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