[mirror_ubuntu-bionic-kernel.git] / include / linux / ptr_ring.h

/*
 *	Definitions for the 'struct ptr_ring' datastructure.
 *
 *	Author:
 *		Michael S. Tsirkin <mst@redhat.com>
 *
 *	Copyright (C) 2016 Red Hat, Inc.
 *
 *	This program is free software; you can redistribute it and/or modify it
 *	under the terms of the GNU General Public License as published by the
 *	Free Software Foundation; either version 2 of the License, or (at your
 *	option) any later version.
 *
 *	This is a limited-size FIFO maintaining pointers in FIFO order, with
 *	one CPU producing entries and another consuming entries from a FIFO.
 *
 *	This implementation tries to minimize cache-contention when there is a
 *	single producer and a single consumer CPU.
 */

#ifndef _LINUX_PTR_RING_H
#define _LINUX_PTR_RING_H 1

#ifdef __KERNEL__
#include <linux/spinlock.h>
#include <linux/cache.h>
#include <linux/types.h>
#include <linux/compiler.h>
#include <linux/cache.h>
#include <linux/slab.h>
#include <asm/errno.h>
#endif

struct ptr_ring {
	int producer ____cacheline_aligned_in_smp;
	spinlock_t producer_lock;
	int consumer ____cacheline_aligned_in_smp;
	spinlock_t consumer_lock;
	/* Shared consumer/producer data */
	/* Read-only by both the producer and the consumer */
	int size ____cacheline_aligned_in_smp; /* max entries in queue */
	void **queue;
};

/* Note: callers invoking this in a loop must use a compiler barrier,
 * for example cpu_relax().  If ring is ever resized, callers must hold
 * producer_lock - see e.g. ptr_ring_full.  Otherwise, if callers don't hold
 * producer_lock, the next call to __ptr_ring_produce may fail.
 */
static inline bool __ptr_ring_full(struct ptr_ring *r)
{
	return r->queue[r->producer];
}

static inline bool ptr_ring_full(struct ptr_ring *r)
{
	bool ret;

	spin_lock(&r->producer_lock);
	ret = __ptr_ring_full(r);
	spin_unlock(&r->producer_lock);

	return ret;
}

static inline bool ptr_ring_full_irq(struct ptr_ring *r)
{
	bool ret;

	spin_lock_irq(&r->producer_lock);
	ret = __ptr_ring_full(r);
	spin_unlock_irq(&r->producer_lock);

	return ret;
}

static inline bool ptr_ring_full_any(struct ptr_ring *r)
{
	unsigned long flags;
	bool ret;

	spin_lock_irqsave(&r->producer_lock, flags);
	ret = __ptr_ring_full(r);
	spin_unlock_irqrestore(&r->producer_lock, flags);

	return ret;
}

static inline bool ptr_ring_full_bh(struct ptr_ring *r)
{
	bool ret;

	spin_lock_bh(&r->producer_lock);
	ret = __ptr_ring_full(r);
	spin_unlock_bh(&r->producer_lock);

	return ret;
}

/* Note: callers invoking this in a loop must use a compiler barrier,
 * for example cpu_relax(). Callers must hold producer_lock.
 */
static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr)
{
	if (unlikely(!r->size) || r->queue[r->producer])
		return -ENOSPC;

	r->queue[r->producer++] = ptr;
	if (unlikely(r->producer >= r->size))
		r->producer = 0;
	return 0;
}

static inline int ptr_ring_produce(struct ptr_ring *r, void *ptr)
{
	int ret;

	spin_lock(&r->producer_lock);
	ret = __ptr_ring_produce(r, ptr);
	spin_unlock(&r->producer_lock);

	return ret;
}

static inline int ptr_ring_produce_irq(struct ptr_ring *r, void *ptr)
{
	int ret;

	spin_lock_irq(&r->producer_lock);
	ret = __ptr_ring_produce(r, ptr);
	spin_unlock_irq(&r->producer_lock);

	return ret;
}

static inline int ptr_ring_produce_any(struct ptr_ring *r, void *ptr)
{
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&r->producer_lock, flags);
	ret = __ptr_ring_produce(r, ptr);
	spin_unlock_irqrestore(&r->producer_lock, flags);

	return ret;
}

static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr)
{
	int ret;

	spin_lock_bh(&r->producer_lock);
	ret = __ptr_ring_produce(r, ptr);
	spin_unlock_bh(&r->producer_lock);

	return ret;
}

/* Note: callers invoking this in a loop must use a compiler barrier,
 * for example cpu_relax(). Callers must take consumer_lock
 * if they dereference the pointer - see e.g. PTR_RING_PEEK_CALL.
 * If ring is never resized, and if the pointer is merely
 * tested, there's no need to take the lock - see e.g.  __ptr_ring_empty.
 */
static inline void *__ptr_ring_peek(struct ptr_ring *r)
{
	if (likely(r->size))
		return r->queue[r->consumer];
	return NULL;
}

/* Note: callers invoking this in a loop must use a compiler barrier,
 * for example cpu_relax(). Callers must take consumer_lock
 * if the ring is ever resized - see e.g. ptr_ring_empty.
 */
static inline bool __ptr_ring_empty(struct ptr_ring *r)
{
	return !__ptr_ring_peek(r);
}

static inline bool ptr_ring_empty(struct ptr_ring *r)
{
	bool ret;

	spin_lock(&r->consumer_lock);
	ret = __ptr_ring_empty(r);
	spin_unlock(&r->consumer_lock);

	return ret;
}

static inline bool ptr_ring_empty_irq(struct ptr_ring *r)
{
	bool ret;

	spin_lock_irq(&r->consumer_lock);
	ret = __ptr_ring_empty(r);
	spin_unlock_irq(&r->consumer_lock);

	return ret;
}

static inline bool ptr_ring_empty_any(struct ptr_ring *r)
{
	unsigned long flags;
	bool ret;

	spin_lock_irqsave(&r->consumer_lock, flags);
	ret = __ptr_ring_empty(r);
	spin_unlock_irqrestore(&r->consumer_lock, flags);

	return ret;
}

static inline bool ptr_ring_empty_bh(struct ptr_ring *r)
{
	bool ret;

	spin_lock_bh(&r->consumer_lock);
	ret = __ptr_ring_empty(r);
	spin_unlock_bh(&r->consumer_lock);

	return ret;
}

/* Must only be called after __ptr_ring_peek returned !NULL */
static inline void __ptr_ring_discard_one(struct ptr_ring *r)
{
	r->queue[r->consumer++] = NULL;
	if (unlikely(r->consumer >= r->size))
		r->consumer = 0;
}

static inline void *__ptr_ring_consume(struct ptr_ring *r)
{
	void *ptr;

	ptr = __ptr_ring_peek(r);
	if (ptr)
		__ptr_ring_discard_one(r);

	return ptr;
}

static inline void *ptr_ring_consume(struct ptr_ring *r)
{
	void *ptr;

	spin_lock(&r->consumer_lock);
	ptr = __ptr_ring_consume(r);
	spin_unlock(&r->consumer_lock);

	return ptr;
}

static inline void *ptr_ring_consume_irq(struct ptr_ring *r)
{
	void *ptr;

	spin_lock_irq(&r->consumer_lock);
	ptr = __ptr_ring_consume(r);
	spin_unlock_irq(&r->consumer_lock);

	return ptr;
}

static inline void *ptr_ring_consume_any(struct ptr_ring *r)
{
	unsigned long flags;
	void *ptr;

	spin_lock_irqsave(&r->consumer_lock, flags);
	ptr = __ptr_ring_consume(r);
	spin_unlock_irqrestore(&r->consumer_lock, flags);

	return ptr;
}

static inline void *ptr_ring_consume_bh(struct ptr_ring *r)
{
	void *ptr;

	spin_lock_bh(&r->consumer_lock);
	ptr = __ptr_ring_consume(r);
	spin_unlock_bh(&r->consumer_lock);

	return ptr;
}

/* Cast to structure type and call a function without discarding from FIFO.
 * Function must return a value.
 * Callers must take consumer_lock.
 */
#define __PTR_RING_PEEK_CALL(r, f) ((f)(__ptr_ring_peek(r)))

#define PTR_RING_PEEK_CALL(r, f) ({ \
	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
	\
	spin_lock(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
	spin_unlock(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v; \
})

#define PTR_RING_PEEK_CALL_IRQ(r, f) ({ \
	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
	\
	spin_lock_irq(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
	spin_unlock_irq(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v; \
})

#define PTR_RING_PEEK_CALL_BH(r, f) ({ \
	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
	\
	spin_lock_bh(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
	spin_unlock_bh(&(r)->consumer_lock); \
	__PTR_RING_PEEK_CALL_v; \
})

#define PTR_RING_PEEK_CALL_ANY(r, f) ({ \
	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
	unsigned long __PTR_RING_PEEK_CALL_f;\
	\
	spin_lock_irqsave(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
	spin_unlock_irqrestore(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
	__PTR_RING_PEEK_CALL_v; \
})

static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
{
	return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
}

static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
{
	r->queue = __ptr_ring_init_queue_alloc(size, gfp);
	if (!r->queue)
		return -ENOMEM;

	r->size = size;
	r->producer = r->consumer = 0;
	spin_lock_init(&r->producer_lock);
	spin_lock_init(&r->consumer_lock);

	return 0;
}

static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
				  void (*destroy)(void *))
{
	unsigned long flags;
	int producer = 0;
	void **queue = __ptr_ring_init_queue_alloc(size, gfp);
	void **old;
	void *ptr;

	if (!queue)
		return -ENOMEM;

	spin_lock_irqsave(&(r)->producer_lock, flags);

	while ((ptr = ptr_ring_consume(r)))
		if (producer < size)
			queue[producer++] = ptr;
		else if (destroy)
			destroy(ptr);

	r->size = size;
	r->producer = producer;
	r->consumer = 0;
	old = r->queue;
	r->queue = queue;

	spin_unlock_irqrestore(&(r)->producer_lock, flags);

	kfree(old);

	return 0;
}

static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
{
	void *ptr;

	if (destroy)
		while ((ptr = ptr_ring_consume(r)))
			destroy(ptr);
	kfree(r->queue);
}

#endif /* _LINUX_PTR_RING_H  */
Commit	Line	Data
2e0ab8ca MT	1	/*
	2	* Definitions for the 'struct ptr_ring' datastructure.
	3	*
	4	* Author:
	5	* Michael S. Tsirkin <mst@redhat.com>
	6	*
	7	* Copyright (C) 2016 Red Hat, Inc.
	8	*
	9	* This program is free software; you can redistribute it and/or modify it
	10	* under the terms of the GNU General Public License as published by the
	11	* Free Software Foundation; either version 2 of the License, or (at your
	12	* option) any later version.
	13	*
	14	* This is a limited-size FIFO maintaining pointers in FIFO order, with
	15	* one CPU producing entries and another consuming entries from a FIFO.
	16	*
	17	* This implementation tries to minimize cache-contention when there is a
	18	* single producer and a single consumer CPU.
	19	*/
	20
	21	#ifndef _LINUX_PTR_RING_H
	22	#define _LINUX_PTR_RING_H 1
	23
	24	#ifdef __KERNEL__
	25	#include <linux/spinlock.h>
	26	#include <linux/cache.h>
	27	#include <linux/types.h>
	28	#include <linux/compiler.h>
	29	#include <linux/cache.h>
	30	#include <linux/slab.h>
	31	#include <asm/errno.h>
	32	#endif
	33
	34	struct ptr_ring {
	35	int producer ____cacheline_aligned_in_smp;
	36	spinlock_t producer_lock;
	37	int consumer ____cacheline_aligned_in_smp;
	38	spinlock_t consumer_lock;
	39	/* Shared consumer/producer data */
	40	/* Read-only by both the producer and the consumer */
	41	int size ____cacheline_aligned_in_smp; /* max entries in queue */
	42	void **queue;
	43	};
	44
	45	/* Note: callers invoking this in a loop must use a compiler barrier,
5d49de53 MT	46	* for example cpu_relax(). If ring is ever resized, callers must hold
	47	* producer_lock - see e.g. ptr_ring_full. Otherwise, if callers don't hold
	48	* producer_lock, the next call to __ptr_ring_produce may fail.
2e0ab8ca MT	49	*/
	50	static inline bool __ptr_ring_full(struct ptr_ring *r)
	51	{
	52	return r->queue[r->producer];
	53	}
	54
	55	static inline bool ptr_ring_full(struct ptr_ring *r)
	56	{
5d49de53 MT	57	bool ret;
	58
	59	spin_lock(&r->producer_lock);
	60	ret = __ptr_ring_full(r);
	61	spin_unlock(&r->producer_lock);
	62
	63	return ret;
	64	}
	65
	66	static inline bool ptr_ring_full_irq(struct ptr_ring *r)
	67	{
	68	bool ret;
	69
	70	spin_lock_irq(&r->producer_lock);
	71	ret = __ptr_ring_full(r);
	72	spin_unlock_irq(&r->producer_lock);
	73
	74	return ret;
	75	}
	76
	77	static inline bool ptr_ring_full_any(struct ptr_ring *r)
	78	{
	79	unsigned long flags;
	80	bool ret;
	81
	82	spin_lock_irqsave(&r->producer_lock, flags);
	83	ret = __ptr_ring_full(r);
	84	spin_unlock_irqrestore(&r->producer_lock, flags);
	85
	86	return ret;
	87	}
	88
	89	static inline bool ptr_ring_full_bh(struct ptr_ring *r)
	90	{
	91	bool ret;
	92
	93	spin_lock_bh(&r->producer_lock);
	94	ret = __ptr_ring_full(r);
	95	spin_unlock_bh(&r->producer_lock);
	96
	97	return ret;
2e0ab8ca MT	98	}
	99
	100	/* Note: callers invoking this in a loop must use a compiler barrier,
5d49de53	101	* for example cpu_relax(). Callers must hold producer_lock.
2e0ab8ca MT	102	*/
	103	static inline int __ptr_ring_produce(struct ptr_ring r, void ptr)
	104	{
982fb490	105	if (unlikely(!r->size) \|\| r->queue[r->producer])
2e0ab8ca MT	106	return -ENOSPC;
	107
	108	r->queue[r->producer++] = ptr;
	109	if (unlikely(r->producer >= r->size))
	110	r->producer = 0;
	111	return 0;
	112	}
	113
	114	static inline int ptr_ring_produce(struct ptr_ring r, void ptr)
	115	{
	116	int ret;
	117
	118	spin_lock(&r->producer_lock);
	119	ret = __ptr_ring_produce(r, ptr);
	120	spin_unlock(&r->producer_lock);
	121
	122	return ret;
	123	}
	124
	125	static inline int ptr_ring_produce_irq(struct ptr_ring r, void ptr)
	126	{
	127	int ret;
	128
	129	spin_lock_irq(&r->producer_lock);
	130	ret = __ptr_ring_produce(r, ptr);
	131	spin_unlock_irq(&r->producer_lock);
	132
	133	return ret;
	134	}
	135
	136	static inline int ptr_ring_produce_any(struct ptr_ring r, void ptr)
	137	{
	138	unsigned long flags;
	139	int ret;
	140
	141	spin_lock_irqsave(&r->producer_lock, flags);
	142	ret = __ptr_ring_produce(r, ptr);
	143	spin_unlock_irqrestore(&r->producer_lock, flags);
	144
	145	return ret;
	146	}
	147
	148	static inline int ptr_ring_produce_bh(struct ptr_ring r, void ptr)
	149	{
	150	int ret;
	151
	152	spin_lock_bh(&r->producer_lock);
	153	ret = __ptr_ring_produce(r, ptr);
	154	spin_unlock_bh(&r->producer_lock);
	155
	156	return ret;
	157	}
	158
	159	/* Note: callers invoking this in a loop must use a compiler barrier,
	160	* for example cpu_relax(). Callers must take consumer_lock
	161	* if they dereference the pointer - see e.g. PTR_RING_PEEK_CALL.
5d49de53 MT	162	* If ring is never resized, and if the pointer is merely
5d49de53 MT	163	* tested, there's no need to take the lock - see e.g. __ptr_ring_empty.
2e0ab8ca MT	164	*/
	165	static inline void __ptr_ring_peek(struct ptr_ring r)
	166	{
982fb490 JW	167	if (likely(r->size))
	168	return r->queue[r->consumer];
	169	return NULL;
2e0ab8ca MT	170	}
2e0ab8ca MT	171
5d49de53 MT	172	/* Note: callers invoking this in a loop must use a compiler barrier,
	173	* for example cpu_relax(). Callers must take consumer_lock
	174	* if the ring is ever resized - see e.g. ptr_ring_empty.
	175	*/
	176	static inline bool __ptr_ring_empty(struct ptr_ring *r)
2e0ab8ca	177	{
2e0ab8ca MT	178	return !__ptr_ring_peek(r);
	179	}
	180
5d49de53 MT	181	static inline bool ptr_ring_empty(struct ptr_ring *r)
	182	{
	183	bool ret;
	184
	185	spin_lock(&r->consumer_lock);
	186	ret = __ptr_ring_empty(r);
	187	spin_unlock(&r->consumer_lock);
	188
	189	return ret;
	190	}
	191
	192	static inline bool ptr_ring_empty_irq(struct ptr_ring *r)
	193	{
	194	bool ret;
	195
	196	spin_lock_irq(&r->consumer_lock);
	197	ret = __ptr_ring_empty(r);
	198	spin_unlock_irq(&r->consumer_lock);
	199
	200	return ret;
	201	}
	202
	203	static inline bool ptr_ring_empty_any(struct ptr_ring *r)
	204	{
	205	unsigned long flags;
	206	bool ret;
	207
	208	spin_lock_irqsave(&r->consumer_lock, flags);
	209	ret = __ptr_ring_empty(r);
	210	spin_unlock_irqrestore(&r->consumer_lock, flags);
	211
	212	return ret;
	213	}
	214
	215	static inline bool ptr_ring_empty_bh(struct ptr_ring *r)
	216	{
	217	bool ret;
	218
	219	spin_lock_bh(&r->consumer_lock);
	220	ret = __ptr_ring_empty(r);
	221	spin_unlock_bh(&r->consumer_lock);
	222
	223	return ret;
	224	}
	225
2e0ab8ca MT	226	/* Must only be called after __ptr_ring_peek returned !NULL */
	227	static inline void __ptr_ring_discard_one(struct ptr_ring *r)
	228	{
	229	r->queue[r->consumer++] = NULL;
	230	if (unlikely(r->consumer >= r->size))
	231	r->consumer = 0;
	232	}
	233
	234	static inline void __ptr_ring_consume(struct ptr_ring r)
	235	{
	236	void *ptr;
	237
	238	ptr = __ptr_ring_peek(r);
	239	if (ptr)
	240	__ptr_ring_discard_one(r);
	241
	242	return ptr;
	243	}
	244
	245	static inline void ptr_ring_consume(struct ptr_ring r)
	246	{
	247	void *ptr;
	248
	249	spin_lock(&r->consumer_lock);
	250	ptr = __ptr_ring_consume(r);
	251	spin_unlock(&r->consumer_lock);
	252
	253	return ptr;
	254	}
	255
	256	static inline void ptr_ring_consume_irq(struct ptr_ring r)
	257	{
	258	void *ptr;
	259
	260	spin_lock_irq(&r->consumer_lock);
	261	ptr = __ptr_ring_consume(r);
	262	spin_unlock_irq(&r->consumer_lock);
	263
	264	return ptr;
	265	}
	266
	267	static inline void ptr_ring_consume_any(struct ptr_ring r)
	268	{
	269	unsigned long flags;
	270	void *ptr;
	271
	272	spin_lock_irqsave(&r->consumer_lock, flags);
	273	ptr = __ptr_ring_consume(r);
	274	spin_unlock_irqrestore(&r->consumer_lock, flags);
	275
	276	return ptr;
	277	}
	278
	279	static inline void ptr_ring_consume_bh(struct ptr_ring r)
	280	{
	281	void *ptr;
	282
	283	spin_lock_bh(&r->consumer_lock);
	284	ptr = __ptr_ring_consume(r);
	285	spin_unlock_bh(&r->consumer_lock);
	286
	287	return ptr;
	288	}
	289
290	/* Cast to structure type and call a function without discarding from FIFO.
291	* Function must return a value.
292	* Callers must take consumer_lock.
293	*/
294	#define __PTR_RING_PEEK_CALL(r, f) ((f)(__ptr_ring_peek(r)))
295
296	#define PTR_RING_PEEK_CALL(r, f) ({ \
297	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
298	\
299	spin_lock(&(r)->consumer_lock); \
300	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
301	spin_unlock(&(r)->consumer_lock); \
302	__PTR_RING_PEEK_CALL_v; \
303	})
304
305	#define PTR_RING_PEEK_CALL_IRQ(r, f) ({ \
306	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
307	\
308	spin_lock_irq(&(r)->consumer_lock); \
309	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
310	spin_unlock_irq(&(r)->consumer_lock); \
311	__PTR_RING_PEEK_CALL_v; \
312	})
313
314	#define PTR_RING_PEEK_CALL_BH(r, f) ({ \
315	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
316	\
317	spin_lock_bh(&(r)->consumer_lock); \
318	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
319	spin_unlock_bh(&(r)->consumer_lock); \
320	__PTR_RING_PEEK_CALL_v; \
321	})
322
323	#define PTR_RING_PEEK_CALL_ANY(r, f) ({ \
324	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
325	unsigned long __PTR_RING_PEEK_CALL_f;\
326	\
327	spin_lock_irqsave(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
328	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
329	spin_unlock_irqrestore(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
330	__PTR_RING_PEEK_CALL_v; \
331	})
332
5d49de53 MT	333	static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
	334	{
	335	return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
	336	}
	337
2e0ab8ca MT	338	static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
2e0ab8ca MT	339	{
5d49de53	340	r->queue = __ptr_ring_init_queue_alloc(size, gfp);
2e0ab8ca MT	341	if (!r->queue)
	342	return -ENOMEM;
	343
	344	r->size = size;
	345	r->producer = r->consumer = 0;
	346	spin_lock_init(&r->producer_lock);
	347	spin_lock_init(&r->consumer_lock);
	348
	349	return 0;
	350	}
	351
5d49de53 MT	352	static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
	353	void (destroy)(void ))
	354	{
	355	unsigned long flags;
	356	int producer = 0;
	357	void **queue = __ptr_ring_init_queue_alloc(size, gfp);
	358	void **old;
	359	void *ptr;
	360
	361	if (!queue)
	362	return -ENOMEM;
	363
	364	spin_lock_irqsave(&(r)->producer_lock, flags);
	365
	366	while ((ptr = ptr_ring_consume(r)))
	367	if (producer < size)
	368	queue[producer++] = ptr;
	369	else if (destroy)
	370	destroy(ptr);
	371
	372	r->size = size;
	373	r->producer = producer;
	374	r->consumer = 0;
	375	old = r->queue;
	376	r->queue = queue;
	377
	378	spin_unlock_irqrestore(&(r)->producer_lock, flags);
	379
	380	kfree(old);
	381
	382	return 0;
	383	}
	384
	385	static inline void ptr_ring_cleanup(struct ptr_ring r, void (destroy)(void *))
2e0ab8ca	386	{
5d49de53 MT	387	void *ptr;
	388
	389	if (destroy)
	390	while ((ptr = ptr_ring_consume(r)))
	391	destroy(ptr);
2e0ab8ca MT	392	kfree(r->queue);
	393	}
	394
	395	#endif /* _LINUX_PTR_RING_H */