xref: /openbmc/linux/fs/coda/psdev.c (revision 4e95bc26) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *      	An implementation of a loadable kernel mode driver providing
4  *		multiple kernel/user space bidirectional communications links.
5  *
6  * 		Author: 	Alan Cox <alan@lxorguk.ukuu.org.uk>
7  *
8  *              Adapted to become the Linux 2.0 Coda pseudo device
9  *              Peter  Braam  <braam@maths.ox.ac.uk>
10  *              Michael Callahan <mjc@emmy.smith.edu>
11  *
12  *              Changes for Linux 2.1
13  *              Copyright (c) 1997 Carnegie-Mellon University
14  */
15 
16 #include <linux/module.h>
17 #include <linux/errno.h>
18 #include <linux/kernel.h>
19 #include <linux/major.h>
20 #include <linux/time.h>
21 #include <linux/sched/signal.h>
22 #include <linux/slab.h>
23 #include <linux/ioport.h>
24 #include <linux/fcntl.h>
25 #include <linux/delay.h>
26 #include <linux/skbuff.h>
27 #include <linux/proc_fs.h>
28 #include <linux/vmalloc.h>
29 #include <linux/fs.h>
30 #include <linux/file.h>
31 #include <linux/poll.h>
32 #include <linux/init.h>
33 #include <linux/list.h>
34 #include <linux/mutex.h>
35 #include <linux/device.h>
36 #include <linux/pid_namespace.h>
37 #include <asm/io.h>
38 #include <linux/uaccess.h>
39 
40 #include <linux/coda.h>
41 #include <linux/coda_psdev.h>
42 
43 #include "coda_linux.h"
44 
45 #include "coda_int.h"
46 
47 /* statistics */
48 int           coda_hard;         /* allows signals during upcalls */
49 unsigned long coda_timeout = 30; /* .. secs, then signals will dequeue */
50 
51 
52 struct venus_comm coda_comms[MAX_CODADEVS];
53 static struct class *coda_psdev_class;
54 
55 /*
56  * Device operations
57  */
58 
59 static __poll_t coda_psdev_poll(struct file *file, poll_table * wait)
60 {
61         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
62 	__poll_t mask = EPOLLOUT | EPOLLWRNORM;
63 
64 	poll_wait(file, &vcp->vc_waitq, wait);
65 	mutex_lock(&vcp->vc_mutex);
66 	if (!list_empty(&vcp->vc_pending))
67                 mask |= EPOLLIN | EPOLLRDNORM;
68 	mutex_unlock(&vcp->vc_mutex);
69 
70 	return mask;
71 }
72 
73 static long coda_psdev_ioctl(struct file * filp, unsigned int cmd, unsigned long arg)
74 {
75 	unsigned int data;
76 
77 	switch(cmd) {
78 	case CIOC_KERNEL_VERSION:
79 		data = CODA_KERNEL_VERSION;
80 		return put_user(data, (int __user *) arg);
81 	default:
82 		return -ENOTTY;
83 	}
84 
85 	return 0;
86 }
87 
88 /*
89  *	Receive a message written by Venus to the psdev
90  */
91 
92 static ssize_t coda_psdev_write(struct file *file, const char __user *buf,
93 				size_t nbytes, loff_t *off)
94 {
95         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
96         struct upc_req *req = NULL;
97         struct upc_req *tmp;
98 	struct list_head *lh;
99 	struct coda_in_hdr hdr;
100 	ssize_t retval = 0, count = 0;
101 	int error;
102 
103         /* Peek at the opcode, uniquefier */
104 	if (copy_from_user(&hdr, buf, 2 * sizeof(u_long)))
105 	        return -EFAULT;
106 
107         if (DOWNCALL(hdr.opcode)) {
108 		union outputArgs *dcbuf;
109 		int size = sizeof(*dcbuf);
110 
111 		if  ( nbytes < sizeof(struct coda_out_hdr) ) {
112 			pr_warn("coda_downcall opc %d uniq %d, not enough!\n",
113 				hdr.opcode, hdr.unique);
114 			count = nbytes;
115 			goto out;
116 		}
117 		if ( nbytes > size ) {
118 			pr_warn("downcall opc %d, uniq %d, too much!",
119 				hdr.opcode, hdr.unique);
120 		        nbytes = size;
121 		}
122 		CODA_ALLOC(dcbuf, union outputArgs *, nbytes);
123 		if (copy_from_user(dcbuf, buf, nbytes)) {
124 			CODA_FREE(dcbuf, nbytes);
125 			retval = -EFAULT;
126 			goto out;
127 		}
128 
129 		/* what downcall errors does Venus handle ? */
130 		error = coda_downcall(vcp, hdr.opcode, dcbuf);
131 
132 		CODA_FREE(dcbuf, nbytes);
133 		if (error) {
134 			pr_warn("%s: coda_downcall error: %d\n",
135 				__func__, error);
136 			retval = error;
137 			goto out;
138 		}
139 		count = nbytes;
140 		goto out;
141 	}
142 
143 	/* Look for the message on the processing queue. */
144 	mutex_lock(&vcp->vc_mutex);
145 	list_for_each(lh, &vcp->vc_processing) {
146 		tmp = list_entry(lh, struct upc_req , uc_chain);
147 		if (tmp->uc_unique == hdr.unique) {
148 			req = tmp;
149 			list_del(&req->uc_chain);
150 			break;
151 		}
152 	}
153 	mutex_unlock(&vcp->vc_mutex);
154 
155 	if (!req) {
156 		pr_warn("%s: msg (%d, %d) not found\n",
157 			__func__, hdr.opcode, hdr.unique);
158 		retval = -ESRCH;
159 		goto out;
160 	}
161 
162         /* move data into response buffer. */
163 	if (req->uc_outSize < nbytes) {
164 		pr_warn("%s: too much cnt: %d, cnt: %ld, opc: %d, uniq: %d.\n",
165 			__func__, req->uc_outSize, (long)nbytes,
166 			hdr.opcode, hdr.unique);
167 		nbytes = req->uc_outSize; /* don't have more space! */
168 	}
169         if (copy_from_user(req->uc_data, buf, nbytes)) {
170 		req->uc_flags |= CODA_REQ_ABORT;
171 		wake_up(&req->uc_sleep);
172 		retval = -EFAULT;
173 		goto out;
174 	}
175 
176 	/* adjust outsize. is this useful ?? */
177 	req->uc_outSize = nbytes;
178 	req->uc_flags |= CODA_REQ_WRITE;
179 	count = nbytes;
180 
181 	/* Convert filedescriptor into a file handle */
182 	if (req->uc_opcode == CODA_OPEN_BY_FD) {
183 		struct coda_open_by_fd_out *outp =
184 			(struct coda_open_by_fd_out *)req->uc_data;
185 		if (!outp->oh.result)
186 			outp->fh = fget(outp->fd);
187 	}
188 
189         wake_up(&req->uc_sleep);
190 out:
191         return(count ? count : retval);
192 }
193 
194 /*
195  *	Read a message from the kernel to Venus
196  */
197 
198 static ssize_t coda_psdev_read(struct file * file, char __user * buf,
199 			       size_t nbytes, loff_t *off)
200 {
201 	DECLARE_WAITQUEUE(wait, current);
202         struct venus_comm *vcp = (struct venus_comm *) file->private_data;
203         struct upc_req *req;
204 	ssize_t retval = 0, count = 0;
205 
206 	if (nbytes == 0)
207 		return 0;
208 
209 	mutex_lock(&vcp->vc_mutex);
210 
211 	add_wait_queue(&vcp->vc_waitq, &wait);
212 	set_current_state(TASK_INTERRUPTIBLE);
213 
214 	while (list_empty(&vcp->vc_pending)) {
215 		if (file->f_flags & O_NONBLOCK) {
216 			retval = -EAGAIN;
217 			break;
218 		}
219 		if (signal_pending(current)) {
220 			retval = -ERESTARTSYS;
221 			break;
222 		}
223 		mutex_unlock(&vcp->vc_mutex);
224 		schedule();
225 		mutex_lock(&vcp->vc_mutex);
226 	}
227 
228 	set_current_state(TASK_RUNNING);
229 	remove_wait_queue(&vcp->vc_waitq, &wait);
230 
231 	if (retval)
232 		goto out;
233 
234 	req = list_entry(vcp->vc_pending.next, struct upc_req,uc_chain);
235 	list_del(&req->uc_chain);
236 
237 	/* Move the input args into userspace */
238 	count = req->uc_inSize;
239 	if (nbytes < req->uc_inSize) {
240 		pr_warn("%s: Venus read %ld bytes of %d in message\n",
241 			__func__, (long)nbytes, req->uc_inSize);
242 		count = nbytes;
243         }
244 
245 	if (copy_to_user(buf, req->uc_data, count))
246 	        retval = -EFAULT;
247 
248 	/* If request was not a signal, enqueue and don't free */
249 	if (!(req->uc_flags & CODA_REQ_ASYNC)) {
250 		req->uc_flags |= CODA_REQ_READ;
251 		list_add_tail(&(req->uc_chain), &vcp->vc_processing);
252 		goto out;
253 	}
254 
255 	CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));
256 	kfree(req);
257 out:
258 	mutex_unlock(&vcp->vc_mutex);
259 	return (count ? count : retval);
260 }
261 
262 static int coda_psdev_open(struct inode * inode, struct file * file)
263 {
264 	struct venus_comm *vcp;
265 	int idx, err;
266 
267 	if (task_active_pid_ns(current) != &init_pid_ns)
268 		return -EINVAL;
269 
270 	if (current_user_ns() != &init_user_ns)
271 		return -EINVAL;
272 
273 	idx = iminor(inode);
274 	if (idx < 0 || idx >= MAX_CODADEVS)
275 		return -ENODEV;
276 
277 	err = -EBUSY;
278 	vcp = &coda_comms[idx];
279 	mutex_lock(&vcp->vc_mutex);
280 
281 	if (!vcp->vc_inuse) {
282 		vcp->vc_inuse++;
283 
284 		INIT_LIST_HEAD(&vcp->vc_pending);
285 		INIT_LIST_HEAD(&vcp->vc_processing);
286 		init_waitqueue_head(&vcp->vc_waitq);
287 		vcp->vc_sb = NULL;
288 		vcp->vc_seq = 0;
289 
290 		file->private_data = vcp;
291 		err = 0;
292 	}
293 
294 	mutex_unlock(&vcp->vc_mutex);
295 	return err;
296 }
297 
298 
299 static int coda_psdev_release(struct inode * inode, struct file * file)
300 {
301 	struct venus_comm *vcp = (struct venus_comm *) file->private_data;
302 	struct upc_req *req, *tmp;
303 
304 	if (!vcp || !vcp->vc_inuse ) {
305 		pr_warn("%s: Not open.\n", __func__);
306 		return -1;
307 	}
308 
309 	mutex_lock(&vcp->vc_mutex);
310 
311 	/* Wakeup clients so they can return. */
312 	list_for_each_entry_safe(req, tmp, &vcp->vc_pending, uc_chain) {
313 		list_del(&req->uc_chain);
314 
315 		/* Async requests need to be freed here */
316 		if (req->uc_flags & CODA_REQ_ASYNC) {
317 			CODA_FREE(req->uc_data, sizeof(struct coda_in_hdr));
318 			kfree(req);
319 			continue;
320 		}
321 		req->uc_flags |= CODA_REQ_ABORT;
322 		wake_up(&req->uc_sleep);
323 	}
324 
325 	list_for_each_entry_safe(req, tmp, &vcp->vc_processing, uc_chain) {
326 		list_del(&req->uc_chain);
327 
328 		req->uc_flags |= CODA_REQ_ABORT;
329 		wake_up(&req->uc_sleep);
330 	}
331 
332 	file->private_data = NULL;
333 	vcp->vc_inuse--;
334 	mutex_unlock(&vcp->vc_mutex);
335 	return 0;
336 }
337 
338 
339 static const struct file_operations coda_psdev_fops = {
340 	.owner		= THIS_MODULE,
341 	.read		= coda_psdev_read,
342 	.write		= coda_psdev_write,
343 	.poll		= coda_psdev_poll,
344 	.unlocked_ioctl	= coda_psdev_ioctl,
345 	.open		= coda_psdev_open,
346 	.release	= coda_psdev_release,
347 	.llseek		= noop_llseek,
348 };
349 
350 static int init_coda_psdev(void)
351 {
352 	int i, err = 0;
353 	if (register_chrdev(CODA_PSDEV_MAJOR, "coda", &coda_psdev_fops)) {
354 		pr_err("%s: unable to get major %d\n",
355 		       __func__, CODA_PSDEV_MAJOR);
356               return -EIO;
357 	}
358 	coda_psdev_class = class_create(THIS_MODULE, "coda");
359 	if (IS_ERR(coda_psdev_class)) {
360 		err = PTR_ERR(coda_psdev_class);
361 		goto out_chrdev;
362 	}
363 	for (i = 0; i < MAX_CODADEVS; i++) {
364 		mutex_init(&(&coda_comms[i])->vc_mutex);
365 		device_create(coda_psdev_class, NULL,
366 			      MKDEV(CODA_PSDEV_MAJOR, i), NULL, "cfs%d", i);
367 	}
368 	coda_sysctl_init();
369 	goto out;
370 
371 out_chrdev:
372 	unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
373 out:
374 	return err;
375 }
376 
377 MODULE_AUTHOR("Jan Harkes, Peter J. Braam");
378 MODULE_DESCRIPTION("Coda Distributed File System VFS interface");
379 MODULE_ALIAS_CHARDEV_MAJOR(CODA_PSDEV_MAJOR);
380 MODULE_LICENSE("GPL");
381 MODULE_VERSION("6.6");
382 
383 static int __init init_coda(void)
384 {
385 	int status;
386 	int i;
387 
388 	status = coda_init_inodecache();
389 	if (status)
390 		goto out2;
391 	status = init_coda_psdev();
392 	if ( status ) {
393 		pr_warn("Problem (%d) in init_coda_psdev\n", status);
394 		goto out1;
395 	}
396 
397 	status = register_filesystem(&coda_fs_type);
398 	if (status) {
399 		pr_warn("failed to register filesystem!\n");
400 		goto out;
401 	}
402 	return 0;
403 out:
404 	for (i = 0; i < MAX_CODADEVS; i++)
405 		device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
406 	class_destroy(coda_psdev_class);
407 	unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
408 	coda_sysctl_clean();
409 out1:
410 	coda_destroy_inodecache();
411 out2:
412 	return status;
413 }
414 
415 static void __exit exit_coda(void)
416 {
417         int err, i;
418 
419 	err = unregister_filesystem(&coda_fs_type);
420 	if (err != 0)
421 		pr_warn("failed to unregister filesystem\n");
422 	for (i = 0; i < MAX_CODADEVS; i++)
423 		device_destroy(coda_psdev_class, MKDEV(CODA_PSDEV_MAJOR, i));
424 	class_destroy(coda_psdev_class);
425 	unregister_chrdev(CODA_PSDEV_MAJOR, "coda");
426 	coda_sysctl_clean();
427 	coda_destroy_inodecache();
428 }
429 
430 module_init(init_coda);
431 module_exit(exit_coda);
432 
433