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 enum {
  54         None,
  55         Flushing,
  56         Flushed,
  57 };
  58
  59 struct v9fs_mux_poll_task;
  60
  61 struct v9fs_req {
  62         spinlock_t lock;
  63         int tag;
  64         struct v9fs_fcall *tcall;
  65         struct v9fs_fcall *rcall;
  66         int err;
  67         v9fs_mux_req_callback cb;
  68         void *cba;
  69         int flush;
  70         struct list_head req_list;
  71 };
  72
  73 struct v9fs_mux_data {
  74         spinlock_t lock;
  75         struct list_head mux_list;
  76         struct v9fs_mux_poll_task *poll_task;
  77         int msize;
  78         unsigned char *extended;
  79         struct v9fs_transport *trans;
  80         struct v9fs_idpool tagpool;
  81         int err;
  82         wait_queue_head_t equeue;
  83         struct list_head req_list;
  84         struct list_head unsent_req_list;
  85         struct v9fs_fcall *rcall;
  86         int rpos;
  87         char *rbuf;
  88         int wpos;
  89         int wsize;
  90         char *wbuf;
  91         wait_queue_t poll_wait[MAXPOLLWADDR];
  92         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  93         poll_table pt;
  94         struct work_struct rq;
  95         struct work_struct wq;
  96         unsigned long wsched;
  97 };
  98
  99 struct v9fs_mux_poll_task {
 100         struct task_struct *task;
 101         struct list_head mux_list;
 102         int muxnum;
 103 };
 104
 105 struct v9fs_mux_rpc {
 106         struct v9fs_mux_data *m;
 107         int err;
 108         struct v9fs_fcall *tcall;
 109         struct v9fs_fcall *rcall;
 110         wait_queue_head_t wqueue;
 111 };
 112
 113 static int v9fs_poll_proc(void *);
 114 static void v9fs_read_work(void *);
 115 static void v9fs_write_work(void *);
 116 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 117                           poll_table * p);
 118 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
 119 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
 120
 121 static DEFINE_MUTEX(v9fs_mux_task_lock);
 122 static struct workqueue_struct *v9fs_mux_wq;
 123
 124 static int v9fs_mux_num;
 125 static int v9fs_mux_poll_task_num;
 126 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
 127
 128 int v9fs_mux_global_init(void)
 129 {
 130         int i;
 131
 132         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
 133                 v9fs_mux_poll_tasks[i].task = NULL;
 134
 135         v9fs_mux_wq = create_workqueue("v9fs");
 136         if (!v9fs_mux_wq)
 137                 return -ENOMEM;
 138
 139         return 0;
 140 }
 141
 142 void v9fs_mux_global_exit(void)
 143 {
 144         destroy_workqueue(v9fs_mux_wq);
 145 }
 146
 147 /**
 148  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 149  * based on the number of mounted v9fs filesystems.
 150  *
 151  * The current implementation returns sqrt of the number of mounts.
 152  */
 153 static int v9fs_mux_calc_poll_procs(int muxnum)
 154 {
 155         int n;
 156
 157         if (v9fs_mux_poll_task_num)
 158                 n = muxnum / v9fs_mux_poll_task_num +
 159                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
 160         else
 161                 n = 1;
 162
 163         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
 164                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
 165
 166         return n;
 167 }
 168
 169 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
 170 {
 171         int i, n;
 172         struct v9fs_mux_poll_task *vpt, *vptlast;
 173         struct task_struct *pproc;
 174
 175         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
 176                 v9fs_mux_poll_task_num);
 177         mutex_lock(&v9fs_mux_task_lock);
 178
 179         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
 180         if (n > v9fs_mux_poll_task_num) {
 181                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 182                         if (v9fs_mux_poll_tasks[i].task == NULL) {
 183                                 vpt = &v9fs_mux_poll_tasks[i];
 184                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
 185                                 pproc = kthread_create(v9fs_poll_proc, vpt,
 186                                                    "v9fs-poll");
 187
 188                                 if (!IS_ERR(pproc)) {
 189                                         vpt->task = pproc;
 190                                         INIT_LIST_HEAD(&vpt->mux_list);
 191                                         vpt->muxnum = 0;
 192                                         v9fs_mux_poll_task_num++;
 193                                         wake_up_process(vpt->task);
 194                                 }
 195                                 break;
 196                         }
 197                 }
 198
 199                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
 200                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
 201         }
 202
 203         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
 204             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
 205
 206         vptlast = NULL;
 207         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 208                 vpt = &v9fs_mux_poll_tasks[i];
 209                 if (vpt->task != NULL) {
 210                         vptlast = vpt;
 211                         if (vpt->muxnum < n) {
 212                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 213                                 list_add(&m->mux_list, &vpt->mux_list);
 214                                 vpt->muxnum++;
 215                                 m->poll_task = vpt;
 216                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 217                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 218                                 break;
 219                         }
 220                 }
 221         }
 222
 223         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
 224                 if (vptlast == NULL)
 225                         return -ENOMEM;
 226
 227                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 228                 list_add(&m->mux_list, &vptlast->mux_list);
 229                 vptlast->muxnum++;
 230                 m->poll_task = vptlast;
 231                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 232                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 233         }
 234
 235         v9fs_mux_num++;
 236         mutex_unlock(&v9fs_mux_task_lock);
 237
 238         return 0;
 239 }
 240
 241 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
 242 {
 243         int i;
 244         struct v9fs_mux_poll_task *vpt;
 245
 246         mutex_lock(&v9fs_mux_task_lock);
 247         vpt = m->poll_task;
 248         list_del(&m->mux_list);
 249         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 250                 if (m->poll_waddr[i] != NULL) {
 251                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 252                         m->poll_waddr[i] = NULL;
 253                 }
 254         }
 255         vpt->muxnum--;
 256         if (!vpt->muxnum) {
 257                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
 258                 send_sig(SIGKILL, vpt->task, 1);
 259                 vpt->task = NULL;
 260                 v9fs_mux_poll_task_num--;
 261         }
 262         v9fs_mux_num--;
 263         mutex_unlock(&v9fs_mux_task_lock);
 264 }
 265
 266 /**
 267  * v9fs_mux_init - allocate and initialize the per-session mux data
 268  * Creates the polling task if this is the first session.
 269  *
 270  * @trans - transport structure
 271  * @msize - maximum message size
 272  * @extended - pointer to the extended flag
 273  */
 274 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
 275                                     unsigned char *extended)
 276 {
 277         int i, n;
 278         struct v9fs_mux_data *m, *mtmp;
 279
 280         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 281         m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
 282         if (!m)
 283                 return ERR_PTR(-ENOMEM);
 284
 285         spin_lock_init(&m->lock);
 286         INIT_LIST_HEAD(&m->mux_list);
 287         m->msize = msize;
 288         m->extended = extended;
 289         m->trans = trans;
 290         idr_init(&m->tagpool.pool);
 291         init_MUTEX(&m->tagpool.lock);
 292         m->err = 0;
 293         init_waitqueue_head(&m->equeue);
 294         INIT_LIST_HEAD(&m->req_list);
 295         INIT_LIST_HEAD(&m->unsent_req_list);
 296         m->rcall = NULL;
 297         m->rpos = 0;
 298         m->rbuf = NULL;
 299         m->wpos = m->wsize = 0;
 300         m->wbuf = NULL;
 301         INIT_WORK(&m->rq, v9fs_read_work, m);
 302         INIT_WORK(&m->wq, v9fs_write_work, m);
 303         m->wsched = 0;
 304         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 305         m->poll_task = NULL;
 306         n = v9fs_mux_poll_start(m);
 307         if (n)
 308                 return ERR_PTR(n);
 309
 310         n = trans->poll(trans, &m->pt);
 311         if (n & POLLIN) {
 312                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 313                 set_bit(Rpending, &m->wsched);
 314         }
 315
 316         if (n & POLLOUT) {
 317                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 318                 set_bit(Wpending, &m->wsched);
 319         }
 320
 321         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 322                 if (IS_ERR(m->poll_waddr[i])) {
 323                         v9fs_mux_poll_stop(m);
 324                         mtmp = (void *)m->poll_waddr;   /* the error code */
 325                         kfree(m);
 326                         m = mtmp;
 327                         break;
 328                 }
 329         }
 330
 331         return m;
 332 }
 333
 334 /**
 335  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
 336  */
 337 void v9fs_mux_destroy(struct v9fs_mux_data *m)
 338 {
 339         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
 340                 m->mux_list.prev, m->mux_list.next);
 341         v9fs_mux_cancel(m, -ECONNRESET);
 342
 343         if (!list_empty(&m->req_list)) {
 344                 /* wait until all processes waiting on this session exit */
 345                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
 346                         m);
 347                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 348                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 349                         list_empty(&m->req_list));
 350         }
 351
 352         v9fs_mux_poll_stop(m);
 353         m->trans = NULL;
 354
 355         kfree(m);
 356 }
 357
 358 /**
 359  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
 360  *      to files wait queue
 361  */
 362 static void
 363 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 364               poll_table * p)
 365 {
 366         int i;
 367         struct v9fs_mux_data *m;
 368
 369         m = container_of(p, struct v9fs_mux_data, pt);
 370         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 371                 if (m->poll_waddr[i] == NULL)
 372                         break;
 373
 374         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 375                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
 376                 return;
 377         }
 378
 379         m->poll_waddr[i] = wait_address;
 380
 381         if (!wait_address) {
 382                 dprintk(DEBUG_ERROR, "no wait_address\n");
 383                 m->poll_waddr[i] = ERR_PTR(-EIO);
 384                 return;
 385         }
 386
 387         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 388         add_wait_queue(wait_address, &m->poll_wait[i]);
 389 }
 390
 391 /**
 392  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
 393  */
 394 static void v9fs_poll_mux(struct v9fs_mux_data *m)
 395 {
 396         int n;
 397
 398         if (m->err < 0)
 399                 return;
 400
 401         n = m->trans->poll(m->trans, NULL);
 402         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 403                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
 404                 if (n >= 0)
 405                         n = -ECONNRESET;
 406                 v9fs_mux_cancel(m, n);
 407         }
 408
 409         if (n & POLLIN) {
 410                 set_bit(Rpending, &m->wsched);
 411                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 412                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 413                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 414                         queue_work(v9fs_mux_wq, &m->rq);
 415                 }
 416         }
 417
 418         if (n & POLLOUT) {
 419                 set_bit(Wpending, &m->wsched);
 420                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 421                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 422                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 423                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 424                         queue_work(v9fs_mux_wq, &m->wq);
 425                 }
 426         }
 427 }
 428
 429 /**
 430  * v9fs_poll_proc - polls all v9fs transports for new events and queues
 431  *      the appropriate work to the work queue
 432  */
 433 static int v9fs_poll_proc(void *a)
 434 {
 435         struct v9fs_mux_data *m, *mtmp;
 436         struct v9fs_mux_poll_task *vpt;
 437
 438         vpt = a;
 439         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
 440         allow_signal(SIGKILL);
 441         while (!kthread_should_stop()) {
 442                 set_current_state(TASK_INTERRUPTIBLE);
 443                 if (signal_pending(current))
 444                         break;
 445
 446                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 447                         v9fs_poll_mux(m);
 448                 }
 449
 450                 dprintk(DEBUG_MUX, "sleeping...\n");
 451                 schedule_timeout(SCHED_TIMEOUT * HZ);
 452         }
 453
 454         __set_current_state(TASK_RUNNING);
 455         dprintk(DEBUG_MUX, "finish\n");
 456         return 0;
 457 }
 458
 459 /**
 460  * v9fs_write_work - called when a transport can send some data
 461  */
 462 static void v9fs_write_work(void *a)
 463 {
 464         int n, err;
 465         struct v9fs_mux_data *m;
 466         struct v9fs_req *req;
 467
 468         m = a;
 469
 470         if (m->err < 0) {
 471                 clear_bit(Wworksched, &m->wsched);
 472                 return;
 473         }
 474
 475         if (!m->wsize) {
 476                 if (list_empty(&m->unsent_req_list)) {
 477                         clear_bit(Wworksched, &m->wsched);
 478                         return;
 479                 }
 480
 481                 spin_lock(&m->lock);
 482 again:
 483                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
 484                                req_list);
 485                 list_move_tail(&req->req_list, &m->req_list);
 486                 if (req->err == ERREQFLUSH)
 487                         goto again;
 488
 489                 m->wbuf = req->tcall->sdata;
 490                 m->wsize = req->tcall->size;
 491                 m->wpos = 0;
 492                 dump_data(m->wbuf, m->wsize);
 493                 spin_unlock(&m->lock);
 494         }
 495
 496         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 497         clear_bit(Wpending, &m->wsched);
 498         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 499         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 500         if (err == -EAGAIN) {
 501                 clear_bit(Wworksched, &m->wsched);
 502                 return;
 503         }
 504
 505         if (err <= 0)
 506                 goto error;
 507
 508         m->wpos += err;
 509         if (m->wpos == m->wsize)
 510                 m->wpos = m->wsize = 0;
 511
 512         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 513                 if (test_and_clear_bit(Wpending, &m->wsched))
 514                         n = POLLOUT;
 515                 else
 516                         n = m->trans->poll(m->trans, NULL);
 517
 518                 if (n & POLLOUT) {
 519                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 520                         queue_work(v9fs_mux_wq, &m->wq);
 521                 } else
 522                         clear_bit(Wworksched, &m->wsched);
 523         } else
 524                 clear_bit(Wworksched, &m->wsched);
 525
 526         return;
 527
 528       error:
 529         v9fs_mux_cancel(m, err);
 530         clear_bit(Wworksched, &m->wsched);
 531 }
 532
 533 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 534 {
 535         int ecode;
 536         struct v9fs_str *ename;
 537
 538         if (!req->err && req->rcall->id == RERROR) {
 539                 ecode = req->rcall->params.rerror.errno;
 540                 ename = &req->rcall->params.rerror.error;
 541
 542                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 543
 544                 if (*m->extended)
 545                         req->err = -ecode;
 546
 547                 if (!req->err) {
 548                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 549
 550                         if (!req->err) {        /* string match failed */
 551                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 552                         }
 553
 554                         if (!req->err)
 555                                 req->err = -ESERVERFAULT;
 556                 }
 557         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 558                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 559                         req->tcall->id + 1, req->rcall->id);
 560                 if (!req->err)
 561                         req->err = -EIO;
 562         }
 563 }
 564
 565 /**
 566  * v9fs_read_work - called when there is some data to be read from a transport
 567  */
 568 static void v9fs_read_work(void *a)
 569 {
 570         int n, err;
 571         struct v9fs_mux_data *m;
 572         struct v9fs_req *req, *rptr, *rreq;
 573         struct v9fs_fcall *rcall;
 574         char *rbuf;
 575
 576         m = a;
 577
 578         if (m->err < 0)
 579                 return;
 580
 581         rcall = NULL;
 582         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 583
 584         if (!m->rcall) {
 585                 m->rcall =
 586                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 587                 if (!m->rcall) {
 588                         err = -ENOMEM;
 589                         goto error;
 590                 }
 591
 592                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 593                 m->rpos = 0;
 594         }
 595
 596         clear_bit(Rpending, &m->wsched);
 597         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 598         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 599         if (err == -EAGAIN) {
 600                 clear_bit(Rworksched, &m->wsched);
 601                 return;
 602         }
 603
 604         if (err <= 0)
 605                 goto error;
 606
 607         m->rpos += err;
 608         while (m->rpos > 4) {
 609                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 610                 if (n >= m->msize) {
 611                         dprintk(DEBUG_ERROR,
 612                                 "requested packet size too big: %d\n", n);
 613                         err = -EIO;
 614                         goto error;
 615                 }
 616
 617                 if (m->rpos < n)
 618                         break;
 619
 620                 dump_data(m->rbuf, n);
 621                 err =
 622                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 623                 if (err < 0) {
 624                         goto error;
 625                 }
 626
 627                 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 628                         char buf[150];
 629
 630                         v9fs_printfcall(buf, sizeof(buf), m->rcall,
 631                                 *m->extended);
 632                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 633                 }
 634
 635                 rcall = m->rcall;
 636                 rbuf = m->rbuf;
 637                 if (m->rpos > n) {
 638                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 639                                            GFP_KERNEL);
 640                         if (!m->rcall) {
 641                                 err = -ENOMEM;
 642                                 goto error;
 643                         }
 644
 645                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 646                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 647                         m->rpos -= n;
 648                 } else {
 649                         m->rcall = NULL;
 650                         m->rbuf = NULL;
 651                         m->rpos = 0;
 652                 }
 653
 654                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 655                         rcall->tag);
 656
 657                 req = NULL;
 658                 spin_lock(&m->lock);
 659                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 660                         if (rreq->tag == rcall->tag) {
 661                                 req = rreq;
 662                                 if (req->flush != Flushing)
 663                                         list_del(&req->req_list);
 664                                 break;
 665                         }
 666                 }
 667                 spin_unlock(&m->lock);
 668
 669                 if (req) {
 670                         req->rcall = rcall;
 671                         process_request(m, req);
 672
 673                         if (req->flush != Flushing) {
 674                                 if (req->cb)
 675                                         (*req->cb) (req, req->cba);
 676                                 else
 677                                         kfree(req->rcall);
 678
 679                                 wake_up(&m->equeue);
 680                         }
 681                 } else {
 682                         if (err >= 0 && rcall->id != RFLUSH)
 683                                 dprintk(DEBUG_ERROR,
 684                                         "unexpected response mux %p id %d tag %d\n",
 685                                         m, rcall->id, rcall->tag);
 686                         kfree(rcall);
 687                 }
 688         }
 689
 690         if (!list_empty(&m->req_list)) {
 691                 if (test_and_clear_bit(Rpending, &m->wsched))
 692                         n = POLLIN;
 693                 else
 694                         n = m->trans->poll(m->trans, NULL);
 695
 696                 if (n & POLLIN) {
 697                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 698                         queue_work(v9fs_mux_wq, &m->rq);
 699                 } else
 700                         clear_bit(Rworksched, &m->wsched);
 701         } else
 702                 clear_bit(Rworksched, &m->wsched);
 703
 704         return;
 705
 706       error:
 707         v9fs_mux_cancel(m, err);
 708         clear_bit(Rworksched, &m->wsched);
 709 }
 710
 711 /**
 712  * v9fs_send_request - send 9P request
 713  * The function can sleep until the request is scheduled for sending.
 714  * The function can be interrupted. Return from the function is not
 715  * a guarantee that the request is sent succesfully. Can return errors
 716  * that can be retrieved by PTR_ERR macros.
 717  *
 718  * @m: mux data
 719  * @tc: request to be sent
 720  * @cb: callback function to call when response is received
 721  * @cba: parameter to pass to the callback function
 722  */
 723 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 724                                           struct v9fs_fcall *tc,
 725                                           v9fs_mux_req_callback cb, void *cba)
 726 {
 727         int n;
 728         struct v9fs_req *req;
 729
 730         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 731                 tc, tc->id);
 732         if (m->err < 0)
 733                 return ERR_PTR(m->err);
 734
 735         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 736         if (!req)
 737                 return ERR_PTR(-ENOMEM);
 738
 739         if (tc->id == TVERSION)
 740                 n = V9FS_NOTAG;
 741         else
 742                 n = v9fs_mux_get_tag(m);
 743
 744         if (n < 0)
 745                 return ERR_PTR(-ENOMEM);
 746
 747         v9fs_set_tag(tc, n);
 748         if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 749                 char buf[150];
 750
 751                 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
 752                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 753         }
 754
 755         spin_lock_init(&req->lock);
 756         req->tag = n;
 757         req->tcall = tc;
 758         req->rcall = NULL;
 759         req->err = 0;
 760         req->cb = cb;
 761         req->cba = cba;
 762         req->flush = None;
 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_free_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 780 {
 781         v9fs_mux_put_tag(m, req->tag);
 782         kfree(req);
 783 }
 784
 785 static void v9fs_mux_flush_cb(struct v9fs_req *freq, void *a)
 786 {
 787         v9fs_mux_req_callback cb;
 788         int tag;
 789         struct v9fs_mux_data *m;
 790         struct v9fs_req *req, *rreq, *rptr;
 791
 792         m = a;
 793         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 794                 freq->tcall, freq->rcall, freq->err,
 795                 freq->tcall->params.tflush.oldtag);
 796
 797         spin_lock(&m->lock);
 798         cb = NULL;
 799         tag = freq->tcall->params.tflush.oldtag;
 800         req = NULL;
 801         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 802                 if (rreq->tag == tag) {
 803                         req = rreq;
 804                         list_del(&req->req_list);
 805                         break;
 806                 }
 807         }
 808         spin_unlock(&m->lock);
 809
 810         if (req) {
 811                 spin_lock(&req->lock);
 812                 req->flush = Flushed;
 813                 spin_unlock(&req->lock);
 814
 815                 if (req->cb)
 816                         (*req->cb) (req, req->cba);
 817                 else
 818                         kfree(req->rcall);
 819
 820                 wake_up(&m->equeue);
 821         }
 822
 823         kfree(freq->tcall);
 824         kfree(freq->rcall);
 825         v9fs_mux_free_request(m, freq);
 826 }
 827
 828 static int
 829 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 830 {
 831         struct v9fs_fcall *fc;
 832         struct v9fs_req *rreq, *rptr;
 833
 834         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 835
 836         /* if a response was received for a request, do nothing */
 837         spin_lock(&req->lock);
 838         if (req->rcall || req->err) {
 839                 spin_unlock(&req->lock);
 840                 dprintk(DEBUG_MUX, "mux %p req %p response already received\n", m, req);
 841                 return 0;
 842         }
 843
 844         req->flush = Flushing;
 845         spin_unlock(&req->lock);
 846
 847         spin_lock(&m->lock);
 848         /* if the request is not sent yet, just remove it from the list */
 849         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 850                 if (rreq->tag == req->tag) {
 851                         dprintk(DEBUG_MUX, "mux %p req %p request is not sent yet\n", m, req);
 852                         list_del(&rreq->req_list);
 853                         req->flush = Flushed;
 854                         spin_unlock(&m->lock);
 855                         if (req->cb)
 856                                 (*req->cb) (req, req->cba);
 857                         return 0;
 858                 }
 859         }
 860         spin_unlock(&m->lock);
 861
 862         clear_thread_flag(TIF_SIGPENDING);
 863         fc = v9fs_create_tflush(req->tag);
 864         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 865         return 1;
 866 }
 867
 868 static void
 869 v9fs_mux_rpc_cb(struct v9fs_req *req, void *a)
 870 {
 871         struct v9fs_mux_rpc *r;
 872
 873         dprintk(DEBUG_MUX, "req %p r %p\n", req, a);
 874         r = a;
 875         r->rcall = req->rcall;
 876         r->err = req->err;
 877
 878         if (req->flush!=None && !req->err)
 879                 r->err = -ERESTARTSYS;
 880
 881         wake_up(&r->wqueue);
 882 }
 883
 884 /**
 885  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 886  *      The function can be interrupted.
 887  * @m: mux data
 888  * @tc: request to be sent
 889  * @rc: pointer where a pointer to the response is stored
 890  */
 891 int
 892 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 893              struct v9fs_fcall **rc)
 894 {
 895         int err, sigpending;
 896         unsigned long flags;
 897         struct v9fs_req *req;
 898         struct v9fs_mux_rpc r;
 899
 900         r.err = 0;
 901         r.tcall = tc;
 902         r.rcall = NULL;
 903         r.m = m;
 904         init_waitqueue_head(&r.wqueue);
 905
 906         if (rc)
 907                 *rc = NULL;
 908
 909         sigpending = 0;
 910         if (signal_pending(current)) {
 911                 sigpending = 1;
 912                 clear_thread_flag(TIF_SIGPENDING);
 913         }
 914
 915         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 916         if (IS_ERR(req)) {
 917                 err = PTR_ERR(req);
 918                 dprintk(DEBUG_MUX, "error %d\n", err);
 919                 return err;
 920         }
 921
 922         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 923         if (r.err < 0)
 924                 err = r.err;
 925
 926         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 927                 if (v9fs_mux_flush_request(m, req)) {
 928                         /* wait until we get response of the flush message */
 929                         do {
 930                                 clear_thread_flag(TIF_SIGPENDING);
 931                                 err = wait_event_interruptible(r.wqueue,
 932                                         r.rcall || r.err);
 933                         } while (!r.rcall && !r.err && err==-ERESTARTSYS &&
 934                                 m->trans->status==Connected && !m->err);
 935                 }
 936                 sigpending = 1;
 937         }
 938
 939         if (sigpending) {
 940                 spin_lock_irqsave(&current->sighand->siglock, flags);
 941                 recalc_sigpending();
 942                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 943         }
 944
 945         if (rc)
 946                 *rc = r.rcall;
 947         else
 948                 kfree(r.rcall);
 949
 950         v9fs_mux_free_request(m, req);
 951         if (err > 0)
 952                 err = -EIO;
 953
 954         return err;
 955 }
 956
 957 #if 0
 958 /**
 959  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 960  * @m: mux data
 961  * @tc: request to be sent
 962  * @cb: callback function to be called when response arrives
 963  * @cba: value to pass to the callback function
 964  */
 965 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 966                    v9fs_mux_req_callback cb, void *a)
 967 {
 968         int err;
 969         struct v9fs_req *req;
 970
 971         req = v9fs_send_request(m, tc, cb, a);
 972         if (IS_ERR(req)) {
 973                 err = PTR_ERR(req);
 974                 dprintk(DEBUG_MUX, "error %d\n", err);
 975                 return PTR_ERR(req);
 976         }
 977
 978         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 979         return 0;
 980 }
 981 #endif  /*  0  */
 982
 983 /**
 984  * v9fs_mux_cancel - cancel all pending requests with error
 985  * @m: mux data
 986  * @err: error code
 987  */
 988 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 989 {
 990         struct v9fs_req *req, *rtmp;
 991         LIST_HEAD(cancel_list);
 992
 993         dprintk(DEBUG_ERROR, "mux %p err %d\n", m, err);
 994         m->err = err;
 995         spin_lock(&m->lock);
 996         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 997                 list_move(&req->req_list, &cancel_list);
 998         }
 999         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1000                 list_move(&req->req_list, &cancel_list);
1001         }
1002         spin_unlock(&m->lock);
1003
1004         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1005                 list_del(&req->req_list);
1006                 if (!req->err)
1007                         req->err = err;
1008
1009                 if (req->cb)
1010                         (*req->cb) (req, req->cba);
1011                 else
1012                         kfree(req->rcall);
1013         }
1014
1015         wake_up(&m->equeue);
1016 }
1017
1018 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
1019 {
1020         int tag;
1021
1022         tag = v9fs_get_idpool(&m->tagpool);
1023         if (tag < 0)
1024                 return V9FS_NOTAG;
1025         else
1026                 return (u16) tag;
1027 }
1028
1029 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
1030 {
1031         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
1032                 v9fs_put_idpool(tag, &m->tagpool);
1033 }