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   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_trans *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_trans *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 (IS_ERR(m->tagpool)) {
 292                 mtmp = ERR_PTR(-ENOMEM);
 293                 kfree(m);
 294                 return mtmp;
 295         }
 296
 297         m->err = 0;
 298         init_waitqueue_head(&m->equeue);
 299         INIT_LIST_HEAD(&m->req_list);
 300         INIT_LIST_HEAD(&m->unsent_req_list);
 301         m->rcall = NULL;
 302         m->rpos = 0;
 303         m->rbuf = NULL;
 304         m->wpos = m->wsize = 0;
 305         m->wbuf = NULL;
 306         INIT_WORK(&m->rq, p9_read_work);
 307         INIT_WORK(&m->wq, p9_write_work);
 308         m->wsched = 0;
 309         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 310         m->poll_task = NULL;
 311         n = p9_mux_poll_start(m);
 312         if (n) {
 313                 kfree(m);
 314                 return ERR_PTR(n);
 315         }
 316
 317         n = trans->poll(trans, &m->pt);
 318         if (n & POLLIN) {
 319                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 320                 set_bit(Rpending, &m->wsched);
 321         }
 322
 323         if (n & POLLOUT) {
 324                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 325                 set_bit(Wpending, &m->wsched);
 326         }
 327
 328         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 329                 if (IS_ERR(m->poll_waddr[i])) {
 330                         p9_mux_poll_stop(m);
 331                         mtmp = (void *)m->poll_waddr;   /* the error code */
 332                         kfree(m);
 333                         m = mtmp;
 334                         break;
 335                 }
 336         }
 337
 338         return m;
 339 }
 340 EXPORT_SYMBOL(p9_conn_create);
 341
 342 /**
 343  * p9_mux_destroy - cancels all pending requests and frees mux resources
 344  */
 345 void p9_conn_destroy(struct p9_conn *m)
 346 {
 347         P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m,
 348                 m->mux_list.prev, m->mux_list.next);
 349         p9_conn_cancel(m, -ECONNRESET);
 350
 351         if (!list_empty(&m->req_list)) {
 352                 /* wait until all processes waiting on this session exit */
 353                 P9_DPRINTK(P9_DEBUG_MUX,
 354                         "mux %p waiting for empty request queue\n", m);
 355                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 356                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 357                         list_empty(&m->req_list));
 358         }
 359
 360         p9_mux_poll_stop(m);
 361         m->trans = NULL;
 362         p9_idpool_destroy(m->tagpool);
 363         kfree(m);
 364 }
 365 EXPORT_SYMBOL(p9_conn_destroy);
 366
 367 /**
 368  * p9_pollwait - called by files poll operation to add v9fs-poll task
 369  *      to files wait queue
 370  */
 371 static void
 372 p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
 373               poll_table * p)
 374 {
 375         int i;
 376         struct p9_conn *m;
 377
 378         m = container_of(p, struct p9_conn, pt);
 379         for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 380                 if (m->poll_waddr[i] == NULL)
 381                         break;
 382
 383         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 384                 P9_DPRINTK(P9_DEBUG_ERROR, "not enough wait_address slots\n");
 385                 return;
 386         }
 387
 388         m->poll_waddr[i] = wait_address;
 389
 390         if (!wait_address) {
 391                 P9_DPRINTK(P9_DEBUG_ERROR, "no wait_address\n");
 392                 m->poll_waddr[i] = ERR_PTR(-EIO);
 393                 return;
 394         }
 395
 396         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 397         add_wait_queue(wait_address, &m->poll_wait[i]);
 398 }
 399
 400 /**
 401  * p9_poll_mux - polls a mux and schedules read or write works if necessary
 402  */
 403 static void p9_poll_mux(struct p9_conn *m)
 404 {
 405         int n;
 406
 407         if (m->err < 0)
 408                 return;
 409
 410         n = m->trans->poll(m->trans, NULL);
 411         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 412                 P9_DPRINTK(P9_DEBUG_MUX, "error mux %p err %d\n", m, n);
 413                 if (n >= 0)
 414                         n = -ECONNRESET;
 415                 p9_conn_cancel(m, n);
 416         }
 417
 418         if (n & POLLIN) {
 419                 set_bit(Rpending, &m->wsched);
 420                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
 421                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 422                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 423                         queue_work(p9_mux_wq, &m->rq);
 424                 }
 425         }
 426
 427         if (n & POLLOUT) {
 428                 set_bit(Wpending, &m->wsched);
 429                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
 430                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 431                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 432                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 433                         queue_work(p9_mux_wq, &m->wq);
 434                 }
 435         }
 436 }
 437
 438 /**
 439  * p9_poll_proc - polls all v9fs transports for new events and queues
 440  *      the appropriate work to the work queue
 441  */
 442 static int p9_poll_proc(void *a)
 443 {
 444         struct p9_conn *m, *mtmp;
 445         struct p9_mux_poll_task *vpt;
 446
 447         vpt = a;
 448         P9_DPRINTK(P9_DEBUG_MUX, "start %p %p\n", current, vpt);
 449         while (!kthread_should_stop()) {
 450                 set_current_state(TASK_INTERRUPTIBLE);
 451
 452                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 453                         p9_poll_mux(m);
 454                 }
 455
 456                 P9_DPRINTK(P9_DEBUG_MUX, "sleeping...\n");
 457                 schedule_timeout(SCHED_TIMEOUT * HZ);
 458         }
 459
 460         __set_current_state(TASK_RUNNING);
 461         P9_DPRINTK(P9_DEBUG_MUX, "finish\n");
 462         return 0;
 463 }
 464
 465 /**
 466  * p9_write_work - called when a transport can send some data
 467  */
 468 static void p9_write_work(struct work_struct *work)
 469 {
 470         int n, err;
 471         struct p9_conn *m;
 472         struct p9_req *req;
 473
 474         m = container_of(work, struct p9_conn, wq);
 475
 476         if (m->err < 0) {
 477                 clear_bit(Wworksched, &m->wsched);
 478                 return;
 479         }
 480
 481         if (!m->wsize) {
 482                 if (list_empty(&m->unsent_req_list)) {
 483                         clear_bit(Wworksched, &m->wsched);
 484                         return;
 485                 }
 486
 487                 spin_lock(&m->lock);
 488 again:
 489                 req = list_entry(m->unsent_req_list.next, struct p9_req,
 490                                req_list);
 491                 list_move_tail(&req->req_list, &m->req_list);
 492                 if (req->err == ERREQFLUSH)
 493                         goto again;
 494
 495                 m->wbuf = req->tcall->sdata;
 496                 m->wsize = req->tcall->size;
 497                 m->wpos = 0;
 498                 spin_unlock(&m->lock);
 499         }
 500
 501         P9_DPRINTK(P9_DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos,
 502                                                                 m->wsize);
 503         clear_bit(Wpending, &m->wsched);
 504         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 505         P9_DPRINTK(P9_DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 506         if (err == -EAGAIN) {
 507                 clear_bit(Wworksched, &m->wsched);
 508                 return;
 509         }
 510
 511         if (err < 0)
 512                 goto error;
 513         else if (err == 0) {
 514                 err = -EREMOTEIO;
 515                 goto error;
 516         }
 517
 518         m->wpos += err;
 519         if (m->wpos == m->wsize)
 520                 m->wpos = m->wsize = 0;
 521
 522         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 523                 if (test_and_clear_bit(Wpending, &m->wsched))
 524                         n = POLLOUT;
 525                 else
 526                         n = m->trans->poll(m->trans, NULL);
 527
 528                 if (n & POLLOUT) {
 529                         P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
 530                         queue_work(p9_mux_wq, &m->wq);
 531                 } else
 532                         clear_bit(Wworksched, &m->wsched);
 533         } else
 534                 clear_bit(Wworksched, &m->wsched);
 535
 536         return;
 537
 538 error:
 539         p9_conn_cancel(m, err);
 540         clear_bit(Wworksched, &m->wsched);
 541 }
 542
 543 static void process_request(struct p9_conn *m, struct p9_req *req)
 544 {
 545         int ecode;
 546         struct p9_str *ename;
 547
 548         if (!req->err && req->rcall->id == P9_RERROR) {
 549                 ecode = req->rcall->params.rerror.errno;
 550                 ename = &req->rcall->params.rerror.error;
 551
 552                 P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
 553                                                                 ename->str);
 554
 555                 if (*m->extended)
 556                         req->err = -ecode;
 557
 558                 if (!req->err) {
 559                         req->err = p9_errstr2errno(ename->str, ename->len);
 560
 561                         if (!req->err) {        /* string match failed */
 562                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 563                         }
 564
 565                         if (!req->err)
 566                                 req->err = -ESERVERFAULT;
 567                 }
 568         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 569                 P9_DPRINTK(P9_DEBUG_ERROR,
 570                                 "fcall mismatch: expected %d, got %d\n",
 571                                 req->tcall->id + 1, req->rcall->id);
 572                 if (!req->err)
 573                         req->err = -EIO;
 574         }
 575 }
 576
 577 /**
 578  * p9_read_work - called when there is some data to be read from a transport
 579  */
 580 static void p9_read_work(struct work_struct *work)
 581 {
 582         int n, err;
 583         struct p9_conn *m;
 584         struct p9_req *req, *rptr, *rreq;
 585         struct p9_fcall *rcall;
 586         char *rbuf;
 587
 588         m = container_of(work, struct p9_conn, rq);
 589
 590         if (m->err < 0)
 591                 return;
 592
 593         rcall = NULL;
 594         P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 595
 596         if (!m->rcall) {
 597                 m->rcall =
 598                     kmalloc(sizeof(struct p9_fcall) + m->msize, GFP_KERNEL);
 599                 if (!m->rcall) {
 600                         err = -ENOMEM;
 601                         goto error;
 602                 }
 603
 604                 m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 605                 m->rpos = 0;
 606         }
 607
 608         clear_bit(Rpending, &m->wsched);
 609         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 610         P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 611         if (err == -EAGAIN) {
 612                 clear_bit(Rworksched, &m->wsched);
 613                 return;
 614         }
 615
 616         if (err <= 0)
 617                 goto error;
 618
 619         m->rpos += err;
 620         while (m->rpos > 4) {
 621                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 622                 if (n >= m->msize) {
 623                         P9_DPRINTK(P9_DEBUG_ERROR,
 624                                 "requested packet size too big: %d\n", n);
 625                         err = -EIO;
 626                         goto error;
 627                 }
 628
 629                 if (m->rpos < n)
 630                         break;
 631
 632                 err =
 633                     p9_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 634                 if (err < 0) {
 635                         goto error;
 636                 }
 637
 638 #ifdef CONFIG_NET_9P_DEBUG
 639                 if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 640                         char buf[150];
 641
 642                         p9_printfcall(buf, sizeof(buf), m->rcall,
 643                                 *m->extended);
 644                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 645                 }
 646 #endif
 647
 648                 rcall = m->rcall;
 649                 rbuf = m->rbuf;
 650                 if (m->rpos > n) {
 651                         m->rcall = kmalloc(sizeof(struct p9_fcall) + m->msize,
 652                                            GFP_KERNEL);
 653                         if (!m->rcall) {
 654                                 err = -ENOMEM;
 655                                 goto error;
 656                         }
 657
 658                         m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
 659                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 660                         m->rpos -= n;
 661                 } else {
 662                         m->rcall = NULL;
 663                         m->rbuf = NULL;
 664                         m->rpos = 0;
 665                 }
 666
 667                 P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
 668                                                         rcall->id, rcall->tag);
 669
 670                 req = NULL;
 671                 spin_lock(&m->lock);
 672                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 673                         if (rreq->tag == rcall->tag) {
 674                                 req = rreq;
 675                                 if (req->flush != Flushing)
 676                                         list_del(&req->req_list);
 677                                 break;
 678                         }
 679                 }
 680                 spin_unlock(&m->lock);
 681
 682                 if (req) {
 683                         req->rcall = rcall;
 684                         process_request(m, req);
 685
 686                         if (req->flush != Flushing) {
 687                                 if (req->cb)
 688                                         (*req->cb) (req, req->cba);
 689                                 else
 690                                         kfree(req->rcall);
 691
 692                                 wake_up(&m->equeue);
 693                         }
 694                 } else {
 695                         if (err >= 0 && rcall->id != P9_RFLUSH)
 696                                 P9_DPRINTK(P9_DEBUG_ERROR,
 697                                   "unexpected response mux %p id %d tag %d\n",
 698                                   m, rcall->id, rcall->tag);
 699                         kfree(rcall);
 700                 }
 701         }
 702
 703         if (!list_empty(&m->req_list)) {
 704                 if (test_and_clear_bit(Rpending, &m->wsched))
 705                         n = POLLIN;
 706                 else
 707                         n = m->trans->poll(m->trans, NULL);
 708
 709                 if (n & POLLIN) {
 710                         P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
 711                         queue_work(p9_mux_wq, &m->rq);
 712                 } else
 713                         clear_bit(Rworksched, &m->wsched);
 714         } else
 715                 clear_bit(Rworksched, &m->wsched);
 716
 717         return;
 718
 719 error:
 720         p9_conn_cancel(m, err);
 721         clear_bit(Rworksched, &m->wsched);
 722 }
 723
 724 /**
 725  * p9_send_request - send 9P request
 726  * The function can sleep until the request is scheduled for sending.
 727  * The function can be interrupted. Return from the function is not
 728  * a guarantee that the request is sent successfully. Can return errors
 729  * that can be retrieved by PTR_ERR macros.
 730  *
 731  * @m: mux data
 732  * @tc: request to be sent
 733  * @cb: callback function to call when response is received
 734  * @cba: parameter to pass to the callback function
 735  */
 736 static struct p9_req *p9_send_request(struct p9_conn *m,
 737                                           struct p9_fcall *tc,
 738                                           p9_conn_req_callback cb, void *cba)
 739 {
 740         int n;
 741         struct p9_req *req;
 742
 743         P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 744                 tc, tc->id);
 745         if (m->err < 0)
 746                 return ERR_PTR(m->err);
 747
 748         req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
 749         if (!req)
 750                 return ERR_PTR(-ENOMEM);
 751
 752         if (tc->id == P9_TVERSION)
 753                 n = P9_NOTAG;
 754         else
 755                 n = p9_mux_get_tag(m);
 756
 757         if (n < 0)
 758                 return ERR_PTR(-ENOMEM);
 759
 760         p9_set_tag(tc, n);
 761
 762 #ifdef CONFIG_NET_9P_DEBUG
 763         if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
 764                 char buf[150];
 765
 766                 p9_printfcall(buf, sizeof(buf), tc, *m->extended);
 767                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 768         }
 769 #endif
 770
 771         spin_lock_init(&req->lock);
 772         req->tag = n;
 773         req->tcall = tc;
 774         req->rcall = NULL;
 775         req->err = 0;
 776         req->cb = cb;
 777         req->cba = cba;
 778         req->flush = None;
 779
 780         spin_lock(&m->lock);
 781         list_add_tail(&req->req_list, &m->unsent_req_list);
 782         spin_unlock(&m->lock);
 783
 784         if (test_and_clear_bit(Wpending, &m->wsched))
 785                 n = POLLOUT;
 786         else
 787                 n = m->trans->poll(m->trans, NULL);
 788
 789         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 790                 queue_work(p9_mux_wq, &m->wq);
 791
 792         return req;
 793 }
 794
 795 static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
 796 {
 797         p9_mux_put_tag(m, req->tag);
 798         kfree(req);
 799 }
 800
 801 static void p9_mux_flush_cb(struct p9_req *freq, void *a)
 802 {
 803         p9_conn_req_callback cb;
 804         int tag;
 805         struct p9_conn *m;
 806         struct p9_req *req, *rreq, *rptr;
 807
 808         m = a;
 809         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 810                 freq->tcall, freq->rcall, freq->err,
 811                 freq->tcall->params.tflush.oldtag);
 812
 813         spin_lock(&m->lock);
 814         cb = NULL;
 815         tag = freq->tcall->params.tflush.oldtag;
 816         req = NULL;
 817         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 818                 if (rreq->tag == tag) {
 819                         req = rreq;
 820                         list_del(&req->req_list);
 821                         break;
 822                 }
 823         }
 824         spin_unlock(&m->lock);
 825
 826         if (req) {
 827                 spin_lock(&req->lock);
 828                 req->flush = Flushed;
 829                 spin_unlock(&req->lock);
 830
 831                 if (req->cb)
 832                         (*req->cb) (req, req->cba);
 833                 else
 834                         kfree(req->rcall);
 835
 836                 wake_up(&m->equeue);
 837         }
 838
 839         kfree(freq->tcall);
 840         kfree(freq->rcall);
 841         p9_mux_free_request(m, freq);
 842 }
 843
 844 static int
 845 p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
 846 {
 847         struct p9_fcall *fc;
 848         struct p9_req *rreq, *rptr;
 849
 850         P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 851
 852         /* if a response was received for a request, do nothing */
 853         spin_lock(&req->lock);
 854         if (req->rcall || req->err) {
 855                 spin_unlock(&req->lock);
 856                 P9_DPRINTK(P9_DEBUG_MUX,
 857                         "mux %p req %p response already received\n", m, req);
 858                 return 0;
 859         }
 860
 861         req->flush = Flushing;
 862         spin_unlock(&req->lock);
 863
 864         spin_lock(&m->lock);
 865         /* if the request is not sent yet, just remove it from the list */
 866         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 867                 if (rreq->tag == req->tag) {
 868                         P9_DPRINTK(P9_DEBUG_MUX,
 869                            "mux %p req %p request is not sent yet\n", m, req);
 870                         list_del(&rreq->req_list);
 871                         req->flush = Flushed;
 872                         spin_unlock(&m->lock);
 873                         if (req->cb)
 874                                 (*req->cb) (req, req->cba);
 875                         return 0;
 876                 }
 877         }
 878         spin_unlock(&m->lock);
 879
 880         clear_thread_flag(TIF_SIGPENDING);
 881         fc = p9_create_tflush(req->tag);
 882         p9_send_request(m, fc, p9_mux_flush_cb, m);
 883         return 1;
 884 }
 885
 886 static void
 887 p9_conn_rpc_cb(struct p9_req *req, void *a)
 888 {
 889         struct p9_mux_rpc *r;
 890
 891         P9_DPRINTK(P9_DEBUG_MUX, "req %p r %p\n", req, a);
 892         r = a;
 893         r->rcall = req->rcall;
 894         r->err = req->err;
 895
 896         if (req->flush != None && !req->err)
 897                 r->err = -ERESTARTSYS;
 898
 899         wake_up(&r->wqueue);
 900 }
 901
 902 /**
 903  * p9_mux_rpc - sends 9P request and waits until a response is available.
 904  *      The function can be interrupted.
 905  * @m: mux data
 906  * @tc: request to be sent
 907  * @rc: pointer where a pointer to the response is stored
 908  */
 909 int
 910 p9_conn_rpc(struct p9_conn *m, struct p9_fcall *tc,
 911              struct p9_fcall **rc)
 912 {
 913         int err, sigpending;
 914         unsigned long flags;
 915         struct p9_req *req;
 916         struct p9_mux_rpc r;
 917
 918         r.err = 0;
 919         r.tcall = tc;
 920         r.rcall = NULL;
 921         r.m = m;
 922         init_waitqueue_head(&r.wqueue);
 923
 924         if (rc)
 925                 *rc = NULL;
 926
 927         sigpending = 0;
 928         if (signal_pending(current)) {
 929                 sigpending = 1;
 930                 clear_thread_flag(TIF_SIGPENDING);
 931         }
 932
 933         req = p9_send_request(m, tc, p9_conn_rpc_cb, &r);
 934         if (IS_ERR(req)) {
 935                 err = PTR_ERR(req);
 936                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 937                 return err;
 938         }
 939
 940         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 941         if (r.err < 0)
 942                 err = r.err;
 943
 944         if (err == -ERESTARTSYS && m->trans->status == Connected
 945                                                         && m->err == 0) {
 946                 if (p9_mux_flush_request(m, req)) {
 947                         /* wait until we get response of the flush message */
 948                         do {
 949                                 clear_thread_flag(TIF_SIGPENDING);
 950                                 err = wait_event_interruptible(r.wqueue,
 951                                         r.rcall || r.err);
 952                         } while (!r.rcall && !r.err && err == -ERESTARTSYS &&
 953                                 m->trans->status == Connected && !m->err);
 954
 955                         err = -ERESTARTSYS;
 956                 }
 957                 sigpending = 1;
 958         }
 959
 960         if (sigpending) {
 961                 spin_lock_irqsave(&current->sighand->siglock, flags);
 962                 recalc_sigpending();
 963                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 964         }
 965
 966         if (rc)
 967                 *rc = r.rcall;
 968         else
 969                 kfree(r.rcall);
 970
 971         p9_mux_free_request(m, req);
 972         if (err > 0)
 973                 err = -EIO;
 974
 975         return err;
 976 }
 977 EXPORT_SYMBOL(p9_conn_rpc);
 978
 979 #ifdef P9_NONBLOCK
 980 /**
 981  * p9_conn_rpcnb - sends 9P request without waiting for response.
 982  * @m: mux data
 983  * @tc: request to be sent
 984  * @cb: callback function to be called when response arrives
 985  * @cba: value to pass to the callback function
 986  */
 987 int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
 988                    p9_conn_req_callback cb, void *a)
 989 {
 990         int err;
 991         struct p9_req *req;
 992
 993         req = p9_send_request(m, tc, cb, a);
 994         if (IS_ERR(req)) {
 995                 err = PTR_ERR(req);
 996                 P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
 997                 return PTR_ERR(req);
 998         }
 999
1000         P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
1001         return 0;
1002 }
1003 EXPORT_SYMBOL(p9_conn_rpcnb);
1004 #endif /* P9_NONBLOCK */
1005
1006 /**
1007  * p9_conn_cancel - cancel all pending requests with error
1008  * @m: mux data
1009  * @err: error code
1010  */
1011 void p9_conn_cancel(struct p9_conn *m, int err)
1012 {
1013         struct p9_req *req, *rtmp;
1014         LIST_HEAD(cancel_list);
1015
1016         P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
1017         m->err = err;
1018         spin_lock(&m->lock);
1019         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
1020                 list_move(&req->req_list, &cancel_list);
1021         }
1022         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1023                 list_move(&req->req_list, &cancel_list);
1024         }
1025         spin_unlock(&m->lock);
1026
1027         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1028                 list_del(&req->req_list);
1029                 if (!req->err)
1030                         req->err = err;
1031
1032                 if (req->cb)
1033                         (*req->cb) (req, req->cba);
1034                 else
1035                         kfree(req->rcall);
1036         }
1037
1038         wake_up(&m->equeue);
1039 }
1040 EXPORT_SYMBOL(p9_conn_cancel);
1041
1042 static u16 p9_mux_get_tag(struct p9_conn *m)
1043 {
1044         int tag;
1045
1046         tag = p9_idpool_get(m->tagpool);
1047         if (tag < 0)
1048                 return P9_NOTAG;
1049         else
1050                 return (u16) tag;
1051 }
1052
1053 static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
1054 {
1055         if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
1056                 p9_idpool_put(tag, m->tagpool);
1057 }