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Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git
[deliverable/linux.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/config.h>
27 #include <linux/module.h>
28 #include <linux/errno.h>
29 #include <linux/fs.h>
30 #include <linux/poll.h>
31 #include <linux/kthread.h>
32 #include <linux/idr.h>
33 #include <linux/mutex.h>
34
35 #include "debug.h"
36 #include "v9fs.h"
37 #include "9p.h"
38 #include "conv.h"
39 #include "transport.h"
40 #include "mux.h"
41
42 #define ERREQFLUSH 1
43 #define SCHED_TIMEOUT 10
44 #define MAXPOLLWADDR 2
45
46 enum {
47 Rworksched = 1, /* read work scheduled or running */
48 Rpending = 2, /* can read */
49 Wworksched = 4, /* write work scheduled or running */
50 Wpending = 8, /* can write */
51 };
52
53 struct v9fs_mux_poll_task;
54
55 struct v9fs_req {
56 int tag;
57 struct v9fs_fcall *tcall;
58 struct v9fs_fcall *rcall;
59 int err;
60 v9fs_mux_req_callback cb;
61 void *cba;
62 struct list_head req_list;
63 };
64
65 struct v9fs_mux_data {
66 spinlock_t lock;
67 struct list_head mux_list;
68 struct v9fs_mux_poll_task *poll_task;
69 int msize;
70 unsigned char *extended;
71 struct v9fs_transport *trans;
72 struct v9fs_idpool tagpool;
73 int err;
74 wait_queue_head_t equeue;
75 struct list_head req_list;
76 struct list_head unsent_req_list;
77 struct v9fs_fcall *rcall;
78 int rpos;
79 char *rbuf;
80 int wpos;
81 int wsize;
82 char *wbuf;
83 wait_queue_t poll_wait[MAXPOLLWADDR];
84 wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
85 poll_table pt;
86 struct work_struct rq;
87 struct work_struct wq;
88 unsigned long wsched;
89 };
90
91 struct v9fs_mux_poll_task {
92 struct task_struct *task;
93 struct list_head mux_list;
94 int muxnum;
95 };
96
97 struct v9fs_mux_rpc {
98 struct v9fs_mux_data *m;
99 struct v9fs_req *req;
100 int err;
101 struct v9fs_fcall *rcall;
102 wait_queue_head_t wqueue;
103 };
104
105 static int v9fs_poll_proc(void *);
106 static void v9fs_read_work(void *);
107 static void v9fs_write_work(void *);
108 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
109 poll_table * p);
110 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
111 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
112
113 static DEFINE_MUTEX(v9fs_mux_task_lock);
114 static struct workqueue_struct *v9fs_mux_wq;
115
116 static int v9fs_mux_num;
117 static int v9fs_mux_poll_task_num;
118 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
119
120 int v9fs_mux_global_init(void)
121 {
122 int i;
123
124 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
125 v9fs_mux_poll_tasks[i].task = NULL;
126
127 v9fs_mux_wq = create_workqueue("v9fs");
128 if (!v9fs_mux_wq)
129 return -ENOMEM;
130
131 return 0;
132 }
133
134 void v9fs_mux_global_exit(void)
135 {
136 destroy_workqueue(v9fs_mux_wq);
137 }
138
139 /**
140 * v9fs_mux_calc_poll_procs - calculates the number of polling procs
141 * based on the number of mounted v9fs filesystems.
142 *
143 * The current implementation returns sqrt of the number of mounts.
144 */
145 static int v9fs_mux_calc_poll_procs(int muxnum)
146 {
147 int n;
148
149 if (v9fs_mux_poll_task_num)
150 n = muxnum / v9fs_mux_poll_task_num +
151 (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
152 else
153 n = 1;
154
155 if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
156 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
157
158 return n;
159 }
160
161 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
162 {
163 int i, n;
164 struct v9fs_mux_poll_task *vpt, *vptlast;
165 struct task_struct *pproc;
166
167 dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
168 v9fs_mux_poll_task_num);
169 mutex_lock(&v9fs_mux_task_lock);
170
171 n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
172 if (n > v9fs_mux_poll_task_num) {
173 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
174 if (v9fs_mux_poll_tasks[i].task == NULL) {
175 vpt = &v9fs_mux_poll_tasks[i];
176 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
177 pproc = kthread_create(v9fs_poll_proc, vpt,
178 "v9fs-poll");
179
180 if (!IS_ERR(pproc)) {
181 vpt->task = pproc;
182 INIT_LIST_HEAD(&vpt->mux_list);
183 vpt->muxnum = 0;
184 v9fs_mux_poll_task_num++;
185 wake_up_process(vpt->task);
186 }
187 break;
188 }
189 }
190
191 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
192 dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
193 }
194
195 n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
196 ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
197
198 vptlast = NULL;
199 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
200 vpt = &v9fs_mux_poll_tasks[i];
201 if (vpt->task != NULL) {
202 vptlast = vpt;
203 if (vpt->muxnum < n) {
204 dprintk(DEBUG_MUX, "put in proc %d\n", i);
205 list_add(&m->mux_list, &vpt->mux_list);
206 vpt->muxnum++;
207 m->poll_task = vpt;
208 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
209 init_poll_funcptr(&m->pt, v9fs_pollwait);
210 break;
211 }
212 }
213 }
214
215 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
216 if (vptlast == NULL)
217 return -ENOMEM;
218
219 dprintk(DEBUG_MUX, "put in proc %d\n", i);
220 list_add(&m->mux_list, &vptlast->mux_list);
221 vptlast->muxnum++;
222 m->poll_task = vptlast;
223 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
224 init_poll_funcptr(&m->pt, v9fs_pollwait);
225 }
226
227 v9fs_mux_num++;
228 mutex_unlock(&v9fs_mux_task_lock);
229
230 return 0;
231 }
232
233 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
234 {
235 int i;
236 struct v9fs_mux_poll_task *vpt;
237
238 mutex_lock(&v9fs_mux_task_lock);
239 vpt = m->poll_task;
240 list_del(&m->mux_list);
241 for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
242 if (m->poll_waddr[i] != NULL) {
243 remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
244 m->poll_waddr[i] = NULL;
245 }
246 }
247 vpt->muxnum--;
248 if (!vpt->muxnum) {
249 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
250 send_sig(SIGKILL, vpt->task, 1);
251 vpt->task = NULL;
252 v9fs_mux_poll_task_num--;
253 }
254 v9fs_mux_num--;
255 mutex_unlock(&v9fs_mux_task_lock);
256 }
257
258 /**
259 * v9fs_mux_init - allocate and initialize the per-session mux data
260 * Creates the polling task if this is the first session.
261 *
262 * @trans - transport structure
263 * @msize - maximum message size
264 * @extended - pointer to the extended flag
265 */
266 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
267 unsigned char *extended)
268 {
269 int i, n;
270 struct v9fs_mux_data *m, *mtmp;
271
272 dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
273 m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
274 if (!m)
275 return ERR_PTR(-ENOMEM);
276
277 spin_lock_init(&m->lock);
278 INIT_LIST_HEAD(&m->mux_list);
279 m->msize = msize;
280 m->extended = extended;
281 m->trans = trans;
282 idr_init(&m->tagpool.pool);
283 init_MUTEX(&m->tagpool.lock);
284 m->err = 0;
285 init_waitqueue_head(&m->equeue);
286 INIT_LIST_HEAD(&m->req_list);
287 INIT_LIST_HEAD(&m->unsent_req_list);
288 m->rcall = NULL;
289 m->rpos = 0;
290 m->rbuf = NULL;
291 m->wpos = m->wsize = 0;
292 m->wbuf = NULL;
293 INIT_WORK(&m->rq, v9fs_read_work, m);
294 INIT_WORK(&m->wq, v9fs_write_work, m);
295 m->wsched = 0;
296 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
297 m->poll_task = NULL;
298 n = v9fs_mux_poll_start(m);
299 if (n)
300 return ERR_PTR(n);
301
302 n = trans->poll(trans, &m->pt);
303 if (n & POLLIN) {
304 dprintk(DEBUG_MUX, "mux %p can read\n", m);
305 set_bit(Rpending, &m->wsched);
306 }
307
308 if (n & POLLOUT) {
309 dprintk(DEBUG_MUX, "mux %p can write\n", m);
310 set_bit(Wpending, &m->wsched);
311 }
312
313 for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
314 if (IS_ERR(m->poll_waddr[i])) {
315 v9fs_mux_poll_stop(m);
316 mtmp = (void *)m->poll_waddr; /* the error code */
317 kfree(m);
318 m = mtmp;
319 break;
320 }
321 }
322
323 return m;
324 }
325
326 /**
327 * v9fs_mux_destroy - cancels all pending requests and frees mux resources
328 */
329 void v9fs_mux_destroy(struct v9fs_mux_data *m)
330 {
331 dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
332 m->mux_list.prev, m->mux_list.next);
333 v9fs_mux_cancel(m, -ECONNRESET);
334
335 if (!list_empty(&m->req_list)) {
336 /* wait until all processes waiting on this session exit */
337 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
338 m);
339 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
340 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
341 list_empty(&m->req_list));
342 }
343
344 v9fs_mux_poll_stop(m);
345 m->trans = NULL;
346
347 kfree(m);
348 }
349
350 /**
351 * v9fs_pollwait - called by files poll operation to add v9fs-poll task
352 * to files wait queue
353 */
354 static void
355 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
356 poll_table * p)
357 {
358 int i;
359 struct v9fs_mux_data *m;
360
361 m = container_of(p, struct v9fs_mux_data, pt);
362 for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
363 if (m->poll_waddr[i] == NULL)
364 break;
365
366 if (i >= ARRAY_SIZE(m->poll_waddr)) {
367 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
368 return;
369 }
370
371 m->poll_waddr[i] = wait_address;
372
373 if (!wait_address) {
374 dprintk(DEBUG_ERROR, "no wait_address\n");
375 m->poll_waddr[i] = ERR_PTR(-EIO);
376 return;
377 }
378
379 init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
380 add_wait_queue(wait_address, &m->poll_wait[i]);
381 }
382
383 /**
384 * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
385 */
386 static void v9fs_poll_mux(struct v9fs_mux_data *m)
387 {
388 int n;
389
390 if (m->err < 0)
391 return;
392
393 n = m->trans->poll(m->trans, NULL);
394 if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
395 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
396 if (n >= 0)
397 n = -ECONNRESET;
398 v9fs_mux_cancel(m, n);
399 }
400
401 if (n & POLLIN) {
402 set_bit(Rpending, &m->wsched);
403 dprintk(DEBUG_MUX, "mux %p can read\n", m);
404 if (!test_and_set_bit(Rworksched, &m->wsched)) {
405 dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
406 queue_work(v9fs_mux_wq, &m->rq);
407 }
408 }
409
410 if (n & POLLOUT) {
411 set_bit(Wpending, &m->wsched);
412 dprintk(DEBUG_MUX, "mux %p can write\n", m);
413 if ((m->wsize || !list_empty(&m->unsent_req_list))
414 && !test_and_set_bit(Wworksched, &m->wsched)) {
415 dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
416 queue_work(v9fs_mux_wq, &m->wq);
417 }
418 }
419 }
420
421 /**
422 * v9fs_poll_proc - polls all v9fs transports for new events and queues
423 * the appropriate work to the work queue
424 */
425 static int v9fs_poll_proc(void *a)
426 {
427 struct v9fs_mux_data *m, *mtmp;
428 struct v9fs_mux_poll_task *vpt;
429
430 vpt = a;
431 dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
432 allow_signal(SIGKILL);
433 while (!kthread_should_stop()) {
434 set_current_state(TASK_INTERRUPTIBLE);
435 if (signal_pending(current))
436 break;
437
438 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
439 v9fs_poll_mux(m);
440 }
441
442 dprintk(DEBUG_MUX, "sleeping...\n");
443 schedule_timeout(SCHED_TIMEOUT * HZ);
444 }
445
446 __set_current_state(TASK_RUNNING);
447 dprintk(DEBUG_MUX, "finish\n");
448 return 0;
449 }
450
451 /**
452 * v9fs_write_work - called when a transport can send some data
453 */
454 static void v9fs_write_work(void *a)
455 {
456 int n, err;
457 struct v9fs_mux_data *m;
458 struct v9fs_req *req;
459
460 m = a;
461
462 if (m->err < 0) {
463 clear_bit(Wworksched, &m->wsched);
464 return;
465 }
466
467 if (!m->wsize) {
468 if (list_empty(&m->unsent_req_list)) {
469 clear_bit(Wworksched, &m->wsched);
470 return;
471 }
472
473 spin_lock(&m->lock);
474 again:
475 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
476 req_list);
477 list_move_tail(&req->req_list, &m->req_list);
478 if (req->err == ERREQFLUSH)
479 goto again;
480
481 m->wbuf = req->tcall->sdata;
482 m->wsize = req->tcall->size;
483 m->wpos = 0;
484 dump_data(m->wbuf, m->wsize);
485 spin_unlock(&m->lock);
486 }
487
488 dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
489 clear_bit(Wpending, &m->wsched);
490 err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
491 dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
492 if (err == -EAGAIN) {
493 clear_bit(Wworksched, &m->wsched);
494 return;
495 }
496
497 if (err <= 0)
498 goto error;
499
500 m->wpos += err;
501 if (m->wpos == m->wsize)
502 m->wpos = m->wsize = 0;
503
504 if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
505 if (test_and_clear_bit(Wpending, &m->wsched))
506 n = POLLOUT;
507 else
508 n = m->trans->poll(m->trans, NULL);
509
510 if (n & POLLOUT) {
511 dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
512 queue_work(v9fs_mux_wq, &m->wq);
513 } else
514 clear_bit(Wworksched, &m->wsched);
515 } else
516 clear_bit(Wworksched, &m->wsched);
517
518 return;
519
520 error:
521 v9fs_mux_cancel(m, err);
522 clear_bit(Wworksched, &m->wsched);
523 }
524
525 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
526 {
527 int ecode, tag;
528 struct v9fs_str *ename;
529
530 tag = req->tag;
531 if (!req->err && req->rcall->id == RERROR) {
532 ecode = req->rcall->params.rerror.errno;
533 ename = &req->rcall->params.rerror.error;
534
535 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
536
537 if (*m->extended)
538 req->err = -ecode;
539
540 if (!req->err) {
541 req->err = v9fs_errstr2errno(ename->str, ename->len);
542
543 if (!req->err) { /* string match failed */
544 PRINT_FCALL_ERROR("unknown error", req->rcall);
545 }
546
547 if (!req->err)
548 req->err = -ESERVERFAULT;
549 }
550 } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
551 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
552 req->tcall->id + 1, req->rcall->id);
553 if (!req->err)
554 req->err = -EIO;
555 }
556
557 if (req->err == ERREQFLUSH)
558 return;
559
560 if (req->cb) {
561 dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
562 req->tcall, req->rcall);
563
564 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
565 req->cb = NULL;
566 } else
567 kfree(req->rcall);
568
569 v9fs_mux_put_tag(m, tag);
570
571 wake_up(&m->equeue);
572 kfree(req);
573 }
574
575 /**
576 * v9fs_read_work - called when there is some data to be read from a transport
577 */
578 static void v9fs_read_work(void *a)
579 {
580 int n, err;
581 struct v9fs_mux_data *m;
582 struct v9fs_req *req, *rptr, *rreq;
583 struct v9fs_fcall *rcall;
584 char *rbuf;
585
586 m = a;
587
588 if (m->err < 0)
589 return;
590
591 rcall = NULL;
592 dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
593
594 if (!m->rcall) {
595 m->rcall =
596 kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
597 if (!m->rcall) {
598 err = -ENOMEM;
599 goto error;
600 }
601
602 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
603 m->rpos = 0;
604 }
605
606 clear_bit(Rpending, &m->wsched);
607 err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
608 dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
609 if (err == -EAGAIN) {
610 clear_bit(Rworksched, &m->wsched);
611 return;
612 }
613
614 if (err <= 0)
615 goto error;
616
617 m->rpos += err;
618 while (m->rpos > 4) {
619 n = le32_to_cpu(*(__le32 *) m->rbuf);
620 if (n >= m->msize) {
621 dprintk(DEBUG_ERROR,
622 "requested packet size too big: %d\n", n);
623 err = -EIO;
624 goto error;
625 }
626
627 if (m->rpos < n)
628 break;
629
630 dump_data(m->rbuf, n);
631 err =
632 v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
633 if (err < 0) {
634 goto error;
635 }
636
637 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
638 char buf[150];
639
640 v9fs_printfcall(buf, sizeof(buf), m->rcall,
641 *m->extended);
642 printk(KERN_NOTICE ">>> %p %s\n", m, buf);
643 }
644
645 rcall = m->rcall;
646 rbuf = m->rbuf;
647 if (m->rpos > n) {
648 m->rcall = kmalloc(sizeof(struct v9fs_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 v9fs_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 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
665 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 req->rcall = rcall;
673 list_del(&req->req_list);
674 spin_unlock(&m->lock);
675 process_request(m, req);
676 break;
677 }
678
679 }
680
681 if (!req) {
682 spin_unlock(&m->lock);
683 if (err >= 0 && rcall->id != RFLUSH)
684 dprintk(DEBUG_ERROR,
685 "unexpected response mux %p id %d tag %d\n",
686 m, rcall->id, rcall->tag);
687 kfree(rcall);
688 }
689 }
690
691 if (!list_empty(&m->req_list)) {
692 if (test_and_clear_bit(Rpending, &m->wsched))
693 n = POLLIN;
694 else
695 n = m->trans->poll(m->trans, NULL);
696
697 if (n & POLLIN) {
698 dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
699 queue_work(v9fs_mux_wq, &m->rq);
700 } else
701 clear_bit(Rworksched, &m->wsched);
702 } else
703 clear_bit(Rworksched, &m->wsched);
704
705 return;
706
707 error:
708 v9fs_mux_cancel(m, err);
709 clear_bit(Rworksched, &m->wsched);
710 }
711
712 /**
713 * v9fs_send_request - send 9P request
714 * The function can sleep until the request is scheduled for sending.
715 * The function can be interrupted. Return from the function is not
716 * a guarantee that the request is sent succesfully. Can return errors
717 * that can be retrieved by PTR_ERR macros.
718 *
719 * @m: mux data
720 * @tc: request to be sent
721 * @cb: callback function to call when response is received
722 * @cba: parameter to pass to the callback function
723 */
724 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
725 struct v9fs_fcall *tc,
726 v9fs_mux_req_callback cb, void *cba)
727 {
728 int n;
729 struct v9fs_req *req;
730
731 dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
732 tc, tc->id);
733 if (m->err < 0)
734 return ERR_PTR(m->err);
735
736 req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
737 if (!req)
738 return ERR_PTR(-ENOMEM);
739
740 if (tc->id == TVERSION)
741 n = V9FS_NOTAG;
742 else
743 n = v9fs_mux_get_tag(m);
744
745 if (n < 0)
746 return ERR_PTR(-ENOMEM);
747
748 v9fs_set_tag(tc, n);
749
750 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
751 char buf[150];
752
753 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
754 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
755 }
756
757 req->tag = n;
758 req->tcall = tc;
759 req->rcall = NULL;
760 req->err = 0;
761 req->cb = cb;
762 req->cba = cba;
763
764 spin_lock(&m->lock);
765 list_add_tail(&req->req_list, &m->unsent_req_list);
766 spin_unlock(&m->lock);
767
768 if (test_and_clear_bit(Wpending, &m->wsched))
769 n = POLLOUT;
770 else
771 n = m->trans->poll(m->trans, NULL);
772
773 if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
774 queue_work(v9fs_mux_wq, &m->wq);
775
776 return req;
777 }
778
779 static void v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc,
780 struct v9fs_fcall *rc, int err)
781 {
782 v9fs_mux_req_callback cb;
783 int tag;
784 struct v9fs_mux_data *m;
785 struct v9fs_req *req, *rptr;
786
787 m = a;
788 dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
789 rc, err, tc->params.tflush.oldtag);
790
791 spin_lock(&m->lock);
792 cb = NULL;
793 tag = tc->params.tflush.oldtag;
794 list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
795 if (req->tag == tag) {
796 list_del(&req->req_list);
797 if (req->cb) {
798 cb = req->cb;
799 req->cb = NULL;
800 spin_unlock(&m->lock);
801 (*cb) (req->cba, req->tcall, req->rcall,
802 req->err);
803 }
804 kfree(req);
805 wake_up(&m->equeue);
806 break;
807 }
808 }
809
810 if (!cb)
811 spin_unlock(&m->lock);
812
813 v9fs_mux_put_tag(m, tag);
814 kfree(tc);
815 kfree(rc);
816 }
817
818 static void
819 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
820 {
821 struct v9fs_fcall *fc;
822
823 dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
824
825 fc = v9fs_create_tflush(req->tag);
826 v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
827 }
828
829 static void
830 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
831 {
832 struct v9fs_mux_rpc *r;
833
834 if (err == ERREQFLUSH) {
835 kfree(rc);
836 dprintk(DEBUG_MUX, "err req flush\n");
837 return;
838 }
839
840 r = a;
841 dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
842 tc, rc, err);
843 r->rcall = rc;
844 r->err = err;
845 wake_up(&r->wqueue);
846 }
847
848 /**
849 * v9fs_mux_rpc - sends 9P request and waits until a response is available.
850 * The function can be interrupted.
851 * @m: mux data
852 * @tc: request to be sent
853 * @rc: pointer where a pointer to the response is stored
854 */
855 int
856 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
857 struct v9fs_fcall **rc)
858 {
859 int err;
860 unsigned long flags;
861 struct v9fs_req *req;
862 struct v9fs_mux_rpc r;
863
864 r.err = 0;
865 r.rcall = NULL;
866 r.m = m;
867 init_waitqueue_head(&r.wqueue);
868
869 if (rc)
870 *rc = NULL;
871
872 req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
873 if (IS_ERR(req)) {
874 err = PTR_ERR(req);
875 dprintk(DEBUG_MUX, "error %d\n", err);
876 return PTR_ERR(req);
877 }
878
879 r.req = req;
880 dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
881 req->tag, &r, req);
882 err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
883 if (r.err < 0)
884 err = r.err;
885
886 if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
887 spin_lock(&m->lock);
888 req->tcall = NULL;
889 req->err = ERREQFLUSH;
890 spin_unlock(&m->lock);
891
892 clear_thread_flag(TIF_SIGPENDING);
893 v9fs_mux_flush_request(m, req);
894 spin_lock_irqsave(&current->sighand->siglock, flags);
895 recalc_sigpending();
896 spin_unlock_irqrestore(&current->sighand->siglock, flags);
897 }
898
899 if (!err) {
900 if (r.rcall)
901 dprintk(DEBUG_MUX, "got response id %d tag %d\n",
902 r.rcall->id, r.rcall->tag);
903
904 if (rc)
905 *rc = r.rcall;
906 else
907 kfree(r.rcall);
908 } else {
909 kfree(r.rcall);
910 dprintk(DEBUG_MUX, "got error %d\n", err);
911 if (err > 0)
912 err = -EIO;
913 }
914
915 return err;
916 }
917
918 #if 0
919 /**
920 * v9fs_mux_rpcnb - sends 9P request without waiting for response.
921 * @m: mux data
922 * @tc: request to be sent
923 * @cb: callback function to be called when response arrives
924 * @cba: value to pass to the callback function
925 */
926 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
927 v9fs_mux_req_callback cb, void *a)
928 {
929 int err;
930 struct v9fs_req *req;
931
932 req = v9fs_send_request(m, tc, cb, a);
933 if (IS_ERR(req)) {
934 err = PTR_ERR(req);
935 dprintk(DEBUG_MUX, "error %d\n", err);
936 return PTR_ERR(req);
937 }
938
939 dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
940 return 0;
941 }
942 #endif /* 0 */
943
944 /**
945 * v9fs_mux_cancel - cancel all pending requests with error
946 * @m: mux data
947 * @err: error code
948 */
949 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
950 {
951 struct v9fs_req *req, *rtmp;
952 LIST_HEAD(cancel_list);
953
954 dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
955 m->err = err;
956 spin_lock(&m->lock);
957 list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
958 list_move(&req->req_list, &cancel_list);
959 }
960 spin_unlock(&m->lock);
961
962 list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
963 list_del(&req->req_list);
964 if (!req->err)
965 req->err = err;
966
967 if (req->cb)
968 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
969 else
970 kfree(req->rcall);
971
972 kfree(req);
973 }
974
975 wake_up(&m->equeue);
976 }
977
978 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
979 {
980 int tag;
981
982 tag = v9fs_get_idpool(&m->tagpool);
983 if (tag < 0)
984 return V9FS_NOTAG;
985 else
986 return (u16) tag;
987 }
988
989 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
990 {
991 if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
992 v9fs_put_idpool(tag, &m->tagpool);
993 }
Linux kernel - Deliverables
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