8a36da99de
Mainly focus on files that use BSD 2-Clause license, however the tool I was using misidentified many licenses so this was mostly a manual - error prone - task. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts.
251 lines
6.3 KiB
C
251 lines
6.3 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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*
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* Copyright (c) 2009 Konstantin Belousov <kib@FreeBSD.org>
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* All rights reserved.
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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
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice unmodified, this list of conditions, and the following
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* 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 the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/rangelock.h>
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#include <sys/systm.h>
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#include <vm/uma.h>
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struct rl_q_entry {
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TAILQ_ENTRY(rl_q_entry) rl_q_link;
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off_t rl_q_start, rl_q_end;
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int rl_q_flags;
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};
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static uma_zone_t rl_entry_zone;
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static void
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rangelock_sys_init(void)
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{
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rl_entry_zone = uma_zcreate("rl_entry", sizeof(struct rl_q_entry),
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NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
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}
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SYSINIT(vfs, SI_SUB_LOCK, SI_ORDER_ANY, rangelock_sys_init, NULL);
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static struct rl_q_entry *
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rlqentry_alloc(void)
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{
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return (uma_zalloc(rl_entry_zone, M_WAITOK));
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}
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void
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rlqentry_free(struct rl_q_entry *rleq)
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{
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uma_zfree(rl_entry_zone, rleq);
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}
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void
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rangelock_init(struct rangelock *lock)
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{
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TAILQ_INIT(&lock->rl_waiters);
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lock->rl_currdep = NULL;
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}
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void
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rangelock_destroy(struct rangelock *lock)
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{
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KASSERT(TAILQ_EMPTY(&lock->rl_waiters), ("Dangling waiters"));
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}
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/*
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* Two entries are compatible if their ranges do not overlap, or both
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* entries are for read.
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*/
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static int
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ranges_overlap(const struct rl_q_entry *e1,
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const struct rl_q_entry *e2)
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{
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if (e1->rl_q_start < e2->rl_q_end && e1->rl_q_end > e2->rl_q_start)
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return (1);
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return (0);
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}
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/*
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* Recalculate the lock->rl_currdep after an unlock.
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*/
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static void
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rangelock_calc_block(struct rangelock *lock)
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{
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struct rl_q_entry *entry, *nextentry, *entry1;
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for (entry = lock->rl_currdep; entry != NULL; entry = nextentry) {
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nextentry = TAILQ_NEXT(entry, rl_q_link);
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if (entry->rl_q_flags & RL_LOCK_READ) {
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/* Reads must not overlap with granted writes. */
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for (entry1 = TAILQ_FIRST(&lock->rl_waiters);
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!(entry1->rl_q_flags & RL_LOCK_READ);
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entry1 = TAILQ_NEXT(entry1, rl_q_link)) {
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if (ranges_overlap(entry, entry1))
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goto out;
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}
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} else {
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/* Write must not overlap with any granted locks. */
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for (entry1 = TAILQ_FIRST(&lock->rl_waiters);
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entry1 != entry;
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entry1 = TAILQ_NEXT(entry1, rl_q_link)) {
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if (ranges_overlap(entry, entry1))
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goto out;
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}
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/* Move grantable write locks to the front. */
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TAILQ_REMOVE(&lock->rl_waiters, entry, rl_q_link);
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TAILQ_INSERT_HEAD(&lock->rl_waiters, entry, rl_q_link);
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}
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/* Grant this lock. */
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entry->rl_q_flags |= RL_LOCK_GRANTED;
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wakeup(entry);
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}
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out:
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lock->rl_currdep = entry;
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}
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static void
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rangelock_unlock_locked(struct rangelock *lock, struct rl_q_entry *entry,
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struct mtx *ilk)
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{
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MPASS(lock != NULL && entry != NULL && ilk != NULL);
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mtx_assert(ilk, MA_OWNED);
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KASSERT(entry != lock->rl_currdep, ("stuck currdep"));
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TAILQ_REMOVE(&lock->rl_waiters, entry, rl_q_link);
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rangelock_calc_block(lock);
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mtx_unlock(ilk);
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if (curthread->td_rlqe == NULL)
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curthread->td_rlqe = entry;
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else
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rlqentry_free(entry);
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}
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void
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rangelock_unlock(struct rangelock *lock, void *cookie, struct mtx *ilk)
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{
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MPASS(lock != NULL && cookie != NULL && ilk != NULL);
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mtx_lock(ilk);
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rangelock_unlock_locked(lock, cookie, ilk);
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}
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/*
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* Unlock the sub-range of granted lock.
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*/
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void *
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rangelock_unlock_range(struct rangelock *lock, void *cookie, off_t start,
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off_t end, struct mtx *ilk)
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{
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struct rl_q_entry *entry;
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MPASS(lock != NULL && cookie != NULL && ilk != NULL);
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entry = cookie;
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KASSERT(entry->rl_q_flags & RL_LOCK_GRANTED,
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("Unlocking non-granted lock"));
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KASSERT(entry->rl_q_start == start, ("wrong start"));
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KASSERT(entry->rl_q_end >= end, ("wrong end"));
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mtx_lock(ilk);
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if (entry->rl_q_end == end) {
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rangelock_unlock_locked(lock, cookie, ilk);
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return (NULL);
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}
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entry->rl_q_end = end;
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rangelock_calc_block(lock);
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mtx_unlock(ilk);
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return (cookie);
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}
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/*
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* Add the lock request to the queue of the pending requests for
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* rangelock. Sleep until the request can be granted.
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*/
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static void *
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rangelock_enqueue(struct rangelock *lock, off_t start, off_t end, int mode,
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struct mtx *ilk)
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{
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struct rl_q_entry *entry;
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struct thread *td;
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MPASS(lock != NULL && ilk != NULL);
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td = curthread;
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if (td->td_rlqe != NULL) {
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entry = td->td_rlqe;
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td->td_rlqe = NULL;
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} else
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entry = rlqentry_alloc();
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MPASS(entry != NULL);
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entry->rl_q_flags = mode;
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entry->rl_q_start = start;
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entry->rl_q_end = end;
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mtx_lock(ilk);
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/*
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* XXXKIB TODO. Check that a thread does not try to enqueue a
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* lock that is incompatible with another request from the same
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* thread.
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*/
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TAILQ_INSERT_TAIL(&lock->rl_waiters, entry, rl_q_link);
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if (lock->rl_currdep == NULL)
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lock->rl_currdep = entry;
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rangelock_calc_block(lock);
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while (!(entry->rl_q_flags & RL_LOCK_GRANTED))
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msleep(entry, ilk, 0, "range", 0);
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mtx_unlock(ilk);
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return (entry);
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}
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void *
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rangelock_rlock(struct rangelock *lock, off_t start, off_t end, struct mtx *ilk)
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{
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return (rangelock_enqueue(lock, start, end, RL_LOCK_READ, ilk));
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}
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void *
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rangelock_wlock(struct rangelock *lock, off_t start, off_t end, struct mtx *ilk)
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{
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return (rangelock_enqueue(lock, start, end, RL_LOCK_WRITE, ilk));
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}
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