break;
 677                         }
 678
 679                 }
 680
 681                 if (!req) {
 682                         spin_unlock(&m->lock);
 683                         if (err >= 0 && rcall->id != RFLUSH)
 684                                 dprintk(DEBUG_ERROR,
 685                                         "unexpected response mux %p id %d tag %d\n",
 686                                         m, rcall->id, rcall->tag);
 687                         kfree(rcall);
 688                 }
 689         }
 690
 691         if (!list_empty(&m->req_list)) {
 692                 if (test_and_clear_bit(Rpending, &m->wsched))
 693                         n = POLLIN;
 694                 else
 695                         n = m->trans->poll(m->trans, NULL);
 696
 697                 if (n & POLLIN) {
 698                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 699                         queue_work(v9fs_mux_wq, &m->rq);
 700                 } else
 701                         clear_bit(Rworksched, &m->wsched);
 702         } else
 703                 clear_bit(Rworksched, &m->wsched);
 704
 705         return;
 706
 707       error:
 708         v9fs_mux_cancel(m, err);
 709         clear_bit(Rworksched, &m->wsched);
 710 }
 711
 712 /**
 713  * v9fs_send_request - send 9P request
 714  * The function can sleep until the request is scheduled for sending.
 715  * The function can be interrupted. Return from the function is not
 716  * a guarantee that the request is sent succesfully. Can return errors
 717  * that can be retrieved by PTR_ERR macros.
 718  *
 719  * @m: mux data
 720  * @tc: request to be sent
 721  * @cb: callback function to call when response is received
 722  * @cba: parameter to pass to the callback function
 723  */
 724 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 725                                           struct v9fs_fcall *tc,
 726                                           v9fs_mux_req_callback cb, void *cba)
 727 {
 728         int n;
 729         struct v9fs_req *req;
 730
 731         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 732                 tc, tc->id);
 733         if (m->err < 0)
 734                 return ERR_PTR(m->err);
 735
 736         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 737         if (!req)
 738                 return ERR_PTR(-ENOMEM);
 739
 740         if (tc->id == TVERSION)
 741                 n = V9FS_NOTAG;
 742         else
 743                 n = v9fs_mux_get_tag(m);
 744
 745         if (n < 0)
 746                 return ERR_PTR(-ENOMEM);
 747
 748         v9fs_set_tag(tc, n);
 749
 750         if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 751                 char buf[150];
 752
 753                 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
 754                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 755         }
 756
 757         req->tag = n;
 758         req->tcall = tc;
 759         req->rcall = NULL;
 760         req->err = 0;
 761         req->cb = cb;
 762         req->cba = cba;
 763
 764         spin_lock(&m->lock);
 765         list_add_tail(&req->req_list, &m->unsent_req_list);
 766         spin_unlock(&m->lock);
 767
 768         if (test_and_clear_bit(Wpending, &m->wsched))
 769                 n = POLLOUT;
 770         else
 771                 n = m->trans->poll(m->trans, NULL);
 772
 773         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 774                 queue_work(v9fs_mux_wq, &m->wq);
 775
 776         return req;
 777 }
 778
 779 static void v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc,
 780                               struct v9fs_fcall *rc, int err)
 781 {
 782         v9fs_mux_req_callback cb;
 783         int tag;
 784         struct v9fs_mux_data *m;
 785         struct v9fs_req *req, *rptr;
 786
 787         m = a;
 788         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
 789                 rc, err, tc->params.tflush.oldtag);
 790
 791         spin_lock(&m->lock);
 792         cb = NULL;
 793         tag = tc->params.tflush.oldtag;
 794         list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
 795                 if (req->tag == tag) {
 796                         list_del(&req->req_list);
 797                         if (req->cb) {
 798                                 cb = req->cb;
 799                                 req->cb = NULL;
 800                                 spin_unlock(&m->lock);
 801                                 (*cb) (req->cba, req->tcall, req->rcall,
 802                                        req->err);
 803                         }
 804                         kfree(req);
 805                         wake_up(&m->equeue);
 806                         break;
 807                 }
 808         }
 809
 810         if (!cb)
 811                 spin_unlock(&m->lock);
 812
 813         v9fs_mux_put_tag(m, tag);
 814         kfree(tc);
 815         kfree(rc);
 816 }
 817
 818 static void
 819 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 820 {
 821         struct v9fs_fcall *fc;
 822
 823         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 824
 825         fc = v9fs_create_tflush(req->tag);
 826         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 827 }
 828
 829 static void
 830 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
 831 {
 832         struct v9fs_mux_rpc *r;
 833
 834         if (err == ERREQFLUSH) {
 835                 kfree(rc);
 836                 dprintk(DEBUG_MUX, "err req flush\n");
 837                 return;
 838         }
 839
 840         r = a;
 841         dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
 842                 tc, rc, err);
 843         r->rcall = rc;
 844         r->err = err;
 845         wake_up(&r->wqueue);
 846 }
 847
 848 /**
 849  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 850  *      The function can be interrupted.
 851  * @m: mux data
 852  * @tc: request to be sent
 853  * @rc: pointer where a pointer to the response is stored
 854  */
 855 int
 856 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 857              struct v9fs_fcall **rc)
 858 {
 859         int err;
 860         unsigned long flags;
 861         struct v9fs_req *req;
 862         struct v9fs_mux_rpc r;
 863
 864         r.err = 0;
 865         r.rcall = NULL;
 866         r.m = m;
 867         init_waitqueue_head(&r.wqueue);
 868
 869         if (rc)
 870                 *rc = NULL;
 871
 872         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 873         if (IS_ERR(req)) {
 874                 err = PTR_ERR(req);
 875                 dprintk(DEBUG_MUX, "error %d\n", err);
 876                 return PTR_ERR(req);
 877         }
 878
 879         r.req = req;
 880         dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
 881                 req->tag, &r, req);
 882         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 883         if (r.err < 0)
 884                 err = r.err;
 885
 886         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 887                 spin_lock(&m->lock);
 888                 req->tcall = NULL;
 889                 req->err = ERREQFLUSH;
 890                 spin_unlock(&m->lock);
 891
 892                 clear_thread_flag(TIF_SIGPENDING);
 893                 v9fs_mux_flush_request(m, req);
 894                 spin_lock_irqsave(&current->sighand->siglock, flags);
 895                 recalc_sigpending();
 896                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 897         }
 898
 899         if (!err) {
 900                 if (r.rcall)
 901                         dprintk(DEBUG_MUX, "got response id %d tag %d\n",
 902                                 r.rcall->id, r.rcall->tag);
 903
 904                 if (rc)
 905                         *rc = r.rcall;
 906                 else
 907                         kfree(r.rcall);
 908         } else {
 909                 kfree(r.rcall);
 910                 dprintk(DEBUG_MUX, "got error %d\n", err);
 911                 if (err > 0)
 912                         err = -EIO;
 913         }
 914
 915         return err;
 916 }
 917
 918 #if 0
 919 /**
 920  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 921  * @m: mux data
 922  * @tc: request to be sent
 923  * @cb: callback function to be called when response arrives
 924  * @cba: value to pass to the callback function
 925  */
 926 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 927                    v9fs_mux_req_callback cb, void *a)
 928 {
 929         int err;
 930         struct v9fs_req *req;
 931
 932         req = v9fs_send_request(m, tc, cb, a);
 933         if (IS_ERR(req)) {
 934                 err = PTR_ERR(req);
 935                 dprintk(DEBUG_MUX, "error %d\n", err);
 936                 return PTR_ERR(req);
 937         }
 938
 939         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 940         return 0;
 941 }
 942 #endif  /*  0  */
 943
 944 /**
 945  * v9fs_mux_cancel - cancel all pending requests with error
 946  * @m: mux data
 947  * @err: error code
 948  */
 949 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 950 {
 951         struct v9fs_req *req, *rtmp;
 952         LIST_HEAD(cancel_list);
 953
 954         dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
 955         m->err = err;
 956         spin_lock(&m->lock);
 957         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 958                 list_move(&req->req_list, &cancel_list);
 959         }
 960         spin_unlock(&m->lock);
 961
 962         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
 963                 list_del(&req->req_list);
 964                 if (!req->err)
 965                         req->err = err;
 966
 967                 if (req->cb)
 968                         (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 969                 else
 970                         kfree(req->rcall);
 971
 972                 kfree(req);
 973         }
 974
 975         wake_up(&m->equeue);
 976 }
 977
 978 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
 979 {
 980         int tag;
 981
 982         tag = v9fs_get_idpool(&m->tagpool);
 983         if (tag < 0)
 984                 return V9FS_NOTAG;
 985         else
 986                 return (u16) tag;
 987 }
 988
 989 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
 990 {
 991         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
 992                 v9fs_put_idpool(tag, &m->tagpool);
 993 }