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8b33cb8303
as a thin wrapper around native version found in sys/seqc.h. This replaces out-of-base GPLv2-licensed code used by drm-kmod. Reviewed by: hselasky Differential revision: https://reviews.freebsd.org/D31006
137 lines
3.8 KiB
C
137 lines
3.8 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2021 Vladimir Kondratyev <wulf@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _LINUX_SEQLOCK_H__
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#define _LINUX_SEQLOCK_H__
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#include <sys/param.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/seqc.h>
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struct lock_class_key;
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struct seqcount {
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seqc_t seqc;
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};
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typedef struct seqcount seqcount_t;
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struct seqlock {
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struct mtx seql_lock;
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struct seqcount seql_count;
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};
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typedef struct seqlock seqlock_t;
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static inline void
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__seqcount_init(struct seqcount *seqcount, const char *name __unused,
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struct lock_class_key *key __unused)
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{
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seqcount->seqc = 0;
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}
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#define seqcount_init(seqcount) __seqcount_init(seqcount, NULL, NULL)
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static inline void
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write_seqcount_begin(struct seqcount *seqcount)
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{
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seqc_sleepable_write_begin(&seqcount->seqc);
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}
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static inline void
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write_seqcount_end(struct seqcount *seqcount)
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{
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seqc_sleepable_write_end(&seqcount->seqc);
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}
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/*
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* XXX: Are predicts from inline functions still not honored by clang?
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*/
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#define __read_seqcount_retry(seqcount, gen) \
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(!seqc_consistent_nomb(&(seqcount)->seqc, gen))
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#define read_seqcount_retry(seqcount, gen) \
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(!seqc_consistent(&(seqcount)->seqc, gen))
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static inline unsigned
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read_seqcount_begin(const struct seqcount *seqcount)
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{
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return (seqc_read(&seqcount->seqc));
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}
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static inline unsigned
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raw_read_seqcount(const struct seqcount *seqcount)
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{
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return (seqc_read_any(&seqcount->seqc));
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}
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static inline void
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seqlock_init(struct seqlock *seqlock)
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{
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/*
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* Don't enroll to witness(4) to avoid orphaned references after struct
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* seqlock has been freed. There is no seqlock destructor exists so we
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* can't expect automatic mtx_destroy() execution before free().
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*/
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mtx_init(&seqlock->seql_lock, "seqlock", NULL, MTX_DEF|MTX_NOWITNESS);
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seqcount_init(&seqlock->seql_count);
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}
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static inline void
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write_seqlock(struct seqlock *seqlock)
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{
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mtx_lock(&seqlock->seql_lock);
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write_seqcount_begin(&seqlock->seql_count);
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}
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static inline void
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write_sequnlock(struct seqlock *seqlock)
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{
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write_seqcount_end(&seqlock->seql_count);
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mtx_unlock(&seqlock->seql_lock);
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}
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#define write_seqlock_irqsave(seqlock, flags) do { \
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(flags) = 0; \
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write_seqlock(seqlock); \
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} while (0)
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static inline void
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write_sequnlock_irqrestore(struct seqlock *seqlock,
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unsigned long flags __unused)
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{
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write_sequnlock(seqlock);
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}
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static inline unsigned
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read_seqbegin(const struct seqlock *seqlock)
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{
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return (read_seqcount_begin(&seqlock->seql_count));
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}
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#define read_seqretry(seqlock, gen) \
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read_seqcount_retry(&(seqlock)->seql_count, gen)
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#endif /* _LINUX_SEQLOCK_H__ */
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