9p: Use kthread_stop instead of sending a SIGKILL.
[linux-2.6.git] / fs / 9p / mux.c
1 /*
2  * linux/fs/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
34 #include "debug.h"
35 #include "v9fs.h"
36 #include "9p.h"
37 #include "conv.h"
38 #include "transport.h"
39 #include "mux.h"
40
41 #define ERREQFLUSH      1
42 #define SCHED_TIMEOUT   10
43 #define MAXPOLLWADDR    2
44
45 enum {
46         Rworksched = 1,         /* read work scheduled or running */
47         Rpending = 2,           /* can read */
48         Wworksched = 4,         /* write work scheduled or running */
49         Wpending = 8,           /* can write */
50 };
51
52 enum {
53         None,
54         Flushing,
55         Flushed,
56 };
57
58 struct v9fs_mux_poll_task;
59
60 struct v9fs_req {
61         spinlock_t lock;
62         int tag;
63         struct v9fs_fcall *tcall;
64         struct v9fs_fcall *rcall;
65         int err;
66         v9fs_mux_req_callback cb;
67         void *cba;
68         int flush;
69         struct list_head req_list;
70 };
71
72 struct v9fs_mux_data {
73         spinlock_t lock;
74         struct list_head mux_list;
75         struct v9fs_mux_poll_task *poll_task;
76         int msize;
77         unsigned char *extended;
78         struct v9fs_transport *trans;
79         struct v9fs_idpool tagpool;
80         int err;
81         wait_queue_head_t equeue;
82         struct list_head req_list;
83         struct list_head unsent_req_list;
84         struct v9fs_fcall *rcall;
85         int rpos;
86         char *rbuf;
87         int wpos;
88         int wsize;
89         char *wbuf;
90         wait_queue_t poll_wait[MAXPOLLWADDR];
91         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
92         poll_table pt;
93         struct work_struct rq;
94         struct work_struct wq;
95         unsigned long wsched;
96 };
97
98 struct v9fs_mux_poll_task {
99         struct task_struct *task;
100         struct list_head mux_list;
101         int muxnum;
102 };
103
104 struct v9fs_mux_rpc {
105         struct v9fs_mux_data *m;
106         int err;
107         struct v9fs_fcall *tcall;
108         struct v9fs_fcall *rcall;
109         wait_queue_head_t wqueue;
110 };
111
112 static int v9fs_poll_proc(void *);
113 static void v9fs_read_work(struct work_struct *work);
114 static void v9fs_write_work(struct work_struct *work);
115 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
116                           poll_table * p);
117 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
118 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
119
120 static DEFINE_MUTEX(v9fs_mux_task_lock);
121 static struct workqueue_struct *v9fs_mux_wq;
122
123 static int v9fs_mux_num;
124 static int v9fs_mux_poll_task_num;
125 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
126
127 int v9fs_mux_global_init(void)
128 {
129         int i;
130
131         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
132                 v9fs_mux_poll_tasks[i].task = NULL;
133
134         v9fs_mux_wq = create_workqueue("v9fs");
135         if (!v9fs_mux_wq) {
136                 printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
137                 return -ENOMEM;
138         }
139
140         return 0;
141 }
142
143 void v9fs_mux_global_exit(void)
144 {
145         destroy_workqueue(v9fs_mux_wq);
146 }
147
148 /**
149  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
150  * based on the number of mounted v9fs filesystems.
151  *
152  * The current implementation returns sqrt of the number of mounts.
153  */
154 static int v9fs_mux_calc_poll_procs(int muxnum)
155 {
156         int n;
157
158         if (v9fs_mux_poll_task_num)
159                 n = muxnum / v9fs_mux_poll_task_num +
160                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
161         else
162                 n = 1;
163
164         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
165                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
166
167         return n;
168 }
169
170 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
171 {
172         int i, n;
173         struct v9fs_mux_poll_task *vpt, *vptlast;
174         struct task_struct *pproc;
175
176         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
177                 v9fs_mux_poll_task_num);
178         mutex_lock(&v9fs_mux_task_lock);
179
180         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
181         if (n > v9fs_mux_poll_task_num) {
182                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
183                         if (v9fs_mux_poll_tasks[i].task == NULL) {
184                                 vpt = &v9fs_mux_poll_tasks[i];
185                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
186                                 pproc = kthread_create(v9fs_poll_proc, vpt,
187                                                    "v9fs-poll");
188
189                                 if (!IS_ERR(pproc)) {
190                                         vpt->task = pproc;
191                                         INIT_LIST_HEAD(&vpt->mux_list);
192                                         vpt->muxnum = 0;
193                                         v9fs_mux_poll_task_num++;
194                                         wake_up_process(vpt->task);
195                                 }
196                                 break;
197                         }
198                 }
199
200                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
201                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
202         }
203
204         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
205             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
206
207         vptlast = NULL;
208         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
209                 vpt = &v9fs_mux_poll_tasks[i];
210                 if (vpt->task != NULL) {
211                         vptlast = vpt;
212                         if (vpt->muxnum < n) {
213                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
214                                 list_add(&m->mux_list, &vpt->mux_list);
215                                 vpt->muxnum++;
216                                 m->poll_task = vpt;
217                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
218                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
219                                 break;
220                         }
221                 }
222         }
223
224         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
225                 if (vptlast == NULL)
226                         return -ENOMEM;
227
228                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
229                 list_add(&m->mux_list, &vptlast->mux_list);
230                 vptlast->muxnum++;
231                 m->poll_task = vptlast;
232                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
233                 init_poll_funcptr(&m->pt, v9fs_pollwait);
234         }
235
236         v9fs_mux_num++;
237         mutex_unlock(&v9fs_mux_task_lock);
238
239         return 0;
240 }
241
242 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
243 {
244         int i;
245         struct v9fs_mux_poll_task *vpt;
246
247         mutex_lock(&v9fs_mux_task_lock);
248         vpt = m->poll_task;
249         list_del(&m->mux_list);
250         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
251                 if (m->poll_waddr[i] != NULL) {
252                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
253                         m->poll_waddr[i] = NULL;
254                 }
255         }
256         vpt->muxnum--;
257         if (!vpt->muxnum) {
258                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
259                 kthread_stop(vpt->task);
260                 vpt->task = NULL;
261                 v9fs_mux_poll_task_num--;
262         }
263         v9fs_mux_num--;
264         mutex_unlock(&v9fs_mux_task_lock);
265 }
266
267 /**
268  * v9fs_mux_init - allocate and initialize the per-session mux data
269  * Creates the polling task if this is the first session.
270  *
271  * @trans - transport structure
272  * @msize - maximum message size
273  * @extended - pointer to the extended flag
274  */
275 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
276                                     unsigned char *extended)
277 {
278         int i, n;
279         struct v9fs_mux_data *m, *mtmp;
280
281         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
282         m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
283         if (!m)
284                 return ERR_PTR(-ENOMEM);
285
286         spin_lock_init(&m->lock);
287         INIT_LIST_HEAD(&m->mux_list);
288         m->msize = msize;
289         m->extended = extended;
290         m->trans = trans;
291         idr_init(&m->tagpool.pool);
292         init_MUTEX(&m->tagpool.lock);
293         m->err = 0;
294         init_waitqueue_head(&m->equeue);
295         INIT_LIST_HEAD(&m->req_list);
296         INIT_LIST_HEAD(&m->unsent_req_list);
297         m->rcall = NULL;
298         m->rpos = 0;
299         m->rbuf = NULL;
300         m->wpos = m->wsize = 0;
301         m->wbuf = NULL;
302         INIT_WORK(&m->rq, v9fs_read_work);
303         INIT_WORK(&m->wq, v9fs_write_work);
304         m->wsched = 0;
305         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
306         m->poll_task = NULL;
307         n = v9fs_mux_poll_start(m);
308         if (n)
309                 return ERR_PTR(n);
310
311         n = trans->poll(trans, &m->pt);
312         if (n & POLLIN) {
313                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
314                 set_bit(Rpending, &m->wsched);
315         }
316
317         if (n & POLLOUT) {
318                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
319                 set_bit(Wpending, &m->wsched);
320         }
321
322         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
323                 if (IS_ERR(m->poll_waddr[i])) {
324                         v9fs_mux_poll_stop(m);
325                         mtmp = (void *)m->poll_waddr;   /* the error code */
326                         kfree(m);
327                         m = mtmp;
328                         break;
329                 }
330         }
331
332         return m;
333 }
334
335 /**
336  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
337  */
338 void v9fs_mux_destroy(struct v9fs_mux_data *m)
339 {
340         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
341                 m->mux_list.prev, m->mux_list.next);
342         v9fs_mux_cancel(m, -ECONNRESET);
343
344         if (!list_empty(&m->req_list)) {
345                 /* wait until all processes waiting on this session exit */
346                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
347                         m);
348                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
349                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
350                         list_empty(&m->req_list));
351         }
352
353         v9fs_mux_poll_stop(m);
354         m->trans = NULL;
355
356         kfree(m);
357 }
358
359 /**
360  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
361  *      to files wait queue
362  */
363 static void
364 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
365               poll_table * p)
366 {
367         int i;
368         struct v9fs_mux_data *m;
369
370         m = container_of(p, struct v9fs_mux_data, pt);
371         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
372                 if (m->poll_waddr[i] == NULL)
373                         break;
374
375         if (i >= ARRAY_SIZE(m->poll_waddr)) {
376                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
377                 return;
378         }
379
380         m->poll_waddr[i] = wait_address;
381
382         if (!wait_address) {
383                 dprintk(DEBUG_ERROR, "no wait_address\n");
384                 m->poll_waddr[i] = ERR_PTR(-EIO);
385                 return;
386         }
387
388         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
389         add_wait_queue(wait_address, &m->poll_wait[i]);
390 }
391
392 /**
393  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
394  */
395 static void v9fs_poll_mux(struct v9fs_mux_data *m)
396 {
397         int n;
398
399         if (m->err < 0)
400                 return;
401
402         n = m->trans->poll(m->trans, NULL);
403         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
404                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
405                 if (n >= 0)
406                         n = -ECONNRESET;
407                 v9fs_mux_cancel(m, n);
408         }
409
410         if (n & POLLIN) {
411                 set_bit(Rpending, &m->wsched);
412                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
413                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
414                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
415                         queue_work(v9fs_mux_wq, &m->rq);
416                 }
417         }
418
419         if (n & POLLOUT) {
420                 set_bit(Wpending, &m->wsched);
421                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
422                 if ((m->wsize || !list_empty(&m->unsent_req_list))
423                     && !test_and_set_bit(Wworksched, &m->wsched)) {
424                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
425                         queue_work(v9fs_mux_wq, &m->wq);
426                 }
427         }
428 }
429
430 /**
431  * v9fs_poll_proc - polls all v9fs transports for new events and queues
432  *      the appropriate work to the work queue
433  */
434 static int v9fs_poll_proc(void *a)
435 {
436         struct v9fs_mux_data *m, *mtmp;
437         struct v9fs_mux_poll_task *vpt;
438
439         vpt = a;
440         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
441         while (!kthread_should_stop()) {
442                 set_current_state(TASK_INTERRUPTIBLE);
443
444                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
445                         v9fs_poll_mux(m);
446                 }
447
448                 dprintk(DEBUG_MUX, "sleeping...\n");
449                 schedule_timeout(SCHED_TIMEOUT * HZ);
450         }
451
452         __set_current_state(TASK_RUNNING);
453         dprintk(DEBUG_MUX, "finish\n");
454         return 0;
455 }
456
457 /**
458  * v9fs_write_work - called when a transport can send some data
459  */
460 static void v9fs_write_work(struct work_struct *work)
461 {
462         int n, err;
463         struct v9fs_mux_data *m;
464         struct v9fs_req *req;
465
466         m = container_of(work, struct v9fs_mux_data, wq);
467
468         if (m->err < 0) {
469                 clear_bit(Wworksched, &m->wsched);
470                 return;
471         }
472
473         if (!m->wsize) {
474                 if (list_empty(&m->unsent_req_list)) {
475                         clear_bit(Wworksched, &m->wsched);
476                         return;
477                 }
478
479                 spin_lock(&m->lock);
480 again:
481                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
482                                req_list);
483                 list_move_tail(&req->req_list, &m->req_list);
484                 if (req->err == ERREQFLUSH)
485                         goto again;
486
487                 m->wbuf = req->tcall->sdata;
488                 m->wsize = req->tcall->size;
489                 m->wpos = 0;
490                 dump_data(m->wbuf, m->wsize);
491                 spin_unlock(&m->lock);
492         }
493
494         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
495         clear_bit(Wpending, &m->wsched);
496         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
497         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
498         if (err == -EAGAIN) {
499                 clear_bit(Wworksched, &m->wsched);
500                 return;
501         }
502
503         if (err <= 0)
504                 goto error;
505
506         m->wpos += err;
507         if (m->wpos == m->wsize)
508                 m->wpos = m->wsize = 0;
509
510         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
511                 if (test_and_clear_bit(Wpending, &m->wsched))
512                         n = POLLOUT;
513                 else
514                         n = m->trans->poll(m->trans, NULL);
515
516                 if (n & POLLOUT) {
517                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
518                         queue_work(v9fs_mux_wq, &m->wq);
519                 } else
520                         clear_bit(Wworksched, &m->wsched);
521         } else
522                 clear_bit(Wworksched, &m->wsched);
523
524         return;
525
526       error:
527         v9fs_mux_cancel(m, err);
528         clear_bit(Wworksched, &m->wsched);
529 }
530
531 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
532 {
533         int ecode;
534         struct v9fs_str *ename;
535
536         if (!req->err && req->rcall->id == RERROR) {
537                 ecode = req->rcall->params.rerror.errno;
538                 ename = &req->rcall->params.rerror.error;
539
540                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
541
542                 if (*m->extended)
543                         req->err = -ecode;
544
545                 if (!req->err) {
546                         req->err = v9fs_errstr2errno(ename->str, ename->len);
547
548                         if (!req->err) {        /* string match failed */
549                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
550                         }
551
552                         if (!req->err)
553                                 req->err = -ESERVERFAULT;
554                 }
555         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
556                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
557                         req->tcall->id + 1, req->rcall->id);
558                 if (!req->err)
559                         req->err = -EIO;
560         }
561 }
562
563 /**
564  * v9fs_read_work - called when there is some data to be read from a transport
565  */
566 static void v9fs_read_work(struct work_struct *work)
567 {
568         int n, err;
569         struct v9fs_mux_data *m;
570         struct v9fs_req *req, *rptr, *rreq;
571         struct v9fs_fcall *rcall;
572         char *rbuf;
573
574         m = container_of(work, struct v9fs_mux_data, rq);
575
576         if (m->err < 0)
577                 return;
578
579         rcall = NULL;
580         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
581
582         if (!m->rcall) {
583                 m->rcall =
584                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
585                 if (!m->rcall) {
586                         err = -ENOMEM;
587                         goto error;
588                 }
589
590                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
591                 m->rpos = 0;
592         }
593
594         clear_bit(Rpending, &m->wsched);
595         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
596         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
597         if (err == -EAGAIN) {
598                 clear_bit(Rworksched, &m->wsched);
599                 return;
600         }
601
602         if (err <= 0)
603                 goto error;
604
605         m->rpos += err;
606         while (m->rpos > 4) {
607                 n = le32_to_cpu(*(__le32 *) m->rbuf);
608                 if (n >= m->msize) {
609                         dprintk(DEBUG_ERROR,
610                                 "requested packet size too big: %d\n", n);
611                         err = -EIO;
612                         goto error;
613                 }
614
615                 if (m->rpos < n)
616                         break;
617
618                 dump_data(m->rbuf, n);
619                 err =
620                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
621                 if (err < 0) {
622                         goto error;
623                 }
624
625                 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
626                         char buf[150];
627
628                         v9fs_printfcall(buf, sizeof(buf), m->rcall,
629                                 *m->extended);
630                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
631                 }
632
633                 rcall = m->rcall;
634                 rbuf = m->rbuf;
635                 if (m->rpos > n) {
636                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
637                                            GFP_KERNEL);
638                         if (!m->rcall) {
639                                 err = -ENOMEM;
640                                 goto error;
641                         }
642
643                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
644                         memmove(m->rbuf, rbuf + n, m->rpos - n);
645                         m->rpos -= n;
646                 } else {
647                         m->rcall = NULL;
648                         m->rbuf = NULL;
649                         m->rpos = 0;
650                 }
651
652                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
653                         rcall->tag);
654
655                 req = NULL;
656                 spin_lock(&m->lock);
657                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
658                         if (rreq->tag == rcall->tag) {
659                                 req = rreq;
660                                 if (req->flush != Flushing)
661                                         list_del(&req->req_list);
662                                 break;
663                         }
664                 }
665                 spin_unlock(&m->lock);
666
667                 if (req) {
668                         req->rcall = rcall;
669                         process_request(m, req);
670
671                         if (req->flush != Flushing) {
672                                 if (req->cb)
673                                         (*req->cb) (req, req->cba);
674                                 else
675                                         kfree(req->rcall);
676
677                                 wake_up(&m->equeue);
678                         }
679                 } else {
680                         if (err >= 0 && rcall->id != RFLUSH)
681                                 dprintk(DEBUG_ERROR,
682                                         "unexpected response mux %p id %d tag %d\n",
683                                         m, rcall->id, rcall->tag);
684                         kfree(rcall);
685                 }
686         }
687
688         if (!list_empty(&m->req_list)) {
689                 if (test_and_clear_bit(Rpending, &m->wsched))
690                         n = POLLIN;
691                 else
692                         n = m->trans->poll(m->trans, NULL);
693
694                 if (n & POLLIN) {
695                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
696                         queue_work(v9fs_mux_wq, &m->rq);
697                 } else
698                         clear_bit(Rworksched, &m->wsched);
699         } else
700                 clear_bit(Rworksched, &m->wsched);
701
702         return;
703
704       error:
705         v9fs_mux_cancel(m, err);
706         clear_bit(Rworksched, &m->wsched);
707 }
708
709 /**
710  * v9fs_send_request - send 9P request
711  * The function can sleep until the request is scheduled for sending.
712  * The function can be interrupted. Return from the function is not
713  * a guarantee that the request is sent successfully. Can return errors
714  * that can be retrieved by PTR_ERR macros.
715  *
716  * @m: mux data
717  * @tc: request to be sent
718  * @cb: callback function to call when response is received
719  * @cba: parameter to pass to the callback function
720  */
721 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
722                                           struct v9fs_fcall *tc,
723                                           v9fs_mux_req_callback cb, void *cba)
724 {
725         int n;
726         struct v9fs_req *req;
727
728         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
729                 tc, tc->id);
730         if (m->err < 0)
731                 return ERR_PTR(m->err);
732
733         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
734         if (!req)
735                 return ERR_PTR(-ENOMEM);
736
737         if (tc->id == TVERSION)
738                 n = V9FS_NOTAG;
739         else
740                 n = v9fs_mux_get_tag(m);
741
742         if (n < 0)
743                 return ERR_PTR(-ENOMEM);
744
745         v9fs_set_tag(tc, n);
746         if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
747                 char buf[150];
748
749                 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
750                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
751         }
752
753         spin_lock_init(&req->lock);
754         req->tag = n;
755         req->tcall = tc;
756         req->rcall = NULL;
757         req->err = 0;
758         req->cb = cb;
759         req->cba = cba;
760         req->flush = None;
761
762         spin_lock(&m->lock);
763         list_add_tail(&req->req_list, &m->unsent_req_list);
764         spin_unlock(&m->lock);
765
766         if (test_and_clear_bit(Wpending, &m->wsched))
767                 n = POLLOUT;
768         else
769                 n = m->trans->poll(m->trans, NULL);
770
771         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
772                 queue_work(v9fs_mux_wq, &m->wq);
773
774         return req;
775 }
776
777 static void v9fs_mux_free_request(struct v9fs_mux_data *m, struct v9fs_req *req)
778 {
779         v9fs_mux_put_tag(m, req->tag);
780         kfree(req);
781 }
782
783 static void v9fs_mux_flush_cb(struct v9fs_req *freq, void *a)
784 {
785         v9fs_mux_req_callback cb;
786         int tag;
787         struct v9fs_mux_data *m;
788         struct v9fs_req *req, *rreq, *rptr;
789
790         m = a;
791         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
792                 freq->tcall, freq->rcall, freq->err,
793                 freq->tcall->params.tflush.oldtag);
794
795         spin_lock(&m->lock);
796         cb = NULL;
797         tag = freq->tcall->params.tflush.oldtag;
798         req = NULL;
799         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
800                 if (rreq->tag == tag) {
801                         req = rreq;
802                         list_del(&req->req_list);
803                         break;
804                 }
805         }
806         spin_unlock(&m->lock);
807
808         if (req) {
809                 spin_lock(&req->lock);
810                 req->flush = Flushed;
811                 spin_unlock(&req->lock);
812
813                 if (req->cb)
814                         (*req->cb) (req, req->cba);
815                 else
816                         kfree(req->rcall);
817
818                 wake_up(&m->equeue);
819         }
820
821         kfree(freq->tcall);
822         kfree(freq->rcall);
823         v9fs_mux_free_request(m, freq);
824 }
825
826 static int
827 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
828 {
829         struct v9fs_fcall *fc;
830         struct v9fs_req *rreq, *rptr;
831
832         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
833
834         /* if a response was received for a request, do nothing */
835         spin_lock(&req->lock);
836         if (req->rcall || req->err) {
837                 spin_unlock(&req->lock);
838                 dprintk(DEBUG_MUX, "mux %p req %p response already received\n", m, req);
839                 return 0;
840         }
841
842         req->flush = Flushing;
843         spin_unlock(&req->lock);
844
845         spin_lock(&m->lock);
846         /* if the request is not sent yet, just remove it from the list */
847         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
848                 if (rreq->tag == req->tag) {
849                         dprintk(DEBUG_MUX, "mux %p req %p request is not sent yet\n", m, req);
850                         list_del(&rreq->req_list);
851                         req->flush = Flushed;
852                         spin_unlock(&m->lock);
853                         if (req->cb)
854                                 (*req->cb) (req, req->cba);
855                         return 0;
856                 }
857         }
858         spin_unlock(&m->lock);
859
860         clear_thread_flag(TIF_SIGPENDING);
861         fc = v9fs_create_tflush(req->tag);
862         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
863         return 1;
864 }
865
866 static void
867 v9fs_mux_rpc_cb(struct v9fs_req *req, void *a)
868 {
869         struct v9fs_mux_rpc *r;
870
871         dprintk(DEBUG_MUX, "req %p r %p\n", req, a);
872         r = a;
873         r->rcall = req->rcall;
874         r->err = req->err;
875
876         if (req->flush!=None && !req->err)
877                 r->err = -ERESTARTSYS;
878
879         wake_up(&r->wqueue);
880 }
881
882 /**
883  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
884  *      The function can be interrupted.
885  * @m: mux data
886  * @tc: request to be sent
887  * @rc: pointer where a pointer to the response is stored
888  */
889 int
890 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
891              struct v9fs_fcall **rc)
892 {
893         int err, sigpending;
894         unsigned long flags;
895         struct v9fs_req *req;
896         struct v9fs_mux_rpc r;
897
898         r.err = 0;
899         r.tcall = tc;
900         r.rcall = NULL;
901         r.m = m;
902         init_waitqueue_head(&r.wqueue);
903
904         if (rc)
905                 *rc = NULL;
906
907         sigpending = 0;
908         if (signal_pending(current)) {
909                 sigpending = 1;
910                 clear_thread_flag(TIF_SIGPENDING);
911         }
912
913         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
914         if (IS_ERR(req)) {
915                 err = PTR_ERR(req);
916                 dprintk(DEBUG_MUX, "error %d\n", err);
917                 return err;
918         }
919
920         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
921         if (r.err < 0)
922                 err = r.err;
923
924         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
925                 if (v9fs_mux_flush_request(m, req)) {
926                         /* wait until we get response of the flush message */
927                         do {
928                                 clear_thread_flag(TIF_SIGPENDING);
929                                 err = wait_event_interruptible(r.wqueue,
930                                         r.rcall || r.err);
931                         } while (!r.rcall && !r.err && err==-ERESTARTSYS &&
932                                 m->trans->status==Connected && !m->err);
933
934                         err = -ERESTARTSYS;
935                 }
936                 sigpending = 1;
937         }
938
939         if (sigpending) {
940                 spin_lock_irqsave(&current->sighand->siglock, flags);
941                 recalc_sigpending();
942                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
943         }
944
945         if (rc)
946                 *rc = r.rcall;
947         else
948                 kfree(r.rcall);
949
950         v9fs_mux_free_request(m, req);
951         if (err > 0)
952                 err = -EIO;
953
954         return err;
955 }
956
957 #if 0
958 /**
959  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
960  * @m: mux data
961  * @tc: request to be sent
962  * @cb: callback function to be called when response arrives
963  * @cba: value to pass to the callback function
964  */
965 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
966                    v9fs_mux_req_callback cb, void *a)
967 {
968         int err;
969         struct v9fs_req *req;
970
971         req = v9fs_send_request(m, tc, cb, a);
972         if (IS_ERR(req)) {
973                 err = PTR_ERR(req);
974                 dprintk(DEBUG_MUX, "error %d\n", err);
975                 return PTR_ERR(req);
976         }
977
978         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
979         return 0;
980 }
981 #endif  /*  0  */
982
983 /**
984  * v9fs_mux_cancel - cancel all pending requests with error
985  * @m: mux data
986  * @err: error code
987  */
988 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
989 {
990         struct v9fs_req *req, *rtmp;
991         LIST_HEAD(cancel_list);
992
993         dprintk(DEBUG_ERROR, "mux %p err %d\n", m, err);
994         m->err = err;
995         spin_lock(&m->lock);
996         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
997                 list_move(&req->req_list, &cancel_list);
998         }
999         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1000                 list_move(&req->req_list, &cancel_list);
1001         }
1002         spin_unlock(&m->lock);
1003
1004         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1005                 list_del(&req->req_list);
1006                 if (!req->err)
1007                         req->err = err;
1008
1009                 if (req->cb)
1010                         (*req->cb) (req, req->cba);
1011                 else
1012                         kfree(req->rcall);
1013         }
1014
1015         wake_up(&m->equeue);
1016 }
1017
1018 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
1019 {
1020         int tag;
1021
1022         tag = v9fs_get_idpool(&m->tagpool);
1023         if (tag < 0)
1024                 return V9FS_NOTAG;
1025         else
1026                 return (u16) tag;
1027 }
1028
1029 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
1030 {
1031         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
1032                 v9fs_put_idpool(tag, &m->tagpool);
1033 }