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![Michael S. Tsirkin](/assets/img/avatar_default.png)
Sometimes, we need support resizing multiple queues at once. This is because it was not easy to recover to recover from a partial failure of multiple queues resizing. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
448 lines
9.8 KiB
C
448 lines
9.8 KiB
C
/*
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* Definitions for the 'struct ptr_ring' datastructure.
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*
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* Author:
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* Michael S. Tsirkin <mst@redhat.com>
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*
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* Copyright (C) 2016 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*
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* This is a limited-size FIFO maintaining pointers in FIFO order, with
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* one CPU producing entries and another consuming entries from a FIFO.
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*
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* This implementation tries to minimize cache-contention when there is a
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* single producer and a single consumer CPU.
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*/
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#ifndef _LINUX_PTR_RING_H
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#define _LINUX_PTR_RING_H 1
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#ifdef __KERNEL__
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#include <linux/spinlock.h>
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#include <linux/cache.h>
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#include <linux/types.h>
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#include <linux/compiler.h>
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#include <linux/cache.h>
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#include <linux/slab.h>
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#include <asm/errno.h>
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#endif
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struct ptr_ring {
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int producer ____cacheline_aligned_in_smp;
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spinlock_t producer_lock;
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int consumer ____cacheline_aligned_in_smp;
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spinlock_t consumer_lock;
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/* Shared consumer/producer data */
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/* Read-only by both the producer and the consumer */
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int size ____cacheline_aligned_in_smp; /* max entries in queue */
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void **queue;
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};
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/* Note: callers invoking this in a loop must use a compiler barrier,
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* for example cpu_relax(). If ring is ever resized, callers must hold
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* producer_lock - see e.g. ptr_ring_full. Otherwise, if callers don't hold
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* producer_lock, the next call to __ptr_ring_produce may fail.
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*/
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static inline bool __ptr_ring_full(struct ptr_ring *r)
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{
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return r->queue[r->producer];
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}
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static inline bool ptr_ring_full(struct ptr_ring *r)
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{
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bool ret;
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spin_lock(&r->producer_lock);
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ret = __ptr_ring_full(r);
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spin_unlock(&r->producer_lock);
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return ret;
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}
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static inline bool ptr_ring_full_irq(struct ptr_ring *r)
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{
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bool ret;
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spin_lock_irq(&r->producer_lock);
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ret = __ptr_ring_full(r);
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spin_unlock_irq(&r->producer_lock);
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return ret;
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}
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static inline bool ptr_ring_full_any(struct ptr_ring *r)
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{
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unsigned long flags;
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bool ret;
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spin_lock_irqsave(&r->producer_lock, flags);
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ret = __ptr_ring_full(r);
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spin_unlock_irqrestore(&r->producer_lock, flags);
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return ret;
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}
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static inline bool ptr_ring_full_bh(struct ptr_ring *r)
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{
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bool ret;
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spin_lock_bh(&r->producer_lock);
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ret = __ptr_ring_full(r);
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spin_unlock_bh(&r->producer_lock);
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return ret;
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}
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/* Note: callers invoking this in a loop must use a compiler barrier,
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* for example cpu_relax(). Callers must hold producer_lock.
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*/
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static inline int __ptr_ring_produce(struct ptr_ring *r, void *ptr)
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{
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if (unlikely(!r->size) || r->queue[r->producer])
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return -ENOSPC;
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r->queue[r->producer++] = ptr;
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if (unlikely(r->producer >= r->size))
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r->producer = 0;
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return 0;
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}
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static inline int ptr_ring_produce(struct ptr_ring *r, void *ptr)
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{
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int ret;
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spin_lock(&r->producer_lock);
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ret = __ptr_ring_produce(r, ptr);
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spin_unlock(&r->producer_lock);
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return ret;
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}
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static inline int ptr_ring_produce_irq(struct ptr_ring *r, void *ptr)
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{
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int ret;
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spin_lock_irq(&r->producer_lock);
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ret = __ptr_ring_produce(r, ptr);
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spin_unlock_irq(&r->producer_lock);
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return ret;
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}
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static inline int ptr_ring_produce_any(struct ptr_ring *r, void *ptr)
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{
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unsigned long flags;
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int ret;
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spin_lock_irqsave(&r->producer_lock, flags);
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ret = __ptr_ring_produce(r, ptr);
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spin_unlock_irqrestore(&r->producer_lock, flags);
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return ret;
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}
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static inline int ptr_ring_produce_bh(struct ptr_ring *r, void *ptr)
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{
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int ret;
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spin_lock_bh(&r->producer_lock);
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ret = __ptr_ring_produce(r, ptr);
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spin_unlock_bh(&r->producer_lock);
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return ret;
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}
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/* Note: callers invoking this in a loop must use a compiler barrier,
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* for example cpu_relax(). Callers must take consumer_lock
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* if they dereference the pointer - see e.g. PTR_RING_PEEK_CALL.
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* If ring is never resized, and if the pointer is merely
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* tested, there's no need to take the lock - see e.g. __ptr_ring_empty.
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*/
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static inline void *__ptr_ring_peek(struct ptr_ring *r)
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{
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if (likely(r->size))
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return r->queue[r->consumer];
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return NULL;
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}
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/* Note: callers invoking this in a loop must use a compiler barrier,
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* for example cpu_relax(). Callers must take consumer_lock
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* if the ring is ever resized - see e.g. ptr_ring_empty.
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*/
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static inline bool __ptr_ring_empty(struct ptr_ring *r)
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{
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return !__ptr_ring_peek(r);
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}
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static inline bool ptr_ring_empty(struct ptr_ring *r)
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{
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bool ret;
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spin_lock(&r->consumer_lock);
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ret = __ptr_ring_empty(r);
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spin_unlock(&r->consumer_lock);
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return ret;
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}
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static inline bool ptr_ring_empty_irq(struct ptr_ring *r)
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{
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bool ret;
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spin_lock_irq(&r->consumer_lock);
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ret = __ptr_ring_empty(r);
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spin_unlock_irq(&r->consumer_lock);
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return ret;
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}
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static inline bool ptr_ring_empty_any(struct ptr_ring *r)
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{
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unsigned long flags;
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bool ret;
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spin_lock_irqsave(&r->consumer_lock, flags);
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ret = __ptr_ring_empty(r);
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spin_unlock_irqrestore(&r->consumer_lock, flags);
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return ret;
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}
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static inline bool ptr_ring_empty_bh(struct ptr_ring *r)
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{
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bool ret;
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spin_lock_bh(&r->consumer_lock);
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ret = __ptr_ring_empty(r);
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spin_unlock_bh(&r->consumer_lock);
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return ret;
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}
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/* Must only be called after __ptr_ring_peek returned !NULL */
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static inline void __ptr_ring_discard_one(struct ptr_ring *r)
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{
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r->queue[r->consumer++] = NULL;
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if (unlikely(r->consumer >= r->size))
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r->consumer = 0;
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}
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static inline void *__ptr_ring_consume(struct ptr_ring *r)
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{
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void *ptr;
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ptr = __ptr_ring_peek(r);
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if (ptr)
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__ptr_ring_discard_one(r);
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return ptr;
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}
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static inline void *ptr_ring_consume(struct ptr_ring *r)
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{
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void *ptr;
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spin_lock(&r->consumer_lock);
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ptr = __ptr_ring_consume(r);
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spin_unlock(&r->consumer_lock);
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return ptr;
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}
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static inline void *ptr_ring_consume_irq(struct ptr_ring *r)
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{
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void *ptr;
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spin_lock_irq(&r->consumer_lock);
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ptr = __ptr_ring_consume(r);
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spin_unlock_irq(&r->consumer_lock);
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return ptr;
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}
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static inline void *ptr_ring_consume_any(struct ptr_ring *r)
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{
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unsigned long flags;
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void *ptr;
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spin_lock_irqsave(&r->consumer_lock, flags);
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ptr = __ptr_ring_consume(r);
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spin_unlock_irqrestore(&r->consumer_lock, flags);
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return ptr;
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}
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static inline void *ptr_ring_consume_bh(struct ptr_ring *r)
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{
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void *ptr;
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spin_lock_bh(&r->consumer_lock);
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ptr = __ptr_ring_consume(r);
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spin_unlock_bh(&r->consumer_lock);
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return ptr;
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}
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/* Cast to structure type and call a function without discarding from FIFO.
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* Function must return a value.
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* Callers must take consumer_lock.
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*/
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#define __PTR_RING_PEEK_CALL(r, f) ((f)(__ptr_ring_peek(r)))
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#define PTR_RING_PEEK_CALL(r, f) ({ \
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typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
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\
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spin_lock(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
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spin_unlock(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v; \
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})
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#define PTR_RING_PEEK_CALL_IRQ(r, f) ({ \
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typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
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\
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spin_lock_irq(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
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spin_unlock_irq(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v; \
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})
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#define PTR_RING_PEEK_CALL_BH(r, f) ({ \
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typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
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\
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spin_lock_bh(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
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spin_unlock_bh(&(r)->consumer_lock); \
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__PTR_RING_PEEK_CALL_v; \
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})
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#define PTR_RING_PEEK_CALL_ANY(r, f) ({ \
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typeof((f)(NULL)) __PTR_RING_PEEK_CALL_v; \
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unsigned long __PTR_RING_PEEK_CALL_f;\
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\
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spin_lock_irqsave(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
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__PTR_RING_PEEK_CALL_v = __PTR_RING_PEEK_CALL(r, f); \
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spin_unlock_irqrestore(&(r)->consumer_lock, __PTR_RING_PEEK_CALL_f); \
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__PTR_RING_PEEK_CALL_v; \
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})
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static inline void **__ptr_ring_init_queue_alloc(int size, gfp_t gfp)
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{
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return kzalloc(ALIGN(size * sizeof(void *), SMP_CACHE_BYTES), gfp);
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}
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static inline int ptr_ring_init(struct ptr_ring *r, int size, gfp_t gfp)
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{
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r->queue = __ptr_ring_init_queue_alloc(size, gfp);
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if (!r->queue)
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return -ENOMEM;
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r->size = size;
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r->producer = r->consumer = 0;
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spin_lock_init(&r->producer_lock);
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spin_lock_init(&r->consumer_lock);
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return 0;
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}
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static inline void **__ptr_ring_swap_queue(struct ptr_ring *r, void **queue,
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int size, gfp_t gfp,
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void (*destroy)(void *))
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{
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int producer = 0;
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void **old;
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void *ptr;
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while ((ptr = ptr_ring_consume(r)))
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if (producer < size)
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queue[producer++] = ptr;
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else if (destroy)
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destroy(ptr);
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r->size = size;
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r->producer = producer;
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r->consumer = 0;
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old = r->queue;
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r->queue = queue;
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return old;
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}
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static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
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void (*destroy)(void *))
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{
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unsigned long flags;
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void **queue = __ptr_ring_init_queue_alloc(size, gfp);
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void **old;
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if (!queue)
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return -ENOMEM;
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spin_lock_irqsave(&(r)->producer_lock, flags);
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old = __ptr_ring_swap_queue(r, queue, size, gfp, destroy);
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spin_unlock_irqrestore(&(r)->producer_lock, flags);
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kfree(old);
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return 0;
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}
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static inline int ptr_ring_resize_multiple(struct ptr_ring **rings, int nrings,
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int size,
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gfp_t gfp, void (*destroy)(void *))
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{
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unsigned long flags;
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void ***queues;
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int i;
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queues = kmalloc(nrings * sizeof *queues, gfp);
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if (!queues)
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goto noqueues;
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for (i = 0; i < nrings; ++i) {
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queues[i] = __ptr_ring_init_queue_alloc(size, gfp);
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if (!queues[i])
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goto nomem;
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}
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for (i = 0; i < nrings; ++i) {
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spin_lock_irqsave(&(rings[i])->producer_lock, flags);
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queues[i] = __ptr_ring_swap_queue(rings[i], queues[i],
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size, gfp, destroy);
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spin_unlock_irqrestore(&(rings[i])->producer_lock, flags);
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}
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for (i = 0; i < nrings; ++i)
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kfree(queues[i]);
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kfree(queues);
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return 0;
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nomem:
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while (--i >= 0)
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kfree(queues[i]);
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kfree(queues);
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noqueues:
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return -ENOMEM;
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}
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static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
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{
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void *ptr;
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if (destroy)
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while ((ptr = ptr_ring_consume(r)))
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destroy(ptr);
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kfree(r->queue);
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}
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#endif /* _LINUX_PTR_RING_H */
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