[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 (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)
{
	return r->queue[r->consumer];
}

/* 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	{
5d49de53	105	if (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	{
	167	return r->queue[r->consumer];
	168	}
	169
5d49de53 MT	170	/* Note: callers invoking this in a loop must use a compiler barrier,
	171	* for example cpu_relax(). Callers must take consumer_lock
	172	* if the ring is ever resized - see e.g. ptr_ring_empty.
	173	*/
	174	static inline bool __ptr_ring_empty(struct ptr_ring *r)
2e0ab8ca	175	{
2e0ab8ca MT	176	return !__ptr_ring_peek(r);
	177	}
	178
5d49de53 MT	179	static inline bool ptr_ring_empty(struct ptr_ring *r)
	180	{
	181	bool ret;
	182
	183	spin_lock(&r->consumer_lock);
	184	ret = __ptr_ring_empty(r);
	185	spin_unlock(&r->consumer_lock);
	186
	187	return ret;
	188	}
	189
	190	static inline bool ptr_ring_empty_irq(struct ptr_ring *r)
	191	{
	192	bool ret;
	193
	194	spin_lock_irq(&r->consumer_lock);
	195	ret = __ptr_ring_empty(r);
	196	spin_unlock_irq(&r->consumer_lock);
	197
	198	return ret;
	199	}
	200
	201	static inline bool ptr_ring_empty_any(struct ptr_ring *r)
	202	{
	203	unsigned long flags;
	204	bool ret;
	205
	206	spin_lock_irqsave(&r->consumer_lock, flags);
	207	ret = __ptr_ring_empty(r);
	208	spin_unlock_irqrestore(&r->consumer_lock, flags);
	209
	210	return ret;
	211	}
	212
	213	static inline bool ptr_ring_empty_bh(struct ptr_ring *r)
	214	{
	215	bool ret;
	216
	217	spin_lock_bh(&r->consumer_lock);
	218	ret = __ptr_ring_empty(r);
	219	spin_unlock_bh(&r->consumer_lock);
	220
	221	return ret;
	222	}
	223
2e0ab8ca MT	224	/* Must only be called after __ptr_ring_peek returned !NULL */
	225	static inline void __ptr_ring_discard_one(struct ptr_ring *r)
	226	{
	227	r->queue[r->consumer++] = NULL;
	228	if (unlikely(r->consumer >= r->size))
	229	r->consumer = 0;
	230	}
	231
	232	static inline void __ptr_ring_consume(struct ptr_ring r)
	233	{
	234	void *ptr;
	235
	236	ptr = __ptr_ring_peek(r);
	237	if (ptr)
	238	__ptr_ring_discard_one(r);
	239
	240	return ptr;
	241	}
	242
	243	static inline void ptr_ring_consume(struct ptr_ring r)
	244	{
	245	void *ptr;
	246
	247	spin_lock(&r->consumer_lock);
	248	ptr = __ptr_ring_consume(r);
	249	spin_unlock(&r->consumer_lock);
	250
	251	return ptr;
	252	}
	253
	254	static inline void ptr_ring_consume_irq(struct ptr_ring r)
	255	{
	256	void *ptr;
	257
	258	spin_lock_irq(&r->consumer_lock);
	259	ptr = __ptr_ring_consume(r);
	260	spin_unlock_irq(&r->consumer_lock);
	261
	262	return ptr;
	263	}
	264
	265	static inline void ptr_ring_consume_any(struct ptr_ring r)
	266	{
	267	unsigned long flags;
	268	void *ptr;
	269
	270	spin_lock_irqsave(&r->consumer_lock, flags);
	271	ptr = __ptr_ring_consume(r);
	272	spin_unlock_irqrestore(&r->consumer_lock, flags);
	273
	274	return ptr;
	275	}
	276
	277	static inline void ptr_ring_consume_bh(struct ptr_ring r)
	278	{
	279	void *ptr;
	280
	281	spin_lock_bh(&r->consumer_lock);
	282	ptr = __ptr_ring_consume(r);
	283	spin_unlock_bh(&r->consumer_lock);
	284
	285	return ptr;
	286	}
	287
288	/* Cast to structure type and call a function without discarding from FIFO.
289	* Function must return a value.
290	* Callers must take consumer_lock.
291	*/
292	#define __PTR_RING_PEEK_CALL(r, f) ((f)(__ptr_ring_peek(r)))
293
294	#define PTR_RING_PEEK_CALL(r, f) ({ \
295	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
296	\
297	spin_lock(&(r)->consumer_lock); \
298	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
299	spin_unlock(&(r)->consumer_lock); \
300	__PTR_RING_PEEK_CALL_v; \
301	})
302
303	#define PTR_RING_PEEK_CALL_IRQ(r, f) ({ \
304	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
305	\
306	spin_lock_irq(&(r)->consumer_lock); \
307	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
308	spin_unlock_irq(&(r)->consumer_lock); \
309	__PTR_RING_PEEK_CALL_v; \
310	})
311
312	#define PTR_RING_PEEK_CALL_BH(r, f) ({ \
313	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
314	\
315	spin_lock_bh(&(r)->consumer_lock); \
316	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
317	spin_unlock_bh(&(r)->consumer_lock); \
318	__PTR_RING_PEEK_CALL_v; \
319	})
320
321	#define PTR_RING_PEEK_CALL_ANY(r, f) ({ \
322	typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
323	unsigned long __PTR_RING_PEEK_CALL_f;\
324	\
325	spin_lock_irqsave(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
326	__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
327	spin_unlock_irqrestore(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
328	__PTR_RING_PEEK_CALL_v; \
329	})
330
5d49de53 MT	331	static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
	332	{
	333	return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
	334	}
	335
2e0ab8ca MT	336	static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
2e0ab8ca MT	337	{
5d49de53	338	r->queue = __ptr_ring_init_queue_alloc(size, gfp);
2e0ab8ca MT	339	if (!r->queue)
	340	return -ENOMEM;
	341
	342	r->size = size;
	343	r->producer = r->consumer = 0;
	344	spin_lock_init(&r->producer_lock);
	345	spin_lock_init(&r->consumer_lock);
	346
	347	return 0;
	348	}
	349
5d49de53 MT	350	static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
	351	void (destroy)(void ))
	352	{
	353	unsigned long flags;
	354	int producer = 0;
	355	void **queue = __ptr_ring_init_queue_alloc(size, gfp);
	356	void **old;
	357	void *ptr;
	358
	359	if (!queue)
	360	return -ENOMEM;
	361
	362	spin_lock_irqsave(&(r)->producer_lock, flags);
	363
	364	while ((ptr = ptr_ring_consume(r)))
	365	if (producer < size)
	366	queue[producer++] = ptr;
	367	else if (destroy)
	368	destroy(ptr);
	369
	370	r->size = size;
	371	r->producer = producer;
	372	r->consumer = 0;
	373	old = r->queue;
	374	r->queue = queue;
	375
	376	spin_unlock_irqrestore(&(r)->producer_lock, flags);
	377
	378	kfree(old);
	379
	380	return 0;
	381	}
	382
	383	static inline void ptr_ring_cleanup(struct ptr_ring r, void (destroy)(void *))
2e0ab8ca	384	{
5d49de53 MT	385	void *ptr;
	386
	387	if (destroy)
	388	while ((ptr = ptr_ring_consume(r)))
	389	destroy(ptr);
2e0ab8ca MT	390	kfree(r->queue);
	391	}
	392
	393	#endif /* _LINUX_PTR_RING_H */