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 <linux/parser.h>
  35 #include <net/9p/transport.h>
  36 #include <net/9p/conn.h>
  37
  38 #define ERREQFLUSH      1
  39 #define SCHED_TIMEOUT   10
  40 #define MAXPOLLWADDR    2
  41
  42 enum {
  43         Rworksched = 1,         /* read work scheduled or running */
  44         Rpending = 2,           /* can read */
  45         Wworksched = 4,         /* write work scheduled or running */
  46         Wpending = 8,           /* can write */
  47 };
  48
  49 enum {
  50         None,
  51         Flushing,
  52         Flushed,
  53 };
  54
  55 struct p9_mux_poll_task;
  56
  57 struct p9_req {
  58         spinlock_t lock; /* protect request structure */
  59         int tag;
  60         struct p9_fcall *tcall;
  61         struct p9_fcall *rcall;
  62         int err;
  63         p9_conn_req_callback cb;
  64         void *cba;
  65         int flush;
  66         struct list_head req_list;
  67 };
  68
  69 struct p9_conn {
  70         spinlock_t lock; /* protect lock structure */
  71         struct list_head mux_list;
  72         struct p9_mux_poll_task *poll_task;
  73         int msize;
  74         unsigned char *extended;
  75         struct p9_trans *trans;
  76         struct p9_idpool *tagpool;
  77         int err;
  78         wait_queue_head_t equeue;
  79         struct list_head req_list;
  80         struct list_head unsent_req_list;
  81         struct p9_fcall *rcall;
  82         int rpos;
  83         char *rbuf;
  84         int wpos;
  85         int wsize;
  86         char *wbuf;
  87         wait_queue_t poll_wait[MAXPOLLWADDR];
  88         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  89         poll_table pt;
  90         struct work_struct rq;
  91         struct work_struct wq;
  92         unsigned long wsched;
  93 };
  94
  95 struct p9_mux_poll_task {
  96         struct task_struct *task;
  97         struct list_head mux_list;
  98         int muxnum;
  99 };
 100
 101 struct p9_mux_rpc {
 102         struct p9_conn *m;
 103         int err;
 104         struct p9_fcall *tcall;
 105         struct p9_fcall *rcall;
 106         wait_queue_head_t wqueue;
 107 };
 108
 109 static int p9_poll_proc(void *);
 110 static void p9_read_work(struct work_struct *work);
 111 static void p9_write_work(struct work_struct *work);
 112 static void p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
 113                           poll_table * p);
 114 static u16 p9_mux_get_tag(struct p9_conn *);
 115 static void p9_mux_put_tag(struct p9_conn *, u16);
 116
 117 static DEFINE_MUTEX(p9_mux_task_lock);
 118 static struct workqueue_struct *p9_mux_wq;
 119
 120 static int p9_mux_num;
 121 static int p9_mux_poll_task_num;
 122 static struct p9_mux_poll_task p9_mux_poll_tasks[100];
 123
 124 int p9_mux_global_init(void)
 125 {
 126         int i;
 127
 128         for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++)
 129                 p9_mux_poll_tasks[i].task = NULL;
 130
 131         p9_mux_wq = create_workqueue("v9fs");
 132         if (!p9_mux_wq) {
 133                 printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
 134                 return -ENOMEM;
 135         }
 136
 137         return 0;
 138 }
 139
 140 void p9_mux_global_exit(void)
 141 {
 142         destroy_workqueue(p9_mux_wq);
 143 }
 144
 145 /**
 146  * p9_mux_calc_poll_procs - calculates the number of polling procs
 147  * based on the number of mounted v9fs filesystems.
 148  *
 149  * The current implementation returns sqrt of the number of mounts.
 150  */
 151 static int p9_mux_calc_poll_procs(int muxnum)
 152 {
 153         int n;
 154
 155         if (p9_mux_poll_task_num)
 156                 n = muxnum / p9_mux_poll_task_num +
 157                     (muxnum % p9_mux_poll_task_num ? 1 : 0);
 158         else
 159                 n = 1;
 160
 161         if (n > ARRAY_SIZE(p9_mux_poll_tasks))
 162                 n = ARRAY_SIZE(p9_mux_poll_tasks);
 163
 164         return n;
 165 }
 166
 167 static int p9_mux_poll_start(struct p9_conn *m)
 168 {
 169         int i, n;
 170         struct p9_mux_poll_task *vpt, *vptlast;
 171         struct task_struct *pproc;
 172
 173         P9_DPRINTK(P9_DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, p9_mux_num,
 174                 p9_mux_poll_task_num);
 175         mutex_lock(&p9_mux_task_lock);
 176
 177         n = p9_mux_calc_poll_procs(p9_mux_num + 1);
 178         if (n > p9_mux_poll_task_num) {
 179                 for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
 180                         if (p9_mux_poll_tasks[i].task == NULL) {
 181                                 vpt = &p9_mux_poll_tasks[i];
 182                                 P9_DPRINTK(P9_DEBUG_MUX, "create proc %p\n",
 183                                                                         vpt);
 184                                 pproc = kthread_create(p9_poll_proc, vpt,
 185                                                                 "v9fs-poll");
 186
 187                                 if (!IS_ERR(pproc)) {
 188                                         vpt->task = pproc;
 189                                         INIT_LIST_HEAD(&vpt->mux_list);
 190                                         vpt->muxnum = 0;
 191                                         p9_mux_poll_task_num++;
 192                                         wake_up_process(vpt->task);
 193                                 }
 194                                 break;
 195                         }
 196                 }
 197
 198                 if (i >= ARRAY_SIZE(p9_mux_poll_tasks))
 199                         P9_DPRINTK(P9_DEBUG_ERROR,
 200                                         "warning: no free poll slots\n");
 201         }
 202
 203         n = (p9_mux_num + 1) / p9_mux_poll_task_num +
 204             ((p9_mux_num + 1) % p9_mux_poll_task_num ? 1 : 0);
 205
 206         vptlast = NULL;
 207         for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
 208                 vpt = &p9_mux_poll_tasks[i];
 209                 if (vpt->task != NULL) {
 210                         vptlast = vpt;
 211                         if (vpt->muxnum < n) {
 212                                 P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
 213                                 list_add(&m->mux_list, &vpt->mux_list);
 214                                 vpt->muxnum++;
 215                                 m->poll_task = vpt;
 216                                 memset(&m->poll_waddr, 0,
 217                                                         sizeof(m->poll_waddr));
 218                                 init_poll_funcptr(&m->pt, p9_pollwait);
 219                                 break;
 220                         }
 221                 }
 222         }
 223
 224         if (i >= ARRAY_SIZE(p9_mux_poll_tasks)) {
 225                 if (vptlast == NULL)
 226                         return -ENOMEM;
 227
 228                 P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
 229                 list_add(&m->mux_list, &vptlast->mux_list);
 230                 vptlast->muxnum++;
 231                 m->poll_task = vptlast;
 232                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 233                 init_poll_funcptr(&m->pt, p9_pollwait);
 234         }
 235
 236         p9_mux_num++;
 237         mutex_unlock(&p9_mux_task_lock);
 238
 239         return 0;
 240 }
 241
 242 static void p9_mux_poll_stop(struct p9_conn *m)
 243 {
 244         int i;
 245         struct p9_mux_poll_task *vpt;
 246
 247         mutex_lock(&p9_mux_task_lock);
 248         vpt = m->poll_task;
 249         list_del(&m->mux_list);
 250         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 251                 if (m->poll_waddr[i] != NULL) {
 252                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 253                         m->poll_waddr[i] = NULL;
 254                 }
 255         }
 256         vpt->muxnum--;
 257         if (!vpt->muxnum) {
 258                 P9_DPRINTK(P9_DEBUG_MUX, "destroy proc %p\n", vpt);
 259                 kthread_stop(vpt->task);
 260                 vpt->task = NULL;
 261                 p9_mux_poll_task_num--;
 262         }
 263         p9_mux_num--;
 264         mutex_unlock(&p9_mux_task_lock);
 265 }
 266
 267 /**
 268  * p9_conn_create - allocate and initialize the per-session mux data
 269  * Creates the polling task if this is the first session.
 270  *
 271  * @trans - transport structure
 272  * @msize - maximum message size
 273  * @extended - pointer to the extended flag
 274  */
 275 struct p9_conn *p9_conn_create(struct p9_trans *trans, int msize,
 276                                     unsigned char *extended)
 277 {
 278         int i, n;
 279         struct p9_conn *m, *mtmp;
 280
 281         P9_DPRINTK(P9_DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 282         m = kmalloc(sizeof(struct p9_conn), GFP_KERNEL);
 283         if (!m)
 284                 return ERR_PTR(-ENOMEM);
 285
 286         spin_lock_init(&m->lock);
 287         INIT_LIST_HEAD(&m->mux_list);
 288         m->msize = msize;
 289         m->extended = extended;
 290         m->trans = trans;
 291         m->tagpool = p9_idpool_create();
 292         if (IS_ERR(m->tagpool)) {
 293                 mtmp = ERR_PTR(-ENOMEM);
 294                 kfree(m);
 295                 return mtmp;
 296         }
 297
 298         m->err = 0;
 299         init_waitqueue_head(&m->equeue);
 300         INIT_LIST_HEAD(&m->req_list);
 301         INIT_LIST_HEAD(&m->unsent_req_list);
 302         m->rcall = NULL;
 303         m->rpos = 0;
 304         m->rbuf = NULL;
 305         m->wpos = m->wsize = 0;
 306         m->wbuf = NULL;
 307         INIT_WORK(&m->rq, p9_read_work);
 308         INIT_WORK(&m->wq, p9_write_work);
 309         m->wsched = 0;
 310         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 311         m->poll_task = NULL;
 312         n = p9_mux_poll_start(m);
 313         if (n) {
 314                 kfree(m);
 315                 return ERR_PTR(n);
 316         }
 317
 318         n = trans->poll(trans, &m->pt);
 319         if (n & POLLIN) {
 320                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 321                 set_bit(Rpending, &m->wsched);
 322         }
 323
 324         if (n & POLLOUT) {
 325                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 326                 set_bit(Wpending, &m->wsched);
 327         }
 328
 329         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 330                 if (IS_ERR(m->poll_waddr[i])) {
 331                         p9_mux_poll_stop(m);
 332                         mtmp = (void *)m->poll_waddr;   /* the error code */
 333                         kfree(m);
 334                         m = mtmp;
 335                         break;
 336                 }
 337         }
 338
 339         return m;
 340 }
 341 EXPORT_SYMBOL(p9_conn_create);
 342
 343 /**
 344  * p9_mux_destroy - cancels all pending requests and frees mux resources
 345  */
 346 void p9_conn_destroy(struct p9_conn *m)
 347 {
 348         P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m,
 349                 m->mux_list.prev, m->mux_list.next);
 350         p9_conn_cancel(m, -ECONNRESET);
 351
 352         if (!list_empty(&m->req_list)) {
 353                 /* wait until all processes waiting on this session exit */
 354                 P9_DPRINTK(P9_DEBUG_MUX,
 355                         "mux %p waiting for empty request queue\n", m);
 356                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 357                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 358                         list_empty(&m->req_list));
 359         }
 360
 361         p9_mux_poll_stop(m);
 362         m->trans = NULL;
 363         p9_idpool_destroy(m->tagpool);
 364         kfree(m);
 365 }
 366 EXPORT_SYMBOL(p9_conn_destroy);
 367
 368 /**
 369  * p9_pollwait - called by files poll operation to add v9fs-poll task
 370  *      to files wait queue
 371  */
 372 static void
 373 p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
 374               poll_table * p)
 375 {
 376         int i;
 377         struct p9_conn *m;
 378
 379         m = container_of(p, struct p9_conn, pt);
 380         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 381                 if (m->poll_waddr[i] == NULL)
 382                         break;
 383
 384         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 385                 P9_DPRINTK(P9_DEBUG_ERROR, "not enough wait_address slots\n");
 386                 return;
 387         }
 388
 389         m->poll_waddr[i] = wait_address;
 390
 391         if (!wait_address) {
 392                 P9_DPRINTK(P9_DEBUG_ERROR, "no wait_address\n");
 393                 m->poll_waddr[i] = ERR_PTR(-EIO);
 394                 return;
 395         }
 396
 397         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 398         add_wait_queue(wait_address, &m->poll_wait[i]);
 399 }
 400
 401 /**
 402  * p9_poll_mux - polls a mux and schedules read or write works if necessary
 403  */
 404 static void p9_poll_mux(struct p9_conn *m)
 405 {
 406         int n;
 407
 408         if (m->err < 0)
 409                 return;
 410
 411         n = m->trans->poll(m->trans, NULL);
 412         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 413                 P9_DPRINTK(P9_DEBUG_MUX, "error mux %p err %d\n", m, n);
 414                 if (n >= 0)
 415                         n = -ECONNRESET;
 416                 p9_conn_cancel(m, n);
 417         }
 418
 419         if (n & POLLIN) {
 420                 set_bit(Rpending, &m->wsched);
 421                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 422                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 423                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 424                         queue_work(p9_mux_wq, &m->rq);
 425                 }
 426         }
 427
 428         if (n & POLLOUT) {
 429                 set_bit(Wpending, &m->wsched);
 430                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 431                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 432                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 433                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 434                         queue_work(p9_mux_wq, &m->wq);
 435                 }
 436         }
 437 }
 438
 439 /**
 440  * p9_poll_proc - polls all v9fs transports for new events and queues
 441  *      the appropriate work to the work queue
 442  */
 443 static int p9_poll_proc(void *a)
 444 {
 445         struct p9_conn *m, *mtmp;
 446         struct p9_mux_poll_task *vpt;
 447
 448         vpt = a;
 449         P9_DPRINTK(P9_DEBUG_MUX, "start %p %p\n", current, vpt);
 450         while (!kthread_should_stop()) {
 451                 set_current_state(TASK_INTERRUPTIBLE);
 452
 453                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 454                         p9_poll_mux(m);
 455                 }
 456
 457                 P9_DPRINTK(P9_DEBUG_MUX, "sleeping...\n");
 458                 schedule_timeout(SCHED_TIMEOUT * HZ);
 459         }
 460
 461         __set_current_state(TASK_RUNNING);
 462         P9_DPRINTK(P9_DEBUG_MUX, "finish\n");
 463         return 0;
 464 }
 465
 466 /**
 467  * p9_write_work - called when a transport can send some data
 468  */
 469 static void p9_write_work(struct work_struct *work)
 470 {
 471         int n, err;
 472         struct p9_conn *m;
 473         struct p9_req *req;
 474
 475         m = container_of(work, struct p9_conn, wq);
 476
 477         if (m->err < 0) {
 478                 clear_bit(Wworksched, &m->wsched);
 479                 return;
 480         }
 481
 482         if (!m->wsize) {
 483                 if (list_empty(&m->unsent_req_list)) {
 484                         clear_bit(Wworksched, &m->wsched);
 485                         return;
 486                 }
 487
 488                 spin_lock(&m->lock);
 489 again:
 490                 req = list_entry(m->unsent_req_list.next, struct p9_req,
 491                                req_list);
 492                 list_move_tail(&req->req_list, &m->req_list);
 493                 if (req->err == ERREQFLUSH)
 494                         goto again;
 495
 496                 m->wbuf = req->tcall->sdata;
 497                 m->wsize = req->tcall->size;
 498                 m->wpos = 0;
 499                 spin_unlock(&m->lock);
 500         }
 501
 502         P9_DPRINTK(P9_DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos,
 503                                                                 m->wsize);
 504         clear_bit(Wpending, &m->wsched);
 505         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 506         P9_DPRINTK(P9_DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 507         if (err == -EAGAIN) {
 508                 clear_bit(Wworksched, &m->wsched);
 509                 return;
 510         }
 511
 512         if (err < 0)
 513                 goto error;
 514         else if (err == 0) {
 515                 err = -EREMOTEIO;
 516                 goto error;
 517         }
 518
 519         m->wpos += err;
 520         if (m->wpos == m->wsize)
 521                 m->wpos = m->wsize = 0;
 522
 523         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 524                 if (test_and_clear_bit(Wpending, &m->wsched))
 525                         n = POLLOUT;
 526                 else
 527                         n = m->trans->poll(m->trans, NULL);
 528
 529                 if (n & POLLOUT) {
 530                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 531                         queue_work(p9_mux_wq, &m->wq);
 532                 } else
 533                         clear_bit(Wworksched, &m->wsched);
 534         } else
 535                 clear_bit(Wworksched, &m->wsched);
 536
 537         return;
 538
 539 error:
 540         p9_conn_cancel(m, err);
 541         clear_bit(Wworksched, &m->wsched);
 542 }
 543
 544 static void process_request(struct p9_conn *m, struct p9_req *req)
 545 {
 546         int ecode;
 547         struct p9_str *ename;
 548
 549         if (!req->err && req->rcall->id == P9_RERROR) {
 550                 ecode = req->rcall->params.rerror.errno;
 551                 ename = &req->rcall->params.rerror.error;
 552
 553                 P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
 554                                                                 ename->str);
 555
 556                 if (*m->extended)
 557                         req->err = -ecode;
 558
 559                 if (!req->err) {
 560                         req->err = p9_errstr2errno(ename->str, ename->len);
 561
 562                         if (!req->err) {        /* string match failed */
 563                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 564                         }
 565
 566                         if (!req->err)
 567                                 req->err = -ESERVERFAULT;
 568                 }
 569         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 570                 P9_DPRINTK(P9_DEBUG_ERROR,
 571                                 "fcall mismatch: expected %d, got %d\n",
 572                                 req->tcall->id + 1, req->rcall->id);
 573                 if (!req->err)
 574                         req->err = -EIO;
 575         }
 576 }
 577
 578 /**
 579  * p9_read_work - called when there is some data to be read from a transport
 580  */
 581 static void p9_read_work(struct work_struct *work)
 582 {
 583         int n, err;
 584         struct p9_conn *m;
 585         struct p9_req *req, *rptr, *rreq;
 586         struct p9_fcall *rcall;
 587         char *rbuf;
 588
 589         m = container_of(work, struct p9_conn, rq);
 590
 591         if (m->err < 0)
 592                 return;
 593
 594         rcall = NULL;
 595         P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 596
 597         if (!m->rcall) {
 598                 m->rcall =
 599                     kmalloc(sizeof(struct p9_fcall) + m->msize, GFP_KERNEL);
 600                 if (!m->rcall) {
 601                         err = -ENOMEM;
 602                         goto error;
 603                 }
 604
 605                 m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 606                 m->rpos = 0;
 607         }
 608
 609         clear_bit(Rpending, &m->wsched);
 610         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 611         P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 612         if (err == -EAGAIN) {
 613                 clear_bit(Rworksched, &m->wsched);
 614                 return;
 615         }
 616
 617         if (err <= 0)
 618                 goto error;
 619
 620         m->rpos += err;
 621         while (m->rpos > 4) {
 622                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 623                 if (n >= m->msize) {
 624                         P9_DPRINTK(P9_DEBUG_ERROR,
 625                                 "requested packet size too big: %d\n", n);
 626                         err = -EIO;
 627                         goto error;
 628                 }
 629
 630                 if (m->rpos < n)
 631                         break;
 632
 633                 err =
 634                     p9_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 635                 if (err < 0) {
 636                         goto error;
 637                 }
 638
 639 #ifdef CONFIG_NET_9P_DEBUG
 640                 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 641                         char buf[150];
 642
 643                         p9_printfcall(buf, sizeof(buf), m->rcall,
 644                                 *m->extended);
 645                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 646                 }
 647 #endif
 648
 649                 rcall = m->rcall;
 650                 rbuf = m->rbuf;
 651                 if (m->rpos > n) {
 652                         m->rcall = kmalloc(sizeof(struct p9_fcall) + m->msize,
 653                                            GFP_KERNEL);
 654                         if (!m->rcall) {
 655                                 err = -ENOMEM;
 656                                 goto error;
 657                         }
 658
 659                         m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 660                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 661                         m->rpos -= n;
 662                 } else {
 663                         m->rcall = NULL;
 664                         m->rbuf = NULL;
 665                         m->rpos = 0;
 666                 }
 667
 668                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
 669                                                         rcall->id, rcall->tag);
 670
 671                 req = NULL;
 672                 spin_lock(&m->lock);
 673                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 674                         if (rreq->tag == rcall->tag) {
 675                                 req = rreq;
 676                                 if (req->flush != Flushing)
 677                                         list_del(&req->req_list);
 678                                 break;
 679                         }
 680                 }
 681                 spin_unlock(&m->lock);
 682
 683                 if (req) {
 684                         req->rcall = rcall;
 685                         process_request(m, req);
 686
 687                         if (req->flush != Flushing) {
 688                                 if (req->cb)
 689                                         (*req->cb) (req, req->cba);
 690                                 else
 691                                         kfree(req->rcall);
 692
 693                                 wake_up(&m->equeue);
 694                         }
 695                 } else {
 696                         if (err >= 0 && rcall->id != P9_RFLUSH)
 697                                 P9_DPRINTK(P9_DEBUG_ERROR,
 698                                   "unexpected response mux %p id %d tag %d\n",
 699                                   m, rcall->id, rcall->tag);
 700                         kfree(rcall);
 701                 }
 702         }
 703
 704         if (!list_empty(&m->req_list)) {
 705                 if (test_and_clear_bit(Rpending, &m->wsched))
 706                         n = POLLIN;
 707                 else
 708                         n = m->trans->poll(m->trans, NULL);
 709
 710                 if (n & POLLIN) {
 711                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 712                         queue_work(p9_mux_wq, &m->rq);
 713                 } else
 714                         clear_bit(Rworksched, &m->wsched);
 715         } else
 716                 clear_bit(Rworksched, &m->wsched);
 717
 718         return;
 719
 720 error:
 721         p9_conn_cancel(m, err);
 722         clear_bit(Rworksched, &m->wsched);
 723 }
 724
 725 /**
 726  * p9_send_request - send 9P request
 727  * The function can sleep until the request is scheduled for sending.
 728  * The function can be interrupted. Return from the function is not
 729  * a guarantee that the request is sent successfully. Can return errors
 730  * that can be retrieved by PTR_ERR macros.
 731  *
 732  * @m: mux data
 733  * @tc: request to be sent
 734  * @cb: callback function to call when response is received
 735  * @cba: parameter to pass to the callback function
 736  */
 737 static struct p9_req *p9_send_request(struct p9_conn *m,
 738                                           struct p9_fcall *tc,
 739                                           p9_conn_req_callback cb, void *cba)
 740 {
 741         int n;
 742         struct p9_req *req;
 743
 744         P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 745                 tc, tc->id);
 746         if (m->err < 0)
 747                 return ERR_PTR(m->err);
 748
 749         req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
 750         if (!req)
 751                 return ERR_PTR(-ENOMEM);
 752
 753         if (tc->id == P9_TVERSION)
 754                 n = P9_NOTAG;
 755         else
 756                 n = p9_mux_get_tag(m);
 757
 758         if (n < 0)
 759                 return ERR_PTR(-ENOMEM);
 760
 761         p9_set_tag(tc, n);
 762
 763 #ifdef CONFIG_NET_9P_DEBUG
 764         if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 765                 char buf[150];
 766
 767                 p9_printfcall(buf, sizeof(buf), tc, *m->extended);
 768                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 769         }
 770 #endif
 771
 772         spin_lock_init(&req->lock);
 773         req->tag = n;
 774         req->tcall = tc;
 775         req->rcall = NULL;
 776         req->err = 0;
 777         req->cb = cb;
 778         req->cba = cba;
 779         req->flush = None;
 780
 781         spin_lock(&m->lock);
 782         list_add_tail(&req->req_list, &m->unsent_req_list);
 783         spin_unlock(&m->lock);
 784
 785         if (test_and_clear_bit(Wpending, &m->wsched))
 786                 n = POLLOUT;
 787         else
 788                 n = m->trans->poll(m->trans, NULL);
 789
 790         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 791                 queue_work(p9_mux_wq, &m->wq);
 792
 793         return req;
 794 }
 795
 796 static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
 797 {
 798         p9_mux_put_tag(m, req->tag);
 799         kfree(req);
 800 }
 801
 802 static void p9_mux_flush_cb(struct p9_req *freq, void *a)
 803 {
 804         p9_conn_req_callback cb;
 805         int tag;
 806         struct p9_conn *m;
 807         struct p9_req *req, *rreq, *rptr;
 808
 809         m = a;
 810         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 811                 freq->tcall, freq->rcall, freq->err,
 812                 freq->tcall->params.tflush.oldtag);
 813
 814         spin_lock(&m->lock);
 815         cb = NULL;
 816         tag = freq->tcall->params.tflush.oldtag;
 817         req = NULL;
 818         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 819                 if (rreq->tag == tag) {
 820                         req = rreq;
 821                         list_del(&req->req_list);
 822                         break;
 823                 }
 824         }
 825         spin_unlock(&m->lock);
 826
 827         if (req) {
 828                 spin_lock(&req->lock);
 829                 req->flush = Flushed;
 830                 spin_unlock(&req->lock);
 831
 832                 if (req->cb)
 833                         (*req->cb) (req, req->cba);
 834                 else
 835                         kfree(req->rcall);
 836
 837                 wake_up(&m->equeue);
 838         }
 839
 840         kfree(freq->tcall);
 841         kfree(freq->rcall);
 842         p9_mux_free_request(m, freq);
 843 }
 844
 845 static int
 846 p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
 847 {
 848         struct p9_fcall *fc;
 849         struct p9_req *rreq, *rptr;
 850
 851         P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 852
 853         /* if a response was received for a request, do nothing */
 854         spin_lock(&req->lock);
 855         if (req->rcall || req->err) {
 856                 spin_unlock(&req->lock);
 857                 P9_DPRINTK(P9_DEBUG_MUX,
 858                         "mux %p req %p response already received\n", m, req);
 859                 return 0;
 860         }
 861
 862         req->flush = Flushing;
 863         spin_unlock(&req->lock);
 864
 865         spin_lock(&m->lock);
 866         /* if the request is not sent yet, just remove it from the list */
 867         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 868                 if (rreq->tag == req->tag) {
 869                         P9_DPRINTK(P9_DEBUG_MUX,
 870                            "mux %p req %p request is not sent yet\n", m, req);
 871                         list_del(&rreq->req_list);
 872                         req->flush = Flushed;
 873                         spin_unlock(&m->lock);
 874                         if (req->cb)
 875                                 (*req->cb) (req, req->cba);
 876                         return 0;
 877                 }
 878         }
 879         spin_unlock(&m->lock);
 880
 881         clear_thread_flag(TIF_SIGPENDING);
 882         fc = p9_create_tflush(req->tag);
 883         p9_send_request(m, fc, p9_mux_flush_cb, m);
 884         return 1;
 885 }
 886
 887 static void
 888 p9_conn_rpc_cb(struct p9_req *req, void *a)
 889 {
 890         struct p9_mux_rpc *r;
 891
 892         P9_DPRINTK(P9_DEBUG_MUX, "req %p r %p\n", req, a);
 893         r = a;
 894         r->rcall = req->rcall;
 895         r->err = req->err;
 896
 897         if (req->flush != None && !req->err)
 898                 r->err = -ERESTARTSYS;
 899
 900         wake_up(&r->wqueue);
 901 }
 902
 903 /**
 904  * p9_mux_rpc - sends 9P request and waits until a response is available.
 905  *      The function can be interrupted.
 906  * @m: mux data
 907  * @tc: request to be sent
 908  * @rc: pointer where a pointer to the response is stored
 909  */
 910 int
 911 p9_conn_rpc(struct p9_conn *m, struct p9_fcall *tc,
 912              struct p9_fcall **rc)
 913 {
 914         int err, sigpending;
 915         unsigned long flags;
 916         struct p9_req *req;
 917         struct p9_mux_rpc r;
 918
 919         r.err = 0;
 920         r.tcall = tc;
 921         r.rcall = NULL;
 922         r.m = m;
 923         init_waitqueue_head(&r.wqueue);
 924
 925         if (rc)
 926                 *rc = NULL;
 927
 928         sigpending = 0;
 929         if (signal_pending(current)) {
 930                 sigpending = 1;
 931                 clear_thread_flag(TIF_SIGPENDING);
 932         }
 933
 934         req = p9_send_request(m, tc, p9_conn_rpc_cb, &r);
 935         if (IS_ERR(req)) {
 936                 err = PTR_ERR(req);
 937                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 938                 return err;
 939         }
 940
 941         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 942         if (r.err < 0)
 943                 err = r.err;
 944
 945         if (err == -ERESTARTSYS && m->trans->status == Connected
 946                                                         && m->err == 0) {
 947                 if (p9_mux_flush_request(m, req)) {
 948                         /* wait until we get response of the flush message */
 949                         do {
 950                                 clear_thread_flag(TIF_SIGPENDING);
 951                                 err = wait_event_interruptible(r.wqueue,
 952                                         r.rcall || r.err);
 953                         } while (!r.rcall && !r.err && err == -ERESTARTSYS &&
 954                                 m->trans->status == Connected && !m->err);
 955
 956                         err = -ERESTARTSYS;
 957                 }
 958                 sigpending = 1;
 959         }
 960
 961         if (sigpending) {
 962                 spin_lock_irqsave(&current->sighand->siglock, flags);
 963                 recalc_sigpending();
 964                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 965         }
 966
 967         if (rc)
 968                 *rc = r.rcall;
 969         else
 970                 kfree(r.rcall);
 971
 972         p9_mux_free_request(m, req);
 973         if (err > 0)
 974                 err = -EIO;
 975
 976         return err;
 977 }
 978 EXPORT_SYMBOL(p9_conn_rpc);
 979
 980 #ifdef P9_NONBLOCK
 981 /**
 982  * p9_conn_rpcnb - sends 9P request without waiting for response.
 983  * @m: mux data
 984  * @tc: request to be sent
 985  * @cb: callback function to be called when response arrives
 986  * @cba: value to pass to the callback function
 987  */
 988 int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
 989                    p9_conn_req_callback cb, void *a)
 990 {
 991         int err;
 992         struct p9_req *req;
 993
 994         req = p9_send_request(m, tc, cb, a);
 995         if (IS_ERR(req)) {
 996                 err = PTR_ERR(req);
 997                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 998                 return PTR_ERR(req);
 999         }
1000
1001         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
1002         return 0;
1003 }
1004 EXPORT_SYMBOL(p9_conn_rpcnb);
1005 #endif /* P9_NONBLOCK */
1006
1007 /**
1008  * p9_conn_cancel - cancel all pending requests with error
1009  * @m: mux data
1010  * @err: error code
1011  */
1012 void p9_conn_cancel(struct p9_conn *m, int err)
1013 {
1014         struct p9_req *req, *rtmp;
1015         LIST_HEAD(cancel_list);
1016
1017         P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
1018         m->err = err;
1019         spin_lock(&m->lock);
1020         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
1021                 list_move(&req->req_list, &cancel_list);
1022         }
1023         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1024                 list_move(&req->req_list, &cancel_list);
1025         }
1026         spin_unlock(&m->lock);
1027
1028         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1029                 list_del(&req->req_list);
1030                 if (!req->err)
1031                         req->err = err;
1032
1033                 if (req->cb)
1034                         (*req->cb) (req, req->cba);
1035                 else
1036                         kfree(req->rcall);
1037         }
1038
1039         wake_up(&m->equeue);
1040 }
1041 EXPORT_SYMBOL(p9_conn_cancel);
1042
1043 static u16 p9_mux_get_tag(struct p9_conn *m)
1044 {
1045         int tag;
1046
1047         tag = p9_idpool_get(m->tagpool);
1048         if (tag < 0)
1049                 return P9_NOTAG;
1050         else
1051                 return (u16) tag;
1052 }
1053
1054 static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
1055 {
1056         if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
1057                 p9_idpool_put(tag, m->tagpool);
1058 }