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[sfrench/cifs-2.6.git] / 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 }