0d975d6341
sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
1021 lines
27 KiB
C
1021 lines
27 KiB
C
/*-
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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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* $FreeBSD$
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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 "opt_adaptive_mutexes.h"
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#include "opt_ddb.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/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/sbuf.h>
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#include <sys/stdint.h>
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#include <sys/sysctl.h>
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#include <sys/vmmeter.h>
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#include <machine/atomic.h>
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#include <machine/bus.h>
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#include <machine/clock.h>
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#include <machine/cpu.h>
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#include <ddb/ddb.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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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_owner(m) (mtx_unowned((m)) ? NULL \
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: (struct thread *)((m)->mtx_lock & MTX_FLAGMASK))
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/* XXXKSE This test will change. */
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#define thread_running(td) \
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((td)->td_kse != NULL && (td)->td_kse->ke_oncpu != NOCPU)
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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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"sleep mutex",
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LC_SLEEPLOCK | LC_RECURSABLE
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};
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struct lock_class lock_class_mtx_spin = {
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"spin mutex",
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LC_SPINLOCK | LC_RECURSABLE
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};
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/*
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* System-wide mutexes
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*/
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struct mtx sched_lock;
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struct mtx Giant;
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/*
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* Prototypes for non-exported routines.
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*/
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static void propagate_priority(struct thread *);
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static void
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propagate_priority(struct thread *td)
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{
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int pri = td->td_priority;
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struct mtx *m = td->td_blocked;
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mtx_assert(&sched_lock, MA_OWNED);
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for (;;) {
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struct thread *td1;
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td = mtx_owner(m);
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if (td == NULL) {
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/*
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* This really isn't quite right. Really
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* ought to bump priority of thread that
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* next acquires the mutex.
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*/
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MPASS(m->mtx_lock == MTX_CONTESTED);
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return;
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}
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KASSERT(td->td_state != TDS_SURPLUS, ("Mutex owner SURPLUS"));
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MPASS(td->td_proc != NULL);
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MPASS(td->td_proc->p_magic == P_MAGIC);
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KASSERT(td->td_state != TDS_SLP,
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("sleeping thread owns a mutex"));
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if (td->td_priority <= pri) /* lower is higher priority */
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return;
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/*
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* If lock holder is actually running, just bump priority.
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*/
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if (td->td_state == TDS_RUNNING) {
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td->td_priority = pri;
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return;
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}
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#ifndef SMP
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/*
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* For UP, we check to see if td is curthread (this shouldn't
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* ever happen however as it would mean we are in a deadlock.)
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*/
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KASSERT(td != curthread, ("Deadlock detected"));
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#endif
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/*
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* If on run queue move to new run queue, and quit.
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* XXXKSE this gets a lot more complicated under threads
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* but try anyhow.
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* We should have a special call to do this more efficiently.
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*/
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if (td->td_state == TDS_RUNQ) {
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MPASS(td->td_blocked == NULL);
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remrunqueue(td);
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td->td_priority = pri;
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setrunqueue(td);
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return;
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}
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/*
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* Adjust for any other cases.
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*/
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td->td_priority = pri;
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/*
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* If we aren't blocked on a mutex, we should be.
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*/
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KASSERT(td->td_state == TDS_MTX, (
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"process %d(%s):%d holds %s but isn't blocked on a mutex\n",
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td->td_proc->p_pid, td->td_proc->p_comm, td->td_state,
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m->mtx_object.lo_name));
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/*
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* Pick up the mutex that td is blocked on.
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*/
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m = td->td_blocked;
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MPASS(m != NULL);
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/*
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* Check if the thread needs to be moved up on
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* the blocked chain
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*/
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if (td == TAILQ_FIRST(&m->mtx_blocked)) {
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continue;
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}
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td1 = TAILQ_PREV(td, threadqueue, td_blkq);
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if (td1->td_priority <= pri) {
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continue;
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}
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/*
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* Remove thread from blocked chain and determine where
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* it should be moved up to. Since we know that td1 has
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* a lower priority than td, we know that at least one
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* thread in the chain has a lower priority and that
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* td1 will thus not be NULL after the loop.
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*/
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TAILQ_REMOVE(&m->mtx_blocked, td, td_blkq);
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TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) {
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MPASS(td1->td_proc->p_magic == P_MAGIC);
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if (td1->td_priority > pri)
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break;
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}
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MPASS(td1 != NULL);
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TAILQ_INSERT_BEFORE(td1, td, td_blkq);
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CTR4(KTR_LOCK,
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"propagate_priority: p %p moved before %p on [%p] %s",
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td, td1, m, m->mtx_object.lo_name);
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}
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}
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#ifdef MUTEX_PROFILING
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SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging");
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SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling");
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static int mutex_prof_enable = 0;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW,
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&mutex_prof_enable, 0, "Enable tracing of mutex holdtime");
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struct mutex_prof {
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const char *name;
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const char *file;
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int line;
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#define MPROF_MAX 0
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#define MPROF_TOT 1
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#define MPROF_CNT 2
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#define MPROF_AVG 3
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uintmax_t counter[4];
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struct mutex_prof *next;
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};
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/*
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* mprof_buf is a static pool of profiling records to avoid possible
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* reentrance of the memory allocation functions.
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*
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* Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE.
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*/
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#define NUM_MPROF_BUFFERS 1000
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static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS];
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static int first_free_mprof_buf;
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#define MPROF_HASH_SIZE 1009
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static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE];
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static int mutex_prof_acquisitions;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD,
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&mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded");
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static int mutex_prof_records;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD,
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&mutex_prof_records, 0, "Number of profiling records");
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static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD,
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&mutex_prof_maxrecords, 0, "Maximum number of profiling records");
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static int mutex_prof_rejected;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD,
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&mutex_prof_rejected, 0, "Number of rejected profiling records");
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static int mutex_prof_hashsize = MPROF_HASH_SIZE;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD,
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&mutex_prof_hashsize, 0, "Hash size");
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static int mutex_prof_collisions = 0;
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SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD,
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&mutex_prof_collisions, 0, "Number of hash collisions");
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/*
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* mprof_mtx protects the profiling buffers and the hash.
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*/
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static struct mtx mprof_mtx;
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MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET);
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static u_int64_t
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nanoseconds(void)
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{
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struct timespec tv;
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nanotime(&tv);
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return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec);
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}
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static int
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dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
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{
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struct sbuf *sb;
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int error, i;
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if (first_free_mprof_buf == 0)
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return SYSCTL_OUT(req, "No locking recorded",
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sizeof("No locking recorded"));
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sb = sbuf_new(NULL, NULL, 1024, SBUF_AUTOEXTEND);
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sbuf_printf(sb, "%12s %12s %12s %12s %s\n",
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"max", "total", "count", "average", "name");
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mtx_lock_spin(&mprof_mtx);
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for (i = 0; i < first_free_mprof_buf; ++i)
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sbuf_printf(sb, "%12ju %12ju %12ju %12ju %s:%d (%s)\n",
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mprof_buf[i].counter[MPROF_MAX] / 1000,
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mprof_buf[i].counter[MPROF_TOT] / 1000,
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mprof_buf[i].counter[MPROF_CNT],
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mprof_buf[i].counter[MPROF_AVG] / 1000,
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mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name);
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mtx_unlock_spin(&mprof_mtx);
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sbuf_finish(sb);
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error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
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sbuf_delete(sb);
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return (error);
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}
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SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING|CTLFLAG_RD,
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NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics");
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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(struct mtx *m, int opts, const char *file, int line)
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{
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MPASS(curthread != NULL);
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KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
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("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
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file, line));
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_get_sleep_lock(m, curthread, opts, file, line);
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LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
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line);
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WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
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#ifdef MUTEX_PROFILING
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/* don't reset the timer when/if recursing */
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if (m->mtx_acqtime == 0) {
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m->mtx_filename = file;
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m->mtx_lineno = line;
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m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0;
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++mutex_prof_acquisitions;
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}
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#endif
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}
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void
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_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
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{
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MPASS(curthread != NULL);
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KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
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("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
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file, line));
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WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
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LOCK_LOG_LOCK("UNLOCK", &m->mtx_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 MUTEX_PROFILING
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if (m->mtx_acqtime != 0) {
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static const char *unknown = "(unknown)";
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struct mutex_prof *mpp;
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u_int64_t acqtime, now;
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const char *p, *q;
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volatile u_int hash;
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now = nanoseconds();
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acqtime = m->mtx_acqtime;
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m->mtx_acqtime = 0;
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if (now <= acqtime)
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goto out;
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for (p = m->mtx_filename; strncmp(p, "../", 3) == 0; p += 3)
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/* nothing */ ;
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if (p == NULL || *p == '\0')
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p = unknown;
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for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q)
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hash = (hash * 2 + *q) % MPROF_HASH_SIZE;
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mtx_lock_spin(&mprof_mtx);
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for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next)
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if (mpp->line == m->mtx_lineno &&
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strcmp(mpp->file, p) == 0)
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break;
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if (mpp == NULL) {
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/* Just exit if we cannot get a trace buffer */
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if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) {
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++mutex_prof_rejected;
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goto unlock;
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}
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mpp = &mprof_buf[first_free_mprof_buf++];
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mpp->name = mtx_name(m);
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mpp->file = p;
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mpp->line = m->mtx_lineno;
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mpp->next = mprof_hash[hash];
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if (mprof_hash[hash] != NULL)
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++mutex_prof_collisions;
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mprof_hash[hash] = mpp;
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++mutex_prof_records;
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}
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/*
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* Record if the mutex has been held longer now than ever
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* before
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*/
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if ((now - acqtime) > mpp->counter[MPROF_MAX])
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mpp->counter[MPROF_MAX] = now - acqtime;
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mpp->counter[MPROF_TOT] += now - acqtime;
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mpp->counter[MPROF_CNT] += 1;
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mpp->counter[MPROF_AVG] =
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mpp->counter[MPROF_TOT] / mpp->counter[MPROF_CNT];
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unlock:
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mtx_unlock_spin(&mprof_mtx);
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}
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out:
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#endif
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_rel_sleep_lock(m, curthread, opts, file, line);
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}
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void
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_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
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{
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MPASS(curthread != NULL);
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KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
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("mtx_lock_spin() of sleep mutex %s @ %s:%d",
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m->mtx_object.lo_name, file, line));
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#if defined(SMP) || LOCK_DEBUG > 0 || 1
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_get_spin_lock(m, curthread, opts, file, line);
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#else
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critical_enter();
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#endif
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LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
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line);
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WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
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}
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void
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_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
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{
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MPASS(curthread != NULL);
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KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
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("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
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m->mtx_object.lo_name, file, line));
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WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
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LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
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line);
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mtx_assert(m, MA_OWNED);
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#if defined(SMP) || LOCK_DEBUG > 0 || 1
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_rel_spin_lock(m);
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#else
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critical_exit();
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#endif
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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.' We do NOT handle recursion here; we assume that
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* if we're called, it's because we know we don't already own this lock.
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*/
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int
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_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
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{
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int rval;
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MPASS(curthread != NULL);
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rval = _obtain_lock(m, curthread);
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LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
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if (rval) {
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/*
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* We do not handle recursion in _mtx_trylock; see the
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* note at the top of the routine.
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*/
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KASSERT(!mtx_recursed(m),
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("mtx_trylock() called on a recursed mutex"));
|
|
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
|
|
file, line);
|
|
}
|
|
|
|
return (rval);
|
|
}
|
|
|
|
/*
|
|
* _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.
|
|
*/
|
|
void
|
|
_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
|
|
{
|
|
struct thread *td = curthread;
|
|
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
|
|
struct thread *owner;
|
|
#endif
|
|
#ifdef KTR
|
|
int cont_logged = 0;
|
|
#endif
|
|
|
|
if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)td) {
|
|
m->mtx_recurse++;
|
|
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
|
|
return;
|
|
}
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR4(KTR_LOCK,
|
|
"_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
|
|
m->mtx_object.lo_name, (void *)m->mtx_lock, file, line);
|
|
|
|
while (!_obtain_lock(m, td)) {
|
|
uintptr_t v;
|
|
struct thread *td1;
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
/*
|
|
* Check if the lock has been released while spinning for
|
|
* the sched_lock.
|
|
*/
|
|
if ((v = m->mtx_lock) == MTX_UNOWNED) {
|
|
mtx_unlock_spin(&sched_lock);
|
|
#ifdef __i386__
|
|
ia32_pause();
|
|
#endif
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* The mutex was marked contested on release. This means that
|
|
* there are threads blocked on it.
|
|
*/
|
|
if (v == MTX_CONTESTED) {
|
|
td1 = TAILQ_FIRST(&m->mtx_blocked);
|
|
MPASS(td1 != NULL);
|
|
m->mtx_lock = (uintptr_t)td | MTX_CONTESTED;
|
|
|
|
if (td1->td_priority < td->td_priority)
|
|
td->td_priority = td1->td_priority;
|
|
mtx_unlock_spin(&sched_lock);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* 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_cmpset_ptr(&m->mtx_lock, (void *)v,
|
|
(void *)(v | MTX_CONTESTED))) {
|
|
mtx_unlock_spin(&sched_lock);
|
|
#ifdef __i386__
|
|
ia32_pause();
|
|
#endif
|
|
continue;
|
|
}
|
|
|
|
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
|
|
/*
|
|
* If the current owner of the lock is executing on another
|
|
* CPU, spin instead of blocking.
|
|
*/
|
|
owner = (struct thread *)(v & MTX_FLAGMASK);
|
|
if (m != &Giant && thread_running(owner)) {
|
|
mtx_unlock_spin(&sched_lock);
|
|
while (mtx_owner(m) == owner && thread_running(owner)) {
|
|
#ifdef __i386__
|
|
ia32_pause();
|
|
#endif
|
|
}
|
|
continue;
|
|
}
|
|
#endif /* SMP && ADAPTIVE_MUTEXES */
|
|
|
|
/*
|
|
* We definitely must sleep for this lock.
|
|
*/
|
|
mtx_assert(m, MA_NOTOWNED);
|
|
|
|
#ifdef notyet
|
|
/*
|
|
* If we're borrowing an interrupted thread's VM context, we
|
|
* must clean up before going to sleep.
|
|
*/
|
|
if (td->td_ithd != NULL) {
|
|
struct ithd *it = td->td_ithd;
|
|
|
|
if (it->it_interrupted) {
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR2(KTR_LOCK,
|
|
"_mtx_lock_sleep: %p interrupted %p",
|
|
it, it->it_interrupted);
|
|
intr_thd_fixup(it);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Put us on the list of threads blocked on this mutex.
|
|
*/
|
|
if (TAILQ_EMPTY(&m->mtx_blocked)) {
|
|
td1 = mtx_owner(m);
|
|
LIST_INSERT_HEAD(&td1->td_contested, m, mtx_contested);
|
|
TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq);
|
|
} else {
|
|
TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq)
|
|
if (td1->td_priority > td->td_priority)
|
|
break;
|
|
if (td1)
|
|
TAILQ_INSERT_BEFORE(td1, td, td_blkq);
|
|
else
|
|
TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq);
|
|
}
|
|
#ifdef KTR
|
|
if (!cont_logged) {
|
|
CTR6(KTR_CONTENTION,
|
|
"contention: %p at %s:%d wants %s, taken by %s:%d",
|
|
td, file, line, m->mtx_object.lo_name,
|
|
WITNESS_FILE(&m->mtx_object),
|
|
WITNESS_LINE(&m->mtx_object));
|
|
cont_logged = 1;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Save who we're blocked on.
|
|
*/
|
|
td->td_blocked = m;
|
|
td->td_mtxname = m->mtx_object.lo_name;
|
|
td->td_state = TDS_MTX;
|
|
propagate_priority(td);
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR3(KTR_LOCK,
|
|
"_mtx_lock_sleep: p %p blocked on [%p] %s", td, m,
|
|
m->mtx_object.lo_name);
|
|
|
|
td->td_proc->p_stats->p_ru.ru_nvcsw++;
|
|
mi_switch();
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR3(KTR_LOCK,
|
|
"_mtx_lock_sleep: p %p free from blocked on [%p] %s",
|
|
td, m, m->mtx_object.lo_name);
|
|
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
#ifdef KTR
|
|
if (cont_logged) {
|
|
CTR4(KTR_CONTENTION,
|
|
"contention end: %s acquired by %p at %s:%d",
|
|
m->mtx_object.lo_name, td, file, line);
|
|
}
|
|
#endif
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* _mtx_lock_spin: 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.
|
|
*/
|
|
void
|
|
_mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
|
|
{
|
|
int i = 0;
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
|
|
|
|
for (;;) {
|
|
if (_obtain_lock(m, curthread))
|
|
break;
|
|
|
|
/* Give interrupts a chance while we spin. */
|
|
critical_exit();
|
|
while (m->mtx_lock != MTX_UNOWNED) {
|
|
if (i++ < 10000000) {
|
|
#ifdef __i386__
|
|
ia32_pause();
|
|
#endif
|
|
continue;
|
|
}
|
|
if (i < 60000000)
|
|
DELAY(1);
|
|
#ifdef DDB
|
|
else if (!db_active)
|
|
#else
|
|
else
|
|
#endif
|
|
panic("spin lock %s held by %p for > 5 seconds",
|
|
m->mtx_object.lo_name, (void *)m->mtx_lock);
|
|
#ifdef __i386__
|
|
ia32_pause();
|
|
#endif
|
|
}
|
|
critical_enter();
|
|
}
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
|
|
*
|
|
* We are only called here if the lock is recursed or contested (i.e. we
|
|
* need to wake up a blocked thread).
|
|
*/
|
|
void
|
|
_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
|
|
{
|
|
struct thread *td, *td1;
|
|
struct mtx *m1;
|
|
int pri;
|
|
|
|
td = curthread;
|
|
|
|
if (mtx_recursed(m)) {
|
|
if (--(m->mtx_recurse) == 0)
|
|
atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
|
|
return;
|
|
}
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
|
|
|
|
td1 = TAILQ_FIRST(&m->mtx_blocked);
|
|
#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
|
|
if (td1 == NULL) {
|
|
_release_lock_quick(m);
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
|
|
mtx_unlock_spin(&sched_lock);
|
|
return;
|
|
}
|
|
#endif
|
|
MPASS(td->td_proc->p_magic == P_MAGIC);
|
|
MPASS(td1->td_proc->p_magic == P_MAGIC);
|
|
|
|
TAILQ_REMOVE(&m->mtx_blocked, td1, td_blkq);
|
|
|
|
if (TAILQ_EMPTY(&m->mtx_blocked)) {
|
|
LIST_REMOVE(m, mtx_contested);
|
|
_release_lock_quick(m);
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
|
|
} else
|
|
atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED);
|
|
|
|
pri = PRI_MAX;
|
|
LIST_FOREACH(m1, &td->td_contested, mtx_contested) {
|
|
int cp = TAILQ_FIRST(&m1->mtx_blocked)->td_priority;
|
|
if (cp < pri)
|
|
pri = cp;
|
|
}
|
|
|
|
if (pri > td->td_base_pri)
|
|
pri = td->td_base_pri;
|
|
td->td_priority = pri;
|
|
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p",
|
|
m, td1);
|
|
|
|
td1->td_blocked = NULL;
|
|
setrunqueue(td1);
|
|
|
|
if (td->td_critnest == 1 && td1->td_priority < pri) {
|
|
#ifdef notyet
|
|
if (td->td_ithd != NULL) {
|
|
struct ithd *it = td->td_ithd;
|
|
|
|
if (it->it_interrupted) {
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR2(KTR_LOCK,
|
|
"_mtx_unlock_sleep: %p interrupted %p",
|
|
it, it->it_interrupted);
|
|
intr_thd_fixup(it);
|
|
}
|
|
}
|
|
#endif
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR2(KTR_LOCK,
|
|
"_mtx_unlock_sleep: %p switching out lock=%p", m,
|
|
(void *)m->mtx_lock);
|
|
|
|
td->td_proc->p_stats->p_ru.ru_nivcsw++;
|
|
mi_switch();
|
|
if (LOCK_LOG_TEST(&m->mtx_object, opts))
|
|
CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
|
|
m, (void *)m->mtx_lock);
|
|
}
|
|
|
|
mtx_unlock_spin(&sched_lock);
|
|
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* All the unlocking of MTX_SPIN locks is done inline.
|
|
* See the _rel_spin_lock() macro for the details.
|
|
*/
|
|
|
|
/*
|
|
* The backing function for the INVARIANTS-enabled mtx_assert()
|
|
*/
|
|
#ifdef INVARIANT_SUPPORT
|
|
void
|
|
_mtx_assert(struct mtx *m, int what, const char *file, int line)
|
|
{
|
|
|
|
if (panicstr != NULL)
|
|
return;
|
|
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->mtx_object.lo_name, file, line);
|
|
if (mtx_recursed(m)) {
|
|
if ((what & MA_NOTRECURSED) != 0)
|
|
panic("mutex %s recursed at %s:%d",
|
|
m->mtx_object.lo_name, file, line);
|
|
} else if ((what & MA_RECURSED) != 0) {
|
|
panic("mutex %s unrecursed at %s:%d",
|
|
m->mtx_object.lo_name, file, line);
|
|
}
|
|
break;
|
|
case MA_NOTOWNED:
|
|
if (mtx_owned(m))
|
|
panic("mutex %s owned at %s:%d",
|
|
m->mtx_object.lo_name, file, line);
|
|
break;
|
|
default:
|
|
panic("unknown mtx_assert at %s:%d", file, line);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* The MUTEX_DEBUG-enabled mtx_validate()
|
|
*
|
|
* Most of these checks have been moved off into the LO_INITIALIZED flag
|
|
* maintained by the witness code.
|
|
*/
|
|
#ifdef MUTEX_DEBUG
|
|
|
|
void mtx_validate(struct mtx *);
|
|
|
|
void
|
|
mtx_validate(struct mtx *m)
|
|
{
|
|
|
|
/*
|
|
* XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly
|
|
* we can re-enable the kernacc() checks.
|
|
*/
|
|
#ifndef __alpha__
|
|
/*
|
|
* Can't call kernacc() from early init386(), especially when
|
|
* initializing Giant mutex, because some stuff in kernacc()
|
|
* requires Giant itself.
|
|
*/
|
|
if (!cold)
|
|
if (!kernacc((caddr_t)m, sizeof(m),
|
|
VM_PROT_READ | VM_PROT_WRITE))
|
|
panic("Can't read and write to mutex %p", m);
|
|
#endif
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* General init routine used by the MTX_SYSINIT() macro.
|
|
*/
|
|
void
|
|
mtx_sysinit(void *arg)
|
|
{
|
|
struct mtx_args *margs = arg;
|
|
|
|
mtx_init(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(struct mtx *m, const char *name, const char *type, int opts)
|
|
{
|
|
struct lock_object *lock;
|
|
|
|
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
|
|
MTX_SLEEPABLE | MTX_NOWITNESS | MTX_DUPOK)) == 0);
|
|
|
|
#ifdef MUTEX_DEBUG
|
|
/* Diagnostic and error correction */
|
|
mtx_validate(m);
|
|
#endif
|
|
|
|
lock = &m->mtx_object;
|
|
KASSERT((lock->lo_flags & LO_INITIALIZED) == 0,
|
|
("mutex %s %p already initialized", name, m));
|
|
bzero(m, sizeof(*m));
|
|
if (opts & MTX_SPIN)
|
|
lock->lo_class = &lock_class_mtx_spin;
|
|
else
|
|
lock->lo_class = &lock_class_mtx_sleep;
|
|
lock->lo_name = name;
|
|
lock->lo_type = type != NULL ? type : name;
|
|
if (opts & MTX_QUIET)
|
|
lock->lo_flags = LO_QUIET;
|
|
if (opts & MTX_RECURSE)
|
|
lock->lo_flags |= LO_RECURSABLE;
|
|
if (opts & MTX_SLEEPABLE)
|
|
lock->lo_flags |= LO_SLEEPABLE;
|
|
if ((opts & MTX_NOWITNESS) == 0)
|
|
lock->lo_flags |= LO_WITNESS;
|
|
if (opts & MTX_DUPOK)
|
|
lock->lo_flags |= LO_DUPOK;
|
|
|
|
m->mtx_lock = MTX_UNOWNED;
|
|
TAILQ_INIT(&m->mtx_blocked);
|
|
|
|
LOCK_LOG_INIT(lock, opts);
|
|
|
|
WITNESS_INIT(lock);
|
|
}
|
|
|
|
/*
|
|
* 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(struct mtx *m)
|
|
{
|
|
|
|
LOCK_LOG_DESTROY(&m->mtx_object, 0);
|
|
|
|
if (!mtx_owned(m))
|
|
MPASS(mtx_unowned(m));
|
|
else {
|
|
MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
|
|
|
|
/* Tell witness this isn't locked to make it happy. */
|
|
WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__,
|
|
__LINE__);
|
|
}
|
|
|
|
WITNESS_DESTROY(&m->mtx_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 thread0 so that mutexes work. */
|
|
LIST_INIT(&thread0.td_contested);
|
|
|
|
/*
|
|
* Initialize mutexes.
|
|
*/
|
|
mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
|
|
mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
|
|
mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
|
|
mtx_lock(&Giant);
|
|
}
|
|
|
|
/*
|
|
* Encapsulated Giant mutex routines. These routines provide encapsulation
|
|
* control for the Giant mutex, allowing sysctls to be used to turn on and
|
|
* off Giant around certain subsystems. The default value for the sysctls
|
|
* are set to what developers believe is stable and working in regards to
|
|
* the Giant pushdown. Developers should not turn off Giant via these
|
|
* sysctls unless they know what they are doing.
|
|
*
|
|
* Callers of mtx_lock_giant() are expected to pass the return value to an
|
|
* accompanying mtx_unlock_giant() later on. If multiple subsystems are
|
|
* effected by a Giant wrap, all related sysctl variables must be zero for
|
|
* the subsystem call to operate without Giant (as determined by the caller).
|
|
*/
|
|
|
|
SYSCTL_NODE(_kern, OID_AUTO, giant, CTLFLAG_RD, NULL, "Giant mutex manipulation");
|
|
|
|
static int kern_giant_all = 0;
|
|
SYSCTL_INT(_kern_giant, OID_AUTO, all, CTLFLAG_RW, &kern_giant_all, 0, "");
|
|
|
|
int kern_giant_proc = 1; /* Giant around PROC locks */
|
|
int kern_giant_file = 1; /* Giant around struct file & filedesc */
|
|
int kern_giant_ucred = 1; /* Giant around ucred */
|
|
SYSCTL_INT(_kern_giant, OID_AUTO, proc, CTLFLAG_RW, &kern_giant_proc, 0, "");
|
|
SYSCTL_INT(_kern_giant, OID_AUTO, file, CTLFLAG_RW, &kern_giant_file, 0, "");
|
|
SYSCTL_INT(_kern_giant, OID_AUTO, ucred, CTLFLAG_RW, &kern_giant_ucred, 0, "");
|
|
|
|
int
|
|
mtx_lock_giant(int sysctlvar)
|
|
{
|
|
if (sysctlvar || kern_giant_all) {
|
|
mtx_lock(&Giant);
|
|
return(1);
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
void
|
|
mtx_unlock_giant(int s)
|
|
{
|
|
if (s)
|
|
mtx_unlock(&Giant);
|
|
}
|
|
|