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Linux/fs/coda/psdev.c

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  1 /*
  2  *              An implementation of a loadable kernel mode driver providing
  3  *              multiple kernel/user space bidirectional communications links.
  4  *
  5  *              Author:         Alan Cox <alan@lxorguk.ukuu.org.uk>
  6  *
  7  *              This program is free software; you can redistribute it and/or
  8  *              modify it under the terms of the GNU General Public License
  9  *              as published by the Free Software Foundation; either version
 10  *              2 of the License, or (at your option) any later version.
 11  * 
 12  *              Adapted to become the Linux 2.0 Coda pseudo device
 13  *              Peter  Braam  <braam@maths.ox.ac.uk> 
 14  *              Michael Callahan <mjc@emmy.smith.edu>           
 15  *
 16  *              Changes for Linux 2.1
 17  *              Copyright (c) 1997 Carnegie-Mellon University
 18  */
 19 
 20 #include <linux/module.h>
 21 #include <linux/errno.h>
 22 #include <linux/kernel.h>
 23 #include <linux/major.h>
 24 #include <linux/time.h>
 25 #include <linux/sched/signal.h>
 26 #include <linux/slab.h>
 27 #include <linux/ioport.h>
 28 #include <linux/fcntl.h>
 29 #include <linux/delay.h>
 30 #include <linux/skbuff.h>
 31 #include <linux/proc_fs.h>
 32 #include <linux/vmalloc.h>
 33 #include <linux/fs.h>
 34 #include <linux/file.h>
 35 #include <linux/poll.h>
 36 #include <linux/init.h>
 37 #include <linux/list.h>
 38 #include <linux/mutex.h>
 39 #include <linux/device.h>
 40 #include <linux/pid_namespace.h>
 41 #include <asm/io.h>
 42 #include <linux/poll.h>
 43 #include <linux/uaccess.h>
 44 
 45 #include <linux/coda.h>
 46 #include <linux/coda_psdev.h>
 47 
 48 #include "coda_linux.h"
 49 
 50 #include "coda_int.h"
 51 
 52 /* statistics */
 53 int           coda_hard;         /* allows signals during upcalls */
 54 unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */
 55 
 56 
 57 struct venus_comm coda_comms[MAX_CODADEVS];
 58 static struct class *coda_psdev_class;
 59 
 60 /*
 61  * Device operations
 62  */
 63 
 64 static __poll_t coda_psdev_poll(struct file *file, poll_table * wait)
 65 {
 66         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
 67         __poll_t mask = EPOLLOUT | EPOLLWRNORM;
 68 
 69         poll_wait(file, &vcp->vc_waitq, wait);
 70         mutex_lock(&vcp->vc_mutex);
 71         if (!list_empty(&vcp->vc_pending))
 72                 mask |= EPOLLIN | EPOLLRDNORM;
 73         mutex_unlock(&vcp->vc_mutex);
 74 
 75         return mask;
 76 }
 77 
 78 static long coda_psdev_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
 79 {
 80         unsigned int data;
 81 
 82         switch(cmd) {
 83         case CIOC_KERNEL_VERSION:
 84                 data = CODA_KERNEL_VERSION;
 85                 return put_user(data, (int __user *) arg);
 86         default:
 87                 return -ENOTTY;
 88         }
 89 
 90         return 0;
 91 }
 92 
 93 /*
 94  *      Receive a message written by Venus to the psdev
 95  */
 96  
 97 static ssize_t coda_psdev_write(struct file *file, const char __user *buf, 
 98                                 size_t nbytes, loff_t *off)
 99 {
100         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
101         struct upc_req *req = NULL;
102         struct upc_req *tmp;
103         struct list_head *lh;
104         struct coda_in_hdr hdr;
105         ssize_t retval = 0, count = 0;
106         int error;
107 
108         /* Peek at the opcode, uniquefier */
109         if (copy_from_user(&hdr, buf, 2 * sizeof(u_long)))
110                 return -EFAULT;
111 
112         if (DOWNCALL(hdr.opcode)) {
113                 union outputArgs *dcbuf;
114                 int size = sizeof(*dcbuf);
115 
116                 if  ( nbytes < sizeof(struct coda_out_hdr) ) {
117                         pr_warn("coda_downcall opc %d uniq %d, not enough!\n",
118                                 hdr.opcode, hdr.unique);
119                         count = nbytes;
120                         goto out;
121                 }
122                 if ( nbytes > size ) {
123                         pr_warn("downcall opc %d, uniq %d, too much!",
124                                 hdr.opcode, hdr.unique);
125                         nbytes = size;
126                 }
127                 CODA_ALLOC(dcbuf, union outputArgs *, nbytes);
128                 if (copy_from_user(dcbuf, buf, nbytes)) {
129                         CODA_FREE(dcbuf, nbytes);
130                         retval = -EFAULT;
131                         goto out;
132                 }
133 
134                 /* what downcall errors does Venus handle ? */
135                 error = coda_downcall(vcp, hdr.opcode, dcbuf);
136 
137                 CODA_FREE(dcbuf, nbytes);
138                 if (error) {
139                         pr_warn("%s: coda_downcall error: %d\n",
140                                 __func__, error);
141                         retval = error;
142                         goto out;
143                 }
144                 count = nbytes;
145                 goto out;
146         }
147         
148         /* Look for the message on the processing queue. */
149         mutex_lock(&vcp->vc_mutex);
150         list_for_each(lh, &vcp->vc_processing) {
151                 tmp = list_entry(lh, struct upc_req , uc_chain);
152                 if (tmp->uc_unique == hdr.unique) {
153                         req = tmp;
154                         list_del(&req->uc_chain);
155                         break;
156                 }
157         }
158         mutex_unlock(&vcp->vc_mutex);
159 
160         if (!req) {
161                 pr_warn("%s: msg (%d, %d) not found\n",
162                         __func__, hdr.opcode, hdr.unique);
163                 retval = -ESRCH;
164                 goto out;
165         }
166 
167         /* move data into response buffer. */
168         if (req->uc_outSize < nbytes) {
169                 pr_warn("%s: too much cnt: %d, cnt: %ld, opc: %d, uniq: %d.\n",
170                         __func__, req->uc_outSize, (long)nbytes,
171                         hdr.opcode, hdr.unique);
172                 nbytes = req->uc_outSize; /* don't have more space! */
173         }
174         if (copy_from_user(req->uc_data, buf, nbytes)) {
175                 req->uc_flags |= CODA_REQ_ABORT;
176                 wake_up(&req->uc_sleep);
177                 retval = -EFAULT;
178                 goto out;
179         }
180 
181         /* adjust outsize. is this useful ?? */
182         req->uc_outSize = nbytes;
183         req->uc_flags |= CODA_REQ_WRITE;
184         count = nbytes;
185 
186         /* Convert filedescriptor into a file handle */
187         if (req->uc_opcode == CODA_OPEN_BY_FD) {
188                 struct coda_open_by_fd_out *outp =
189                         (struct coda_open_by_fd_out *)req->uc_data;
190                 if (!outp->oh.result)
191                         outp->fh = fget(outp->fd);
192         }
193 
194         wake_up(&req->uc_sleep);
195 out:
196         return(count ? count : retval);  
197 }
198 
199 /*
200  *      Read a message from the kernel to Venus
201  */
202 
203 static ssize_t coda_psdev_read(struct file * file, char __user * buf, 
204                                size_t nbytes, loff_t *off)
205 {
206         DECLARE_WAITQUEUE(wait, current);
207         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
208         struct upc_req *req;
209         ssize_t retval = 0, count = 0;
210 
211         if (nbytes == 0)
212                 return 0;
213 
214         mutex_lock(&vcp->vc_mutex);
215 
216         add_wait_queue(&vcp->vc_waitq, &wait);
217         set_current_state(TASK_INTERRUPTIBLE);
218 
219         while (list_empty(&vcp->vc_pending)) {
220                 if (file->f_flags & O_NONBLOCK) {
221                         retval = -EAGAIN;
222                         break;
223                 }
224                 if (signal_pending(current)) {
225                         retval = -ERESTARTSYS;
226                         break;
227                 }
228                 mutex_unlock(&vcp->vc_mutex);
229                 schedule();
230                 mutex_lock(&vcp->vc_mutex);
231         }
232 
233         set_current_state(TASK_RUNNING);
234         remove_wait_queue(&vcp->vc_waitq, &wait);
235 
236         if (retval)
237                 goto out;
238 
239         req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);
240         list_del(&req->uc_chain);
241 
242         /* Move the input args into userspace */
243         count = req->uc_inSize;
244         if (nbytes < req->uc_inSize) {
245                 pr_warn("%s: Venus read %ld bytes of %d in message\n",
246                         __func__, (long)nbytes, req->uc_inSize);
247                 count = nbytes;
248         }
249 
250         if (copy_to_user(buf, req->uc_data, count))
251                 retval = -EFAULT;
252         
253         /* If request was not a signal, enqueue and don't free */
254         if (!(req->uc_flags & CODA_REQ_ASYNC)) {
255                 req->uc_flags |= CODA_REQ_READ;
256                 list_add_tail(&(req->uc_chain), &vcp->vc_processing);
257                 goto out;
258         }
259 
260         CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));
261         kfree(req);
262 out:
263         mutex_unlock(&vcp->vc_mutex);
264         return (count ? count : retval);
265 }
266 
267 static int coda_psdev_open(struct inode * inode, struct file * file)
268 {
269         struct venus_comm *vcp;
270         int idx, err;
271 
272         if (task_active_pid_ns(current) != &init_pid_ns)
273                 return -EINVAL;
274 
275         if (current_user_ns() != &init_user_ns)
276                 return -EINVAL;
277 
278         idx = iminor(inode);
279         if (idx < 0 || idx >= MAX_CODADEVS)
280                 return -ENODEV;
281 
282         err = -EBUSY;
283         vcp = &coda_comms[idx];
284         mutex_lock(&vcp->vc_mutex);
285 
286         if (!vcp->vc_inuse) {
287                 vcp->vc_inuse++;
288 
289                 INIT_LIST_HEAD(&vcp->vc_pending);
290                 INIT_LIST_HEAD(&vcp->vc_processing);
291                 init_waitqueue_head(&vcp->vc_waitq);
292                 vcp->vc_sb = NULL;
293                 vcp->vc_seq = 0;
294 
295                 file->private_data = vcp;
296                 err = 0;
297         }
298 
299         mutex_unlock(&vcp->vc_mutex);
300         return err;
301 }
302 
303 
304 static int coda_psdev_release(struct inode * inode, struct file * file)
305 {
306         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
307         struct upc_req *req, *tmp;
308 
309         if (!vcp || !vcp->vc_inuse ) {
310                 pr_warn("%s: Not open.\n", __func__);
311                 return -1;
312         }
313 
314         mutex_lock(&vcp->vc_mutex);
315 
316         /* Wakeup clients so they can return. */
317         list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
318                 list_del(&req->uc_chain);
319 
320                 /* Async requests need to be freed here */
321                 if (req->uc_flags & CODA_REQ_ASYNC) {
322                         CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));
323                         kfree(req);
324                         continue;
325                 }
326                 req->uc_flags |= CODA_REQ_ABORT;
327                 wake_up(&req->uc_sleep);
328         }
329 
330         list_for_each_entry_safe(req, tmp, &vcp->vc_processing, uc_chain) {
331                 list_del(&req->uc_chain);
332 
333                 req->uc_flags |= CODA_REQ_ABORT;
334                 wake_up(&req->uc_sleep);
335         }
336 
337         file->private_data = NULL;
338         vcp->vc_inuse--;
339         mutex_unlock(&vcp->vc_mutex);
340         return 0;
341 }
342 
343 
344 static const struct file_operations coda_psdev_fops = {
345         .owner          = THIS_MODULE,
346         .read           = coda_psdev_read,
347         .write          = coda_psdev_write,
348         .poll           = coda_psdev_poll,
349         .unlocked_ioctl = coda_psdev_ioctl,
350         .open           = coda_psdev_open,
351         .release        = coda_psdev_release,
352         .llseek         = noop_llseek,
353 };
354 
355 static int init_coda_psdev(void)
356 {
357         int i, err = 0;
358         if (register_chrdev(CODA_PSDEV_MAJOR, "coda", &coda_psdev_fops)) {
359                 pr_err("%s: unable to get major %d\n",
360                        __func__, CODA_PSDEV_MAJOR);
361               return -EIO;
362         }
363         coda_psdev_class = class_create(THIS_MODULE, "coda");
364         if (IS_ERR(coda_psdev_class)) {
365                 err = PTR_ERR(coda_psdev_class);
366                 goto out_chrdev;
367         }               
368         for (i = 0; i < MAX_CODADEVS; i++) {
369                 mutex_init(&(&coda_comms[i])->vc_mutex);
370                 device_create(coda_psdev_class, NULL,
371                               MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
372         }
373         coda_sysctl_init();
374         goto out;
375 
376 out_chrdev:
377         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
378 out:
379         return err;
380 }
381 
382 MODULE_AUTHOR("Jan Harkes, Peter J. Braam");
383 MODULE_DESCRIPTION("Coda Distributed File System VFS interface");
384 MODULE_ALIAS_CHARDEV_MAJOR(CODA_PSDEV_MAJOR);
385 MODULE_LICENSE("GPL");
386 MODULE_VERSION("6.6");
387 
388 static int __init init_coda(void)
389 {
390         int status;
391         int i;
392 
393         status = coda_init_inodecache();
394         if (status)
395                 goto out2;
396         status = init_coda_psdev();
397         if ( status ) {
398                 pr_warn("Problem (%d) in init_coda_psdev\n", status);
399                 goto out1;
400         }
401         
402         status = register_filesystem(&coda_fs_type);
403         if (status) {
404                 pr_warn("failed to register filesystem!\n");
405                 goto out;
406         }
407         return 0;
408 out:
409         for (i = 0; i < MAX_CODADEVS; i++)
410                 device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
411         class_destroy(coda_psdev_class);
412         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
413         coda_sysctl_clean();
414 out1:
415         coda_destroy_inodecache();
416 out2:
417         return status;
418 }
419 
420 static void __exit exit_coda(void)
421 {
422         int err, i;
423 
424         err = unregister_filesystem(&coda_fs_type);
425         if (err != 0)
426                 pr_warn("failed to unregister filesystem\n");
427         for (i = 0; i < MAX_CODADEVS; i++)
428                 device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
429         class_destroy(coda_psdev_class);
430         unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
431         coda_sysctl_clean();
432         coda_destroy_inodecache();
433 }
434 
435 module_init(init_coda);
436 module_exit(exit_coda);
437 
438 

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