708d904451
The value of *tail should be the prod->tail not prod->head. After
modification, it can record 'tail' so head/tail can be updated
accordingly.
Fixes: 664ff4b172 ("ring: introduce peek style API")
Signed-off-by: Feifei Wang <feifei.wang2@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
111 lines
2.9 KiB
C
111 lines
2.9 KiB
C
/* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 2010-2020 Intel Corporation
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* Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
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* All rights reserved.
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* Derived from FreeBSD's bufring.h
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* Used as BSD-3 Licensed with permission from Kip Macy.
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*/
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#ifndef _RTE_RING_PEEK_C11_MEM_H_
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#define _RTE_RING_PEEK_C11_MEM_H_
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/**
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* @file rte_ring_peek_c11_mem.h
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* It is not recommended to include this file directly,
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* include <rte_ring.h> instead.
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* Contains internal helper functions for rte_ring peek API.
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* For more information please refer to <rte_ring_peek.h>.
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*/
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/**
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* @internal get current tail value.
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* This function should be used only for single thread producer/consumer.
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* Check that user didn't request to move tail above the head.
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* In that situation:
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* - return zero, that will cause abort any pending changes and
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* return head to its previous position.
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* - throw an assert in debug mode.
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*/
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static __rte_always_inline uint32_t
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__rte_ring_st_get_tail(struct rte_ring_headtail *ht, uint32_t *tail,
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uint32_t num)
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{
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uint32_t h, n, t;
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h = ht->head;
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t = ht->tail;
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n = h - t;
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RTE_ASSERT(n >= num);
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num = (n >= num) ? num : 0;
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*tail = t;
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return num;
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}
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/**
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* @internal set new values for head and tail.
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* This function should be used only for single thread producer/consumer.
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* Should be used only in conjunction with __rte_ring_st_get_tail.
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*/
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static __rte_always_inline void
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__rte_ring_st_set_head_tail(struct rte_ring_headtail *ht, uint32_t tail,
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uint32_t num, uint32_t enqueue)
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{
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uint32_t pos;
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RTE_SET_USED(enqueue);
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pos = tail + num;
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ht->head = pos;
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__atomic_store_n(&ht->tail, pos, __ATOMIC_RELEASE);
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}
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/**
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* @internal get current tail value.
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* This function should be used only for producer/consumer in MT_HTS mode.
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* Check that user didn't request to move tail above the head.
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* In that situation:
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* - return zero, that will cause abort any pending changes and
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* return head to its previous position.
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* - throw an assert in debug mode.
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*/
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static __rte_always_inline uint32_t
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__rte_ring_hts_get_tail(struct rte_ring_hts_headtail *ht, uint32_t *tail,
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uint32_t num)
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{
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uint32_t n;
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union __rte_ring_hts_pos p;
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p.raw = __atomic_load_n(&ht->ht.raw, __ATOMIC_RELAXED);
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n = p.pos.head - p.pos.tail;
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RTE_ASSERT(n >= num);
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num = (n >= num) ? num : 0;
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*tail = p.pos.tail;
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return num;
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}
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/**
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* @internal set new values for head and tail as one atomic 64 bit operation.
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* This function should be used only for producer/consumer in MT_HTS mode.
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* Should be used only in conjunction with __rte_ring_hts_get_tail.
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*/
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static __rte_always_inline void
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__rte_ring_hts_set_head_tail(struct rte_ring_hts_headtail *ht, uint32_t tail,
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uint32_t num, uint32_t enqueue)
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{
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union __rte_ring_hts_pos p;
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RTE_SET_USED(enqueue);
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p.pos.head = tail + num;
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p.pos.tail = p.pos.head;
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__atomic_store_n(&ht->ht.raw, p.raw, __ATOMIC_RELEASE);
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}
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#endif /* _RTE_RING_PEEK_C11_MEM_H_ */
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