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[PATCH] v9fs: fix corner cases when flushing request
[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 as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to:
21 * Free Software Foundation
22 * 51 Franklin Street, Fifth Floor
23 * Boston, MA 02111-1301 USA
24 *
25 */
26
27 #include <linux/config.h>
28 #include <linux/module.h>
29 #include <linux/errno.h>
30 #include <linux/fs.h>
31 #include <linux/poll.h>
32 #include <linux/kthread.h>
33 #include <linux/idr.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 tidpool;
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 DECLARE_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 inline 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 up(&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 down(&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 up(&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 down(&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->tidpool.pool);
283 init_MUTEX(&m->tidpool.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 inline 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 rcall = m->rcall;
638 rbuf = m->rbuf;
639 if (m->rpos > n) {
640 m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
641 GFP_KERNEL);
642 if (!m->rcall) {
643 err = -ENOMEM;
644 goto error;
645 }
646
647 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
648 memmove(m->rbuf, rbuf + n, m->rpos - n);
649 m->rpos -= n;
650 } else {
651 m->rcall = NULL;
652 m->rbuf = NULL;
653 m->rpos = 0;
654 }
655
656 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
657 rcall->tag);
658
659 req = NULL;
660 spin_lock(&m->lock);
661 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
662 if (rreq->tag == rcall->tag) {
663 req = rreq;
664 req->rcall = rcall;
665 list_del(&req->req_list);
666 spin_unlock(&m->lock);
667 process_request(m, req);
668 break;
669 }
670
671 }
672
673 if (!req) {
674 spin_unlock(&m->lock);
675 if (err >= 0 && rcall->id != RFLUSH)
676 dprintk(DEBUG_ERROR,
677 "unexpected response mux %p id %d tag %d\n",
678 m, rcall->id, rcall->tag);
679 kfree(rcall);
680 }
681 }
682
683 if (!list_empty(&m->req_list)) {
684 if (test_and_clear_bit(Rpending, &m->wsched))
685 n = POLLIN;
686 else
687 n = m->trans->poll(m->trans, NULL);
688
689 if (n & POLLIN) {
690 dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
691 queue_work(v9fs_mux_wq, &m->rq);
692 } else
693 clear_bit(Rworksched, &m->wsched);
694 } else
695 clear_bit(Rworksched, &m->wsched);
696
697 return;
698
699 error:
700 v9fs_mux_cancel(m, err);
701 clear_bit(Rworksched, &m->wsched);
702 }
703
704 /**
705 * v9fs_send_request - send 9P request
706 * The function can sleep until the request is scheduled for sending.
707 * The function can be interrupted. Return from the function is not
708 * a guarantee that the request is sent succesfully. Can return errors
709 * that can be retrieved by PTR_ERR macros.
710 *
711 * @m: mux data
712 * @tc: request to be sent
713 * @cb: callback function to call when response is received
714 * @cba: parameter to pass to the callback function
715 */
716 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
717 struct v9fs_fcall *tc,
718 v9fs_mux_req_callback cb, void *cba)
719 {
720 int n;
721 struct v9fs_req *req;
722
723 dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
724 tc, tc->id);
725 if (m->err < 0)
726 return ERR_PTR(m->err);
727
728 req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
729 if (!req)
730 return ERR_PTR(-ENOMEM);
731
732 if (tc->id == TVERSION)
733 n = V9FS_NOTAG;
734 else
735 n = v9fs_mux_get_tag(m);
736
737 if (n < 0)
738 return ERR_PTR(-ENOMEM);
739
740 v9fs_set_tag(tc, n);
741
742 req->tag = n;
743 req->tcall = tc;
744 req->rcall = NULL;
745 req->err = 0;
746 req->cb = cb;
747 req->cba = cba;
748
749 spin_lock(&m->lock);
750 list_add_tail(&req->req_list, &m->unsent_req_list);
751 spin_unlock(&m->lock);
752
753 if (test_and_clear_bit(Wpending, &m->wsched))
754 n = POLLOUT;
755 else
756 n = m->trans->poll(m->trans, NULL);
757
758 if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
759 queue_work(v9fs_mux_wq, &m->wq);
760
761 return req;
762 }
763
764 static inline void
765 v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc,
766 int err)
767 {
768 v9fs_mux_req_callback cb;
769 int tag;
770 struct v9fs_mux_data *m;
771 struct v9fs_req *req, *rptr;
772
773 m = a;
774 dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
775 rc, err, tc->params.tflush.oldtag);
776
777 spin_lock(&m->lock);
778 cb = NULL;
779 tag = tc->params.tflush.oldtag;
780 list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
781 if (req->tag == tag) {
782 list_del(&req->req_list);
783 if (req->cb) {
784 cb = req->cb;
785 req->cb = NULL;
786 spin_unlock(&m->lock);
787 (*cb) (req->cba, req->tcall, req->rcall,
788 req->err);
789 }
790 kfree(req);
791 wake_up(&m->equeue);
792 break;
793 }
794 }
795
796 if (!cb)
797 spin_unlock(&m->lock);
798
799 v9fs_mux_put_tag(m, tag);
800 kfree(tc);
801 kfree(rc);
802 }
803
804 static void
805 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
806 {
807 struct v9fs_fcall *fc;
808
809 dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
810
811 fc = v9fs_create_tflush(req->tag);
812 v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
813 }
814
815 static void
816 v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
817 {
818 struct v9fs_mux_rpc *r;
819
820 if (err == ERREQFLUSH) {
821 kfree(rc);
822 dprintk(DEBUG_MUX, "err req flush\n");
823 return;
824 }
825
826 r = a;
827 dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
828 tc, rc, err);
829 r->rcall = rc;
830 r->err = err;
831 wake_up(&r->wqueue);
832 }
833
834 /**
835 * v9fs_mux_rpc - sends 9P request and waits until a response is available.
836 * The function can be interrupted.
837 * @m: mux data
838 * @tc: request to be sent
839 * @rc: pointer where a pointer to the response is stored
840 */
841 int
842 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
843 struct v9fs_fcall **rc)
844 {
845 int err;
846 unsigned long flags;
847 struct v9fs_req *req;
848 struct v9fs_mux_rpc r;
849
850 r.err = 0;
851 r.rcall = NULL;
852 r.m = m;
853 init_waitqueue_head(&r.wqueue);
854
855 if (rc)
856 *rc = NULL;
857
858 req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
859 if (IS_ERR(req)) {
860 err = PTR_ERR(req);
861 dprintk(DEBUG_MUX, "error %d\n", err);
862 return PTR_ERR(req);
863 }
864
865 r.req = req;
866 dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
867 req->tag, &r, req);
868 err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
869 if (r.err < 0)
870 err = r.err;
871
872 if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
873 spin_lock(&m->lock);
874 req->tcall = NULL;
875 req->err = ERREQFLUSH;
876 spin_unlock(&m->lock);
877
878 clear_thread_flag(TIF_SIGPENDING);
879 v9fs_mux_flush_request(m, req);
880 spin_lock_irqsave(&current->sighand->siglock, flags);
881 recalc_sigpending();
882 spin_unlock_irqrestore(&current->sighand->siglock, flags);
883 }
884
885 if (!err) {
886 if (r.rcall)
887 dprintk(DEBUG_MUX, "got response id %d tag %d\n",
888 r.rcall->id, r.rcall->tag);
889
890 if (rc)
891 *rc = r.rcall;
892 else
893 kfree(r.rcall);
894 } else {
895 kfree(r.rcall);
896 dprintk(DEBUG_MUX, "got error %d\n", err);
897 if (err > 0)
898 err = -EIO;
899 }
900
901 return err;
902 }
903
904 /**
905 * v9fs_mux_rpcnb - sends 9P request without waiting for response.
906 * @m: mux data
907 * @tc: request to be sent
908 * @cb: callback function to be called when response arrives
909 * @cba: value to pass to the callback function
910 */
911 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
912 v9fs_mux_req_callback cb, void *a)
913 {
914 int err;
915 struct v9fs_req *req;
916
917 req = v9fs_send_request(m, tc, cb, a);
918 if (IS_ERR(req)) {
919 err = PTR_ERR(req);
920 dprintk(DEBUG_MUX, "error %d\n", err);
921 return PTR_ERR(req);
922 }
923
924 dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
925 return 0;
926 }
927
928 /**
929 * v9fs_mux_cancel - cancel all pending requests with error
930 * @m: mux data
931 * @err: error code
932 */
933 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
934 {
935 struct v9fs_req *req, *rtmp;
936 LIST_HEAD(cancel_list);
937
938 dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
939 m->err = err;
940 spin_lock(&m->lock);
941 list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
942 list_move(&req->req_list, &cancel_list);
943 }
944 spin_unlock(&m->lock);
945
946 list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
947 list_del(&req->req_list);
948 if (!req->err)
949 req->err = err;
950
951 if (req->cb)
952 (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
953 else
954 kfree(req->rcall);
955
956 kfree(req);
957 }
958
959 wake_up(&m->equeue);
960 }
961
962 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
963 {
964 int tag;
965
966 tag = v9fs_get_idpool(&m->tidpool);
967 if (tag < 0)
968 return V9FS_NOTAG;
969 else
970 return (u16) tag;
971 }
972
973 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
974 {
975 if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tidpool))
976 v9fs_put_idpool(tag, &m->tidpool);
977 }
Linux kernel - Deliverables
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