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 "transport.h"
  39 #include "conv.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         int rpos;
  78         char *rbuf;
  79         int wpos;
  80         int wsize;
  81         char *wbuf;
  82         wait_queue_t poll_wait[MAXPOLLWADDR];
  83         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  84         poll_table pt;
  85         struct work_struct rq;
  86         struct work_struct wq;
  87         unsigned long wsched;
  88 };
  89
  90 struct v9fs_mux_poll_task {
  91         struct task_struct *task;
  92         struct list_head mux_list;
  93         int muxnum;
  94 };
  95
  96 struct v9fs_mux_rpc {
  97         struct v9fs_mux_data *m;
  98         struct v9fs_req *req;
  99         int err;
 100         struct v9fs_fcall *rcall;
 101         wait_queue_head_t wqueue;
 102 };
 103
 104 static int v9fs_poll_proc(void *);
 105 static void v9fs_read_work(void *);
 106 static void v9fs_write_work(void *);
 107 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 108                           poll_table * p);
 109
 110 static DECLARE_MUTEX(v9fs_mux_task_lock);
 111 static struct workqueue_struct *v9fs_mux_wq;
 112
 113 static int v9fs_mux_num;
 114 static int v9fs_mux_poll_task_num;
 115 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
 116
 117 void v9fs_mux_global_init(void)
 118 {
 119         int i;
 120
 121         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
 122                 v9fs_mux_poll_tasks[i].task = NULL;
 123
 124         v9fs_mux_wq = create_workqueue("v9fs");
 125 }
 126
 127 void v9fs_mux_global_exit(void)
 128 {
 129         destroy_workqueue(v9fs_mux_wq);
 130 }
 131
 132 /**
 133  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 134  * based on the number of mounted v9fs filesystems.
 135  *
 136  * The current implementation returns sqrt of the number of mounts.
 137  */
 138 inline int v9fs_mux_calc_poll_procs(int muxnum)
 139 {
 140         int n;
 141
 142         if (v9fs_mux_poll_task_num)
 143                 n = muxnum / v9fs_mux_poll_task_num +
 144                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
 145         else
 146                 n = 1;
 147
 148         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
 149                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
 150
 151         return n;
 152 }
 153
 154 static void v9fs_mux_poll_start(struct v9fs_mux_data *m)
 155 {
 156         int i, n;
 157         struct v9fs_mux_poll_task *vpt, *vptlast;
 158
 159         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
 160                 v9fs_mux_poll_task_num);
 161         up(&v9fs_mux_task_lock);
 162
 163         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
 164         if (n > v9fs_mux_poll_task_num) {
 165                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 166                         if (v9fs_mux_poll_tasks[i].task == NULL) {
 167                                 vpt = &v9fs_mux_poll_tasks[i];
 168                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
 169                                 vpt->task = kthread_create(v9fs_poll_proc,
 170                                         vpt, "v9fs-poll");
 171                                 INIT_LIST_HEAD(&vpt->mux_list);
 172                                 vpt->muxnum = 0;
 173                                 v9fs_mux_poll_task_num++;
 174                                 wake_up_process(vpt->task);
 175                                 break;
 176                         }
 177                 }
 178
 179                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
 180                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
 181         }
 182
 183         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
 184             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
 185
 186         vptlast = NULL;
 187         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 188                 vpt = &v9fs_mux_poll_tasks[i];
 189                 if (vpt->task != NULL) {
 190                         vptlast = vpt;
 191                         if (vpt->muxnum < n) {
 192                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 193                                 list_add(&m->mux_list, &vpt->mux_list);
 194                                 vpt->muxnum++;
 195                                 m->poll_task = vpt;
 196                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 197                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 198                                 break;
 199                         }
 200                 }
 201         }
 202
 203         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
 204                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 205                 list_add(&m->mux_list, &vptlast->mux_list);
 206                 vptlast->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         }
 211
 212         v9fs_mux_num++;
 213         down(&v9fs_mux_task_lock);
 214 }
 215
 216 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
 217 {
 218         int i;
 219         struct v9fs_mux_poll_task *vpt;
 220
 221         up(&v9fs_mux_task_lock);
 222         vpt = m->poll_task;
 223         list_del(&m->mux_list);
 224         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 225                 if (m->poll_waddr[i] != NULL) {
 226                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 227                         m->poll_waddr[i] = NULL;
 228                 }
 229         }
 230         vpt->muxnum--;
 231         if (!vpt->muxnum) {
 232                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
 233                 send_sig(SIGKILL, vpt->task, 1);
 234                 vpt->task = NULL;
 235                 v9fs_mux_poll_task_num--;
 236         }
 237         v9fs_mux_num--;
 238         down(&v9fs_mux_task_lock);
 239 }
 240
 241 /**
 242  * v9fs_mux_init - allocate and initialize the per-session mux data
 243  * Creates the polling task if this is the first session.
 244  *
 245  * @trans - transport structure
 246  * @msize - maximum message size
 247  * @extended - pointer to the extended flag
 248  */
 249 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
 250                                     unsigned char *extended)
 251 {
 252         int i, n;
 253         struct v9fs_mux_data *m, *mtmp;
 254
 255         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 256         m = kmalloc(sizeof(struct v9fs_mux_data) + 2 * msize, GFP_KERNEL);
 257         if (!m)
 258                 return ERR_PTR(-ENOMEM);
 259
 260         spin_lock_init(&m->lock);
 261         INIT_LIST_HEAD(&m->mux_list);
 262         m->msize = msize;
 263         m->extended = extended;
 264         m->trans = trans;
 265         idr_init(&m->tidpool.pool);
 266         init_MUTEX(&m->tidpool.lock);
 267         m->err = 0;
 268         init_waitqueue_head(&m->equeue);
 269         INIT_LIST_HEAD(&m->req_list);
 270         INIT_LIST_HEAD(&m->unsent_req_list);
 271         m->rpos = 0;
 272         m->rbuf = (char *)m + sizeof(struct v9fs_mux_data);
 273         m->wpos = m->wsize = 0;
 274         m->wbuf = m->rbuf + msize;
 275         INIT_WORK(&m->rq, v9fs_read_work, m);
 276         INIT_WORK(&m->wq, v9fs_write_work, m);
 277         m->wsched = 0;
 278         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 279         v9fs_mux_poll_start(m);
 280
 281         n = trans->poll(trans, &m->pt);
 282         if (n & POLLIN) {
 283                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 284                 set_bit(Rpending, &m->wsched);
 285         }
 286
 287         if (n & POLLOUT) {
 288                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 289                 set_bit(Wpending, &m->wsched);
 290         }
 291
 292         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 293                 if (IS_ERR(m->poll_waddr[i])) {
 294                         v9fs_mux_poll_stop(m);
 295                         mtmp = (void *)m->poll_waddr;   /* the error code */
 296                         kfree(m);
 297                         m = mtmp;
 298                         break;
 299                 }
 300         }
 301
 302         return m;
 303 }
 304
 305 /**
 306  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
 307  */
 308 void v9fs_mux_destroy(struct v9fs_mux_data *m)
 309 {
 310         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
 311                 m->mux_list.prev, m->mux_list.next);
 312         v9fs_mux_cancel(m, -ECONNRESET);
 313
 314         if (!list_empty(&m->req_list)) {
 315                 /* wait until all processes waiting on this session exit */
 316                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
 317                         m);
 318                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 319                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 320                         list_empty(&m->req_list));
 321         }
 322
 323         v9fs_mux_poll_stop(m);
 324         m->trans = NULL;
 325
 326         kfree(m);
 327 }
 328
 329 /**
 330  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
 331  *      to files wait queue
 332  */
 333 static void
 334 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 335               poll_table * p)
 336 {
 337         int i;
 338         struct v9fs_mux_data *m;
 339
 340         m = container_of(p, struct v9fs_mux_data, pt);
 341         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 342                 if (m->poll_waddr[i] == NULL)
 343                         break;
 344
 345         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 346                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
 347                 return;
 348         }
 349
 350         m->poll_waddr[i] = wait_address;
 351
 352         if (!wait_address) {
 353                 dprintk(DEBUG_ERROR, "no wait_address\n");
 354                 m->poll_waddr[i] = ERR_PTR(-EIO);
 355                 return;
 356         }
 357
 358         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 359         add_wait_queue(wait_address, &m->poll_wait[i]);
 360 }
 361
 362 /**
 363  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
 364  */
 365 static inline void v9fs_poll_mux(struct v9fs_mux_data *m)
 366 {
 367         int n;
 368
 369         if (m->err < 0)
 370                 return;
 371
 372         n = m->trans->poll(m->trans, NULL);
 373         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 374                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
 375                 if (n >= 0)
 376                         n = -ECONNRESET;
 377                 v9fs_mux_cancel(m, n);
 378         }
 379
 380         if (n & POLLIN) {
 381                 set_bit(Rpending, &m->wsched);
 382                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 383                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 384                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 385                         queue_work(v9fs_mux_wq, &m->rq);
 386                 }
 387         }
 388
 389         if (n & POLLOUT) {
 390                 set_bit(Wpending, &m->wsched);
 391                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 392                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 393                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 394                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 395                         queue_work(v9fs_mux_wq, &m->wq);
 396                 }
 397         }
 398 }
 399
 400 /**
 401  * v9fs_poll_proc - polls all v9fs transports for new events and queues
 402  *      the appropriate work to the work queue
 403  */
 404 static int v9fs_poll_proc(void *a)
 405 {
 406         struct v9fs_mux_data *m, *mtmp;
 407         struct v9fs_mux_poll_task *vpt;
 408
 409         vpt = a;
 410         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
 411         allow_signal(SIGKILL);
 412         while (!kthread_should_stop()) {
 413                 set_current_state(TASK_INTERRUPTIBLE);
 414                 if (signal_pending(current))
 415                         break;
 416
 417                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 418                         v9fs_poll_mux(m);
 419                 }
 420
 421                 dprintk(DEBUG_MUX, "sleeping...\n");
 422                 schedule_timeout(SCHED_TIMEOUT * HZ);
 423         }
 424
 425         __set_current_state(TASK_RUNNING);
 426         dprintk(DEBUG_MUX, "finish\n");
 427         return 0;
 428 }
 429
 430 static inline int v9fs_write_req(struct v9fs_mux_data *m, struct v9fs_req *req)
 431 {
 432         int n;
 433
 434         list_move_tail(&req->req_list, &m->req_list);
 435         n = v9fs_serialize_fcall(req->tcall, m->wbuf, m->msize, *m->extended);
 436         if (n < 0) {
 437                 req->err = n;
 438                 list_del(&req->req_list);
 439                 if (req->cb) {
 440                         spin_unlock(&m->lock);
 441                         (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 442                         req->cb = NULL;
 443                         spin_lock(&m->lock);
 444                 } else
 445                         kfree(req->rcall);
 446
 447                 kfree(req);
 448         }
 449
 450         return n;
 451 }
 452
 453 /**
 454  * v9fs_write_work - called when a transport can send some data
 455  */
 456 static void v9fs_write_work(void *a)
 457 {
 458         int n, err;
 459         struct v9fs_mux_data *m;
 460         struct v9fs_req *req, *rtmp;
 461
 462         m = a;
 463
 464         if (m->err < 0) {
 465                 clear_bit(Wworksched, &m->wsched);
 466                 return;
 467         }
 468
 469         if (!m->wsize) {
 470                 if (list_empty(&m->unsent_req_list)) {
 471                         clear_bit(Wworksched, &m->wsched);
 472                         return;
 473                 }
 474
 475                 err = 0;
 476                 spin_lock(&m->lock);
 477                 list_for_each_entry_safe(req, rtmp, &m->unsent_req_list,
 478                                          req_list) {
 479                         err = v9fs_write_req(m, req);
 480                         if (err > 0)
 481                                 break;
 482                 }
 483
 484                 m->wsize = err;
 485                 m->wpos = 0;
 486                 spin_unlock(&m->lock);
 487         }
 488
 489         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 490         clear_bit(Wpending, &m->wsched);
 491         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 492         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 493         if (err == -EAGAIN) {
 494                 clear_bit(Wworksched, &m->wsched);
 495                 return;
 496         }
 497
 498         if (err <= 0)
 499                 goto error;
 500
 501         m->wpos += err;
 502         if (m->wpos == m->wsize)
 503                 m->wpos = m->wsize = 0;
 504
 505         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 506                 if (test_and_clear_bit(Wpending, &m->wsched))
 507                         n = POLLOUT;
 508                 else
 509                         n = m->trans->poll(m->trans, NULL);
 510
 511                 if (n & POLLOUT) {
 512                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 513                         queue_work(v9fs_mux_wq, &m->wq);
 514                 } else
 515                         clear_bit(Wworksched, &m->wsched);
 516         } else
 517                 clear_bit(Wworksched, &m->wsched);
 518
 519         return;
 520
 521       error:
 522         v9fs_mux_cancel(m, err);
 523         clear_bit(Wworksched, &m->wsched);
 524 }
 525
 526 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 527 {
 528         int ecode, tag;
 529         char *ename;
 530
 531         tag = req->tag;
 532         if (req->rcall->id == RERROR && !req->err) {
 533                 ecode = req->rcall->params.rerror.errno;
 534                 ename = req->rcall->params.rerror.error;
 535
 536                 dprintk(DEBUG_MUX, "Rerror %s\n", ename);
 537
 538                 if (*m->extended)
 539                         req->err = -ecode;
 540
 541                 if (!req->err) {
 542                         req->err = v9fs_errstr2errno(ename);
 543
 544                         if (!req->err) {        /* string match failed */
 545                                 dprintk(DEBUG_ERROR, "unknown error: %s\n",
 546                                         ename);
 547                         }
 548
 549                         if (!req->err)
 550                                 req->err = -ESERVERFAULT;
 551                 }
 552         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 553                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 554                         req->tcall->id + 1, req->rcall->id);
 555                 if (!req->err)
 556                         req->err = -EIO;
 557         }
 558
 559         if (req->cb && req->err != ERREQFLUSH) {
 560                 dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
 561                         req->tcall, req->rcall);
 562
 563                 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 564                 req->cb = NULL;
 565         } else
 566                 kfree(req->rcall);
 567
 568         if (tag != V9FS_NOTAG)
 569                 v9fs_put_idpool(tag, &m->tidpool);
 570
 571         wake_up(&m->equeue);
 572         kfree(req);
 573 }
 574
 575 /**
 576  * v9fs_read_work - called when there is some data to be read from a transport
 577  */
 578 static void v9fs_read_work(void *a)
 579 {
 580         int n, err, rcallen;
 581         struct v9fs_mux_data *m;
 582         struct v9fs_req *req, *rptr, *rreq;
 583         struct v9fs_fcall *rcall;
 584
 585         m = a;
 586
 587         if (m->err < 0)
 588                 return;
 589
 590         rcall = NULL;
 591         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 592         clear_bit(Rpending, &m->wsched);
 593         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 594         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 595         if (err == -EAGAIN) {
 596                 clear_bit(Rworksched, &m->wsched);
 597                 return;
 598         }
 599
 600         if (err <= 0)
 601                 goto error;
 602
 603         m->rpos += err;
 604         while (m->rpos > 4) {
 605                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 606                 if (n >= m->msize) {
 607                         dprintk(DEBUG_ERROR,
 608                                 "requested packet size too big: %d\n", n);
 609                         err = -EIO;
 610                         goto error;
 611                 }
 612
 613                 if (m->rpos < n)
 614                         break;
 615
 616                 rcallen = n + V9FS_FCALLHDRSZ;
 617                 rcall = kmalloc(rcallen, GFP_KERNEL);
 618                 if (!rcall) {
 619                         err = -ENOMEM;
 620                         goto error;
 621                 }
 622
 623                 dump_data(m->rbuf, n);
 624                 err = v9fs_deserialize_fcall(m->rbuf, n, rcall, rcallen,
 625                                              *m->extended);
 626                 if (err < 0) {
 627                         kfree(rcall);
 628                         goto error;
 629                 }
 630
 631                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 632                         rcall->tag);
 633
 634                 req = NULL;
 635                 spin_lock(&m->lock);
 636                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 637                         if (rreq->tag == rcall->tag) {
 638                                 req = rreq;
 639                                 req->rcall = rcall;
 640                                 list_del(&req->req_list);
 641                                 spin_unlock(&m->lock);
 642                                 process_request(m, req);
 643                                 break;
 644                         }
 645                 }
 646
 647                 if (!req) {
 648                         spin_unlock(&m->lock);
 649                         if (err >= 0 && rcall->id != RFLUSH)
 650                                 dprintk(DEBUG_ERROR,
 651                                         "unexpected response mux %p id %d tag %d\n",
 652                                         m, rcall->id, rcall->tag);
 653                         kfree(rcall);
 654                 }
 655
 656                 if (m->rpos > n)
 657                         memmove(m->rbuf, m->rbuf + n, m->rpos - n);
 658                 m->rpos -= n;
 659         }
 660
 661         if (!list_empty(&m->req_list)) {
 662                 if (test_and_clear_bit(Rpending, &m->wsched))
 663                         n = POLLIN;
 664                 else
 665                         n = m->trans->poll(m->trans, NULL);
 666
 667                 if (n & POLLIN) {
 668                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 669                         queue_work(v9fs_mux_wq, &m->rq);
 670                 } else
 671                         clear_bit(Rworksched, &m->wsched);
 672         } else
 673                 clear_bit(Rworksched, &m->wsched);
 674
 675         return;
 676
 677       error:
 678         v9fs_mux_cancel(m, err);
 679         clear_bit(Rworksched, &m->wsched);
 680 }
 681
 682 /**
 683  * v9fs_send_request - send 9P request
 684  * The function can sleep until the request is scheduled for sending.
 685  * The function can be interrupted. Return from the function is not
 686  * a guarantee that the request is sent succesfully. Can return errors
 687  * that can be retrieved by PTR_ERR macros.
 688  *
 689  * @m: mux data
 690  * @tc: request to be sent
 691  * @cb: callback function to call when response is received
 692  * @cba: parameter to pass to the callback function
 693  */
 694 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 695                                           struct v9fs_fcall *tc,
 696                                           v9fs_mux_req_callback cb, void *cba)
 697 {
 698         int n;
 699         struct v9fs_req *req;
 700
 701         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 702                 tc, tc->id);
 703         if (m->err < 0)
 704                 return ERR_PTR(m->err);
 705
 706         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 707         if (!req)
 708                 return ERR_PTR(-ENOMEM);
 709
 710         if (tc->id == TVERSION)
 711                 n = V9FS_NOTAG;
 712         else
 713                 n = v9fs_get_idpool(&m->tidpool);
 714
 715         if (n < 0)
 716                 return ERR_PTR(-ENOMEM);
 717
 718         tc->tag = n;
 719         req->tag = n;
 720         req->tcall = tc;
 721         req->rcall = NULL;
 722         req->err = 0;
 723         req->cb = cb;
 724         req->cba = cba;
 725
 726         spin_lock(&m->lock);
 727         list_add_tail(&req->req_list, &m->unsent_req_list);
 728         spin_unlock(&m->lock);
 729
 730         if (test_and_clear_bit(Wpending, &m->wsched))
 731                 n = POLLOUT;
 732         else
 733                 n = m->trans->poll(m->trans, NULL);
 734
 735         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 736                 queue_work(v9fs_mux_wq, &m->wq);
 737
 738         return req;
 739 }
 740
 741 static inline void
 742 v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc,
 743                   int err)
 744 {
 745         v9fs_mux_req_callback cb;
 746         int tag;
 747         struct v9fs_mux_data *m;
 748         struct v9fs_req *req, *rptr;
 749
 750         m = a;
 751         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
 752                 rc, err, tc->params.tflush.oldtag);
 753
 754         spin_lock(&m->lock);
 755         cb = NULL;
 756         tag = tc->params.tflush.oldtag;
 757         list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
 758                 if (req->tag == tag) {
 759                         list_del(&req->req_list);
 760                         if (req->cb) {
 761                                 cb = req->cb;
 762                                 req->cb = NULL;
 763                                 spin_unlock(&m->lock);
 764                                 (*cb) (req->cba, req->tcall, req->rcall,
 765                                        req->err);
 766                         }
 767                         kfree(req);
 768                         wake_up(&m->equeue);
 769                         break;
 770                 }
 771         }
 772
 773         if (!cb)
 774                 spin_unlock(&m->lock);
 775
 776         if (v9fs_check_idpool(tag, &m->tidpool))
 777                 v9fs_put_idpool(tag, &m->tidpool);
 778
 779         kfree(tc);
 780         kfree(rc);
 781 }
 782
 783 static void
 784 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 785 {
 786         struct v9fs_fcall *fc;
 787
 788         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 789
 790         fc = kmalloc(sizeof(struct v9fs_fcall), GFP_KERNEL);
 791         fc->id = TFLUSH;
 792         fc->params.tflush.oldtag = req->tag;
 793
 794         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 795 }
 796
 797 static void
 798 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
 799 {
 800         struct v9fs_mux_rpc *r;
 801
 802         if (err == ERREQFLUSH) {
 803                 dprintk(DEBUG_MUX, "err req flush\n");
 804                 return;
 805         }
 806
 807         r = a;
 808         dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
 809                 tc, rc, err);
 810         r->rcall = rc;
 811         r->err = err;
 812         wake_up(&r->wqueue);
 813 }
 814
 815 /**
 816  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 817  *      The function can be interrupted.
 818  * @m: mux data
 819  * @tc: request to be sent
 820  * @rc: pointer where a pointer to the response is stored
 821  */
 822 int
 823 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 824              struct v9fs_fcall **rc)
 825 {
 826         int err;
 827         unsigned long flags;
 828         struct v9fs_req *req;
 829         struct v9fs_mux_rpc r;
 830
 831         r.err = 0;
 832         r.rcall = NULL;
 833         r.m = m;
 834         init_waitqueue_head(&r.wqueue);
 835
 836         if (rc)
 837                 *rc = NULL;
 838
 839         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 840         if (IS_ERR(req)) {
 841                 err = PTR_ERR(req);
 842                 dprintk(DEBUG_MUX, "error %d\n", err);
 843                 return PTR_ERR(req);
 844         }
 845
 846         r.req = req;
 847         dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
 848                 req->tag, &r, req);
 849         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 850         if (r.err < 0)
 851                 err = r.err;
 852
 853         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 854                 spin_lock(&m->lock);
 855                 req->tcall = NULL;
 856                 req->err = ERREQFLUSH;
 857                 spin_unlock(&m->lock);
 858
 859                 clear_thread_flag(TIF_SIGPENDING);
 860                 v9fs_mux_flush_request(m, req);
 861                 spin_lock_irqsave(&current->sighand->siglock, flags);
 862                 recalc_sigpending();
 863                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 864         }
 865
 866         if (!err) {
 867                 if (r.rcall)
 868                         dprintk(DEBUG_MUX, "got response id %d tag %d\n",
 869                                 r.rcall->id, r.rcall->tag);
 870
 871                 if (rc)
 872                         *rc = r.rcall;
 873                 else
 874                         kfree(r.rcall);
 875         } else {
 876                 kfree(r.rcall);
 877                 dprintk(DEBUG_MUX, "got error %d\n", err);
 878                 if (err > 0)
 879                         err = -EIO;
 880         }
 881
 882         return err;
 883 }
 884
 885 /**
 886  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 887  * @m: mux data
 888  * @tc: request to be sent
 889  * @cb: callback function to be called when response arrives
 890  * @cba: value to pass to the callback function
 891  */
 892 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 893                    v9fs_mux_req_callback cb, void *a)
 894 {
 895         int err;
 896         struct v9fs_req *req;
 897
 898         req = v9fs_send_request(m, tc, cb, a);
 899         if (IS_ERR(req)) {
 900                 err = PTR_ERR(req);
 901                 dprintk(DEBUG_MUX, "error %d\n", err);
 902                 return PTR_ERR(req);
 903         }
 904
 905         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 906         return 0;
 907 }
 908
 909 /**
 910  * v9fs_mux_cancel - cancel all pending requests with error
 911  * @m: mux data
 912  * @err: error code
 913  */
 914 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 915 {
 916         struct v9fs_req *req, *rtmp;
 917         LIST_HEAD(cancel_list);
 918
 919         dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
 920         m->err = err;
 921         spin_lock(&m->lock);
 922         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 923                 list_move(&req->req_list, &cancel_list);
 924         }
 925         spin_unlock(&m->lock);
 926
 927         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
 928                 list_del(&req->req_list);
 929                 if (!req->err)
 930                         req->err = err;
 931
 932                 if (req->cb)
 933                         (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
 934                 else
 935                         kfree(req->rcall);
 936
 937                 kfree(req);
 938         }
 939
 940         wake_up(&m->equeue);
 941 }