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   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 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 DECLARE_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 inline 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         up(&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         down(&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         up(&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         down(&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->tidpool.pool);
 283         init_MUTEX(&m->tidpool.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 inline 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                 req =
 475                     list_entry(m->unsent_req_list.next, struct v9fs_req,
 476                                req_list);
 477                 list_move_tail(&req->req_list, &m->req_list);
 478                 m->wbuf = req->tcall->sdata;
 479                 m->wsize = req->tcall->size;
 480                 m->wpos = 0;
 481                 dump_data(m->wbuf, m->wsize);
 482                 spin_unlock(&m->lock);
 483         }
 484
 485         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 486         clear_bit(Wpending, &m->wsched);
 487         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 488         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 489         if (err == -EAGAIN) {
 490                 clear_bit(Wworksched, &m->wsched);
 491                 return;
 492         }
 493
 494         if (err <= 0)
 495                 goto error;
 496
 497         m->wpos += err;
 498         if (m->wpos == m->wsize)
 499                 m->wpos = m->wsize = 0;
 500
 501         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 502                 if (test_and_clear_bit(Wpending, &m->wsched))
 503                         n = POLLOUT;
 504                 else
 505                         n = m->trans->poll(m->trans, NULL);
 506
 507                 if (n & POLLOUT) {
 508                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 509                         queue_work(v9fs_mux_wq, &m->wq);
 510                 } else
 511                         clear_bit(Wworksched, &m->wsched);
 512         } else
 513                 clear_bit(Wworksched, &m->wsched);
 514
 515         return;
 516
 517       error:
 518         v9fs_mux_cancel(m, err);
 519         clear_bit(Wworksched, &m->wsched);
 520 }
 521
 522 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 523 {
 524         int ecode, tag;
 525         struct v9fs_str *ename;
 526
 527         tag = req->tag;
 528         if (req->rcall->id == RERROR && !req->err) {
 529                 ecode = req->rcall->params.rerror.errno;
 530                 ename = &req->rcall->params.rerror.error;
 531
 532                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 533
 534                 if (*m->extended)
 535                         req->err = -ecode;
 536
 537                 if (!req->err) {
 538                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 539
 540                         if (!req->err) {        /* string match failed */
 541                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 542                         }
 543
 544                         if (!req->err)
 545                                 req->err = -ESERVERFAULT;
 546                 }
 547         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 548                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 549                         req->tcall->id + 1, req->rcall->id);
 550                 if (!req->err)
 551                         req->err = -EIO;
 552         }
 553
 554         if (req->cb && req->err != ERREQFLUSH) {
 555                 dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
 556                         req->tcall, req->rcall);
 557
 558                 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 559                 req->cb = NULL;
 560         } else
 561                 kfree(req->rcall);
 562
 563         v9fs_mux_put_tag(m, tag);
 564
 565         wake_up(&m->equeue);
 566         kfree(req);
 567 }
 568
 569 /**
 570  * v9fs_read_work - called when there is some data to be read from a transport
 571  */
 572 static void v9fs_read_work(void *a)
 573 {
 574         int n, err;
 575         struct v9fs_mux_data *m;
 576         struct v9fs_req *req, *rptr, *rreq;
 577         struct v9fs_fcall *rcall;
 578         char *rbuf;
 579
 580         m = a;
 581
 582         if (m->err < 0)
 583                 return;
 584
 585         rcall = NULL;
 586         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 587
 588         if (!m->rcall) {
 589                 m->rcall =
 590                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 591                 if (!m->rcall) {
 592                         err = -ENOMEM;
 593                         goto error;
 594                 }
 595
 596                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 597                 m->rpos = 0;
 598         }
 599
 600         clear_bit(Rpending, &m->wsched);
 601         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 602         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 603         if (err == -EAGAIN) {
 604                 clear_bit(Rworksched, &m->wsched);
 605                 return;
 606         }
 607
 608         if (err <= 0)
 609                 goto error;
 610
 611         m->rpos += err;
 612         while (m->rpos > 4) {
 613                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 614                 if (n >= m->msize) {
 615                         dprintk(DEBUG_ERROR,
 616                                 "requested packet size too big: %d\n", n);
 617                         err = -EIO;
 618                         goto error;
 619                 }
 620
 621                 if (m->rpos < n)
 622                         break;
 623
 624                 dump_data(m->rbuf, n);
 625                 err =
 626                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 627                 if (err < 0) {
 628                         goto error;
 629                 }
 630
 631                 rcall = m->rcall;
 632                 rbuf = m->rbuf;
 633                 if (m->rpos > n) {
 634                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 635                                            GFP_KERNEL);
 636                         if (!m->rcall) {
 637                                 err = -ENOMEM;
 638                                 goto error;
 639                         }
 640
 641                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 642                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 643                         m->rpos -= n;
 644                 } else {
 645                         m->rcall = NULL;
 646                         m->rbuf = NULL;
 647                         m->rpos = 0;
 648                 }
 649
 650                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 651                         rcall->tag);
 652
 653                 req = NULL;
 654                 spin_lock(&m->lock);
 655                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 656                         if (rreq->tag == rcall->tag) {
 657                                 req = rreq;
 658                                 req->rcall = rcall;
 659                                 list_del(&req->req_list);
 660                                 spin_unlock(&m->lock);
 661                                 process_request(m, req);
 662                                 break;
 663                         }
 664
 665                 }
 666
 667                 if (!req) {
 668                         spin_unlock(&m->lock);
 669                         if (err >= 0 && rcall->id != RFLUSH)
 670                                 dprintk(DEBUG_ERROR,
 671                                         "unexpected response mux %p id %d tag %d\n",
 672                                         m, rcall->id, rcall->tag);
 673                         kfree(rcall);
 674                 }
 675         }
 676
 677         if (!list_empty(&m->req_list)) {
 678                 if (test_and_clear_bit(Rpending, &m->wsched))
 679                         n = POLLIN;
 680                 else
 681                         n = m->trans->poll(m->trans, NULL);
 682
 683                 if (n & POLLIN) {
 684                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 685                         queue_work(v9fs_mux_wq, &m->rq);
 686                 } else
 687                         clear_bit(Rworksched, &m->wsched);
 688         } else
 689                 clear_bit(Rworksched, &m->wsched);
 690
 691         return;
 692
 693       error:
 694         v9fs_mux_cancel(m, err);
 695         clear_bit(Rworksched, &m->wsched);
 696 }
 697
 698 /**
 699  * v9fs_send_request - send 9P request
 700  * The function can sleep until the request is scheduled for sending.
 701  * The function can be interrupted. Return from the function is not
 702  * a guarantee that the request is sent succesfully. Can return errors
 703  * that can be retrieved by PTR_ERR macros.
 704  *
 705  * @m: mux data
 706  * @tc: request to be sent
 707  * @cb: callback function to call when response is received
 708  * @cba: parameter to pass to the callback function
 709  */
 710 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 711                                           struct v9fs_fcall *tc,
 712                                           v9fs_mux_req_callback cb, void *cba)
 713 {
 714         int n;
 715         struct v9fs_req *req;
 716
 717         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 718                 tc, tc->id);
 719         if (m->err < 0)
 720                 return ERR_PTR(m->err);
 721
 722         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 723         if (!req)
 724                 return ERR_PTR(-ENOMEM);
 725
 726         if (tc->id == TVERSION)
 727                 n = V9FS_NOTAG;
 728         else
 729                 n = v9fs_mux_get_tag(m);
 730
 731         if (n < 0)
 732                 return ERR_PTR(-ENOMEM);
 733
 734         v9fs_set_tag(tc, n);
 735
 736         req->tag = n;
 737         req->tcall = tc;
 738         req->rcall = NULL;
 739         req->err = 0;
 740         req->cb = cb;
 741         req->cba = cba;
 742
 743         spin_lock(&m->lock);
 744         list_add_tail(&req->req_list, &m->unsent_req_list);
 745         spin_unlock(&m->lock);
 746
 747         if (test_and_clear_bit(Wpending, &m->wsched))
 748                 n = POLLOUT;
 749         else
 750                 n = m->trans->poll(m->trans, NULL);
 751
 752         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 753                 queue_work(v9fs_mux_wq, &m->wq);
 754
 755         return req;
 756 }
 757
 758 static inline void
 759 v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc,
 760                   int err)
 761 {
 762         v9fs_mux_req_callback cb;
 763         int tag;
 764         struct v9fs_mux_data *m;
 765         struct v9fs_req *req, *rptr;
 766
 767         m = a;
 768         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
 769                 rc, err, tc->params.tflush.oldtag);
 770
 771         spin_lock(&m->lock);
 772         cb = NULL;
 773         tag = tc->params.tflush.oldtag;
 774         list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
 775                 if (req->tag == tag) {
 776                         list_del(&req->req_list);
 777                         if (req->cb) {
 778                                 cb = req->cb;
 779                                 req->cb = NULL;
 780                                 spin_unlock(&m->lock);
 781                                 (*cb) (req->cba, req->tcall, req->rcall,
 782                                        req->err);
 783                         }
 784                         kfree(req);
 785                         wake_up(&m->equeue);
 786                         break;
 787                 }
 788         }
 789
 790         if (!cb)
 791                 spin_unlock(&m->lock);
 792
 793         v9fs_mux_put_tag(m, tag);
 794         kfree(tc);
 795         kfree(rc);
 796 }
 797
 798 static void
 799 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 800 {
 801         struct v9fs_fcall *fc;
 802
 803         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 804
 805         fc = v9fs_create_tflush(req->tag);
 806         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 807 }
 808
 809 static void
 810 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
 811 {
 812         struct v9fs_mux_rpc *r;
 813
 814         if (err == ERREQFLUSH) {
 815                 dprintk(DEBUG_MUX, "err req flush\n");
 816                 return;
 817         }
 818
 819         r = a;
 820         dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
 821                 tc, rc, err);
 822         r->rcall = rc;
 823         r->err = err;
 824         wake_up(&r->wqueue);
 825 }
 826
 827 /**
 828  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 829  *      The function can be interrupted.
 830  * @m: mux data
 831  * @tc: request to be sent
 832  * @rc: pointer where a pointer to the response is stored
 833  */
 834 int
 835 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 836              struct v9fs_fcall **rc)
 837 {
 838         int err;
 839         unsigned long flags;
 840         struct v9fs_req *req;
 841         struct v9fs_mux_rpc r;
 842
 843         r.err = 0;
 844         r.rcall = NULL;
 845         r.m = m;
 846         init_waitqueue_head(&r.wqueue);
 847
 848         if (rc)
 849                 *rc = NULL;
 850
 851         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 852         if (IS_ERR(req)) {
 853                 err = PTR_ERR(req);
 854                 dprintk(DEBUG_MUX, "error %d\n", err);
 855                 return PTR_ERR(req);
 856         }
 857
 858         r.req = req;
 859         dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
 860                 req->tag, &r, req);
 861         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 862         if (r.err < 0)
 863                 err = r.err;
 864
 865         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 866                 spin_lock(&m->lock);
 867                 req->tcall = NULL;
 868                 req->err = ERREQFLUSH;
 869                 spin_unlock(&m->lock);
 870
 871                 clear_thread_flag(TIF_SIGPENDING);
 872                 v9fs_mux_flush_request(m, req);
 873                 spin_lock_irqsave(&current->sighand->siglock, flags);
 874                 recalc_sigpending();
 875                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 876         }
 877
 878         if (!err) {
 879                 if (r.rcall)
 880                         dprintk(DEBUG_MUX, "got response id %d tag %d\n",
 881                                 r.rcall->id, r.rcall->tag);
 882
 883                 if (rc)
 884                         *rc = r.rcall;
 885                 else
 886                         kfree(r.rcall);
 887         } else {
 888                 kfree(r.rcall);
 889                 dprintk(DEBUG_MUX, "got error %d\n", err);
 890                 if (err > 0)
 891                         err = -EIO;
 892         }
 893
 894         return err;
 895 }
 896
 897 /**
 898  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 899  * @m: mux data
 900  * @tc: request to be sent
 901  * @cb: callback function to be called when response arrives
 902  * @cba: value to pass to the callback function
 903  */
 904 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 905                    v9fs_mux_req_callback cb, void *a)
 906 {
 907         int err;
 908         struct v9fs_req *req;
 909
 910         req = v9fs_send_request(m, tc, cb, a);
 911         if (IS_ERR(req)) {
 912                 err = PTR_ERR(req);
 913                 dprintk(DEBUG_MUX, "error %d\n", err);
 914                 return PTR_ERR(req);
 915         }
 916
 917         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 918         return 0;
 919 }
 920
 921 /**
 922  * v9fs_mux_cancel - cancel all pending requests with error
 923  * @m: mux data
 924  * @err: error code
 925  */
 926 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 927 {
 928         struct v9fs_req *req, *rtmp;
 929         LIST_HEAD(cancel_list);
 930
 931         dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
 932         m->err = err;
 933         spin_lock(&m->lock);
 934         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 935                 list_move(&req->req_list, &cancel_list);
 936         }
 937         spin_unlock(&m->lock);
 938
 939         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
 940                 list_del(&req->req_list);
 941                 if (!req->err)
 942                         req->err = err;
 943
 944                 if (req->cb)
 945                         (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 946                 else
 947                         kfree(req->rcall);
 948
 949                 kfree(req);
 950         }
 951
 952         wake_up(&m->equeue);
 953 }
 954
 955 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
 956 {
 957         int tag;
 958
 959         tag = v9fs_get_idpool(&m->tidpool);
 960         if (tag < 0)
 961                 return V9FS_NOTAG;
 962         else
 963                 return (u16) tag;
 964 }
 965
 966 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
 967 {
 968         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tidpool))
 969                 v9fs_put_idpool(tag, &m->tidpool);
 970 }