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-rw-r--r--fs/9p/mux.c440
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diff --git a/fs/9p/mux.c b/fs/9p/mux.c
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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 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/kthread.h>
32#include <linux/idr.h>
33
34#include "debug.h"
35#include "v9fs.h"
36#include "9p.h"
37#include "transport.h"
38#include "conv.h"
39#include "mux.h"
40
41/**
42 * dprintcond - print condition of session info
43 * @v9ses: session info structure
44 * @req: RPC request structure
45 *
46 */
47
48static inline int
49dprintcond(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
50{
51 dprintk(DEBUG_MUX, "condition: %d, %p\n", v9ses->transport->status,
52 req->rcall);
53 return 0;
54}
55
56/**
57 * xread - force read of a certain number of bytes
58 * @v9ses: session info structure
59 * @ptr: pointer to buffer
60 * @sz: number of bytes to read
61 *
62 * Chuck Cranor CS-533 project1
63 */
64
65static int xread(struct v9fs_session_info *v9ses, void *ptr, unsigned long sz)
66{
67 int rd = 0;
68 int ret = 0;
69 while (rd < sz) {
70 ret = v9ses->transport->read(v9ses->transport, ptr, sz - rd);
71 if (ret <= 0) {
72 dprintk(DEBUG_ERROR, "xread errno %d\n", ret);
73 return ret;
74 }
75 rd += ret;
76 ptr += ret;
77 }
78 return (rd);
79}
80
81/**
82 * read_message - read a full 9P2000 fcall packet
83 * @v9ses: session info structure
84 * @rcall: fcall structure to read into
85 * @rcalllen: size of fcall buffer
86 *
87 */
88
89static int
90read_message(struct v9fs_session_info *v9ses,
91 struct v9fs_fcall *rcall, int rcalllen)
92{
93 unsigned char buf[4];
94 void *data;
95 int size = 0;
96 int res = 0;
97
98 res = xread(v9ses, buf, sizeof(buf));
99 if (res < 0) {
100 dprintk(DEBUG_ERROR,
101 "Reading of count field failed returned: %d\n", res);
102 return res;
103 }
104
105 if (res < 4) {
106 dprintk(DEBUG_ERROR,
107 "Reading of count field failed returned: %d\n", res);
108 return -EIO;
109 }
110
111 size = buf[0] | (buf[1] << 8) | (buf[2] << 16) | (buf[3] << 24);
112 dprintk(DEBUG_MUX, "got a packet count: %d\n", size);
113
114 /* adjust for the four bytes of size */
115 size -= 4;
116
117 if (size > v9ses->maxdata) {
118 dprintk(DEBUG_ERROR, "packet too big: %d\n", size);
119 return -E2BIG;
120 }
121
122 data = kmalloc(size, GFP_KERNEL);
123 if (!data) {
124 eprintk(KERN_WARNING, "out of memory\n");
125 return -ENOMEM;
126 }
127
128 res = xread(v9ses, data, size);
129 if (res < size) {
130 dprintk(DEBUG_ERROR, "Reading of fcall failed returned: %d\n",
131 res);
132 kfree(data);
133 return res;
134 }
135
136 /* we now have an in-memory string that is the reply.
137 * deserialize it. There is very little to go wrong at this point
138 * save for v9fs_alloc errors.
139 */
140 res = v9fs_deserialize_fcall(v9ses, size, data, v9ses->maxdata,
141 rcall, rcalllen);
142
143 kfree(data);
144
145 if (res < 0)
146 return res;
147
148 return 0;
149}
150
151/**
152 * v9fs_recv - receive an RPC response for a particular tag
153 * @v9ses: session info structure
154 * @req: RPC request structure
155 *
156 */
157
158static int v9fs_recv(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
159{
160 int ret = 0;
161
162 dprintk(DEBUG_MUX, "waiting for response: %d\n", req->tcall->tag);
163 ret = wait_event_interruptible(v9ses->read_wait,
164 ((v9ses->transport->status != Connected) ||
165 (req->rcall != 0) || dprintcond(v9ses, req)));
166
167 dprintk(DEBUG_MUX, "got it: rcall %p\n", req->rcall);
168 if (v9ses->transport->status == Disconnected)
169 return -ECONNRESET;
170
171 if (ret == 0) {
172 spin_lock(&v9ses->muxlock);
173 list_del(&req->next);
174 spin_unlock(&v9ses->muxlock);
175 }
176
177 return ret;
178}
179
180/**
181 * v9fs_send - send a 9P request
182 * @v9ses: session info structure
183 * @req: RPC request to send
184 *
185 */
186
187static int v9fs_send(struct v9fs_session_info *v9ses, struct v9fs_rpcreq *req)
188{
189 int ret = -1;
190 void *data = NULL;
191 struct v9fs_fcall *tcall = req->tcall;
192
193 data = kmalloc(v9ses->maxdata + V9FS_IOHDRSZ, GFP_KERNEL);
194 if (!data)
195 return -ENOMEM;
196
197 tcall->size = 0; /* enforce size recalculation */
198 ret =
199 v9fs_serialize_fcall(v9ses, tcall, data,
200 v9ses->maxdata + V9FS_IOHDRSZ);
201 if (ret < 0)
202 goto free_data;
203
204 spin_lock(&v9ses->muxlock);
205 list_add(&req->next, &v9ses->mux_fcalls);
206 spin_unlock(&v9ses->muxlock);
207
208 dprintk(DEBUG_MUX, "sending message: tag %d size %d\n", tcall->tag,
209 tcall->size);
210 ret = v9ses->transport->write(v9ses->transport, data, tcall->size);
211
212 if (ret != tcall->size) {
213 spin_lock(&v9ses->muxlock);
214 list_del(&req->next);
215 kfree(req->rcall);
216
217 spin_unlock(&v9ses->muxlock);
218 if (ret >= 0)
219 ret = -EREMOTEIO;
220 } else
221 ret = 0;
222
223 free_data:
224 kfree(data);
225 return ret;
226}
227
228/**
229 * v9fs_mux_rpc - send a request, receive a response
230 * @v9ses: session info structure
231 * @tcall: fcall to send
232 * @rcall: buffer to place response into
233 *
234 */
235
236long
237v9fs_mux_rpc(struct v9fs_session_info *v9ses, struct v9fs_fcall *tcall,
238 struct v9fs_fcall **rcall)
239{
240 int tid = -1;
241 struct v9fs_fcall *fcall = NULL;
242 struct v9fs_rpcreq req;
243 int ret = -1;
244
245 if (!v9ses)
246 return -EINVAL;
247
248 if (rcall)
249 *rcall = NULL;
250
251 if (tcall->id != TVERSION) {
252 tid = v9fs_get_idpool(&v9ses->tidpool);
253 if (tid < 0)
254 return -ENOMEM;
255 }
256
257 tcall->tag = tid;
258
259 req.tcall = tcall;
260 req.rcall = NULL;
261
262 ret = v9fs_send(v9ses, &req);
263
264 if (ret < 0) {
265 if (tcall->id != TVERSION)
266 v9fs_put_idpool(tid, &v9ses->tidpool);
267 dprintk(DEBUG_MUX, "error %d\n", ret);
268 return ret;
269 }
270
271 ret = v9fs_recv(v9ses, &req);
272
273 fcall = req.rcall;
274
275 dprintk(DEBUG_MUX, "received: tag=%x, ret=%d\n", tcall->tag, ret);
276 if (ret == -ERESTARTSYS) {
277 if (v9ses->transport->status != Disconnected
278 && tcall->id != TFLUSH) {
279 unsigned long flags;
280
281 dprintk(DEBUG_MUX, "flushing the tag: %d\n",
282 tcall->tag);
283 clear_thread_flag(TIF_SIGPENDING);
284 v9fs_t_flush(v9ses, tcall->tag);
285 spin_lock_irqsave(&current->sighand->siglock, flags);
286 recalc_sigpending();
287 spin_unlock_irqrestore(&current->sighand->siglock,
288 flags);
289 dprintk(DEBUG_MUX, "flushing done\n");
290 }
291
292 goto release_req;
293 } else if (ret < 0)
294 goto release_req;
295
296 if (!fcall)
297 ret = -EIO;
298 else {
299 if (fcall->id == RERROR) {
300 ret = v9fs_errstr2errno(fcall->params.rerror.error);
301 if (ret == 0) { /* string match failed */
302 if (fcall->params.rerror.errno)
303 ret = -(fcall->params.rerror.errno);
304 else
305 ret = -ESERVERFAULT;
306 }
307 } else if (fcall->id != tcall->id + 1) {
308 dprintk(DEBUG_ERROR,
309 "fcall mismatch: expected %d, got %d\n",
310 tcall->id + 1, fcall->id);
311 ret = -EIO;
312 }
313 }
314
315 release_req:
316 if (tcall->id != TVERSION)
317 v9fs_put_idpool(tid, &v9ses->tidpool);
318 if (rcall)
319 *rcall = fcall;
320 else
321 kfree(fcall);
322
323 return ret;
324}
325
326/**
327 * v9fs_recvproc - kproc to handle demultiplexing responses
328 * @data: session info structure
329 *
330 */
331
332static int v9fs_recvproc(void *data)
333{
334 struct v9fs_session_info *v9ses = (struct v9fs_session_info *)data;
335 struct v9fs_fcall *rcall = NULL;
336 struct v9fs_rpcreq *rptr;
337 struct v9fs_rpcreq *req;
338 struct v9fs_rpcreq *rreq;
339 int err = 0;
340
341 allow_signal(SIGKILL);
342 set_current_state(TASK_INTERRUPTIBLE);
343 complete(&v9ses->proccmpl);
344 while (!kthread_should_stop() && err >= 0) {
345 req = rptr = rreq = NULL;
346
347 rcall = kmalloc(v9ses->maxdata + V9FS_IOHDRSZ, GFP_KERNEL);
348 if (!rcall) {
349 eprintk(KERN_ERR, "no memory for buffers\n");
350 break;
351 }
352
353 err = read_message(v9ses, rcall, v9ses->maxdata + V9FS_IOHDRSZ);
354 if (err < 0) {
355 kfree(rcall);
356 break;
357 }
358 spin_lock(&v9ses->muxlock);
359 list_for_each_entry_safe(rreq, rptr, &v9ses->mux_fcalls, next) {
360 if (rreq->tcall->tag == rcall->tag) {
361 req = rreq;
362 req->rcall = rcall;
363 break;
364 }
365 }
366
367 if (req && (req->tcall->id == TFLUSH)) {
368 struct v9fs_rpcreq *treq = NULL;
369 list_for_each_entry_safe(treq, rptr, &v9ses->mux_fcalls, next) {
370 if (treq->tcall->tag ==
371 req->tcall->params.tflush.oldtag) {
372 list_del(&rptr->next);
373 kfree(treq->rcall);
374 break;
375 }
376 }
377 }
378
379 spin_unlock(&v9ses->muxlock);
380
381 if (!req) {
382 dprintk(DEBUG_ERROR,
383 "unexpected response: id %d tag %d\n",
384 rcall->id, rcall->tag);
385
386 kfree(rcall);
387 }
388
389 wake_up_all(&v9ses->read_wait);
390 set_current_state(TASK_INTERRUPTIBLE);
391 }
392
393 /* Inform all pending processes about the failure */
394 wake_up_all(&v9ses->read_wait);
395
396 if (signal_pending(current))
397 complete(&v9ses->proccmpl);
398
399 dprintk(DEBUG_MUX, "recvproc: end\n");
400 v9ses->recvproc = NULL;
401
402 return err >= 0;
403}
404
405/**
406 * v9fs_mux_init - initialize multiplexer (spawn kproc)
407 * @v9ses: session info structure
408 * @dev_name: mount device information (to create unique kproc)
409 *
410 */
411
412int v9fs_mux_init(struct v9fs_session_info *v9ses, const char *dev_name)
413{
414 char procname[60];
415
416 strncpy(procname, dev_name, sizeof(procname));
417 procname[sizeof(procname) - 1] = 0;
418
419 init_waitqueue_head(&v9ses->read_wait);
420 init_completion(&v9ses->fcread);
421 init_completion(&v9ses->proccmpl);
422 spin_lock_init(&v9ses->muxlock);
423 INIT_LIST_HEAD(&v9ses->mux_fcalls);
424 v9ses->recvproc = NULL;
425 v9ses->curfcall = NULL;
426
427 v9ses->recvproc = kthread_create(v9fs_recvproc, v9ses,
428 "v9fs_recvproc %s", procname);
429
430 if (IS_ERR(v9ses->recvproc)) {
431 eprintk(KERN_ERR, "cannot create receiving thread\n");
432 v9fs_session_close(v9ses);
433 return -ECONNABORTED;
434 }
435
436 wake_up_process(v9ses->recvproc);
437 wait_for_completion(&v9ses->proccmpl);
438
439 return 0;
440}