/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 2007 Stephan Uphoff <ups@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Machine independent bits of reader/writer lock implementation.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/kdb.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/rmlock.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/turnstile.h>
#include <sys/lock_profile.h>
#include <machine/cpu.h>
#ifdef DDB
#include <ddb/ddb.h>
#endif
/*
* A cookie to mark destroyed rmlocks. This is stored in the head of
* rm_activeReaders.
*/
#define RM_DESTROYED ((void *)0xdead)
#define rm_destroyed(rm) \
(LIST_FIRST(&(rm)->rm_activeReaders) == RM_DESTROYED)
#define RMPF_ONQUEUE 1
#define RMPF_SIGNAL 2
#ifndef INVARIANTS
#define _rm_assert(c, what, file, line)
#endif
static void assert_rm(const struct lock_object *lock, int what);
#ifdef DDB
static void db_show_rm(const struct lock_object *lock);
#endif
static void lock_rm(struct lock_object *lock, uintptr_t how);
#ifdef KDTRACE_HOOKS
static int owner_rm(const struct lock_object *lock, struct thread **owner);
#endif
static uintptr_t unlock_rm(struct lock_object *lock);
struct lock_class lock_class_rm = {
.lc_name = "rm",
.lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
.lc_assert = assert_rm,
#ifdef DDB
.lc_ddb_show = db_show_rm,
#endif
.lc_lock = lock_rm,
.lc_unlock = unlock_rm,
#ifdef KDTRACE_HOOKS
.lc_owner = owner_rm,
#endif
};
struct lock_class lock_class_rm_sleepable = {
.lc_name = "sleepable rm",
.lc_flags = LC_SLEEPLOCK | LC_SLEEPABLE | LC_RECURSABLE,
.lc_assert = assert_rm,
#ifdef DDB
.lc_ddb_show = db_show_rm,
#endif
.lc_lock = lock_rm,
.lc_unlock = unlock_rm,
#ifdef KDTRACE_HOOKS
.lc_owner = owner_rm,
#endif
};
static void
assert_rm(const struct lock_object *lock, int what)
{
rm_assert((const struct rmlock *)lock, what);
}
static void
lock_rm(struct lock_object *lock, uintptr_t how)
{
struct rmlock *rm;
struct rm_priotracker *tracker;
rm = (struct rmlock *)lock;
if (how == 0)
rm_wlock(rm);
else {
tracker = (struct rm_priotracker *)how;
rm_rlock(rm, tracker);
}
}
static uintptr_t
unlock_rm(struct lock_object *lock)
{
struct thread *td;
struct pcpu *pc;
struct rmlock *rm;
struct rm_queue *queue;
struct rm_priotracker *tracker;
uintptr_t how;
rm = (struct rmlock *)lock;
tracker = NULL;
how = 0;
rm_assert(rm, RA_LOCKED | RA_NOTRECURSED);
if (rm_wowned(rm))
rm_wunlock(rm);
else {
/*
* Find the right rm_priotracker structure for curthread.
* The guarantee about its uniqueness is given by the fact
* we already asserted the lock wasn't recursively acquired.
*/
critical_enter();
td = curthread;
pc = get_pcpu();
for (queue = pc->pc_rm_queue.rmq_next;
queue != &pc->pc_rm_queue; queue = queue->rmq_next) {
tracker = (struct rm_priotracker *)queue;
if ((tracker->rmp_rmlock == rm) &&
(tracker->rmp_thread == td)) {
how = (uintptr_t)tracker;
break;
}
}
KASSERT(tracker != NULL,
("rm_priotracker is non-NULL when lock held in read mode"));
critical_exit();
rm_runlock(rm, tracker);
}
return (how);
}
#ifdef KDTRACE_HOOKS
static int
owner_rm(const struct lock_object *lock, struct thread **owner)
{
const struct rmlock *rm;
struct lock_class *lc;
rm = (const struct rmlock *)lock;
lc = LOCK_CLASS(&rm->rm_wlock_object);
return (lc->lc_owner(&rm->rm_wlock_object, owner));
}
#endif
static struct mtx rm_spinlock;
MTX_SYSINIT(rm_spinlock, &rm_spinlock, "rm_spinlock", MTX_SPIN);
/*
* Add or remove tracker from per-cpu list.
*
* The per-cpu list can be traversed at any time in forward direction from an
* interrupt on the *local* cpu.
*/
static void inline
rm_tracker_add(struct pcpu *pc, struct rm_priotracker *tracker)
{
struct rm_queue *next;
/* Initialize all tracker pointers */
tracker->rmp_cpuQueue.rmq_prev = &pc->pc_rm_queue;
next = pc->pc_rm_queue.rmq_next;
tracker->rmp_cpuQueue.rmq_next = next;
/* rmq_prev is not used during froward traversal. */
next->rmq_prev = &tracker->rmp_cpuQueue;
/* Update pointer to first element. */
pc->pc_rm_queue.rmq_next = &tracker->rmp_cpuQueue;
}
/*
* Return a count of the number of trackers the thread 'td' already
* has on this CPU for the lock 'rm'.
*/
static int
rm_trackers_present(const struct pcpu *pc, const struct rmlock *rm,
const struct thread *td)
{
struct rm_queue *queue;
struct rm_priotracker *tracker;
int count;
count = 0;
for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue;
queue = queue->rmq_next) {
tracker = (struct rm_priotracker *)queue;
if ((tracker->rmp_rmlock == rm) && (tracker->rmp_thread == td))
count++;
}
return (count);
}
static void inline
rm_tracker_remove(struct pcpu *pc, struct rm_priotracker *tracker)
{
struct rm_queue *next, *prev;
next = tracker->rmp_cpuQueue.rmq_next;
prev = tracker->rmp_cpuQueue.rmq_prev;
/* Not used during forward traversal. */
next->rmq_prev = prev;
/* Remove from list. */
prev->rmq_next = next;
}
static void
rm_cleanIPI(void *arg)
{
struct pcpu *pc;
struct rmlock *rm = arg;
struct rm_priotracker *tracker;
struct rm_queue *queue;
pc = get_pcpu();
for (queue = pc->pc_rm_queue.rmq_next; queue != &pc->pc_rm_queue;
queue = queue->rmq_next) {
tracker = (struct rm_priotracker *)queue;
if (tracker->rmp_rmlock == rm && tracker->rmp_flags == 0) {
tracker->rmp_flags = RMPF_ONQUEUE;
mtx_lock_spin(&rm_spinlock);
LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker,
rmp_qentry);
mtx_unlock_spin(&rm_spinlock);
}
}
}
void
rm_init_flags(struct rmlock *rm, const char *name, int opts)
{
struct lock_class *lc;
int liflags, xflags;
liflags = 0;
if (!(opts & RM_NOWITNESS))
liflags |= LO_WITNESS;
if (opts & RM_RECURSE)
liflags |= LO_RECURSABLE;
if (opts & RM_NEW)
liflags |= LO_NEW;
rm->rm_writecpus = all_cpus;
LIST_INIT(&rm->rm_activeReaders);
if (opts & RM_SLEEPABLE) {
liflags |= LO_SLEEPABLE;
lc = &lock_class_rm_sleepable;
xflags = (opts & RM_NEW ? SX_NEW : 0);
sx_init_flags(&rm->rm_lock_sx, "rmlock_sx",
xflags | SX_NOWITNESS);
} else {
lc = &lock_class_rm;
xflags = (opts & RM_NEW ? MTX_NEW : 0);
mtx_init(&rm->rm_lock_mtx, name, "rmlock_mtx",
xflags | MTX_NOWITNESS);
}
lock_init(&rm->lock_object, lc, name, NULL, liflags);
}
void
rm_init(struct rmlock *rm, const char *name)
{
rm_init_flags(rm, name, 0);
}
void
rm_destroy(struct rmlock *rm)
{
rm_assert(rm, RA_UNLOCKED);
LIST_FIRST(&rm->rm_activeReaders) = RM_DESTROYED;
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
sx_destroy(&rm->rm_lock_sx);
else
mtx_destroy(&rm->rm_lock_mtx);
lock_destroy(&rm->lock_object);
}
int
rm_wowned(const struct rmlock *rm)
{
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
return (sx_xlocked(&rm->rm_lock_sx));
else
return (mtx_owned(&rm->rm_lock_mtx));
}
void
rm_sysinit(void *arg)
{
struct rm_args *args;
args = arg;
rm_init_flags(args->ra_rm, args->ra_desc, args->ra_flags);
}
static __noinline int
_rm_rlock_hard(struct rmlock *rm, struct rm_priotracker *tracker, int trylock)
{
struct pcpu *pc;
critical_enter();
pc = get_pcpu();
/* Check if we just need to do a proper critical_exit. */
if (!CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus)) {
critical_exit();
return (1);
}
/* Remove our tracker from the per-cpu list. */
rm_tracker_remove(pc, tracker);
/*
* Check to see if the IPI granted us the lock after all. The load of
* rmp_flags must happen after the tracker is removed from the list.
*/
__compiler_membar();
if (tracker->rmp_flags) {
/* Just add back tracker - we hold the lock. */
rm_tracker_add(pc, tracker);
critical_exit();
return (1);
}
/*
* We allow readers to acquire a lock even if a writer is blocked if
* the lock is recursive and the reader already holds the lock.
*/
if ((rm->lock_object.lo_flags & LO_RECURSABLE) != 0) {
/*
* Just grant the lock if this thread already has a tracker
* for this lock on the per-cpu queue.
*/
if (rm_trackers_present(pc, rm, curthread) != 0) {
mtx_lock_spin(&rm_spinlock);
LIST_INSERT_HEAD(&rm->rm_activeReaders, tracker,
rmp_qentry);
tracker->rmp_flags = RMPF_ONQUEUE;
mtx_unlock_spin(&rm_spinlock);
rm_tracker_add(pc, tracker);
critical_exit();
return (1);
}
}
sched_unpin();
critical_exit();
if (trylock) {
if (rm->lock_object.lo_flags & LO_SLEEPABLE) {
if (!sx_try_xlock(&rm->rm_lock_sx))
return (0);
} else {
if (!mtx_trylock(&rm->rm_lock_mtx))
return (0);
}
} else {
if (rm->lock_object.lo_flags & LO_SLEEPABLE) {
THREAD_SLEEPING_OK();
sx_xlock(&rm->rm_lock_sx);
THREAD_NO_SLEEPING();
} else
mtx_lock(&rm->rm_lock_mtx);
}
critical_enter();
pc = get_pcpu();
CPU_CLR(pc->pc_cpuid, &rm->rm_writecpus);
rm_tracker_add(pc, tracker);
sched_pin();
critical_exit();
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
sx_xunlock(&rm->rm_lock_sx);
else
mtx_unlock(&rm->rm_lock_mtx);
return (1);
}
int
_rm_rlock(struct rmlock *rm, struct rm_priotracker *tracker, int trylock)
{
struct thread *td = curthread;
struct pcpu *pc;
if (SCHEDULER_STOPPED())
return (1);
tracker->rmp_flags = 0;
tracker->rmp_thread = td;
tracker->rmp_rmlock = rm;
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
THREAD_NO_SLEEPING();
td->td_critnest++; /* critical_enter(); */
__compiler_membar();
pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */
rm_tracker_add(pc, tracker);
sched_pin();
__compiler_membar();
td->td_critnest--;
/*
* Fast path to combine two common conditions into a single
* conditional jump.
*/
if (__predict_true(0 == (td->td_owepreempt |
CPU_ISSET(pc->pc_cpuid, &rm->rm_writecpus))))
return (1);
/* We do not have a read token and need to acquire one. */
return _rm_rlock_hard(rm, tracker, trylock);
}
static __noinline void
_rm_unlock_hard(struct thread *td,struct rm_priotracker *tracker)
{
if (td->td_owepreempt) {
td->td_critnest++;
critical_exit();
}
if (!tracker->rmp_flags)
return;
mtx_lock_spin(&rm_spinlock);
LIST_REMOVE(tracker, rmp_qentry);
if (tracker->rmp_flags & RMPF_SIGNAL) {
struct rmlock *rm;
struct turnstile *ts;
rm = tracker->rmp_rmlock;
turnstile_chain_lock(&rm->lock_object);
mtx_unlock_spin(&rm_spinlock);
ts = turnstile_lookup(&rm->lock_object);
turnstile_signal(ts, TS_EXCLUSIVE_QUEUE);
turnstile_unpend(ts);
turnstile_chain_unlock(&rm->lock_object);
} else
mtx_unlock_spin(&rm_spinlock);
}
void
_rm_runlock(struct rmlock *rm, struct rm_priotracker *tracker)
{
struct pcpu *pc;
struct thread *td = tracker->rmp_thread;
if (SCHEDULER_STOPPED())
return;
td->td_critnest++; /* critical_enter(); */
pc = cpuid_to_pcpu[td->td_oncpu]; /* pcpu_find(td->td_oncpu); */
rm_tracker_remove(pc, tracker);
td->td_critnest--;
sched_unpin();
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
THREAD_SLEEPING_OK();
if (__predict_true(0 == (td->td_owepreempt | tracker->rmp_flags)))
return;
_rm_unlock_hard(td, tracker);
}
void
_rm_wlock(struct rmlock *rm)
{
struct rm_priotracker *prio;
struct turnstile *ts;
cpuset_t readcpus;
if (SCHEDULER_STOPPED())
return;
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
sx_xlock(&rm->rm_lock_sx);
else
mtx_lock(&rm->rm_lock_mtx);
if (CPU_CMP(&rm->rm_writecpus, &all_cpus)) {
/* Get all read tokens back */
readcpus = all_cpus;
CPU_NAND(&readcpus, &rm->rm_writecpus);
rm->rm_writecpus = all_cpus;
/*
* Assumes rm->rm_writecpus update is visible on other CPUs
* before rm_cleanIPI is called.
*/
#ifdef SMP
smp_rendezvous_cpus(readcpus,
smp_no_rendezvous_barrier,
rm_cleanIPI,
smp_no_rendezvous_barrier,
rm);
#else
rm_cleanIPI(rm);
#endif
mtx_lock_spin(&rm_spinlock);
while ((prio = LIST_FIRST(&rm->rm_activeReaders)) != NULL) {
ts = turnstile_trywait(&rm->lock_object);
prio->rmp_flags = RMPF_ONQUEUE | RMPF_SIGNAL;
mtx_unlock_spin(&rm_spinlock);
turnstile_wait(ts, prio->rmp_thread,
TS_EXCLUSIVE_QUEUE);
mtx_lock_spin(&rm_spinlock);
}
mtx_unlock_spin(&rm_spinlock);
}
}
void
_rm_wunlock(struct rmlock *rm)
{
if (rm->lock_object.lo_flags & LO_SLEEPABLE)
sx_xunlock(&rm->rm_lock_sx);
else
mtx_unlock(&rm->rm_lock_mtx);
}
#if LOCK_DEBUG > 0
void
_rm_wlock_debug(struct rmlock *rm, const char *file, int line)
{
if (SCHEDULER_STOPPED())
return;
KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
("rm_wlock() by idle thread %p on rmlock %s @ %s:%d",
curthread, rm->lock_object.lo_name, file, line));
KASSERT(!rm_destroyed(rm),
("rm_wlock() of destroyed rmlock @ %s:%d", file, line));
_rm_assert(rm, RA_UNLOCKED, file, line);
WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER | LOP_EXCLUSIVE,
file, line, NULL);
_rm_wlock(rm);
LOCK_LOG_LOCK("RMWLOCK", &rm->lock_object, 0, 0, file, line);
WITNESS_LOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line);
TD_LOCKS_INC(curthread);
}
void
_rm_wunlock_debug(struct rmlock *rm, const char *file, int line)
{
if (SCHEDULER_STOPPED())
return;
KASSERT(!rm_destroyed(rm),
("rm_wunlock() of destroyed rmlock @ %s:%d", file, line));
_rm_assert(rm, RA_WLOCKED, file, line);
WITNESS_UNLOCK(&rm->lock_object, LOP_EXCLUSIVE, file, line);
LOCK_LOG_LOCK("RMWUNLOCK", &rm->lock_object, 0, 0, file, line);
_rm_wunlock(rm);
TD_LOCKS_DEC(curthread);
}
int
_rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
int trylock, const char *file, int line)
{
if (SCHEDULER_STOPPED())
return (1);
#ifdef INVARIANTS
if (!(rm->lock_object.lo_flags & LO_RECURSABLE) && !trylock) {
critical_enter();
KASSERT(rm_trackers_present(get_pcpu(), rm,
curthread) == 0,
("rm_rlock: recursed on non-recursive rmlock %s @ %s:%d\n",
rm->lock_object.lo_name, file, line));
critical_exit();
}
#endif
KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
("rm_rlock() by idle thread %p on rmlock %s @ %s:%d",
curthread, rm->lock_object.lo_name, file, line));
KASSERT(!rm_destroyed(rm),
("rm_rlock() of destroyed rmlock @ %s:%d", file, line));
if (!trylock) {
KASSERT(!rm_wowned(rm),
("rm_rlock: wlock already held for %s @ %s:%d",
rm->lock_object.lo_name, file, line));
WITNESS_CHECKORDER(&rm->lock_object, LOP_NEWORDER, file, line,
NULL);
}
if (_rm_rlock(rm, tracker, trylock)) {
if (trylock)
LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 1, file,
line);
else
LOCK_LOG_LOCK("RMRLOCK", &rm->lock_object, 0, 0, file,
line);
WITNESS_LOCK(&rm->lock_object, 0, file, line);
TD_LOCKS_INC(curthread);
return (1);
} else if (trylock)
LOCK_LOG_TRY("RMRLOCK", &rm->lock_object, 0, 0, file, line);
return (0);
}
void
_rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
const char *file, int line)
{
if (SCHEDULER_STOPPED())
return;
KASSERT(!rm_destroyed(rm),
("rm_runlock() of destroyed rmlock @ %s:%d", file, line));
_rm_assert(rm, RA_RLOCKED, file, line);
WITNESS_UNLOCK(&rm->lock_object, 0, file, line);
LOCK_LOG_LOCK("RMRUNLOCK", &rm->lock_object, 0, 0, file, line);
_rm_runlock(rm, tracker);
TD_LOCKS_DEC(curthread);
}
#else
/*
* Just strip out file and line arguments if no lock debugging is enabled in
* the kernel - we are called from a kernel module.
*/
void
_rm_wlock_debug(struct rmlock *rm, const char *file, int line)
{
_rm_wlock(rm);
}
void
_rm_wunlock_debug(struct rmlock *rm, const char *file, int line)
{
_rm_wunlock(rm);
}
int
_rm_rlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
int trylock, const char *file, int line)
{
return _rm_rlock(rm, tracker, trylock);
}
void
_rm_runlock_debug(struct rmlock *rm, struct rm_priotracker *tracker,
const char *file, int line)
{
_rm_runlock(rm, tracker);
}
#endif
#ifdef INVARIANT_SUPPORT
#ifndef INVARIANTS
#undef _rm_assert
#endif
/*
* Note that this does not need to use witness_assert() for read lock
* assertions since an exact count of read locks held by this thread
* is computable.
*/
void
_rm_assert(const struct rmlock *rm, int what, const char *file, int line)
{
int count;
if (SCHEDULER_STOPPED())
return;
switch (what) {
case RA_LOCKED:
case RA_LOCKED | RA_RECURSED:
case RA_LOCKED | RA_NOTRECURSED:
case RA_RLOCKED:
case RA_RLOCKED | RA_RECURSED:
case RA_RLOCKED | RA_NOTRECURSED:
/*
* Handle the write-locked case. Unlike other
* primitives, writers can never recurse.
*/
if (rm_wowned(rm)) {
if (what & RA_RLOCKED)
panic("Lock %s exclusively locked @ %s:%d\n",
rm->lock_object.lo_name, file, line);
if (what & RA_RECURSED)
panic("Lock %s not recursed @ %s:%d\n",
rm->lock_object.lo_name, file, line);
break;
}
critical_enter();
count = rm_trackers_present(get_pcpu(), rm, curthread);
critical_exit();
if (count == 0)
panic("Lock %s not %slocked @ %s:%d\n",
rm->lock_object.lo_name, (what & RA_RLOCKED) ?
"read " : "", file, line);
if (count > 1) {
if (what & RA_NOTRECURSED)
panic("Lock %s recursed @ %s:%d\n",
rm->lock_object.lo_name, file, line);
} else if (what & RA_RECURSED)
panic("Lock %s not recursed @ %s:%d\n",
rm->lock_object.lo_name, file, line);
break;
case RA_WLOCKED:
if (!rm_wowned(rm))
panic("Lock %s not exclusively locked @ %s:%d\n",
rm->lock_object.lo_name, file, line);
break;
case RA_UNLOCKED:
if (rm_wowned(rm))
panic("Lock %s exclusively locked @ %s:%d\n",
rm->lock_object.lo_name, file, line);
critical_enter();
count = rm_trackers_present(get_pcpu(), rm, curthread);
critical_exit();
if (count != 0)
panic("Lock %s read locked @ %s:%d\n",
rm->lock_object.lo_name, file, line);
break;
default:
panic("Unknown rm lock assertion: %d @ %s:%d", what, file,
line);
}
}
#endif /* INVARIANT_SUPPORT */
#ifdef DDB
static void
print_tracker(struct rm_priotracker *tr)
{
struct thread *td;
td = tr->rmp_thread;
db_printf(" thread %p (tid %d, pid %d, \"%s\") {", td, td->td_tid,
td->td_proc->p_pid, td->td_name);
if (tr->rmp_flags & RMPF_ONQUEUE) {
db_printf("ONQUEUE");
if (tr->rmp_flags & RMPF_SIGNAL)
db_printf(",SIGNAL");
} else
db_printf("0");
db_printf("}\n");
}
static void
db_show_rm(const struct lock_object *lock)
{
struct rm_priotracker *tr;
struct rm_queue *queue;
const struct rmlock *rm;
struct lock_class *lc;
struct pcpu *pc;
rm = (const struct rmlock *)lock;
db_printf(" writecpus: ");
ddb_display_cpuset(__DEQUALIFY(const cpuset_t *, &rm->rm_writecpus));
db_printf("\n");
db_printf(" per-CPU readers:\n");
STAILQ_FOREACH(pc, &cpuhead, pc_allcpu)
for (queue = pc->pc_rm_queue.rmq_next;
queue != &pc->pc_rm_queue; queue = queue->rmq_next) {
tr = (struct rm_priotracker *)queue;
if (tr->rmp_rmlock == rm)
print_tracker(tr);
}
db_printf(" active readers:\n");
LIST_FOREACH(tr, &rm->rm_activeReaders, rmp_qentry)
print_tracker(tr);
lc = LOCK_CLASS(&rm->rm_wlock_object);
db_printf("Backing write-lock (%s):\n", lc->lc_name);
lc->lc_ddb_show(&rm->rm_wlock_object);
}
#endif
