Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ericvh...
[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 (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 }