1354 lines
34 KiB
C
1354 lines
34 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1998 Berkeley Software Design, Inc. 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, 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 the
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* documentation and/or other materials provided with the distribution.
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* 3. Berkeley Software Design Inc's name may not be used to endorse or
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* promote products derived from this software without specific prior
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* written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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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* from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
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* and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
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*/
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/*
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* Machine independent bits of mutex implementation.
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*/
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#include <sys/cdefs.h>
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#include "opt_adaptive_mutexes.h"
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#include "opt_ddb.h"
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#include "opt_hwpmc_hooks.h"
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#include "opt_sched.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/bus.h>
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#include <sys/conf.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/sbuf.h>
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#include <sys/smp.h>
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#include <sys/sysctl.h>
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#include <sys/turnstile.h>
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#include <sys/vmmeter.h>
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#include <sys/lock_profile.h>
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#include <machine/atomic.h>
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#include <machine/bus.h>
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#include <machine/cpu.h>
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#include <ddb/ddb.h>
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#include <fs/devfs/devfs_int.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
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#define ADAPTIVE_MUTEXES
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#endif
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#ifdef HWPMC_HOOKS
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#include <sys/pmckern.h>
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PMC_SOFT_DEFINE( , , lock, failed);
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#endif
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/*
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* Return the mutex address when the lock cookie address is provided.
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* This functionality assumes that struct mtx* have a member named mtx_lock.
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*/
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#define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
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/*
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* Internal utility macros.
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*/
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#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
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#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
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static void assert_mtx(const struct lock_object *lock, int what);
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#ifdef DDB
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static void db_show_mtx(const struct lock_object *lock);
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#endif
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static void lock_mtx(struct lock_object *lock, uintptr_t how);
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static void lock_spin(struct lock_object *lock, uintptr_t how);
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#ifdef KDTRACE_HOOKS
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static int owner_mtx(const struct lock_object *lock,
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struct thread **owner);
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#endif
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static uintptr_t unlock_mtx(struct lock_object *lock);
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static uintptr_t unlock_spin(struct lock_object *lock);
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/*
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* Lock classes for sleep and spin mutexes.
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*/
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struct lock_class lock_class_mtx_sleep = {
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.lc_name = "sleep mutex",
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.lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
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.lc_assert = assert_mtx,
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#ifdef DDB
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.lc_ddb_show = db_show_mtx,
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#endif
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.lc_lock = lock_mtx,
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.lc_unlock = unlock_mtx,
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#ifdef KDTRACE_HOOKS
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.lc_owner = owner_mtx,
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#endif
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};
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struct lock_class lock_class_mtx_spin = {
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.lc_name = "spin mutex",
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.lc_flags = LC_SPINLOCK | LC_RECURSABLE,
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.lc_assert = assert_mtx,
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#ifdef DDB
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.lc_ddb_show = db_show_mtx,
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#endif
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.lc_lock = lock_spin,
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.lc_unlock = unlock_spin,
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#ifdef KDTRACE_HOOKS
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.lc_owner = owner_mtx,
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#endif
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};
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#ifdef ADAPTIVE_MUTEXES
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#ifdef MUTEX_CUSTOM_BACKOFF
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static SYSCTL_NODE(_debug, OID_AUTO, mtx, CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
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"mtx debugging");
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static struct lock_delay_config __read_frequently mtx_delay;
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SYSCTL_U16(_debug_mtx, OID_AUTO, delay_base, CTLFLAG_RW, &mtx_delay.base,
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0, "");
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SYSCTL_U16(_debug_mtx, OID_AUTO, delay_max, CTLFLAG_RW, &mtx_delay.max,
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0, "");
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LOCK_DELAY_SYSINIT_DEFAULT(mtx_delay);
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#else
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#define mtx_delay locks_delay
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#endif
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#endif
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#ifdef MUTEX_SPIN_CUSTOM_BACKOFF
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static SYSCTL_NODE(_debug, OID_AUTO, mtx_spin,
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CTLFLAG_RD | CTLFLAG_MPSAFE, NULL,
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"mtx spin debugging");
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static struct lock_delay_config __read_frequently mtx_spin_delay;
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SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_base, CTLFLAG_RW,
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&mtx_spin_delay.base, 0, "");
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SYSCTL_INT(_debug_mtx_spin, OID_AUTO, delay_max, CTLFLAG_RW,
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&mtx_spin_delay.max, 0, "");
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LOCK_DELAY_SYSINIT_DEFAULT(mtx_spin_delay);
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#else
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#define mtx_spin_delay locks_delay
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#endif
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/*
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* System-wide mutexes
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*/
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struct mtx blocked_lock;
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struct mtx __exclusive_cache_line Giant;
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static void _mtx_lock_indefinite_check(struct mtx *, struct lock_delay_arg *);
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void
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assert_mtx(const struct lock_object *lock, int what)
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{
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/*
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* Treat LA_LOCKED as if LA_XLOCKED was asserted.
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*
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* Some callers of lc_assert uses LA_LOCKED to indicate that either
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* a shared lock or write lock was held, while other callers uses
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* the more strict LA_XLOCKED (used as MA_OWNED).
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*
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* Mutex is the only lock class that can not be shared, as a result,
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* we can reasonably consider the caller really intends to assert
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* LA_XLOCKED when they are asserting LA_LOCKED on a mutex object.
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*/
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if (what & LA_LOCKED) {
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what &= ~LA_LOCKED;
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what |= LA_XLOCKED;
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}
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mtx_assert((const struct mtx *)lock, what);
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}
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void
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lock_mtx(struct lock_object *lock, uintptr_t how)
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{
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mtx_lock((struct mtx *)lock);
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}
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void
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lock_spin(struct lock_object *lock, uintptr_t how)
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{
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mtx_lock_spin((struct mtx *)lock);
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}
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uintptr_t
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unlock_mtx(struct lock_object *lock)
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{
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struct mtx *m;
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m = (struct mtx *)lock;
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mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
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mtx_unlock(m);
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return (0);
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}
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uintptr_t
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unlock_spin(struct lock_object *lock)
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{
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struct mtx *m;
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m = (struct mtx *)lock;
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mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
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mtx_unlock_spin(m);
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return (0);
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}
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#ifdef KDTRACE_HOOKS
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int
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owner_mtx(const struct lock_object *lock, struct thread **owner)
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{
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const struct mtx *m;
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uintptr_t x;
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m = (const struct mtx *)lock;
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x = m->mtx_lock;
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*owner = (struct thread *)(x & ~MTX_FLAGMASK);
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return (*owner != NULL);
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}
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#endif
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/*
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* Function versions of the inlined __mtx_* macros. These are used by
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* modules and can also be called from assembly language if needed.
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*/
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void
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__mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
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{
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struct mtx *m;
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uintptr_t tid, v;
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m = mtxlock2mtx(c);
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KASSERT(kdb_active != 0 || SCHEDULER_STOPPED() ||
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!TD_IS_IDLETHREAD(curthread),
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("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
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curthread, m->lock_object.lo_name, file, line));
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_lock() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
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("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
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file, line));
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WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
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LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
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tid = (uintptr_t)curthread;
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v = MTX_UNOWNED;
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if (!_mtx_obtain_lock_fetch(m, &v, tid))
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_mtx_lock_sleep(m, v, opts, file, line);
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else
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LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
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m, 0, 0, file, line);
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LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
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line);
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WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
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file, line);
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TD_LOCKS_INC(curthread);
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}
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void
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__mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
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{
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struct mtx *m;
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m = mtxlock2mtx(c);
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
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("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
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file, line));
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WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
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LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
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line);
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mtx_assert(m, MA_OWNED);
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#ifdef LOCK_PROFILING
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__mtx_unlock_sleep(c, (uintptr_t)curthread, opts, file, line);
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#else
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__mtx_unlock(m, curthread, opts, file, line);
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#endif
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TD_LOCKS_DEC(curthread);
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}
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void
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__mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
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int line)
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{
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struct mtx *m;
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#ifdef SMP
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uintptr_t tid, v;
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#endif
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m = mtxlock2mtx(c);
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
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("mtx_lock_spin() of sleep mutex %s @ %s:%d",
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m->lock_object.lo_name, file, line));
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if (mtx_owned(m))
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KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
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(opts & MTX_RECURSE) != 0,
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("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
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m->lock_object.lo_name, file, line));
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opts &= ~MTX_RECURSE;
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WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
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file, line, NULL);
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#ifdef SMP
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spinlock_enter();
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tid = (uintptr_t)curthread;
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v = MTX_UNOWNED;
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if (!_mtx_obtain_lock_fetch(m, &v, tid))
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_mtx_lock_spin(m, v, opts, file, line);
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else
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LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire,
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m, 0, 0, file, line);
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#else
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__mtx_lock_spin(m, curthread, opts, file, line);
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#endif
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LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
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line);
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WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
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}
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int
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__mtx_trylock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
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int line)
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{
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struct mtx *m;
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if (SCHEDULER_STOPPED())
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return (1);
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m = mtxlock2mtx(c);
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_trylock_spin() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
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("mtx_trylock_spin() of sleep mutex %s @ %s:%d",
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m->lock_object.lo_name, file, line));
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KASSERT((opts & MTX_RECURSE) == 0,
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("mtx_trylock_spin: unsupp. opt MTX_RECURSE on mutex %s @ %s:%d\n",
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m->lock_object.lo_name, file, line));
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if (__mtx_trylock_spin(m, curthread, opts, file, line)) {
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LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 1, file, line);
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WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
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return (1);
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}
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LOCK_LOG_TRY("LOCK", &m->lock_object, opts, 0, file, line);
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return (0);
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}
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void
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__mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
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int line)
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{
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struct mtx *m;
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m = mtxlock2mtx(c);
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
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("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
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m->lock_object.lo_name, file, line));
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WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
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LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
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line);
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mtx_assert(m, MA_OWNED);
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__mtx_unlock_spin(m);
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}
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/*
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* The important part of mtx_trylock{,_flags}()
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* Tries to acquire lock `m.' If this function is called on a mutex that
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* is already owned, it will recursively acquire the lock.
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*/
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int
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_mtx_trylock_flags_int(struct mtx *m, int opts LOCK_FILE_LINE_ARG_DEF)
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{
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struct thread *td;
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uintptr_t tid, v;
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#ifdef LOCK_PROFILING
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uint64_t waittime = 0;
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int contested = 0;
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#endif
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int rval;
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bool recursed;
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td = curthread;
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tid = (uintptr_t)td;
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if (SCHEDULER_STOPPED_TD(td))
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return (1);
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KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(td),
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("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
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curthread, m->lock_object.lo_name, file, line));
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KASSERT(m->mtx_lock != MTX_DESTROYED,
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("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
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KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
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("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
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file, line));
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rval = 1;
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recursed = false;
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v = MTX_UNOWNED;
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for (;;) {
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if (_mtx_obtain_lock_fetch(m, &v, tid))
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break;
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if (v == MTX_UNOWNED)
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continue;
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if (v == tid &&
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((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
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(opts & MTX_RECURSE) != 0)) {
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m->mtx_recurse++;
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atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
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recursed = true;
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break;
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}
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rval = 0;
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break;
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}
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opts &= ~MTX_RECURSE;
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LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
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if (rval) {
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WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
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file, line);
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TD_LOCKS_INC(curthread);
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if (!recursed)
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LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
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m, contested, waittime, file, line);
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}
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return (rval);
|
|
}
|
|
|
|
int
|
|
_mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
|
|
{
|
|
struct mtx *m;
|
|
|
|
m = mtxlock2mtx(c);
|
|
return (_mtx_trylock_flags_int(m, opts LOCK_FILE_LINE_ARG));
|
|
}
|
|
|
|
/*
|
|
* __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
|
|
*
|
|
* We call this if the lock is either contested (i.e. we need to go to
|
|
* sleep waiting for it), or if we need to recurse on it.
|
|
*/
|
|
#if LOCK_DEBUG > 0
|
|
void
|
|
__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v, int opts, const char *file,
|
|
int line)
|
|
#else
|
|
void
|
|
__mtx_lock_sleep(volatile uintptr_t *c, uintptr_t v)
|
|
#endif
|
|
{
|
|
struct thread *td;
|
|
struct mtx *m;
|
|
struct turnstile *ts;
|
|
uintptr_t tid;
|
|
struct thread *owner;
|
|
#ifdef LOCK_PROFILING
|
|
int contested = 0;
|
|
uint64_t waittime = 0;
|
|
#endif
|
|
#if defined(ADAPTIVE_MUTEXES) || defined(KDTRACE_HOOKS)
|
|
struct lock_delay_arg lda;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
u_int sleep_cnt = 0;
|
|
int64_t sleep_time = 0;
|
|
int64_t all_time = 0;
|
|
#endif
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
int doing_lockprof = 0;
|
|
#endif
|
|
|
|
td = curthread;
|
|
tid = (uintptr_t)td;
|
|
m = mtxlock2mtx(c);
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) {
|
|
while (v == MTX_UNOWNED) {
|
|
if (_mtx_obtain_lock_fetch(m, &v, tid))
|
|
goto out_lockstat;
|
|
}
|
|
doing_lockprof = 1;
|
|
all_time -= lockstat_nsecs(&m->lock_object);
|
|
}
|
|
#endif
|
|
#ifdef LOCK_PROFILING
|
|
doing_lockprof = 1;
|
|
#endif
|
|
|
|
if (SCHEDULER_STOPPED_TD(td))
|
|
return;
|
|
|
|
if (__predict_false(v == MTX_UNOWNED))
|
|
v = MTX_READ_VALUE(m);
|
|
|
|
if (__predict_false(lv_mtx_owner(v) == td)) {
|
|
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
|
|
(opts & MTX_RECURSE) != 0,
|
|
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
|
|
m->lock_object.lo_name, file, line));
|
|
#if LOCK_DEBUG > 0
|
|
opts &= ~MTX_RECURSE;
|
|
#endif
|
|
m->mtx_recurse++;
|
|
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
|
|
return;
|
|
}
|
|
#if LOCK_DEBUG > 0
|
|
opts &= ~MTX_RECURSE;
|
|
#endif
|
|
|
|
#if defined(ADAPTIVE_MUTEXES)
|
|
lock_delay_arg_init(&lda, &mtx_delay);
|
|
#elif defined(KDTRACE_HOOKS)
|
|
lock_delay_arg_init_noadapt(&lda);
|
|
#endif
|
|
|
|
#ifdef HWPMC_HOOKS
|
|
PMC_SOFT_CALL( , , lock, failed);
|
|
#endif
|
|
lock_profile_obtain_lock_failed(&m->lock_object, false,
|
|
&contested, &waittime);
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR4(KTR_LOCK,
|
|
"_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
|
|
m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
|
|
|
|
for (;;) {
|
|
if (v == MTX_UNOWNED) {
|
|
if (_mtx_obtain_lock_fetch(m, &v, tid))
|
|
break;
|
|
continue;
|
|
}
|
|
#ifdef KDTRACE_HOOKS
|
|
lda.spin_cnt++;
|
|
#endif
|
|
#ifdef ADAPTIVE_MUTEXES
|
|
/*
|
|
* If the owner is running on another CPU, spin until the
|
|
* owner stops running or the state of the lock changes.
|
|
*/
|
|
owner = lv_mtx_owner(v);
|
|
if (TD_IS_RUNNING(owner)) {
|
|
if (LOCK_LOG_TEST(&m->lock_object, 0))
|
|
CTR3(KTR_LOCK,
|
|
"%s: spinning on %p held by %p",
|
|
__func__, m, owner);
|
|
KTR_STATE1(KTR_SCHED, "thread",
|
|
sched_tdname((struct thread *)tid),
|
|
"spinning", "lockname:\"%s\"",
|
|
m->lock_object.lo_name);
|
|
do {
|
|
lock_delay(&lda);
|
|
v = MTX_READ_VALUE(m);
|
|
owner = lv_mtx_owner(v);
|
|
} while (v != MTX_UNOWNED && TD_IS_RUNNING(owner));
|
|
KTR_STATE0(KTR_SCHED, "thread",
|
|
sched_tdname((struct thread *)tid),
|
|
"running");
|
|
continue;
|
|
}
|
|
#endif
|
|
|
|
ts = turnstile_trywait(&m->lock_object);
|
|
v = MTX_READ_VALUE(m);
|
|
retry_turnstile:
|
|
|
|
/*
|
|
* Check if the lock has been released while spinning for
|
|
* the turnstile chain lock.
|
|
*/
|
|
if (v == MTX_UNOWNED) {
|
|
turnstile_cancel(ts);
|
|
continue;
|
|
}
|
|
|
|
#ifdef ADAPTIVE_MUTEXES
|
|
/*
|
|
* The current lock owner might have started executing
|
|
* on another CPU (or the lock could have changed
|
|
* owners) while we were waiting on the turnstile
|
|
* chain lock. If so, drop the turnstile lock and try
|
|
* again.
|
|
*/
|
|
owner = lv_mtx_owner(v);
|
|
if (TD_IS_RUNNING(owner)) {
|
|
turnstile_cancel(ts);
|
|
continue;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* If the mutex isn't already contested and a failure occurs
|
|
* setting the contested bit, the mutex was either released
|
|
* or the state of the MTX_RECURSED bit changed.
|
|
*/
|
|
if ((v & MTX_CONTESTED) == 0 &&
|
|
!atomic_fcmpset_ptr(&m->mtx_lock, &v, v | MTX_CONTESTED)) {
|
|
goto retry_turnstile;
|
|
}
|
|
|
|
/*
|
|
* We definitely must sleep for this lock.
|
|
*/
|
|
mtx_assert(m, MA_NOTOWNED);
|
|
|
|
/*
|
|
* Block on the turnstile.
|
|
*/
|
|
#ifdef KDTRACE_HOOKS
|
|
sleep_time -= lockstat_nsecs(&m->lock_object);
|
|
#endif
|
|
#ifndef ADAPTIVE_MUTEXES
|
|
owner = mtx_owner(m);
|
|
#endif
|
|
MPASS(owner == mtx_owner(m));
|
|
turnstile_wait(ts, owner, TS_EXCLUSIVE_QUEUE);
|
|
#ifdef KDTRACE_HOOKS
|
|
sleep_time += lockstat_nsecs(&m->lock_object);
|
|
sleep_cnt++;
|
|
#endif
|
|
v = MTX_READ_VALUE(m);
|
|
}
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
if (__predict_true(!doing_lockprof))
|
|
return;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
all_time += lockstat_nsecs(&m->lock_object);
|
|
if (sleep_time)
|
|
LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
|
|
|
|
/*
|
|
* Only record the loops spinning and not sleeping.
|
|
*/
|
|
if (lda.spin_cnt > sleep_cnt)
|
|
LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
|
|
out_lockstat:
|
|
#endif
|
|
LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
|
|
waittime, file, line);
|
|
}
|
|
|
|
#ifdef SMP
|
|
/*
|
|
* _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
|
|
*
|
|
* This is only called if we need to actually spin for the lock. Recursion
|
|
* is handled inline.
|
|
*/
|
|
#if LOCK_DEBUG > 0
|
|
void
|
|
_mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v, int opts,
|
|
const char *file, int line)
|
|
#else
|
|
void
|
|
_mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t v)
|
|
#endif
|
|
{
|
|
struct mtx *m;
|
|
struct lock_delay_arg lda;
|
|
uintptr_t tid;
|
|
#ifdef LOCK_PROFILING
|
|
int contested = 0;
|
|
uint64_t waittime = 0;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
int64_t spin_time = 0;
|
|
#endif
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
int doing_lockprof = 0;
|
|
#endif
|
|
|
|
tid = (uintptr_t)curthread;
|
|
m = mtxlock2mtx(c);
|
|
|
|
#ifdef KDTRACE_HOOKS
|
|
if (LOCKSTAT_PROFILE_ENABLED(adaptive__acquire)) {
|
|
while (v == MTX_UNOWNED) {
|
|
if (_mtx_obtain_lock_fetch(m, &v, tid))
|
|
goto out_lockstat;
|
|
}
|
|
doing_lockprof = 1;
|
|
spin_time -= lockstat_nsecs(&m->lock_object);
|
|
}
|
|
#endif
|
|
#ifdef LOCK_PROFILING
|
|
doing_lockprof = 1;
|
|
#endif
|
|
|
|
if (__predict_false(v == MTX_UNOWNED))
|
|
v = MTX_READ_VALUE(m);
|
|
|
|
if (__predict_false(v == tid)) {
|
|
m->mtx_recurse++;
|
|
return;
|
|
}
|
|
|
|
if (SCHEDULER_STOPPED())
|
|
return;
|
|
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
|
|
KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
|
|
"spinning", "lockname:\"%s\"", m->lock_object.lo_name);
|
|
|
|
lock_delay_arg_init(&lda, &mtx_spin_delay);
|
|
|
|
#ifdef HWPMC_HOOKS
|
|
PMC_SOFT_CALL( , , lock, failed);
|
|
#endif
|
|
lock_profile_obtain_lock_failed(&m->lock_object, true, &contested, &waittime);
|
|
|
|
for (;;) {
|
|
if (v == MTX_UNOWNED) {
|
|
if (_mtx_obtain_lock_fetch(m, &v, tid))
|
|
break;
|
|
continue;
|
|
}
|
|
/* Give interrupts a chance while we spin. */
|
|
spinlock_exit();
|
|
do {
|
|
if (__predict_true(lda.spin_cnt < 10000000)) {
|
|
lock_delay(&lda);
|
|
} else {
|
|
_mtx_lock_indefinite_check(m, &lda);
|
|
}
|
|
v = MTX_READ_VALUE(m);
|
|
} while (v != MTX_UNOWNED);
|
|
spinlock_enter();
|
|
}
|
|
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
|
|
KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
|
|
"running");
|
|
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
if (__predict_true(!doing_lockprof))
|
|
return;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
spin_time += lockstat_nsecs(&m->lock_object);
|
|
if (lda.spin_cnt != 0)
|
|
LOCKSTAT_RECORD1(spin__spin, m, spin_time);
|
|
out_lockstat:
|
|
#endif
|
|
LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire, m,
|
|
contested, waittime, file, line);
|
|
}
|
|
#endif /* SMP */
|
|
|
|
#ifdef INVARIANTS
|
|
static void
|
|
thread_lock_validate(struct mtx *m, int opts, const char *file, int line)
|
|
{
|
|
|
|
KASSERT(m->mtx_lock != MTX_DESTROYED,
|
|
("thread_lock() of destroyed mutex @ %s:%d", file, line));
|
|
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
|
|
("thread_lock() of sleep mutex %s @ %s:%d",
|
|
m->lock_object.lo_name, file, line));
|
|
KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) == 0,
|
|
("thread_lock: got a recursive mutex %s @ %s:%d\n",
|
|
m->lock_object.lo_name, file, line));
|
|
WITNESS_CHECKORDER(&m->lock_object,
|
|
opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
|
|
}
|
|
#else
|
|
#define thread_lock_validate(m, opts, file, line) do { } while (0)
|
|
#endif
|
|
|
|
#ifndef LOCK_PROFILING
|
|
#if LOCK_DEBUG > 0
|
|
void
|
|
_thread_lock(struct thread *td, int opts, const char *file, int line)
|
|
#else
|
|
void
|
|
_thread_lock(struct thread *td)
|
|
#endif
|
|
{
|
|
struct mtx *m;
|
|
uintptr_t tid;
|
|
|
|
tid = (uintptr_t)curthread;
|
|
|
|
if (__predict_false(LOCKSTAT_PROFILE_ENABLED(spin__acquire)))
|
|
goto slowpath_noirq;
|
|
spinlock_enter();
|
|
m = td->td_lock;
|
|
thread_lock_validate(m, 0, file, line);
|
|
if (__predict_false(m == &blocked_lock))
|
|
goto slowpath_unlocked;
|
|
if (__predict_false(!_mtx_obtain_lock(m, tid)))
|
|
goto slowpath_unlocked;
|
|
if (__predict_true(m == td->td_lock)) {
|
|
WITNESS_LOCK(&m->lock_object, LOP_EXCLUSIVE, file, line);
|
|
return;
|
|
}
|
|
_mtx_release_lock_quick(m);
|
|
slowpath_unlocked:
|
|
spinlock_exit();
|
|
slowpath_noirq:
|
|
#if LOCK_DEBUG > 0
|
|
thread_lock_flags_(td, opts, file, line);
|
|
#else
|
|
thread_lock_flags_(td, 0, 0, 0);
|
|
#endif
|
|
}
|
|
#endif
|
|
|
|
void
|
|
thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
|
|
{
|
|
struct mtx *m;
|
|
uintptr_t tid, v;
|
|
struct lock_delay_arg lda;
|
|
#ifdef LOCK_PROFILING
|
|
int contested = 0;
|
|
uint64_t waittime = 0;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
int64_t spin_time = 0;
|
|
#endif
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
int doing_lockprof = 1;
|
|
#endif
|
|
|
|
tid = (uintptr_t)curthread;
|
|
|
|
if (SCHEDULER_STOPPED()) {
|
|
/*
|
|
* Ensure that spinlock sections are balanced even when the
|
|
* scheduler is stopped, since we may otherwise inadvertently
|
|
* re-enable interrupts while dumping core.
|
|
*/
|
|
spinlock_enter();
|
|
return;
|
|
}
|
|
|
|
lock_delay_arg_init(&lda, &mtx_spin_delay);
|
|
|
|
#ifdef HWPMC_HOOKS
|
|
PMC_SOFT_CALL( , , lock, failed);
|
|
#endif
|
|
|
|
#ifdef LOCK_PROFILING
|
|
doing_lockprof = 1;
|
|
#elif defined(KDTRACE_HOOKS)
|
|
doing_lockprof = lockstat_enabled;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
if (__predict_false(doing_lockprof))
|
|
spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
|
|
#endif
|
|
spinlock_enter();
|
|
|
|
for (;;) {
|
|
retry:
|
|
m = td->td_lock;
|
|
thread_lock_validate(m, opts, file, line);
|
|
v = MTX_READ_VALUE(m);
|
|
for (;;) {
|
|
if (v == MTX_UNOWNED) {
|
|
if (_mtx_obtain_lock_fetch(m, &v, tid))
|
|
break;
|
|
continue;
|
|
}
|
|
MPASS(v != tid);
|
|
lock_profile_obtain_lock_failed(&m->lock_object, true,
|
|
&contested, &waittime);
|
|
/* Give interrupts a chance while we spin. */
|
|
spinlock_exit();
|
|
do {
|
|
if (__predict_true(lda.spin_cnt < 10000000)) {
|
|
lock_delay(&lda);
|
|
} else {
|
|
_mtx_lock_indefinite_check(m, &lda);
|
|
}
|
|
if (m != td->td_lock) {
|
|
spinlock_enter();
|
|
goto retry;
|
|
}
|
|
v = MTX_READ_VALUE(m);
|
|
} while (v != MTX_UNOWNED);
|
|
spinlock_enter();
|
|
}
|
|
if (m == td->td_lock)
|
|
break;
|
|
_mtx_release_lock_quick(m);
|
|
}
|
|
LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
|
|
line);
|
|
WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
|
|
|
|
#if defined(KDTRACE_HOOKS) || defined(LOCK_PROFILING)
|
|
if (__predict_true(!doing_lockprof))
|
|
return;
|
|
#endif
|
|
#ifdef KDTRACE_HOOKS
|
|
spin_time += lockstat_nsecs(&m->lock_object);
|
|
#endif
|
|
LOCKSTAT_PROFILE_OBTAIN_SPIN_LOCK_SUCCESS(spin__acquire, m, contested,
|
|
waittime, file, line);
|
|
#ifdef KDTRACE_HOOKS
|
|
if (lda.spin_cnt != 0)
|
|
LOCKSTAT_RECORD1(thread__spin, m, spin_time);
|
|
#endif
|
|
}
|
|
|
|
struct mtx *
|
|
thread_lock_block(struct thread *td)
|
|
{
|
|
struct mtx *lock;
|
|
|
|
lock = td->td_lock;
|
|
mtx_assert(lock, MA_OWNED);
|
|
td->td_lock = &blocked_lock;
|
|
|
|
return (lock);
|
|
}
|
|
|
|
void
|
|
thread_lock_unblock(struct thread *td, struct mtx *new)
|
|
{
|
|
|
|
mtx_assert(new, MA_OWNED);
|
|
KASSERT(td->td_lock == &blocked_lock,
|
|
("thread %p lock %p not blocked_lock %p",
|
|
td, td->td_lock, &blocked_lock));
|
|
atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
|
|
}
|
|
|
|
void
|
|
thread_lock_block_wait(struct thread *td)
|
|
{
|
|
|
|
while (td->td_lock == &blocked_lock)
|
|
cpu_spinwait();
|
|
|
|
/* Acquire fence to be certain that all thread state is visible. */
|
|
atomic_thread_fence_acq();
|
|
}
|
|
|
|
void
|
|
thread_lock_set(struct thread *td, struct mtx *new)
|
|
{
|
|
struct mtx *lock;
|
|
|
|
mtx_assert(new, MA_OWNED);
|
|
lock = td->td_lock;
|
|
mtx_assert(lock, MA_OWNED);
|
|
td->td_lock = new;
|
|
mtx_unlock_spin(lock);
|
|
}
|
|
|
|
/*
|
|
* __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
|
|
*
|
|
* We are only called here if the lock is recursed, contested (i.e. we
|
|
* need to wake up a blocked thread) or lockstat probe is active.
|
|
*/
|
|
#if LOCK_DEBUG > 0
|
|
void
|
|
__mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v, int opts,
|
|
const char *file, int line)
|
|
#else
|
|
void
|
|
__mtx_unlock_sleep(volatile uintptr_t *c, uintptr_t v)
|
|
#endif
|
|
{
|
|
struct mtx *m;
|
|
struct turnstile *ts;
|
|
uintptr_t tid;
|
|
|
|
if (SCHEDULER_STOPPED())
|
|
return;
|
|
|
|
tid = (uintptr_t)curthread;
|
|
m = mtxlock2mtx(c);
|
|
|
|
if (__predict_false(v == tid))
|
|
v = MTX_READ_VALUE(m);
|
|
|
|
if (__predict_false(v & MTX_RECURSED)) {
|
|
if (--(m->mtx_recurse) == 0)
|
|
atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
|
|
return;
|
|
}
|
|
|
|
LOCKSTAT_PROFILE_RELEASE_LOCK(adaptive__release, m);
|
|
if (v == tid && _mtx_release_lock(m, tid))
|
|
return;
|
|
|
|
/*
|
|
* We have to lock the chain before the turnstile so this turnstile
|
|
* can be removed from the hash list if it is empty.
|
|
*/
|
|
turnstile_chain_lock(&m->lock_object);
|
|
_mtx_release_lock_quick(m);
|
|
ts = turnstile_lookup(&m->lock_object);
|
|
MPASS(ts != NULL);
|
|
if (LOCK_LOG_TEST(&m->lock_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
|
|
turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
|
|
|
|
/*
|
|
* This turnstile is now no longer associated with the mutex. We can
|
|
* unlock the chain lock so a new turnstile may take it's place.
|
|
*/
|
|
turnstile_unpend(ts);
|
|
turnstile_chain_unlock(&m->lock_object);
|
|
}
|
|
|
|
/*
|
|
* All the unlocking of MTX_SPIN locks is done inline.
|
|
* See the __mtx_unlock_spin() macro for the details.
|
|
*/
|
|
|
|
/*
|
|
* The backing function for the INVARIANTS-enabled mtx_assert()
|
|
*/
|
|
#ifdef INVARIANT_SUPPORT
|
|
void
|
|
__mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
|
|
{
|
|
const struct mtx *m;
|
|
|
|
if (KERNEL_PANICKED() || dumping || SCHEDULER_STOPPED())
|
|
return;
|
|
|
|
m = mtxlock2mtx(c);
|
|
|
|
switch (what) {
|
|
case MA_OWNED:
|
|
case MA_OWNED | MA_RECURSED:
|
|
case MA_OWNED | MA_NOTRECURSED:
|
|
if (!mtx_owned(m))
|
|
panic("mutex %s not owned at %s:%d",
|
|
m->lock_object.lo_name, file, line);
|
|
if (mtx_recursed(m)) {
|
|
if ((what & MA_NOTRECURSED) != 0)
|
|
panic("mutex %s recursed at %s:%d",
|
|
m->lock_object.lo_name, file, line);
|
|
} else if ((what & MA_RECURSED) != 0) {
|
|
panic("mutex %s unrecursed at %s:%d",
|
|
m->lock_object.lo_name, file, line);
|
|
}
|
|
break;
|
|
case MA_NOTOWNED:
|
|
if (mtx_owned(m))
|
|
panic("mutex %s owned at %s:%d",
|
|
m->lock_object.lo_name, file, line);
|
|
break;
|
|
default:
|
|
panic("unknown mtx_assert at %s:%d", file, line);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* General init routine used by the MTX_SYSINIT() macro.
|
|
*/
|
|
void
|
|
mtx_sysinit(void *arg)
|
|
{
|
|
struct mtx_args *margs = arg;
|
|
|
|
mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
|
|
margs->ma_opts);
|
|
}
|
|
|
|
/*
|
|
* Mutex initialization routine; initialize lock `m' of type contained in
|
|
* `opts' with options contained in `opts' and name `name.' The optional
|
|
* lock type `type' is used as a general lock category name for use with
|
|
* witness.
|
|
*/
|
|
void
|
|
_mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
|
|
{
|
|
struct mtx *m;
|
|
struct lock_class *class;
|
|
int flags;
|
|
|
|
m = mtxlock2mtx(c);
|
|
|
|
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
|
|
MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
|
|
ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
|
|
("%s: mtx_lock not aligned for %s: %p", __func__, name,
|
|
&m->mtx_lock));
|
|
|
|
/* Determine lock class and lock flags. */
|
|
if (opts & MTX_SPIN)
|
|
class = &lock_class_mtx_spin;
|
|
else
|
|
class = &lock_class_mtx_sleep;
|
|
flags = 0;
|
|
if (opts & MTX_QUIET)
|
|
flags |= LO_QUIET;
|
|
if (opts & MTX_RECURSE)
|
|
flags |= LO_RECURSABLE;
|
|
if ((opts & MTX_NOWITNESS) == 0)
|
|
flags |= LO_WITNESS;
|
|
if (opts & MTX_DUPOK)
|
|
flags |= LO_DUPOK;
|
|
if (opts & MTX_NOPROFILE)
|
|
flags |= LO_NOPROFILE;
|
|
if (opts & MTX_NEW)
|
|
flags |= LO_NEW;
|
|
|
|
/* Initialize mutex. */
|
|
lock_init(&m->lock_object, class, name, type, flags);
|
|
|
|
m->mtx_lock = MTX_UNOWNED;
|
|
m->mtx_recurse = 0;
|
|
}
|
|
|
|
/*
|
|
* Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
|
|
* passed in as a flag here because if the corresponding mtx_init() was
|
|
* called with MTX_QUIET set, then it will already be set in the mutex's
|
|
* flags.
|
|
*/
|
|
void
|
|
_mtx_destroy(volatile uintptr_t *c)
|
|
{
|
|
struct mtx *m;
|
|
|
|
m = mtxlock2mtx(c);
|
|
|
|
if (!mtx_owned(m))
|
|
MPASS(mtx_unowned(m));
|
|
else {
|
|
MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
|
|
|
|
/* Perform the non-mtx related part of mtx_unlock_spin(). */
|
|
if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) {
|
|
lock_profile_release_lock(&m->lock_object, true);
|
|
spinlock_exit();
|
|
} else {
|
|
TD_LOCKS_DEC(curthread);
|
|
lock_profile_release_lock(&m->lock_object, false);
|
|
}
|
|
|
|
/* Tell witness this isn't locked to make it happy. */
|
|
WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
|
|
__LINE__);
|
|
}
|
|
|
|
m->mtx_lock = MTX_DESTROYED;
|
|
lock_destroy(&m->lock_object);
|
|
}
|
|
|
|
/*
|
|
* Intialize the mutex code and system mutexes. This is called from the MD
|
|
* startup code prior to mi_startup(). The per-CPU data space needs to be
|
|
* setup before this is called.
|
|
*/
|
|
void
|
|
mutex_init(void)
|
|
{
|
|
|
|
/* Setup turnstiles so that sleep mutexes work. */
|
|
init_turnstiles();
|
|
|
|
/*
|
|
* Initialize mutexes.
|
|
*/
|
|
mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
|
|
mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
|
|
blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
|
|
mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
|
|
mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
|
|
mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
|
|
mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
|
|
mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
|
|
mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
|
|
mtx_lock(&Giant);
|
|
}
|
|
|
|
static void __noinline
|
|
_mtx_lock_indefinite_check(struct mtx *m, struct lock_delay_arg *ldap)
|
|
{
|
|
struct thread *td;
|
|
|
|
ldap->spin_cnt++;
|
|
if (ldap->spin_cnt < 60000000 || kdb_active || KERNEL_PANICKED())
|
|
cpu_lock_delay();
|
|
else {
|
|
td = mtx_owner(m);
|
|
|
|
/* If the mutex is unlocked, try again. */
|
|
if (td == NULL)
|
|
return;
|
|
|
|
printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
|
|
m, m->lock_object.lo_name, td, td->td_tid);
|
|
#ifdef WITNESS
|
|
witness_display_spinlock(&m->lock_object, td, printf);
|
|
#endif
|
|
panic("spin lock held too long");
|
|
}
|
|
cpu_spinwait();
|
|
}
|
|
|
|
void
|
|
mtx_spin_wait_unlocked(struct mtx *m)
|
|
{
|
|
struct lock_delay_arg lda;
|
|
|
|
KASSERT(m->mtx_lock != MTX_DESTROYED,
|
|
("%s() of destroyed mutex %p", __func__, m));
|
|
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
|
|
("%s() of sleep mutex %p (%s)", __func__, m,
|
|
m->lock_object.lo_name));
|
|
KASSERT(!mtx_owned(m), ("%s() waiting on myself on lock %p (%s)", __func__, m,
|
|
m->lock_object.lo_name));
|
|
|
|
lda.spin_cnt = 0;
|
|
|
|
while (atomic_load_acq_ptr(&m->mtx_lock) != MTX_UNOWNED) {
|
|
if (__predict_true(lda.spin_cnt < 10000000)) {
|
|
cpu_spinwait();
|
|
lda.spin_cnt++;
|
|
} else {
|
|
_mtx_lock_indefinite_check(m, &lda);
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
mtx_wait_unlocked(struct mtx *m)
|
|
{
|
|
struct thread *owner;
|
|
uintptr_t v;
|
|
|
|
KASSERT(m->mtx_lock != MTX_DESTROYED,
|
|
("%s() of destroyed mutex %p", __func__, m));
|
|
KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
|
|
("%s() not a sleep mutex %p (%s)", __func__, m,
|
|
m->lock_object.lo_name));
|
|
KASSERT(!mtx_owned(m), ("%s() waiting on myself on lock %p (%s)", __func__, m,
|
|
m->lock_object.lo_name));
|
|
|
|
for (;;) {
|
|
v = atomic_load_acq_ptr(&m->mtx_lock);
|
|
if (v == MTX_UNOWNED) {
|
|
break;
|
|
}
|
|
owner = lv_mtx_owner(v);
|
|
if (!TD_IS_RUNNING(owner)) {
|
|
mtx_lock(m);
|
|
mtx_unlock(m);
|
|
break;
|
|
}
|
|
cpu_spinwait();
|
|
}
|
|
}
|
|
|
|
#ifdef DDB
|
|
void
|
|
db_show_mtx(const struct lock_object *lock)
|
|
{
|
|
struct thread *td;
|
|
const struct mtx *m;
|
|
|
|
m = (const struct mtx *)lock;
|
|
|
|
db_printf(" flags: {");
|
|
if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
|
|
db_printf("SPIN");
|
|
else
|
|
db_printf("DEF");
|
|
if (m->lock_object.lo_flags & LO_RECURSABLE)
|
|
db_printf(", RECURSE");
|
|
if (m->lock_object.lo_flags & LO_DUPOK)
|
|
db_printf(", DUPOK");
|
|
db_printf("}\n");
|
|
db_printf(" state: {");
|
|
if (mtx_unowned(m))
|
|
db_printf("UNOWNED");
|
|
else if (mtx_destroyed(m))
|
|
db_printf("DESTROYED");
|
|
else {
|
|
db_printf("OWNED");
|
|
if (m->mtx_lock & MTX_CONTESTED)
|
|
db_printf(", CONTESTED");
|
|
if (m->mtx_lock & MTX_RECURSED)
|
|
db_printf(", RECURSED");
|
|
}
|
|
db_printf("}\n");
|
|
if (!mtx_unowned(m) && !mtx_destroyed(m)) {
|
|
td = mtx_owner(m);
|
|
db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
|
|
td->td_tid, td->td_proc->p_pid, td->td_name);
|
|
if (mtx_recursed(m))
|
|
db_printf(" recursed: %d\n", m->mtx_recurse);
|
|
}
|
|
}
|
|
#endif
|