net/9p/mux.c

   1 /*
   2  * net/9p/mux.c
   3  *
   4  * Protocol Multiplexer
   5  *
   6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/fs.h>
  29 #include <linux/poll.h>
  30 #include <linux/kthread.h>
  31 #include <linux/idr.h>
  32 #include <linux/mutex.h>
  33 #include <net/9p/9p.h>
  34 #include <net/9p/transport.h>
  35 #include <net/9p/conn.h>
  36
  37 #define ERREQFLUSH      1
  38 #define SCHED_TIMEOUT   10
  39 #define MAXPOLLWADDR    2
  40
  41 enum {
  42         Rworksched = 1,         /* read work scheduled or running */
  43         Rpending = 2,           /* can read */
  44         Wworksched = 4,         /* write work scheduled or running */
  45         Wpending = 8,           /* can write */
  46 };
  47
  48 enum {
  49         None,
  50         Flushing,
  51         Flushed,
  52 };
  53
  54 struct p9_mux_poll_task;
  55
  56 struct p9_req {
  57         spinlock_t lock; /* protect request structure */
  58         int tag;
  59         struct p9_fcall *tcall;
  60         struct p9_fcall *rcall;
  61         int err;
  62         p9_conn_req_callback cb;
  63         void *cba;
  64         int flush;
  65         struct list_head req_list;
  66 };
  67
  68 struct p9_conn {
  69         spinlock_t lock; /* protect lock structure */
  70         struct list_head mux_list;
  71         struct p9_mux_poll_task *poll_task;
  72         int msize;
  73         unsigned char *extended;
  74         struct p9_transport *trans;
  75         struct p9_idpool *tagpool;
  76         int err;
  77         wait_queue_head_t equeue;
  78         struct list_head req_list;
  79         struct list_head unsent_req_list;
  80         struct p9_fcall *rcall;
  81         int rpos;
  82         char *rbuf;
  83         int wpos;
  84         int wsize;
  85         char *wbuf;
  86         wait_queue_t poll_wait[MAXPOLLWADDR];
  87         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  88         poll_table pt;
  89         struct work_struct rq;
  90         struct work_struct wq;
  91         unsigned long wsched;
  92 };
  93
  94 struct p9_mux_poll_task {
  95         struct task_struct *task;
  96         struct list_head mux_list;
  97         int muxnum;
  98 };
  99
 100 struct p9_mux_rpc {
 101         struct p9_conn *m;
 102         int err;
 103         struct p9_fcall *tcall;
 104         struct p9_fcall *rcall;
 105         wait_queue_head_t wqueue;
 106 };
 107
 108 static int p9_poll_proc(void *);
 109 static void p9_read_work(struct work_struct *work);
 110 static void p9_write_work(struct work_struct *work);
 111 static void p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
 112                           poll_table * p);
 113 static u16 p9_mux_get_tag(struct p9_conn *);
 114 static void p9_mux_put_tag(struct p9_conn *, u16);
 115
 116 static DEFINE_MUTEX(p9_mux_task_lock);
 117 static struct workqueue_struct *p9_mux_wq;
 118
 119 static int p9_mux_num;
 120 static int p9_mux_poll_task_num;
 121 static struct p9_mux_poll_task p9_mux_poll_tasks[100];
 122
 123 int p9_mux_global_init(void)
 124 {
 125         int i;
 126
 127         for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++)
 128                 p9_mux_poll_tasks[i].task = NULL;
 129
 130         p9_mux_wq = create_workqueue("v9fs");
 131         if (!p9_mux_wq) {
 132                 printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
 133                 return -ENOMEM;
 134         }
 135
 136         return 0;
 137 }
 138
 139 void p9_mux_global_exit(void)
 140 {
 141         destroy_workqueue(p9_mux_wq);
 142 }
 143
 144 /**
 145  * p9_mux_calc_poll_procs - calculates the number of polling procs
 146  * based on the number of mounted v9fs filesystems.
 147  *
 148  * The current implementation returns sqrt of the number of mounts.
 149  */
 150 static int p9_mux_calc_poll_procs(int muxnum)
 151 {
 152         int n;
 153
 154         if (p9_mux_poll_task_num)
 155                 n = muxnum / p9_mux_poll_task_num +
 156                     (muxnum % p9_mux_poll_task_num ? 1 : 0);
 157         else
 158                 n = 1;
 159
 160         if (n > ARRAY_SIZE(p9_mux_poll_tasks))
 161                 n = ARRAY_SIZE(p9_mux_poll_tasks);
 162
 163         return n;
 164 }
 165
 166 static int p9_mux_poll_start(struct p9_conn *m)
 167 {
 168         int i, n;
 169         struct p9_mux_poll_task *vpt, *vptlast;
 170         struct task_struct *pproc;
 171
 172         P9_DPRINTK(P9_DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, p9_mux_num,
 173                 p9_mux_poll_task_num);
 174         mutex_lock(&p9_mux_task_lock);
 175
 176         n = p9_mux_calc_poll_procs(p9_mux_num + 1);
 177         if (n > p9_mux_poll_task_num) {
 178                 for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
 179                         if (p9_mux_poll_tasks[i].task == NULL) {
 180                                 vpt = &p9_mux_poll_tasks[i];
 181                                 P9_DPRINTK(P9_DEBUG_MUX, "create proc %p\n",
 182                                                                         vpt);
 183                                 pproc = kthread_create(p9_poll_proc, vpt,
 184                                                                 "v9fs-poll");
 185
 186                                 if (!IS_ERR(pproc)) {
 187                                         vpt->task = pproc;
 188                                         INIT_LIST_HEAD(&vpt->mux_list);
 189                                         vpt->muxnum = 0;
 190                                         p9_mux_poll_task_num++;
 191                                         wake_up_process(vpt->task);
 192                                 }
 193                                 break;
 194                         }
 195                 }
 196
 197                 if (i >= ARRAY_SIZE(p9_mux_poll_tasks))
 198                         P9_DPRINTK(P9_DEBUG_ERROR,
 199                                         "warning: no free poll slots\n");
 200         }
 201
 202         n = (p9_mux_num + 1) / p9_mux_poll_task_num +
 203             ((p9_mux_num + 1) % p9_mux_poll_task_num ? 1 : 0);
 204
 205         vptlast = NULL;
 206         for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
 207                 vpt = &p9_mux_poll_tasks[i];
 208                 if (vpt->task != NULL) {
 209                         vptlast = vpt;
 210                         if (vpt->muxnum < n) {
 211                                 P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
 212                                 list_add(&m->mux_list, &vpt->mux_list);
 213                                 vpt->muxnum++;
 214                                 m->poll_task = vpt;
 215                                 memset(&m->poll_waddr, 0,
 216                                                         sizeof(m->poll_waddr));
 217                                 init_poll_funcptr(&m->pt, p9_pollwait);
 218                                 break;
 219                         }
 220                 }
 221         }
 222
 223         if (i >= ARRAY_SIZE(p9_mux_poll_tasks)) {
 224                 if (vptlast == NULL)
 225                         return -ENOMEM;
 226
 227                 P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
 228                 list_add(&m->mux_list, &vptlast->mux_list);
 229                 vptlast->muxnum++;
 230                 m->poll_task = vptlast;
 231                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 232                 init_poll_funcptr(&m->pt, p9_pollwait);
 233         }
 234
 235         p9_mux_num++;
 236         mutex_unlock(&p9_mux_task_lock);
 237
 238         return 0;
 239 }
 240
 241 static void p9_mux_poll_stop(struct p9_conn *m)
 242 {
 243         int i;
 244         struct p9_mux_poll_task *vpt;
 245
 246         mutex_lock(&p9_mux_task_lock);
 247         vpt = m->poll_task;
 248         list_del(&m->mux_list);
 249         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 250                 if (m->poll_waddr[i] != NULL) {
 251                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 252                         m->poll_waddr[i] = NULL;
 253                 }
 254         }
 255         vpt->muxnum--;
 256         if (!vpt->muxnum) {
 257                 P9_DPRINTK(P9_DEBUG_MUX, "destroy proc %p\n", vpt);
 258                 kthread_stop(vpt->task);
 259                 vpt->task = NULL;
 260                 p9_mux_poll_task_num--;
 261         }
 262         p9_mux_num--;
 263         mutex_unlock(&p9_mux_task_lock);
 264 }
 265
 266 /**
 267  * p9_conn_create - allocate and initialize the per-session mux data
 268  * Creates the polling task if this is the first session.
 269  *
 270  * @trans - transport structure
 271  * @msize - maximum message size
 272  * @extended - pointer to the extended flag
 273  */
 274 struct p9_conn *p9_conn_create(struct p9_transport *trans, int msize,
 275                                     unsigned char *extended)
 276 {
 277         int i, n;
 278         struct p9_conn *m, *mtmp;
 279
 280         P9_DPRINTK(P9_DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 281         m = kmalloc(sizeof(struct p9_conn), GFP_KERNEL);
 282         if (!m)
 283                 return ERR_PTR(-ENOMEM);
 284
 285         spin_lock_init(&m->lock);
 286         INIT_LIST_HEAD(&m->mux_list);
 287         m->msize = msize;
 288         m->extended = extended;
 289         m->trans = trans;
 290         m->tagpool = p9_idpool_create();
 291         if (!m->tagpool) {
 292                 kfree(m);
 293                 return ERR_PTR(PTR_ERR(m->tagpool));
 294         }
 295
 296         m->err = 0;
 297         init_waitqueue_head(&m->equeue);
 298         INIT_LIST_HEAD(&m->req_list);
 299         INIT_LIST_HEAD(&m->unsent_req_list);
 300         m->rcall = NULL;
 301         m->rpos = 0;
 302         m->rbuf = NULL;
 303         m->wpos = m->wsize = 0;
 304         m->wbuf = NULL;
 305         INIT_WORK(&m->rq, p9_read_work);
 306         INIT_WORK(&m->wq, p9_write_work);
 307         m->wsched = 0;
 308         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 309         m->poll_task = NULL;
 310         n = p9_mux_poll_start(m);
 311         if (n)
 312                 return ERR_PTR(n);
 313
 314         n = trans->poll(trans, &m->pt);
 315         if (n & POLLIN) {
 316                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 317                 set_bit(Rpending, &m->wsched);
 318         }
 319
 320         if (n & POLLOUT) {
 321                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 322                 set_bit(Wpending, &m->wsched);
 323         }
 324
 325         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 326                 if (IS_ERR(m->poll_waddr[i])) {
 327                         p9_mux_poll_stop(m);
 328                         mtmp = (void *)m->poll_waddr;   /* the error code */
 329                         kfree(m);
 330                         m = mtmp;
 331                         break;
 332                 }
 333         }
 334
 335         return m;
 336 }
 337 EXPORT_SYMBOL(p9_conn_create);
 338
 339 /**
 340  * p9_mux_destroy - cancels all pending requests and frees mux resources
 341  */
 342 void p9_conn_destroy(struct p9_conn *m)
 343 {
 344         P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m,
 345                 m->mux_list.prev, m->mux_list.next);
 346         p9_conn_cancel(m, -ECONNRESET);
 347
 348         if (!list_empty(&m->req_list)) {
 349                 /* wait until all processes waiting on this session exit */
 350                 P9_DPRINTK(P9_DEBUG_MUX,
 351                         "mux %p waiting for empty request queue\n", m);
 352                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 353                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 354                         list_empty(&m->req_list));
 355         }
 356
 357         p9_mux_poll_stop(m);
 358         m->trans = NULL;
 359         p9_idpool_destroy(m->tagpool);
 360         kfree(m);
 361 }
 362 EXPORT_SYMBOL(p9_conn_destroy);
 363
 364 /**
 365  * p9_pollwait - called by files poll operation to add v9fs-poll task
 366  *      to files wait queue
 367  */
 368 static void
 369 p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
 370               poll_table * p)
 371 {
 372         int i;
 373         struct p9_conn *m;
 374
 375         m = container_of(p, struct p9_conn, pt);
 376         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 377                 if (m->poll_waddr[i] == NULL)
 378                         break;
 379
 380         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 381                 P9_DPRINTK(P9_DEBUG_ERROR, "not enough wait_address slots\n");
 382                 return;
 383         }
 384
 385         m->poll_waddr[i] = wait_address;
 386
 387         if (!wait_address) {
 388                 P9_DPRINTK(P9_DEBUG_ERROR, "no wait_address\n");
 389                 m->poll_waddr[i] = ERR_PTR(-EIO);
 390                 return;
 391         }
 392
 393         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 394         add_wait_queue(wait_address, &m->poll_wait[i]);
 395 }
 396
 397 /**
 398  * p9_poll_mux - polls a mux and schedules read or write works if necessary
 399  */
 400 static void p9_poll_mux(struct p9_conn *m)
 401 {
 402         int n;
 403
 404         if (m->err < 0)
 405                 return;
 406
 407         n = m->trans->poll(m->trans, NULL);
 408         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 409                 P9_DPRINTK(P9_DEBUG_MUX, "error mux %p err %d\n", m, n);
 410                 if (n >= 0)
 411                         n = -ECONNRESET;
 412                 p9_conn_cancel(m, n);
 413         }
 414
 415         if (n & POLLIN) {
 416                 set_bit(Rpending, &m->wsched);
 417                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 418                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 419                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 420                         queue_work(p9_mux_wq, &m->rq);
 421                 }
 422         }
 423
 424         if (n & POLLOUT) {
 425                 set_bit(Wpending, &m->wsched);
 426                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 427                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 428                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 429                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 430                         queue_work(p9_mux_wq, &m->wq);
 431                 }
 432         }
 433 }
 434
 435 /**
 436  * p9_poll_proc - polls all v9fs transports for new events and queues
 437  *      the appropriate work to the work queue
 438  */
 439 static int p9_poll_proc(void *a)
 440 {
 441         struct p9_conn *m, *mtmp;
 442         struct p9_mux_poll_task *vpt;
 443
 444         vpt = a;
 445         P9_DPRINTK(P9_DEBUG_MUX, "start %p %p\n", current, vpt);
 446         while (!kthread_should_stop()) {
 447                 set_current_state(TASK_INTERRUPTIBLE);
 448
 449                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 450                         p9_poll_mux(m);
 451                 }
 452
 453                 P9_DPRINTK(P9_DEBUG_MUX, "sleeping...\n");
 454                 schedule_timeout(SCHED_TIMEOUT * HZ);
 455         }
 456
 457         __set_current_state(TASK_RUNNING);
 458         P9_DPRINTK(P9_DEBUG_MUX, "finish\n");
 459         return 0;
 460 }
 461
 462 /**
 463  * p9_write_work - called when a transport can send some data
 464  */
 465 static void p9_write_work(struct work_struct *work)
 466 {
 467         int n, err;
 468         struct p9_conn *m;
 469         struct p9_req *req;
 470
 471         m = container_of(work, struct p9_conn, wq);
 472
 473         if (m->err < 0) {
 474                 clear_bit(Wworksched, &m->wsched);
 475                 return;
 476         }
 477
 478         if (!m->wsize) {
 479                 if (list_empty(&m->unsent_req_list)) {
 480                         clear_bit(Wworksched, &m->wsched);
 481                         return;
 482                 }
 483
 484                 spin_lock(&m->lock);
 485 again:
 486                 req = list_entry(m->unsent_req_list.next, struct p9_req,
 487                                req_list);
 488                 list_move_tail(&req->req_list, &m->req_list);
 489                 if (req->err == ERREQFLUSH)
 490                         goto again;
 491
 492                 m->wbuf = req->tcall->sdata;
 493                 m->wsize = req->tcall->size;
 494                 m->wpos = 0;
 495                 spin_unlock(&m->lock);
 496         }
 497
 498         P9_DPRINTK(P9_DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos,
 499                                                                 m->wsize);
 500         clear_bit(Wpending, &m->wsched);
 501         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 502         P9_DPRINTK(P9_DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 503         if (err == -EAGAIN) {
 504                 clear_bit(Wworksched, &m->wsched);
 505                 return;
 506         }
 507
 508         if (err < 0)
 509                 goto error;
 510         else if (err == 0) {
 511                 err = -EREMOTEIO;
 512                 goto error;
 513         }
 514
 515         m->wpos += err;
 516         if (m->wpos == m->wsize)
 517                 m->wpos = m->wsize = 0;
 518
 519         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 520                 if (test_and_clear_bit(Wpending, &m->wsched))
 521                         n = POLLOUT;
 522                 else
 523                         n = m->trans->poll(m->trans, NULL);
 524
 525                 if (n & POLLOUT) {
 526                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 527                         queue_work(p9_mux_wq, &m->wq);
 528                 } else
 529                         clear_bit(Wworksched, &m->wsched);
 530         } else
 531                 clear_bit(Wworksched, &m->wsched);
 532
 533         return;
 534
 535 error:
 536         p9_conn_cancel(m, err);
 537         clear_bit(Wworksched, &m->wsched);
 538 }
 539
 540 static void process_request(struct p9_conn *m, struct p9_req *req)
 541 {
 542         int ecode;
 543         struct p9_str *ename;
 544
 545         if (!req->err && req->rcall->id == P9_RERROR) {
 546                 ecode = req->rcall->params.rerror.errno;
 547                 ename = &req->rcall->params.rerror.error;
 548
 549                 P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
 550                                                                 ename->str);
 551
 552                 if (*m->extended)
 553                         req->err = -ecode;
 554
 555                 if (!req->err) {
 556                         req->err = p9_errstr2errno(ename->str, ename->len);
 557
 558                         if (!req->err) {        /* string match failed */
 559                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 560                         }
 561
 562                         if (!req->err)
 563                                 req->err = -ESERVERFAULT;
 564                 }
 565         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 566                 P9_DPRINTK(P9_DEBUG_ERROR,
 567                                 "fcall mismatch: expected %d, got %d\n",
 568                                 req->tcall->id + 1, req->rcall->id);
 569                 if (!req->err)
 570                         req->err = -EIO;
 571         }
 572 }
 573
 574 /**
 575  * p9_read_work - called when there is some data to be read from a transport
 576  */
 577 static void p9_read_work(struct work_struct *work)
 578 {
 579         int n, err;
 580         struct p9_conn *m;
 581         struct p9_req *req, *rptr, *rreq;
 582         struct p9_fcall *rcall;
 583         char *rbuf;
 584
 585         m = container_of(work, struct p9_conn, rq);
 586
 587         if (m->err < 0)
 588                 return;
 589
 590         rcall = NULL;
 591         P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 592
 593         if (!m->rcall) {
 594                 m->rcall =
 595                     kmalloc(sizeof(struct p9_fcall) + m->msize, GFP_KERNEL);
 596                 if (!m->rcall) {
 597                         err = -ENOMEM;
 598                         goto error;
 599                 }
 600
 601                 m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 602                 m->rpos = 0;
 603         }
 604
 605         clear_bit(Rpending, &m->wsched);
 606         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 607         P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 608         if (err == -EAGAIN) {
 609                 clear_bit(Rworksched, &m->wsched);
 610                 return;
 611         }
 612
 613         if (err <= 0)
 614                 goto error;
 615
 616         m->rpos += err;
 617         while (m->rpos > 4) {
 618                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 619                 if (n >= m->msize) {
 620                         P9_DPRINTK(P9_DEBUG_ERROR,
 621                                 "requested packet size too big: %d\n", n);
 622                         err = -EIO;
 623                         goto error;
 624                 }
 625
 626                 if (m->rpos < n)
 627                         break;
 628
 629                 err =
 630                     p9_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 631                 if (err < 0) {
 632                         goto error;
 633                 }
 634
 635 #ifdef CONFIG_NET_9P_DEBUG
 636                 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 637                         char buf[150];
 638
 639                         p9_printfcall(buf, sizeof(buf), m->rcall,
 640                                 *m->extended);
 641                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 642                 }
 643 #endif
 644
 645                 rcall = m->rcall;
 646                 rbuf = m->rbuf;
 647                 if (m->rpos > n) {
 648                         m->rcall = kmalloc(sizeof(struct p9_fcall) + m->msize,
 649                                            GFP_KERNEL);
 650                         if (!m->rcall) {
 651                                 err = -ENOMEM;
 652                                 goto error;
 653                         }
 654
 655                         m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 656                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 657                         m->rpos -= n;
 658                 } else {
 659                         m->rcall = NULL;
 660                         m->rbuf = NULL;
 661                         m->rpos = 0;
 662                 }
 663
 664                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
 665                                                         rcall->id, rcall->tag);
 666
 667                 req = NULL;
 668                 spin_lock(&m->lock);
 669                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 670                         if (rreq->tag == rcall->tag) {
 671                                 req = rreq;
 672                                 if (req->flush != Flushing)
 673                                         list_del(&req->req_list);
 674                                 break;
 675                         }
 676                 }
 677                 spin_unlock(&m->lock);
 678
 679                 if (req) {
 680                         req->rcall = rcall;
 681                         process_request(m, req);
 682
 683                         if (req->flush != Flushing) {
 684                                 if (req->cb)
 685                                         (*req->cb) (req, req->cba);
 686                                 else
 687                                         kfree(req->rcall);
 688
 689                                 wake_up(&m->equeue);
 690                         }
 691                 } else {
 692                         if (err >= 0 && rcall->id != P9_RFLUSH)
 693                                 P9_DPRINTK(P9_DEBUG_ERROR,
 694                                   "unexpected response mux %p id %d tag %d\n",
 695                                   m, rcall->id, rcall->tag);
 696                         kfree(rcall);
 697                 }
 698         }
 699
 700         if (!list_empty(&m->req_list)) {
 701                 if (test_and_clear_bit(Rpending, &m->wsched))
 702                         n = POLLIN;
 703                 else
 704                         n = m->trans->poll(m->trans, NULL);
 705
 706                 if (n & POLLIN) {
 707                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 708                         queue_work(p9_mux_wq, &m->rq);
 709                 } else
 710                         clear_bit(Rworksched, &m->wsched);
 711         } else
 712                 clear_bit(Rworksched, &m->wsched);
 713
 714         return;
 715
 716 error:
 717         p9_conn_cancel(m, err);
 718         clear_bit(Rworksched, &m->wsched);
 719 }
 720
 721 /**
 722  * p9_send_request - send 9P request
 723  * The function can sleep until the request is scheduled for sending.
 724  * The function can be interrupted. Return from the function is not
 725  * a guarantee that the request is sent successfully. Can return errors
 726  * that can be retrieved by PTR_ERR macros.
 727  *
 728  * @m: mux data
 729  * @tc: request to be sent
 730  * @cb: callback function to call when response is received
 731  * @cba: parameter to pass to the callback function
 732  */
 733 static struct p9_req *p9_send_request(struct p9_conn *m,
 734                                           struct p9_fcall *tc,
 735                                           p9_conn_req_callback cb, void *cba)
 736 {
 737         int n;
 738         struct p9_req *req;
 739
 740         P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 741                 tc, tc->id);
 742         if (m->err < 0)
 743                 return ERR_PTR(m->err);
 744
 745         req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
 746         if (!req)
 747                 return ERR_PTR(-ENOMEM);
 748
 749         if (tc->id == P9_TVERSION)
 750                 n = P9_NOTAG;
 751         else
 752                 n = p9_mux_get_tag(m);
 753
 754         if (n < 0)
 755                 return ERR_PTR(-ENOMEM);
 756
 757         p9_set_tag(tc, n);
 758
 759 #ifdef CONFIG_NET_9P_DEBUG
 760         if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 761                 char buf[150];
 762
 763                 p9_printfcall(buf, sizeof(buf), tc, *m->extended);
 764                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 765         }
 766 #endif
 767
 768         spin_lock_init(&req->lock);
 769         req->tag = n;
 770         req->tcall = tc;
 771         req->rcall = NULL;
 772         req->err = 0;
 773         req->cb = cb;
 774         req->cba = cba;
 775         req->flush = None;
 776
 777         spin_lock(&m->lock);
 778         list_add_tail(&req->req_list, &m->unsent_req_list);
 779         spin_unlock(&m->lock);
 780
 781         if (test_and_clear_bit(Wpending, &m->wsched))
 782                 n = POLLOUT;
 783         else
 784                 n = m->trans->poll(m->trans, NULL);
 785
 786         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 787                 queue_work(p9_mux_wq, &m->wq);
 788
 789         return req;
 790 }
 791
 792 static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
 793 {
 794         p9_mux_put_tag(m, req->tag);
 795         kfree(req);
 796 }
 797
 798 static void p9_mux_flush_cb(struct p9_req *freq, void *a)
 799 {
 800         p9_conn_req_callback cb;
 801         int tag;
 802         struct p9_conn *m;
 803         struct p9_req *req, *rreq, *rptr;
 804
 805         m = a;
 806         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 807                 freq->tcall, freq->rcall, freq->err,
 808                 freq->tcall->params.tflush.oldtag);
 809
 810         spin_lock(&m->lock);
 811         cb = NULL;
 812         tag = freq->tcall->params.tflush.oldtag;
 813         req = NULL;
 814         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 815                 if (rreq->tag == tag) {
 816                         req = rreq;
 817                         list_del(&req->req_list);
 818                         break;
 819                 }
 820         }
 821         spin_unlock(&m->lock);
 822
 823         if (req) {
 824                 spin_lock(&req->lock);
 825                 req->flush = Flushed;
 826                 spin_unlock(&req->lock);
 827
 828                 if (req->cb)
 829                         (*req->cb) (req, req->cba);
 830                 else
 831                         kfree(req->rcall);
 832
 833                 wake_up(&m->equeue);
 834         }
 835
 836         kfree(freq->tcall);
 837         kfree(freq->rcall);
 838         p9_mux_free_request(m, freq);
 839 }
 840
 841 static int
 842 p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
 843 {
 844         struct p9_fcall *fc;
 845         struct p9_req *rreq, *rptr;
 846
 847         P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 848
 849         /* if a response was received for a request, do nothing */
 850         spin_lock(&req->lock);
 851         if (req->rcall || req->err) {
 852                 spin_unlock(&req->lock);
 853                 P9_DPRINTK(P9_DEBUG_MUX,
 854                         "mux %p req %p response already received\n", m, req);
 855                 return 0;
 856         }
 857
 858         req->flush = Flushing;
 859         spin_unlock(&req->lock);
 860
 861         spin_lock(&m->lock);
 862         /* if the request is not sent yet, just remove it from the list */
 863         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 864                 if (rreq->tag == req->tag) {
 865                         P9_DPRINTK(P9_DEBUG_MUX,
 866                            "mux %p req %p request is not sent yet\n", m, req);
 867                         list_del(&rreq->req_list);
 868                         req->flush = Flushed;
 869                         spin_unlock(&m->lock);
 870                         if (req->cb)
 871                                 (*req->cb) (req, req->cba);
 872                         return 0;
 873                 }
 874         }
 875         spin_unlock(&m->lock);
 876
 877         clear_thread_flag(TIF_SIGPENDING);
 878         fc = p9_create_tflush(req->tag);
 879         p9_send_request(m, fc, p9_mux_flush_cb, m);
 880         return 1;
 881 }
 882
 883 static void
 884 p9_conn_rpc_cb(struct p9_req *req, void *a)
 885 {
 886         struct p9_mux_rpc *r;
 887
 888         P9_DPRINTK(P9_DEBUG_MUX, "req %p r %p\n", req, a);
 889         r = a;
 890         r->rcall = req->rcall;
 891         r->err = req->err;
 892
 893         if (req->flush != None && !req->err)
 894                 r->err = -ERESTARTSYS;
 895
 896         wake_up(&r->wqueue);
 897 }
 898
 899 /**
 900  * p9_mux_rpc - sends 9P request and waits until a response is available.
 901  *      The function can be interrupted.
 902  * @m: mux data
 903  * @tc: request to be sent
 904  * @rc: pointer where a pointer to the response is stored
 905  */
 906 int
 907 p9_conn_rpc(struct p9_conn *m, struct p9_fcall *tc,
 908              struct p9_fcall **rc)
 909 {
 910         int err, sigpending;
 911         unsigned long flags;
 912         struct p9_req *req;
 913         struct p9_mux_rpc r;
 914
 915         r.err = 0;
 916         r.tcall = tc;
 917         r.rcall = NULL;
 918         r.m = m;
 919         init_waitqueue_head(&r.wqueue);
 920
 921         if (rc)
 922                 *rc = NULL;
 923
 924         sigpending = 0;
 925         if (signal_pending(current)) {
 926                 sigpending = 1;
 927                 clear_thread_flag(TIF_SIGPENDING);
 928         }
 929
 930         req = p9_send_request(m, tc, p9_conn_rpc_cb, &r);
 931         if (IS_ERR(req)) {
 932                 err = PTR_ERR(req);
 933                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 934                 return err;
 935         }
 936
 937         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 938         if (r.err < 0)
 939                 err = r.err;
 940
 941         if (err == -ERESTARTSYS && m->trans->status == Connected
 942                                                         && m->err == 0) {
 943                 if (p9_mux_flush_request(m, req)) {
 944                         /* wait until we get response of the flush message */
 945                         do {
 946                                 clear_thread_flag(TIF_SIGPENDING);
 947                                 err = wait_event_interruptible(r.wqueue,
 948                                         r.rcall || r.err);
 949                         } while (!r.rcall && !r.err && err == -ERESTARTSYS &&
 950                                 m->trans->status == Connected && !m->err);
 951
 952                         err = -ERESTARTSYS;
 953                 }
 954                 sigpending = 1;
 955         }
 956
 957         if (sigpending) {
 958                 spin_lock_irqsave(&current->sighand->siglock, flags);
 959                 recalc_sigpending();
 960                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 961         }
 962
 963         if (rc)
 964                 *rc = r.rcall;
 965         else
 966                 kfree(r.rcall);
 967
 968         p9_mux_free_request(m, req);
 969         if (err > 0)
 970                 err = -EIO;
 971
 972         return err;
 973 }
 974 EXPORT_SYMBOL(p9_conn_rpc);
 975
 976 #ifdef P9_NONBLOCK
 977 /**
 978  * p9_conn_rpcnb - sends 9P request without waiting for response.
 979  * @m: mux data
 980  * @tc: request to be sent
 981  * @cb: callback function to be called when response arrives
 982  * @cba: value to pass to the callback function
 983  */
 984 int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
 985                    p9_conn_req_callback cb, void *a)
 986 {
 987         int err;
 988         struct p9_req *req;
 989
 990         req = p9_send_request(m, tc, cb, a);
 991         if (IS_ERR(req)) {
 992                 err = PTR_ERR(req);
 993                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 994                 return PTR_ERR(req);
 995         }
 996
 997         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 998         return 0;
 999 }
1000 EXPORT_SYMBOL(p9_conn_rpcnb);
1001 #endif /* P9_NONBLOCK */
1002
1003 /**
1004  * p9_conn_cancel - cancel all pending requests with error
1005  * @m: mux data
1006  * @err: error code
1007  */
1008 void p9_conn_cancel(struct p9_conn *m, int err)
1009 {
1010         struct p9_req *req, *rtmp;
1011         LIST_HEAD(cancel_list);
1012
1013         P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
1014         m->err = err;
1015         spin_lock(&m->lock);
1016         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
1017                 list_move(&req->req_list, &cancel_list);
1018         }
1019         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1020                 list_move(&req->req_list, &cancel_list);
1021         }
1022         spin_unlock(&m->lock);
1023
1024         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1025                 list_del(&req->req_list);
1026                 if (!req->err)
1027                         req->err = err;
1028
1029                 if (req->cb)
1030                         (*req->cb) (req, req->cba);
1031                 else
1032                         kfree(req->rcall);
1033         }
1034
1035         wake_up(&m->equeue);
1036 }
1037 EXPORT_SYMBOL(p9_conn_cancel);
1038
1039 static u16 p9_mux_get_tag(struct p9_conn *m)
1040 {
1041         int tag;
1042
1043         tag = p9_idpool_get(m->tagpool);
1044         if (tag < 0)
1045                 return P9_NOTAG;
1046         else
1047                 return (u16) tag;
1048 }
1049
1050 static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
1051 {
1052         if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
1053                 p9_idpool_put(tag, m->tagpool);
1054 }