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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Stefani Seibold45465482009-12-21 14:37:26 -08002 * A generic kernel FIFO implementation.
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
Stefani Seibold45465482009-12-21 14:37:26 -08004 * Copyright (C) 2009 Stefani Seibold <stefani@seibold.net>
Linus Torvalds1da177e2005-04-16 15:20:36 -07005 * Copyright (C) 2004 Stelian Pop <stelian@popies.net>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 *
21 */
Stefani Seibold7acd72e2009-12-21 14:37:28 -080022
23/*
24 * Howto porting drivers to the new generic fifo API:
25 *
26 * - Modify the declaration of the "struct kfifo *" object into a
27 * in-place "struct kfifo" object
28 * - Init the in-place object with kfifo_alloc() or kfifo_init()
29 * Note: The address of the in-place "struct kfifo" object must be
30 * passed as the first argument to this functions
31 * - Replace the use of __kfifo_put into kfifo_in and __kfifo_get
32 * into kfifo_out
33 * - Replace the use of kfifo_put into kfifo_in_locked and kfifo_get
34 * into kfifo_out_locked
35 * Note: the spinlock pointer formerly passed to kfifo_init/kfifo_alloc
36 * must be passed now to the kfifo_in_locked and kfifo_out_locked
37 * as the last parameter.
38 * - All formerly name __kfifo_* functions has been renamed into kfifo_*
39 */
40
Linus Torvalds1da177e2005-04-16 15:20:36 -070041#ifndef _LINUX_KFIFO_H
42#define _LINUX_KFIFO_H
43
Linus Torvalds1da177e2005-04-16 15:20:36 -070044#include <linux/kernel.h>
45#include <linux/spinlock.h>
46
47struct kfifo {
48 unsigned char *buffer; /* the buffer holding the data */
49 unsigned int size; /* the size of the allocated buffer */
50 unsigned int in; /* data is added at offset (in % size) */
51 unsigned int out; /* data is extracted from off. (out % size) */
Linus Torvalds1da177e2005-04-16 15:20:36 -070052};
53
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080054/*
55 * Macros for declaration and initialization of the kfifo datatype
56 */
57
58/* helper macro */
59#define __kfifo_initializer(s, b) \
60 (struct kfifo) { \
61 .size = s, \
62 .in = 0, \
63 .out = 0, \
64 .buffer = b \
65 }
66
67/**
68 * DECLARE_KFIFO - macro to declare a kfifo and the associated buffer
69 * @name: name of the declared kfifo datatype
Andi Kleen5dab6002010-01-15 17:01:17 -080070 * @size: size of the fifo buffer. Must be a power of two.
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080071 *
Randy Dunlap9c717de2009-12-23 09:23:33 -080072 * Note1: the macro can be used inside struct or union declaration
73 * Note2: the macro creates two objects:
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080074 * A kfifo object with the given name and a buffer for the kfifo
75 * object named name##kfifo_buffer
76 */
77#define DECLARE_KFIFO(name, size) \
78union { \
79 struct kfifo name; \
80 unsigned char name##kfifo_buffer[size + sizeof(struct kfifo)]; \
81}
82
83/**
Rolf Eike Beered656d82009-12-26 17:58:11 +010084 * INIT_KFIFO - Initialize a kfifo declared by DECLARE_KFIFO
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080085 * @name: name of the declared kfifo datatype
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080086 */
87#define INIT_KFIFO(name) \
88 name = __kfifo_initializer(sizeof(name##kfifo_buffer) - \
89 sizeof(struct kfifo), name##kfifo_buffer)
90
91/**
92 * DEFINE_KFIFO - macro to define and initialize a kfifo
93 * @name: name of the declared kfifo datatype
Andi Kleen5dab6002010-01-15 17:01:17 -080094 * @size: size of the fifo buffer. Must be a power of two.
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080095 *
Randy Dunlap9c717de2009-12-23 09:23:33 -080096 * Note1: the macro can be used for global and local kfifo data type variables
97 * Note2: the macro creates two objects:
Stefani Seibold37bdfbb2009-12-21 14:37:30 -080098 * A kfifo object with the given name and a buffer for the kfifo
99 * object named name##kfifo_buffer
100 */
101#define DEFINE_KFIFO(name, size) \
102 unsigned char name##kfifo_buffer[size]; \
103 struct kfifo name = __kfifo_initializer(size, name##kfifo_buffer)
104
105#undef __kfifo_initializer
106
Andi Kleen8ecc2952010-01-15 17:01:12 -0800107extern void kfifo_init(struct kfifo *fifo, void *buffer,
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800108 unsigned int size);
Stefani Seibold45465482009-12-21 14:37:26 -0800109extern __must_check int kfifo_alloc(struct kfifo *fifo, unsigned int size,
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800110 gfp_t gfp_mask);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700111extern void kfifo_free(struct kfifo *fifo);
Stefani Seibold9842c382009-12-21 14:37:29 -0800112extern unsigned int kfifo_in(struct kfifo *fifo,
Andi Kleen8ecc2952010-01-15 17:01:12 -0800113 const void *from, unsigned int len);
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800114extern __must_check unsigned int kfifo_out(struct kfifo *fifo,
Andi Kleen8ecc2952010-01-15 17:01:12 -0800115 void *to, unsigned int len);
Andi Kleena5b9e2c2010-01-15 17:01:16 -0800116extern __must_check unsigned int kfifo_out_peek(struct kfifo *fifo,
117 void *to, unsigned int len, unsigned offset);
118
Andi Kleend994ffc2010-01-15 17:01:17 -0800119/**
120 * kfifo_initialized - Check if kfifo is initialized.
121 * @fifo: fifo to check
122 * Return %true if FIFO is initialized, otherwise %false.
123 * Assumes the fifo was 0 before.
124 */
125static inline bool kfifo_initialized(struct kfifo *fifo)
126{
Anton Vorontsov5a5e0f42010-01-27 17:09:38 +0300127 return fifo->buffer != NULL;
Andi Kleend994ffc2010-01-15 17:01:17 -0800128}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129
130/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700131 * kfifo_reset - removes the entire FIFO contents
132 * @fifo: the fifo to be emptied.
133 */
134static inline void kfifo_reset(struct kfifo *fifo)
135{
Stefani Seibolde64c0262009-12-21 14:37:28 -0800136 fifo->in = fifo->out = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137}
138
139/**
Stefani Seibolda121f242009-12-21 14:37:31 -0800140 * kfifo_reset_out - skip FIFO contents
141 * @fifo: the fifo to be emptied.
142 */
143static inline void kfifo_reset_out(struct kfifo *fifo)
144{
145 smp_mb();
146 fifo->out = fifo->in;
147}
148
149/**
Stefani Seibold37bdfbb2009-12-21 14:37:30 -0800150 * kfifo_size - returns the size of the fifo in bytes
151 * @fifo: the fifo to be used.
152 */
153static inline __must_check unsigned int kfifo_size(struct kfifo *fifo)
154{
155 return fifo->size;
156}
157
158/**
Stefani Seibolde64c0262009-12-21 14:37:28 -0800159 * kfifo_len - returns the number of used bytes in the FIFO
Linus Torvalds1da177e2005-04-16 15:20:36 -0700160 * @fifo: the fifo to be used.
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800161 */
Stefani Seibolde64c0262009-12-21 14:37:28 -0800162static inline unsigned int kfifo_len(struct kfifo *fifo)
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800163{
164 register unsigned int out;
165
166 out = fifo->out;
167 smp_rmb();
168 return fifo->in - out;
169}
170
171/**
Stefani Seibold37bdfbb2009-12-21 14:37:30 -0800172 * kfifo_is_empty - returns true if the fifo is empty
173 * @fifo: the fifo to be used.
174 */
175static inline __must_check int kfifo_is_empty(struct kfifo *fifo)
176{
177 return fifo->in == fifo->out;
178}
179
180/**
181 * kfifo_is_full - returns true if the fifo is full
182 * @fifo: the fifo to be used.
183 */
184static inline __must_check int kfifo_is_full(struct kfifo *fifo)
185{
186 return kfifo_len(fifo) == kfifo_size(fifo);
187}
188
189/**
190 * kfifo_avail - returns the number of bytes available in the FIFO
191 * @fifo: the fifo to be used.
192 */
193static inline __must_check unsigned int kfifo_avail(struct kfifo *fifo)
194{
195 return kfifo_size(fifo) - kfifo_len(fifo);
196}
197
198/**
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800199 * kfifo_in_locked - puts some data into the FIFO using a spinlock for locking
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800200 * @fifo: the fifo to be used.
201 * @from: the data to be added.
202 * @n: the length of the data to be added.
203 * @lock: pointer to the spinlock to use for locking.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 *
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800205 * This function copies at most @len bytes from the @from buffer into
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 * the FIFO depending on the free space, and returns the number of
207 * bytes copied.
208 */
Stefani Seibold9842c382009-12-21 14:37:29 -0800209static inline unsigned int kfifo_in_locked(struct kfifo *fifo,
Andi Kleen8ecc2952010-01-15 17:01:12 -0800210 const void *from, unsigned int n, spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211{
212 unsigned long flags;
213 unsigned int ret;
214
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800215 spin_lock_irqsave(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800217 ret = kfifo_in(fifo, from, n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800219 spin_unlock_irqrestore(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221 return ret;
222}
223
224/**
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800225 * kfifo_out_locked - gets some data from the FIFO using a spinlock for locking
Linus Torvalds1da177e2005-04-16 15:20:36 -0700226 * @fifo: the fifo to be used.
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800227 * @to: where the data must be copied.
228 * @n: the size of the destination buffer.
229 * @lock: pointer to the spinlock to use for locking.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700230 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800231 * This function copies at most @len bytes from the FIFO into the
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800232 * @to buffer and returns the number of copied bytes.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 */
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800234static inline __must_check unsigned int kfifo_out_locked(struct kfifo *fifo,
Andi Kleen8ecc2952010-01-15 17:01:12 -0800235 void *to, unsigned int n, spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700236{
237 unsigned long flags;
238 unsigned int ret;
239
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800240 spin_lock_irqsave(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Stefani Seibold7acd72e2009-12-21 14:37:28 -0800242 ret = kfifo_out(fifo, to, n);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243
Stefani Seiboldc1e13f22009-12-21 14:37:27 -0800244 spin_unlock_irqrestore(lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245
246 return ret;
247}
248
Stefani Seibolda121f242009-12-21 14:37:31 -0800249extern void kfifo_skip(struct kfifo *fifo, unsigned int len);
250
Andi Kleen64ce1032010-01-15 17:01:15 -0800251extern __must_check int kfifo_from_user(struct kfifo *fifo,
252 const void __user *from, unsigned int n, unsigned *lenout);
Stefani Seibolda121f242009-12-21 14:37:31 -0800253
Andi Kleen64ce1032010-01-15 17:01:15 -0800254extern __must_check int kfifo_to_user(struct kfifo *fifo,
255 void __user *to, unsigned int n, unsigned *lenout);
Stefani Seibolda121f242009-12-21 14:37:31 -0800256
Randy Dunlap9c717de2009-12-23 09:23:33 -0800257/*
Stefani Seibolda121f242009-12-21 14:37:31 -0800258 * __kfifo_add_out internal helper function for updating the out offset
259 */
260static inline void __kfifo_add_out(struct kfifo *fifo,
261 unsigned int off)
262{
263 smp_mb();
264 fifo->out += off;
265}
266
Randy Dunlap9c717de2009-12-23 09:23:33 -0800267/*
Stefani Seibolda121f242009-12-21 14:37:31 -0800268 * __kfifo_add_in internal helper function for updating the in offset
269 */
270static inline void __kfifo_add_in(struct kfifo *fifo,
271 unsigned int off)
272{
273 smp_wmb();
274 fifo->in += off;
275}
276
Randy Dunlap9c717de2009-12-23 09:23:33 -0800277/*
Stefani Seibolda121f242009-12-21 14:37:31 -0800278 * __kfifo_off internal helper function for calculating the index of a
279 * given offeset
280 */
281static inline unsigned int __kfifo_off(struct kfifo *fifo, unsigned int off)
282{
283 return off & (fifo->size - 1);
284}
285
Randy Dunlap9c717de2009-12-23 09:23:33 -0800286/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800287 * __kfifo_peek_n internal helper function for determinate the length of
288 * the next record in the fifo
289 */
290static inline unsigned int __kfifo_peek_n(struct kfifo *fifo,
291 unsigned int recsize)
292{
293#define __KFIFO_GET(fifo, off, shift) \
294 ((fifo)->buffer[__kfifo_off((fifo), (fifo)->out+(off))] << (shift))
295
296 unsigned int l;
297
298 l = __KFIFO_GET(fifo, 0, 0);
299
300 if (--recsize)
301 l |= __KFIFO_GET(fifo, 1, 8);
302
303 return l;
304#undef __KFIFO_GET
305}
306
Randy Dunlap9c717de2009-12-23 09:23:33 -0800307/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800308 * __kfifo_poke_n internal helper function for storing the length of
309 * the next record into the fifo
310 */
311static inline void __kfifo_poke_n(struct kfifo *fifo,
312 unsigned int recsize, unsigned int n)
313{
314#define __KFIFO_PUT(fifo, off, val, shift) \
315 ( \
316 (fifo)->buffer[__kfifo_off((fifo), (fifo)->in+(off))] = \
317 (unsigned char)((val) >> (shift)) \
318 )
319
320 __KFIFO_PUT(fifo, 0, n, 0);
321
322 if (--recsize)
323 __KFIFO_PUT(fifo, 1, n, 8);
324#undef __KFIFO_PUT
325}
326
Randy Dunlap9c717de2009-12-23 09:23:33 -0800327/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800328 * __kfifo_in_... internal functions for put date into the fifo
329 * do not call it directly, use kfifo_in_rec() instead
330 */
331extern unsigned int __kfifo_in_n(struct kfifo *fifo,
332 const void *from, unsigned int n, unsigned int recsize);
333
334extern unsigned int __kfifo_in_generic(struct kfifo *fifo,
335 const void *from, unsigned int n, unsigned int recsize);
336
337static inline unsigned int __kfifo_in_rec(struct kfifo *fifo,
338 const void *from, unsigned int n, unsigned int recsize)
339{
340 unsigned int ret;
341
342 ret = __kfifo_in_n(fifo, from, n, recsize);
343
344 if (likely(ret == 0)) {
345 if (recsize)
346 __kfifo_poke_n(fifo, recsize, n);
347 __kfifo_add_in(fifo, n + recsize);
348 }
349 return ret;
350}
351
352/**
353 * kfifo_in_rec - puts some record data into the FIFO
354 * @fifo: the fifo to be used.
355 * @from: the data to be added.
356 * @n: the length of the data to be added.
357 * @recsize: size of record field
358 *
359 * This function copies @n bytes from the @from into the FIFO and returns
360 * the number of bytes which cannot be copied.
361 * A returned value greater than the @n value means that the record doesn't
362 * fit into the buffer.
363 *
364 * Note that with only one concurrent reader and one concurrent
365 * writer, you don't need extra locking to use these functions.
366 */
367static inline __must_check unsigned int kfifo_in_rec(struct kfifo *fifo,
368 void *from, unsigned int n, unsigned int recsize)
369{
370 if (!__builtin_constant_p(recsize))
371 return __kfifo_in_generic(fifo, from, n, recsize);
372 return __kfifo_in_rec(fifo, from, n, recsize);
373}
374
Randy Dunlap9c717de2009-12-23 09:23:33 -0800375/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800376 * __kfifo_out_... internal functions for get date from the fifo
377 * do not call it directly, use kfifo_out_rec() instead
378 */
379extern unsigned int __kfifo_out_n(struct kfifo *fifo,
380 void *to, unsigned int reclen, unsigned int recsize);
381
382extern unsigned int __kfifo_out_generic(struct kfifo *fifo,
383 void *to, unsigned int n,
384 unsigned int recsize, unsigned int *total);
385
386static inline unsigned int __kfifo_out_rec(struct kfifo *fifo,
387 void *to, unsigned int n, unsigned int recsize,
388 unsigned int *total)
389{
390 unsigned int l;
391
392 if (!recsize) {
393 l = n;
394 if (total)
395 *total = l;
396 } else {
397 l = __kfifo_peek_n(fifo, recsize);
398 if (total)
399 *total = l;
400 if (n < l)
401 return l;
402 }
403
404 return __kfifo_out_n(fifo, to, l, recsize);
405}
406
407/**
408 * kfifo_out_rec - gets some record data from the FIFO
409 * @fifo: the fifo to be used.
410 * @to: where the data must be copied.
411 * @n: the size of the destination buffer.
412 * @recsize: size of record field
413 * @total: pointer where the total number of to copied bytes should stored
414 *
415 * This function copies at most @n bytes from the FIFO to @to and returns the
416 * number of bytes which cannot be copied.
417 * A returned value greater than the @n value means that the record doesn't
418 * fit into the @to buffer.
419 *
420 * Note that with only one concurrent reader and one concurrent
421 * writer, you don't need extra locking to use these functions.
422 */
423static inline __must_check unsigned int kfifo_out_rec(struct kfifo *fifo,
424 void *to, unsigned int n, unsigned int recsize,
425 unsigned int *total)
426
427{
428 if (!__builtin_constant_p(recsize))
429 return __kfifo_out_generic(fifo, to, n, recsize, total);
430 return __kfifo_out_rec(fifo, to, n, recsize, total);
431}
432
Randy Dunlap9c717de2009-12-23 09:23:33 -0800433/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800434 * __kfifo_from_user_... internal functions for transfer from user space into
435 * the fifo. do not call it directly, use kfifo_from_user_rec() instead
436 */
437extern unsigned int __kfifo_from_user_n(struct kfifo *fifo,
438 const void __user *from, unsigned int n, unsigned int recsize);
439
440extern unsigned int __kfifo_from_user_generic(struct kfifo *fifo,
441 const void __user *from, unsigned int n, unsigned int recsize);
442
443static inline unsigned int __kfifo_from_user_rec(struct kfifo *fifo,
444 const void __user *from, unsigned int n, unsigned int recsize)
445{
446 unsigned int ret;
447
448 ret = __kfifo_from_user_n(fifo, from, n, recsize);
449
450 if (likely(ret == 0)) {
451 if (recsize)
452 __kfifo_poke_n(fifo, recsize, n);
453 __kfifo_add_in(fifo, n + recsize);
454 }
455 return ret;
456}
457
458/**
459 * kfifo_from_user_rec - puts some data from user space into the FIFO
460 * @fifo: the fifo to be used.
461 * @from: pointer to the data to be added.
462 * @n: the length of the data to be added.
463 * @recsize: size of record field
464 *
465 * This function copies @n bytes from the @from into the
466 * FIFO and returns the number of bytes which cannot be copied.
467 *
468 * If the returned value is equal or less the @n value, the copy_from_user()
469 * functions has failed. Otherwise the record doesn't fit into the buffer.
470 *
471 * Note that with only one concurrent reader and one concurrent
472 * writer, you don't need extra locking to use these functions.
473 */
474static inline __must_check unsigned int kfifo_from_user_rec(struct kfifo *fifo,
475 const void __user *from, unsigned int n, unsigned int recsize)
476{
477 if (!__builtin_constant_p(recsize))
478 return __kfifo_from_user_generic(fifo, from, n, recsize);
479 return __kfifo_from_user_rec(fifo, from, n, recsize);
480}
481
Randy Dunlap9c717de2009-12-23 09:23:33 -0800482/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800483 * __kfifo_to_user_... internal functions for transfer fifo data into user space
484 * do not call it directly, use kfifo_to_user_rec() instead
485 */
486extern unsigned int __kfifo_to_user_n(struct kfifo *fifo,
487 void __user *to, unsigned int n, unsigned int reclen,
488 unsigned int recsize);
489
490extern unsigned int __kfifo_to_user_generic(struct kfifo *fifo,
491 void __user *to, unsigned int n, unsigned int recsize,
492 unsigned int *total);
493
494static inline unsigned int __kfifo_to_user_rec(struct kfifo *fifo,
495 void __user *to, unsigned int n,
496 unsigned int recsize, unsigned int *total)
497{
498 unsigned int l;
499
500 if (!recsize) {
501 l = n;
502 if (total)
503 *total = l;
504 } else {
505 l = __kfifo_peek_n(fifo, recsize);
506 if (total)
507 *total = l;
508 if (n < l)
509 return l;
510 }
511
512 return __kfifo_to_user_n(fifo, to, n, l, recsize);
513}
514
515/**
516 * kfifo_to_user_rec - gets data from the FIFO and write it to user space
517 * @fifo: the fifo to be used.
518 * @to: where the data must be copied.
519 * @n: the size of the destination buffer.
520 * @recsize: size of record field
521 * @total: pointer where the total number of to copied bytes should stored
522 *
523 * This function copies at most @n bytes from the FIFO to the @to.
524 * In case of an error, the function returns the number of bytes which cannot
525 * be copied.
526 * If the returned value is equal or less the @n value, the copy_to_user()
527 * functions has failed. Otherwise the record doesn't fit into the @to buffer.
528 *
529 * Note that with only one concurrent reader and one concurrent
530 * writer, you don't need extra locking to use these functions.
531 */
532static inline __must_check unsigned int kfifo_to_user_rec(struct kfifo *fifo,
533 void __user *to, unsigned int n, unsigned int recsize,
534 unsigned int *total)
535{
536 if (!__builtin_constant_p(recsize))
537 return __kfifo_to_user_generic(fifo, to, n, recsize, total);
538 return __kfifo_to_user_rec(fifo, to, n, recsize, total);
539}
540
Randy Dunlap9c717de2009-12-23 09:23:33 -0800541/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800542 * __kfifo_peek_... internal functions for peek into the next fifo record
543 * do not call it directly, use kfifo_peek_rec() instead
544 */
545extern unsigned int __kfifo_peek_generic(struct kfifo *fifo,
546 unsigned int recsize);
547
548/**
549 * kfifo_peek_rec - gets the size of the next FIFO record data
550 * @fifo: the fifo to be used.
551 * @recsize: size of record field
552 *
553 * This function returns the size of the next FIFO record in number of bytes
554 */
555static inline __must_check unsigned int kfifo_peek_rec(struct kfifo *fifo,
556 unsigned int recsize)
557{
558 if (!__builtin_constant_p(recsize))
559 return __kfifo_peek_generic(fifo, recsize);
560 if (!recsize)
561 return kfifo_len(fifo);
562 return __kfifo_peek_n(fifo, recsize);
563}
564
Randy Dunlap9c717de2009-12-23 09:23:33 -0800565/*
Stefani Seibold86d48802009-12-21 14:37:32 -0800566 * __kfifo_skip_... internal functions for skip the next fifo record
567 * do not call it directly, use kfifo_skip_rec() instead
568 */
569extern void __kfifo_skip_generic(struct kfifo *fifo, unsigned int recsize);
570
571static inline void __kfifo_skip_rec(struct kfifo *fifo,
572 unsigned int recsize)
573{
574 unsigned int l;
575
576 if (recsize) {
577 l = __kfifo_peek_n(fifo, recsize);
578
579 if (l + recsize <= kfifo_len(fifo)) {
580 __kfifo_add_out(fifo, l + recsize);
581 return;
582 }
583 }
584 kfifo_reset_out(fifo);
585}
586
587/**
588 * kfifo_skip_rec - skip the next fifo out record
589 * @fifo: the fifo to be used.
590 * @recsize: size of record field
591 *
592 * This function skips the next FIFO record
593 */
594static inline void kfifo_skip_rec(struct kfifo *fifo,
595 unsigned int recsize)
596{
597 if (!__builtin_constant_p(recsize))
598 __kfifo_skip_generic(fifo, recsize);
599 else
600 __kfifo_skip_rec(fifo, recsize);
601}
602
603/**
604 * kfifo_avail_rec - returns the number of bytes available in a record FIFO
605 * @fifo: the fifo to be used.
606 * @recsize: size of record field
607 */
608static inline __must_check unsigned int kfifo_avail_rec(struct kfifo *fifo,
609 unsigned int recsize)
610{
611 unsigned int l = kfifo_size(fifo) - kfifo_len(fifo);
612
613 return (l > recsize) ? l - recsize : 0;
614}
615
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616#endif