Current File : //usr/src/kernels/3.10.0-957.21.3.el7.centos.plus.x86_64/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;
}
/*
* Note: resize (below) nests producer lock within consumer lock, so if you
* consume in interrupt or BH context, you must disable interrupts/BH when
* calling this.
*/
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;
}
/*
* Note: resize (below) nests producer lock within consumer lock, so if you
* call this in interrupt or BH context, you must disable interrupts/BH when
* producing.
*/
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 void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
int size, gfp_t gfp,
void (*destroy)(void *))
{
int producer = 0;
void **old;
void *ptr;
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;
return old;
}
/*
* Note: producer lock is nested within consumer lock, so if you
* resize you must make sure all uses nest correctly.
* In particular if you consume ring in interrupt or BH context, you must
* disable interrupts/BH when doing so.
*/
static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
void (*destroy)(void *))
{
unsigned long flags;
void **queue = __ptr_ring_init_queue_alloc(size, gfp);
void **old;
if (!queue)
return -ENOMEM;
spin_lock_irqsave(&(r)->consumer_lock, flags);
spin_lock(&(r)->producer_lock);
old = __ptr_ring_swap_queue(r, queue, size, gfp, destroy);
spin_unlock(&(r)->producer_lock);
spin_unlock_irqrestore(&(r)->consumer_lock, flags);
kfree(old);
return 0;
}
/*
* Note: producer lock is nested within consumer lock, so if you
* resize you must make sure all uses nest correctly.
* In particular if you consume ring in interrupt or BH context, you must
* disable interrupts/BH when doing so.
*/
static inline int ptr_ring_resize_multiple(struct ptr_ring **rings, int nrings,
int size,
gfp_t gfp, void (*destroy)(void *))
{
unsigned long flags;
void ***queues;
int i;
queues = kmalloc(nrings * sizeof *queues, gfp);
if (!queues)
goto noqueues;
for (i = 0; i < nrings; ++i) {
queues[i] = __ptr_ring_init_queue_alloc(size, gfp);
if (!queues[i])
goto nomem;
}
for (i = 0; i < nrings; ++i) {
spin_lock_irqsave(&(rings[i])->consumer_lock, flags);
spin_lock(&(rings[i])->producer_lock);
queues[i] = __ptr_ring_swap_queue(rings[i], queues[i],
size, gfp, destroy);
spin_unlock(&(rings[i])->producer_lock);
spin_unlock_irqrestore(&(rings[i])->consumer_lock, flags);
}
for (i = 0; i < nrings; ++i)
kfree(queues[i]);
kfree(queues);
return 0;
nomem:
while (--i >= 0)
kfree(queues[i]);
kfree(queues);
noqueues:
return -ENOMEM;
}
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 */
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