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freebsd-skq/sys/kern/kern_umtx.c
David Xu 326bf9493d 1) Check NULL pointer before calling umtx_pi_adjust_locked(), this avoids 
a PANIC.
2) Rework locking for POSIX priority-mutex, this fixes a
   race where a thread may wait there forever even if the mutex is unlocked.
2009-03-13 06:06:20 +00:00

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/*-
* Copyright (c) 2004, David Xu <davidxu@freebsd.org>
* Copyright (c) 2002, Jeffrey Roberson <jeff@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 unmodified, 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/smp.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/eventhandler.h>
#include <sys/umtx.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <machine/cpu.h>
#ifdef COMPAT_IA32
#include <compat/freebsd32/freebsd32_proto.h>
#endif
#define TYPE_SIMPLE_WAIT 0
#define TYPE_CV 1
#define TYPE_SIMPLE_LOCK 2
#define TYPE_NORMAL_UMUTEX 3
#define TYPE_PI_UMUTEX 4
#define TYPE_PP_UMUTEX 5
#define TYPE_RWLOCK 6
#define _UMUTEX_TRY 1
#define _UMUTEX_WAIT 2
/* Key to represent a unique userland synchronous object */
struct umtx_key {
int hash;
int type;
int shared;
union {
struct {
vm_object_t object;
uintptr_t offset;
} shared;
struct {
struct vmspace *vs;
uintptr_t addr;
} private;
struct {
void *a;
uintptr_t b;
} both;
} info;
};
/* Priority inheritance mutex info. */
struct umtx_pi {
/* Owner thread */
struct thread *pi_owner;
/* Reference count */
int pi_refcount;
/* List entry to link umtx holding by thread */
TAILQ_ENTRY(umtx_pi) pi_link;
/* List entry in hash */
TAILQ_ENTRY(umtx_pi) pi_hashlink;
/* List for waiters */
TAILQ_HEAD(,umtx_q) pi_blocked;
/* Identify a userland lock object */
struct umtx_key pi_key;
};
/* A userland synchronous object user. */
struct umtx_q {
/* Linked list for the hash. */
TAILQ_ENTRY(umtx_q) uq_link;
/* Umtx key. */
struct umtx_key uq_key;
/* Umtx flags. */
int uq_flags;
#define UQF_UMTXQ 0x0001
/* The thread waits on. */
struct thread *uq_thread;
/*
* Blocked on PI mutex. read can use chain lock
* or umtx_lock, write must have both chain lock and
* umtx_lock being hold.
*/
struct umtx_pi *uq_pi_blocked;
/* On blocked list */
TAILQ_ENTRY(umtx_q) uq_lockq;
/* Thread contending with us */
TAILQ_HEAD(,umtx_pi) uq_pi_contested;
/* Inherited priority from PP mutex */
u_char uq_inherited_pri;
};
TAILQ_HEAD(umtxq_head, umtx_q);
/* Userland lock object's wait-queue chain */
struct umtxq_chain {
/* Lock for this chain. */
struct mtx uc_lock;
/* List of sleep queues. */
struct umtxq_head uc_queue[2];
#define UMTX_SHARED_QUEUE 0
#define UMTX_EXCLUSIVE_QUEUE 1
/* Busy flag */
char uc_busy;
/* Chain lock waiters */
int uc_waiters;
/* All PI in the list */
TAILQ_HEAD(,umtx_pi) uc_pi_list;
};
#define UMTXQ_LOCKED_ASSERT(uc) mtx_assert(&(uc)->uc_lock, MA_OWNED)
#define UMTXQ_BUSY_ASSERT(uc) KASSERT(&(uc)->uc_busy, ("umtx chain is not busy"))
/*
* Don't propagate time-sharing priority, there is a security reason,
* a user can simply introduce PI-mutex, let thread A lock the mutex,
* and let another thread B block on the mutex, because B is
* sleeping, its priority will be boosted, this causes A's priority to
* be boosted via priority propagating too and will never be lowered even
* if it is using 100%CPU, this is unfair to other processes.
*/
#define UPRI(td) (((td)->td_user_pri >= PRI_MIN_TIMESHARE &&\
(td)->td_user_pri <= PRI_MAX_TIMESHARE) ?\
PRI_MAX_TIMESHARE : (td)->td_user_pri)
#define GOLDEN_RATIO_PRIME 2654404609U
#define UMTX_CHAINS 128
#define UMTX_SHIFTS (__WORD_BIT - 7)
#define THREAD_SHARE 0
#define PROCESS_SHARE 1
#define AUTO_SHARE 2
#define GET_SHARE(flags) \
(((flags) & USYNC_PROCESS_SHARED) == 0 ? THREAD_SHARE : PROCESS_SHARE)
#define BUSY_SPINS 200
static uma_zone_t umtx_pi_zone;
static struct umtxq_chain umtxq_chains[2][UMTX_CHAINS];
static MALLOC_DEFINE(M_UMTX, "umtx", "UMTX queue memory");
static int umtx_pi_allocated;
SYSCTL_NODE(_debug, OID_AUTO, umtx, CTLFLAG_RW, 0, "umtx debug");
SYSCTL_INT(_debug_umtx, OID_AUTO, umtx_pi_allocated, CTLFLAG_RD,
&umtx_pi_allocated, 0, "Allocated umtx_pi");
static void umtxq_sysinit(void *);
static void umtxq_hash(struct umtx_key *key);
static struct umtxq_chain *umtxq_getchain(struct umtx_key *key);
static void umtxq_lock(struct umtx_key *key);
static void umtxq_unlock(struct umtx_key *key);
static void umtxq_busy(struct umtx_key *key);
static void umtxq_unbusy(struct umtx_key *key);
static void umtxq_insert_queue(struct umtx_q *uq, int q);
static void umtxq_remove_queue(struct umtx_q *uq, int q);
static int umtxq_sleep(struct umtx_q *uq, const char *wmesg, int timo);
static int umtxq_count(struct umtx_key *key);
static int umtx_key_match(const struct umtx_key *k1, const struct umtx_key *k2);
static int umtx_key_get(void *addr, int type, int share,
struct umtx_key *key);
static void umtx_key_release(struct umtx_key *key);
static struct umtx_pi *umtx_pi_alloc(int);
static void umtx_pi_free(struct umtx_pi *pi);
static void umtx_pi_adjust_locked(struct thread *td, u_char oldpri);
static int do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags);
static void umtx_thread_cleanup(struct thread *td);
static void umtx_exec_hook(void *arg __unused, struct proc *p __unused,
struct image_params *imgp __unused);
SYSINIT(umtx, SI_SUB_EVENTHANDLER+1, SI_ORDER_MIDDLE, umtxq_sysinit, NULL);
#define umtxq_signal(key, nwake) umtxq_signal_queue((key), (nwake), UMTX_SHARED_QUEUE)
#define umtxq_insert(uq) umtxq_insert_queue((uq), UMTX_SHARED_QUEUE)
#define umtxq_remove(uq) umtxq_remove_queue((uq), UMTX_SHARED_QUEUE)
static struct mtx umtx_lock;
static void
umtxq_sysinit(void *arg __unused)
{
int i, j;
umtx_pi_zone = uma_zcreate("umtx pi", sizeof(struct umtx_pi),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
for (i = 0; i < 2; ++i) {
for (j = 0; j < UMTX_CHAINS; ++j) {
mtx_init(&umtxq_chains[i][j].uc_lock, "umtxql", NULL,
MTX_DEF | MTX_DUPOK);
TAILQ_INIT(&umtxq_chains[i][j].uc_queue[0]);
TAILQ_INIT(&umtxq_chains[i][j].uc_queue[1]);
TAILQ_INIT(&umtxq_chains[i][j].uc_pi_list);
umtxq_chains[i][j].uc_busy = 0;
umtxq_chains[i][j].uc_waiters = 0;
}
}
mtx_init(&umtx_lock, "umtx lock", NULL, MTX_SPIN);
EVENTHANDLER_REGISTER(process_exec, umtx_exec_hook, NULL,
EVENTHANDLER_PRI_ANY);
}
struct umtx_q *
umtxq_alloc(void)
{
struct umtx_q *uq;
uq = malloc(sizeof(struct umtx_q), M_UMTX, M_WAITOK | M_ZERO);
TAILQ_INIT(&uq->uq_pi_contested);
uq->uq_inherited_pri = PRI_MAX;
return (uq);
}
void
umtxq_free(struct umtx_q *uq)
{
free(uq, M_UMTX);
}
static inline void
umtxq_hash(struct umtx_key *key)
{
unsigned n = (uintptr_t)key->info.both.a + key->info.both.b;
key->hash = ((n * GOLDEN_RATIO_PRIME) >> UMTX_SHIFTS) % UMTX_CHAINS;
}
static inline int
umtx_key_match(const struct umtx_key *k1, const struct umtx_key *k2)
{
return (k1->type == k2->type &&
k1->info.both.a == k2->info.both.a &&
k1->info.both.b == k2->info.both.b);
}
static inline struct umtxq_chain *
umtxq_getchain(struct umtx_key *key)
{
if (key->type <= TYPE_CV)
return (&umtxq_chains[1][key->hash]);
return (&umtxq_chains[0][key->hash]);
}
/*
* Lock a chain.
*/
static inline void
umtxq_lock(struct umtx_key *key)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(key);
mtx_lock(&uc->uc_lock);
}
/*
* Unlock a chain.
*/
static inline void
umtxq_unlock(struct umtx_key *key)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(key);
mtx_unlock(&uc->uc_lock);
}
/*
* Set chain to busy state when following operation
* may be blocked (kernel mutex can not be used).
*/
static inline void
umtxq_busy(struct umtx_key *key)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(key);
mtx_assert(&uc->uc_lock, MA_OWNED);
if (uc->uc_busy) {
#ifdef SMP
if (smp_cpus > 1) {
int count = BUSY_SPINS;
if (count > 0) {
umtxq_unlock(key);
while (uc->uc_busy && --count > 0)
cpu_spinwait();
umtxq_lock(key);
}
}
#endif
while (uc->uc_busy) {
uc->uc_waiters++;
msleep(uc, &uc->uc_lock, 0, "umtxqb", 0);
uc->uc_waiters--;
}
}
uc->uc_busy = 1;
}
/*
* Unbusy a chain.
*/
static inline void
umtxq_unbusy(struct umtx_key *key)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(key);
mtx_assert(&uc->uc_lock, MA_OWNED);
KASSERT(uc->uc_busy != 0, ("not busy"));
uc->uc_busy = 0;
if (uc->uc_waiters)
wakeup_one(uc);
}
static inline void
umtxq_insert_queue(struct umtx_q *uq, int q)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&uq->uq_key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_INSERT_TAIL(&uc->uc_queue[q], uq, uq_link);
uq->uq_flags |= UQF_UMTXQ;
}
static inline void
umtxq_remove_queue(struct umtx_q *uq, int q)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&uq->uq_key);
UMTXQ_LOCKED_ASSERT(uc);
if (uq->uq_flags & UQF_UMTXQ) {
TAILQ_REMOVE(&uc->uc_queue[q], uq, uq_link);
uq->uq_flags &= ~UQF_UMTXQ;
}
}
/*
* Check if there are multiple waiters
*/
static int
umtxq_count(struct umtx_key *key)
{
struct umtxq_chain *uc;
struct umtx_q *uq;
int count = 0;
uc = umtxq_getchain(key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_FOREACH(uq, &uc->uc_queue[UMTX_SHARED_QUEUE], uq_link) {
if (umtx_key_match(&uq->uq_key, key)) {
if (++count > 1)
break;
}
}
return (count);
}
/*
* Check if there are multiple PI waiters and returns first
* waiter.
*/
static int
umtxq_count_pi(struct umtx_key *key, struct umtx_q **first)
{
struct umtxq_chain *uc;
struct umtx_q *uq;
int count = 0;
*first = NULL;
uc = umtxq_getchain(key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_FOREACH(uq, &uc->uc_queue[UMTX_SHARED_QUEUE], uq_link) {
if (umtx_key_match(&uq->uq_key, key)) {
if (++count > 1)
break;
*first = uq;
}
}
return (count);
}
/*
* Wake up threads waiting on an userland object.
*/
static int
umtxq_signal_queue(struct umtx_key *key, int n_wake, int q)
{
struct umtxq_chain *uc;
struct umtx_q *uq, *next;
int ret;
ret = 0;
uc = umtxq_getchain(key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_FOREACH_SAFE(uq, &uc->uc_queue[q], uq_link, next) {
if (umtx_key_match(&uq->uq_key, key)) {
umtxq_remove_queue(uq, q);
wakeup(uq);
if (++ret >= n_wake)
break;
}
}
return (ret);
}
/*
* Wake up specified thread.
*/
static inline void
umtxq_signal_thread(struct umtx_q *uq)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&uq->uq_key);
UMTXQ_LOCKED_ASSERT(uc);
umtxq_remove(uq);
wakeup(uq);
}
/*
* Put thread into sleep state, before sleeping, check if
* thread was removed from umtx queue.
*/
static inline int
umtxq_sleep(struct umtx_q *uq, const char *wmesg, int timo)
{
struct umtxq_chain *uc;
int error;
uc = umtxq_getchain(&uq->uq_key);
UMTXQ_LOCKED_ASSERT(uc);
if (!(uq->uq_flags & UQF_UMTXQ))
return (0);
error = msleep(uq, &uc->uc_lock, PCATCH, wmesg, timo);
if (error == EWOULDBLOCK)
error = ETIMEDOUT;
return (error);
}
/*
* Convert userspace address into unique logical address.
*/
static int
umtx_key_get(void *addr, int type, int share, struct umtx_key *key)
{
struct thread *td = curthread;
vm_map_t map;
vm_map_entry_t entry;
vm_pindex_t pindex;
vm_prot_t prot;
boolean_t wired;
key->type = type;
if (share == THREAD_SHARE) {
key->shared = 0;
key->info.private.vs = td->td_proc->p_vmspace;
key->info.private.addr = (uintptr_t)addr;
} else {
MPASS(share == PROCESS_SHARE || share == AUTO_SHARE);
map = &td->td_proc->p_vmspace->vm_map;
if (vm_map_lookup(&map, (vm_offset_t)addr, VM_PROT_WRITE,
&entry, &key->info.shared.object, &pindex, &prot,
&wired) != KERN_SUCCESS) {
return EFAULT;
}
if ((share == PROCESS_SHARE) ||
(share == AUTO_SHARE &&
VM_INHERIT_SHARE == entry->inheritance)) {
key->shared = 1;
key->info.shared.offset = entry->offset + entry->start -
(vm_offset_t)addr;
vm_object_reference(key->info.shared.object);
} else {
key->shared = 0;
key->info.private.vs = td->td_proc->p_vmspace;
key->info.private.addr = (uintptr_t)addr;
}
vm_map_lookup_done(map, entry);
}
umtxq_hash(key);
return (0);
}
/*
* Release key.
*/
static inline void
umtx_key_release(struct umtx_key *key)
{
if (key->shared)
vm_object_deallocate(key->info.shared.object);
}
/*
* Lock a umtx object.
*/
static int
_do_lock_umtx(struct thread *td, struct umtx *umtx, u_long id, int timo)
{
struct umtx_q *uq;
u_long owner;
u_long old;
int error = 0;
uq = td->td_umtxq;
/*
* Care must be exercised when dealing with umtx structure. It
* can fault on any access.
*/
for (;;) {
/*
* Try the uncontested case. This should be done in userland.
*/
owner = casuword(&umtx->u_owner, UMTX_UNOWNED, id);
/* The acquire succeeded. */
if (owner == UMTX_UNOWNED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If no one owns it but it is contested try to acquire it. */
if (owner == UMTX_CONTESTED) {
owner = casuword(&umtx->u_owner,
UMTX_CONTESTED, id | UMTX_CONTESTED);
if (owner == UMTX_CONTESTED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If this failed the lock has changed, restart. */
continue;
}
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
return (error);
if ((error = umtx_key_get(umtx, TYPE_SIMPLE_LOCK,
AUTO_SHARE, &uq->uq_key)) != 0)
return (error);
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_insert(uq);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
/*
* Set the contested bit so that a release in user space
* knows to use the system call for unlock. If this fails
* either some one else has acquired the lock or it has been
* released.
*/
old = casuword(&umtx->u_owner, owner, owner | UMTX_CONTESTED);
/* The address was invalid. */
if (old == -1) {
umtxq_lock(&uq->uq_key);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (EFAULT);
}
/*
* We set the contested bit, sleep. Otherwise the lock changed
* and we need to retry or we lost a race to the thread
* unlocking the umtx.
*/
umtxq_lock(&uq->uq_key);
if (old == owner)
error = umtxq_sleep(uq, "umtx", timo);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
}
return (0);
}
/*
* Lock a umtx object.
*/
static int
do_lock_umtx(struct thread *td, struct umtx *umtx, u_long id,
struct timespec *timeout)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
int error;
if (timeout == NULL) {
error = _do_lock_umtx(td, umtx, id, 0);
/* Mutex locking is restarted if it is interrupted. */
if (error == EINTR)
error = ERESTART;
} else {
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = _do_lock_umtx(td, umtx, id, tvtohz(&tv));
if (error != ETIMEDOUT)
break;
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
/* Timed-locking is not restarted. */
if (error == ERESTART)
error = EINTR;
}
return (error);
}
/*
* Unlock a umtx object.
*/
static int
do_unlock_umtx(struct thread *td, struct umtx *umtx, u_long id)
{
struct umtx_key key;
u_long owner;
u_long old;
int error;
int count;
/*
* Make sure we own this mtx.
*/
owner = fuword(__DEVOLATILE(u_long *, &umtx->u_owner));
if (owner == -1)
return (EFAULT);
if ((owner & ~UMTX_CONTESTED) != id)
return (EPERM);
/* This should be done in userland */
if ((owner & UMTX_CONTESTED) == 0) {
old = casuword(&umtx->u_owner, owner, UMTX_UNOWNED);
if (old == -1)
return (EFAULT);
if (old == owner)
return (0);
owner = old;
}
/* We should only ever be in here for contested locks */
if ((error = umtx_key_get(umtx, TYPE_SIMPLE_LOCK, AUTO_SHARE,
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
count = umtxq_count(&key);
umtxq_unlock(&key);
/*
* When unlocking the umtx, it must be marked as unowned if
* there is zero or one thread only waiting for it.
* Otherwise, it must be marked as contested.
*/
old = casuword(&umtx->u_owner, owner,
count <= 1 ? UMTX_UNOWNED : UMTX_CONTESTED);
umtxq_lock(&key);
umtxq_signal(&key,1);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
if (old == -1)
return (EFAULT);
if (old != owner)
return (EINVAL);
return (0);
}
#ifdef COMPAT_IA32
/*
* Lock a umtx object.
*/
static int
_do_lock_umtx32(struct thread *td, uint32_t *m, uint32_t id, int timo)
{
struct umtx_q *uq;
uint32_t owner;
uint32_t old;
int error = 0;
uq = td->td_umtxq;
/*
* Care must be exercised when dealing with umtx structure. It
* can fault on any access.
*/
for (;;) {
/*
* Try the uncontested case. This should be done in userland.
*/
owner = casuword32(m, UMUTEX_UNOWNED, id);
/* The acquire succeeded. */
if (owner == UMUTEX_UNOWNED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If no one owns it but it is contested try to acquire it. */
if (owner == UMUTEX_CONTESTED) {
owner = casuword32(m,
UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
if (owner == UMUTEX_CONTESTED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If this failed the lock has changed, restart. */
continue;
}
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
return (error);
if ((error = umtx_key_get(m, TYPE_SIMPLE_LOCK,
AUTO_SHARE, &uq->uq_key)) != 0)
return (error);
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_insert(uq);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
/*
* Set the contested bit so that a release in user space
* knows to use the system call for unlock. If this fails
* either some one else has acquired the lock or it has been
* released.
*/
old = casuword32(m, owner, owner | UMUTEX_CONTESTED);
/* The address was invalid. */
if (old == -1) {
umtxq_lock(&uq->uq_key);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (EFAULT);
}
/*
* We set the contested bit, sleep. Otherwise the lock changed
* and we need to retry or we lost a race to the thread
* unlocking the umtx.
*/
umtxq_lock(&uq->uq_key);
if (old == owner)
error = umtxq_sleep(uq, "umtx", timo);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
}
return (0);
}
/*
* Lock a umtx object.
*/
static int
do_lock_umtx32(struct thread *td, void *m, uint32_t id,
struct timespec *timeout)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
int error;
if (timeout == NULL) {
error = _do_lock_umtx32(td, m, id, 0);
/* Mutex locking is restarted if it is interrupted. */
if (error == EINTR)
error = ERESTART;
} else {
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = _do_lock_umtx32(td, m, id, tvtohz(&tv));
if (error != ETIMEDOUT)
break;
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
/* Timed-locking is not restarted. */
if (error == ERESTART)
error = EINTR;
}
return (error);
}
/*
* Unlock a umtx object.
*/
static int
do_unlock_umtx32(struct thread *td, uint32_t *m, uint32_t id)
{
struct umtx_key key;
uint32_t owner;
uint32_t old;
int error;
int count;
/*
* Make sure we own this mtx.
*/
owner = fuword32(m);
if (owner == -1)
return (EFAULT);
if ((owner & ~UMUTEX_CONTESTED) != id)
return (EPERM);
/* This should be done in userland */
if ((owner & UMUTEX_CONTESTED) == 0) {
old = casuword32(m, owner, UMUTEX_UNOWNED);
if (old == -1)
return (EFAULT);
if (old == owner)
return (0);
owner = old;
}
/* We should only ever be in here for contested locks */
if ((error = umtx_key_get(m, TYPE_SIMPLE_LOCK, AUTO_SHARE,
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
count = umtxq_count(&key);
umtxq_unlock(&key);
/*
* When unlocking the umtx, it must be marked as unowned if
* there is zero or one thread only waiting for it.
* Otherwise, it must be marked as contested.
*/
old = casuword32(m, owner,
count <= 1 ? UMUTEX_UNOWNED : UMUTEX_CONTESTED);
umtxq_lock(&key);
umtxq_signal(&key,1);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
if (old == -1)
return (EFAULT);
if (old != owner)
return (EINVAL);
return (0);
}
#endif
/*
* Fetch and compare value, sleep on the address if value is not changed.
*/
static int
do_wait(struct thread *td, void *addr, u_long id,
struct timespec *timeout, int compat32, int is_private)
{
struct umtx_q *uq;
struct timespec ts, ts2, ts3;
struct timeval tv;
u_long tmp;
int error = 0;
uq = td->td_umtxq;
if ((error = umtx_key_get(addr, TYPE_SIMPLE_WAIT,
is_private ? THREAD_SHARE : AUTO_SHARE, &uq->uq_key)) != 0)
return (error);
umtxq_lock(&uq->uq_key);
umtxq_insert(uq);
umtxq_unlock(&uq->uq_key);
if (compat32 == 0)
tmp = fuword(addr);
else
tmp = fuword32(addr);
if (tmp != id) {
umtxq_lock(&uq->uq_key);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
} else if (timeout == NULL) {
umtxq_lock(&uq->uq_key);
error = umtxq_sleep(uq, "uwait", 0);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
} else {
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
umtxq_lock(&uq->uq_key);
for (;;) {
error = umtxq_sleep(uq, "uwait", tvtohz(&tv));
if (!(uq->uq_flags & UQF_UMTXQ))
break;
if (error != ETIMEDOUT)
break;
umtxq_unlock(&uq->uq_key);
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
umtxq_lock(&uq->uq_key);
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
umtxq_lock(&uq->uq_key);
}
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
}
umtx_key_release(&uq->uq_key);
if (error == ERESTART)
error = EINTR;
return (error);
}
/*
* Wake up threads sleeping on the specified address.
*/
int
kern_umtx_wake(struct thread *td, void *uaddr, int n_wake, int is_private)
{
struct umtx_key key;
int ret;
if ((ret = umtx_key_get(uaddr, TYPE_SIMPLE_WAIT,
is_private ? THREAD_SHARE : AUTO_SHARE, &key)) != 0)
return (ret);
umtxq_lock(&key);
ret = umtxq_signal(&key, n_wake);
umtxq_unlock(&key);
umtx_key_release(&key);
return (0);
}
/*
* Lock PTHREAD_PRIO_NONE protocol POSIX mutex.
*/
static int
_do_lock_normal(struct thread *td, struct umutex *m, uint32_t flags, int timo,
int mode)
{
struct umtx_q *uq;
uint32_t owner, old, id;
int error = 0;
id = td->td_tid;
uq = td->td_umtxq;
/*
* Care must be exercised when dealing with umtx structure. It
* can fault on any access.
*/
for (;;) {
owner = fuword32(__DEVOLATILE(void *, &m->m_owner));
if (mode == _UMUTEX_WAIT) {
if (owner == UMUTEX_UNOWNED || owner == UMUTEX_CONTESTED)
return (0);
} else {
/*
* Try the uncontested case. This should be done in userland.
*/
owner = casuword32(&m->m_owner, UMUTEX_UNOWNED, id);
/* The acquire succeeded. */
if (owner == UMUTEX_UNOWNED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If no one owns it but it is contested try to acquire it. */
if (owner == UMUTEX_CONTESTED) {
owner = casuword32(&m->m_owner,
UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
if (owner == UMUTEX_CONTESTED)
return (0);
/* The address was invalid. */
if (owner == -1)
return (EFAULT);
/* If this failed the lock has changed, restart. */
continue;
}
}
if ((flags & UMUTEX_ERROR_CHECK) != 0 &&
(owner & ~UMUTEX_CONTESTED) == id)
return (EDEADLK);
if (mode == _UMUTEX_TRY)
return (EBUSY);
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
return (error);
if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX,
GET_SHARE(flags), &uq->uq_key)) != 0)
return (error);
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_insert(uq);
umtxq_unlock(&uq->uq_key);
/*
* Set the contested bit so that a release in user space
* knows to use the system call for unlock. If this fails
* either some one else has acquired the lock or it has been
* released.
*/
old = casuword32(&m->m_owner, owner, owner | UMUTEX_CONTESTED);
/* The address was invalid. */
if (old == -1) {
umtxq_lock(&uq->uq_key);
umtxq_remove(uq);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (EFAULT);
}
/*
* We set the contested bit, sleep. Otherwise the lock changed
* and we need to retry or we lost a race to the thread
* unlocking the umtx.
*/
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
if (old == owner)
error = umtxq_sleep(uq, "umtxn", timo);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
}
return (0);
}
/*
* Lock PTHREAD_PRIO_NONE protocol POSIX mutex.
*/
/*
* Unlock PTHREAD_PRIO_NONE protocol POSIX mutex.
*/
static int
do_unlock_normal(struct thread *td, struct umutex *m, uint32_t flags)
{
struct umtx_key key;
uint32_t owner, old, id;
int error;
int count;
id = td->td_tid;
/*
* Make sure we own this mtx.
*/
owner = fuword32(__DEVOLATILE(uint32_t *, &m->m_owner));
if (owner == -1)
return (EFAULT);
if ((owner & ~UMUTEX_CONTESTED) != id)
return (EPERM);
if ((owner & UMUTEX_CONTESTED) == 0) {
old = casuword32(&m->m_owner, owner, UMUTEX_UNOWNED);
if (old == -1)
return (EFAULT);
if (old == owner)
return (0);
owner = old;
}
/* We should only ever be in here for contested locks */
if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX, GET_SHARE(flags),
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
count = umtxq_count(&key);
umtxq_unlock(&key);
/*
* When unlocking the umtx, it must be marked as unowned if
* there is zero or one thread only waiting for it.
* Otherwise, it must be marked as contested.
*/
old = casuword32(&m->m_owner, owner,
count <= 1 ? UMUTEX_UNOWNED : UMUTEX_CONTESTED);
umtxq_lock(&key);
umtxq_signal(&key,1);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
if (old == -1)
return (EFAULT);
if (old != owner)
return (EINVAL);
return (0);
}
/*
* Check if the mutex is available and wake up a waiter,
* only for simple mutex.
*/
static int
do_wake_umutex(struct thread *td, struct umutex *m)
{
struct umtx_key key;
uint32_t owner;
uint32_t flags;
int error;
int count;
owner = fuword32(__DEVOLATILE(uint32_t *, &m->m_owner));
if (owner == -1)
return (EFAULT);
if ((owner & ~UMUTEX_CONTESTED) != 0)
return (0);
flags = fuword32(&m->m_flags);
/* We should only ever be in here for contested locks */
if ((error = umtx_key_get(m, TYPE_NORMAL_UMUTEX, GET_SHARE(flags),
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
count = umtxq_count(&key);
umtxq_unlock(&key);
if (count <= 1)
owner = casuword32(&m->m_owner, UMUTEX_CONTESTED, UMUTEX_UNOWNED);
umtxq_lock(&key);
if (count != 0 && (owner & ~UMUTEX_CONTESTED) == 0)
umtxq_signal(&key, 1);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
return (0);
}
static inline struct umtx_pi *
umtx_pi_alloc(int flags)
{
struct umtx_pi *pi;
pi = uma_zalloc(umtx_pi_zone, M_ZERO | flags);
TAILQ_INIT(&pi->pi_blocked);
atomic_add_int(&umtx_pi_allocated, 1);
return (pi);
}
static inline void
umtx_pi_free(struct umtx_pi *pi)
{
uma_zfree(umtx_pi_zone, pi);
atomic_add_int(&umtx_pi_allocated, -1);
}
/*
* Adjust the thread's position on a pi_state after its priority has been
* changed.
*/
static int
umtx_pi_adjust_thread(struct umtx_pi *pi, struct thread *td)
{
struct umtx_q *uq, *uq1, *uq2;
struct thread *td1;
mtx_assert(&umtx_lock, MA_OWNED);
if (pi == NULL)
return (0);
uq = td->td_umtxq;
/*
* Check if the thread needs to be moved on the blocked chain.
* It needs to be moved if either its priority is lower than
* the previous thread or higher than the next thread.
*/
uq1 = TAILQ_PREV(uq, umtxq_head, uq_lockq);
uq2 = TAILQ_NEXT(uq, uq_lockq);
if ((uq1 != NULL && UPRI(td) < UPRI(uq1->uq_thread)) ||
(uq2 != NULL && UPRI(td) > UPRI(uq2->uq_thread))) {
/*
* Remove thread from blocked chain and determine where
* it should be moved to.
*/
TAILQ_REMOVE(&pi->pi_blocked, uq, uq_lockq);
TAILQ_FOREACH(uq1, &pi->pi_blocked, uq_lockq) {
td1 = uq1->uq_thread;
MPASS(td1->td_proc->p_magic == P_MAGIC);
if (UPRI(td1) > UPRI(td))
break;
}
if (uq1 == NULL)
TAILQ_INSERT_TAIL(&pi->pi_blocked, uq, uq_lockq);
else
TAILQ_INSERT_BEFORE(uq1, uq, uq_lockq);
}
return (1);
}
/*
* Propagate priority when a thread is blocked on POSIX
* PI mutex.
*/
static void
umtx_propagate_priority(struct thread *td)
{
struct umtx_q *uq;
struct umtx_pi *pi;
int pri;
mtx_assert(&umtx_lock, MA_OWNED);
pri = UPRI(td);
uq = td->td_umtxq;
pi = uq->uq_pi_blocked;
if (pi == NULL)
return;
for (;;) {
td = pi->pi_owner;
if (td == NULL)
return;
MPASS(td->td_proc != NULL);
MPASS(td->td_proc->p_magic == P_MAGIC);
if (UPRI(td) <= pri)
return;
thread_lock(td);
sched_lend_user_prio(td, pri);
thread_unlock(td);
/*
* Pick up the lock that td is blocked on.
*/
uq = td->td_umtxq;
pi = uq->uq_pi_blocked;
/* Resort td on the list if needed. */
if (!umtx_pi_adjust_thread(pi, td))
break;
}
}
/*
* Unpropagate priority for a PI mutex when a thread blocked on
* it is interrupted by signal or resumed by others.
*/
static void
umtx_unpropagate_priority(struct umtx_pi *pi)
{
struct umtx_q *uq, *uq_owner;
struct umtx_pi *pi2;
int pri, oldpri;
mtx_assert(&umtx_lock, MA_OWNED);
while (pi != NULL && pi->pi_owner != NULL) {
pri = PRI_MAX;
uq_owner = pi->pi_owner->td_umtxq;
TAILQ_FOREACH(pi2, &uq_owner->uq_pi_contested, pi_link) {
uq = TAILQ_FIRST(&pi2->pi_blocked);
if (uq != NULL) {
if (pri > UPRI(uq->uq_thread))
pri = UPRI(uq->uq_thread);
}
}
if (pri > uq_owner->uq_inherited_pri)
pri = uq_owner->uq_inherited_pri;
thread_lock(pi->pi_owner);
oldpri = pi->pi_owner->td_user_pri;
sched_unlend_user_prio(pi->pi_owner, pri);
thread_unlock(pi->pi_owner);
if (uq_owner->uq_pi_blocked != NULL)
umtx_pi_adjust_locked(pi->pi_owner, oldpri);
pi = uq_owner->uq_pi_blocked;
}
}
/*
* Insert a PI mutex into owned list.
*/
static void
umtx_pi_setowner(struct umtx_pi *pi, struct thread *owner)
{
struct umtx_q *uq_owner;
uq_owner = owner->td_umtxq;
mtx_assert(&umtx_lock, MA_OWNED);
if (pi->pi_owner != NULL)
panic("pi_ower != NULL");
pi->pi_owner = owner;
TAILQ_INSERT_TAIL(&uq_owner->uq_pi_contested, pi, pi_link);
}
/*
* Claim ownership of a PI mutex.
*/
static int
umtx_pi_claim(struct umtx_pi *pi, struct thread *owner)
{
struct umtx_q *uq, *uq_owner;
uq_owner = owner->td_umtxq;
mtx_lock_spin(&umtx_lock);
if (pi->pi_owner == owner) {
mtx_unlock_spin(&umtx_lock);
return (0);
}
if (pi->pi_owner != NULL) {
/*
* userland may have already messed the mutex, sigh.
*/
mtx_unlock_spin(&umtx_lock);
return (EPERM);
}
umtx_pi_setowner(pi, owner);
uq = TAILQ_FIRST(&pi->pi_blocked);
if (uq != NULL) {
int pri;
pri = UPRI(uq->uq_thread);
thread_lock(owner);
if (pri < UPRI(owner))
sched_lend_user_prio(owner, pri);
thread_unlock(owner);
}
mtx_unlock_spin(&umtx_lock);
return (0);
}
static void
umtx_pi_adjust_locked(struct thread *td, u_char oldpri)
{
struct umtx_q *uq;
struct umtx_pi *pi;
uq = td->td_umtxq;
/*
* Pick up the lock that td is blocked on.
*/
pi = uq->uq_pi_blocked;
MPASS(pi != NULL);
/* Resort the turnstile on the list. */
if (!umtx_pi_adjust_thread(pi, td))
return;
/*
* If our priority was lowered and we are at the head of the
* turnstile, then propagate our new priority up the chain.
*/
if (uq == TAILQ_FIRST(&pi->pi_blocked) && UPRI(td) < oldpri)
umtx_propagate_priority(td);
}
/*
* Adjust a thread's order position in its blocked PI mutex,
* this may result new priority propagating process.
*/
void
umtx_pi_adjust(struct thread *td, u_char oldpri)
{
struct umtx_q *uq;
struct umtx_pi *pi;
uq = td->td_umtxq;
mtx_lock_spin(&umtx_lock);
/*
* Pick up the lock that td is blocked on.
*/
pi = uq->uq_pi_blocked;
if (pi != NULL)
umtx_pi_adjust_locked(td, oldpri);
mtx_unlock_spin(&umtx_lock);
}
/*
* Sleep on a PI mutex.
*/
static int
umtxq_sleep_pi(struct umtx_q *uq, struct umtx_pi *pi,
uint32_t owner, const char *wmesg, int timo)
{
struct umtxq_chain *uc;
struct thread *td, *td1;
struct umtx_q *uq1;
int pri;
int error = 0;
td = uq->uq_thread;
KASSERT(td == curthread, ("inconsistent uq_thread"));
uc = umtxq_getchain(&uq->uq_key);
UMTXQ_LOCKED_ASSERT(uc);
UMTXQ_BUSY_ASSERT(uc);
umtxq_insert(uq);
mtx_lock_spin(&umtx_lock);
if (pi->pi_owner == NULL) {
/* XXX
* Current, We only support process private PI-mutex,
* non-contended PI-mutexes are locked in userland.
* Process shared PI-mutex should always be initialized
* by kernel and be registered in kernel, locking should
* always be done by kernel to avoid security problems.
* For process private PI-mutex, we can find owner
* thread and boost its priority safely.
*/
mtx_unlock_spin(&umtx_lock);
PROC_LOCK(curproc);
td1 = thread_find(curproc, owner);
mtx_lock_spin(&umtx_lock);
if (td1 != NULL && pi->pi_owner == NULL) {
uq1 = td1->td_umtxq;
umtx_pi_setowner(pi, td1);
}
PROC_UNLOCK(curproc);
}
TAILQ_FOREACH(uq1, &pi->pi_blocked, uq_lockq) {
pri = UPRI(uq1->uq_thread);
if (pri > UPRI(td))
break;
}
if (uq1 != NULL)
TAILQ_INSERT_BEFORE(uq1, uq, uq_lockq);
else
TAILQ_INSERT_TAIL(&pi->pi_blocked, uq, uq_lockq);
uq->uq_pi_blocked = pi;
thread_lock(td);
td->td_flags |= TDF_UPIBLOCKED;
thread_unlock(td);
umtx_propagate_priority(td);
mtx_unlock_spin(&umtx_lock);
umtxq_unbusy(&uq->uq_key);
if (uq->uq_flags & UQF_UMTXQ) {
error = msleep(uq, &uc->uc_lock, PCATCH, wmesg, timo);
if (error == EWOULDBLOCK)
error = ETIMEDOUT;
if (uq->uq_flags & UQF_UMTXQ) {
umtxq_remove(uq);
}
}
mtx_lock_spin(&umtx_lock);
uq->uq_pi_blocked = NULL;
thread_lock(td);
td->td_flags &= ~TDF_UPIBLOCKED;
thread_unlock(td);
TAILQ_REMOVE(&pi->pi_blocked, uq, uq_lockq);
umtx_unpropagate_priority(pi);
mtx_unlock_spin(&umtx_lock);
umtxq_unlock(&uq->uq_key);
return (error);
}
/*
* Add reference count for a PI mutex.
*/
static void
umtx_pi_ref(struct umtx_pi *pi)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&pi->pi_key);
UMTXQ_LOCKED_ASSERT(uc);
pi->pi_refcount++;
}
/*
* Decrease reference count for a PI mutex, if the counter
* is decreased to zero, its memory space is freed.
*/
static void
umtx_pi_unref(struct umtx_pi *pi)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&pi->pi_key);
UMTXQ_LOCKED_ASSERT(uc);
KASSERT(pi->pi_refcount > 0, ("invalid reference count"));
if (--pi->pi_refcount == 0) {
mtx_lock_spin(&umtx_lock);
if (pi->pi_owner != NULL) {
TAILQ_REMOVE(&pi->pi_owner->td_umtxq->uq_pi_contested,
pi, pi_link);
pi->pi_owner = NULL;
}
KASSERT(TAILQ_EMPTY(&pi->pi_blocked),
("blocked queue not empty"));
mtx_unlock_spin(&umtx_lock);
TAILQ_REMOVE(&uc->uc_pi_list, pi, pi_hashlink);
umtx_pi_free(pi);
}
}
/*
* Find a PI mutex in hash table.
*/
static struct umtx_pi *
umtx_pi_lookup(struct umtx_key *key)
{
struct umtxq_chain *uc;
struct umtx_pi *pi;
uc = umtxq_getchain(key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_FOREACH(pi, &uc->uc_pi_list, pi_hashlink) {
if (umtx_key_match(&pi->pi_key, key)) {
return (pi);
}
}
return (NULL);
}
/*
* Insert a PI mutex into hash table.
*/
static inline void
umtx_pi_insert(struct umtx_pi *pi)
{
struct umtxq_chain *uc;
uc = umtxq_getchain(&pi->pi_key);
UMTXQ_LOCKED_ASSERT(uc);
TAILQ_INSERT_TAIL(&uc->uc_pi_list, pi, pi_hashlink);
}
/*
* Lock a PI mutex.
*/
static int
_do_lock_pi(struct thread *td, struct umutex *m, uint32_t flags, int timo,
int try)
{
struct umtx_q *uq;
struct umtx_pi *pi, *new_pi;
uint32_t id, owner, old;
int error;
id = td->td_tid;
uq = td->td_umtxq;
if ((error = umtx_key_get(m, TYPE_PI_UMUTEX, GET_SHARE(flags),
&uq->uq_key)) != 0)
return (error);
umtxq_lock(&uq->uq_key);
pi = umtx_pi_lookup(&uq->uq_key);
if (pi == NULL) {
new_pi = umtx_pi_alloc(M_NOWAIT);
if (new_pi == NULL) {
umtxq_unlock(&uq->uq_key);
new_pi = umtx_pi_alloc(M_WAITOK);
umtxq_lock(&uq->uq_key);
pi = umtx_pi_lookup(&uq->uq_key);
if (pi != NULL) {
umtx_pi_free(new_pi);
new_pi = NULL;
}
}
if (new_pi != NULL) {
new_pi->pi_key = uq->uq_key;
umtx_pi_insert(new_pi);
pi = new_pi;
}
}
umtx_pi_ref(pi);
umtxq_unlock(&uq->uq_key);
/*
* Care must be exercised when dealing with umtx structure. It
* can fault on any access.
*/
for (;;) {
/*
* Try the uncontested case. This should be done in userland.
*/
owner = casuword32(&m->m_owner, UMUTEX_UNOWNED, id);
/* The acquire succeeded. */
if (owner == UMUTEX_UNOWNED) {
error = 0;
break;
}
/* The address was invalid. */
if (owner == -1) {
error = EFAULT;
break;
}
/* If no one owns it but it is contested try to acquire it. */
if (owner == UMUTEX_CONTESTED) {
owner = casuword32(&m->m_owner,
UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
if (owner == UMUTEX_CONTESTED) {
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
error = umtx_pi_claim(pi, td);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
break;
}
/* The address was invalid. */
if (owner == -1) {
error = EFAULT;
break;
}
/* If this failed the lock has changed, restart. */
continue;
}
if ((flags & UMUTEX_ERROR_CHECK) != 0 &&
(owner & ~UMUTEX_CONTESTED) == id) {
error = EDEADLK;
break;
}
if (try != 0) {
error = EBUSY;
break;
}
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
break;
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
/*
* Set the contested bit so that a release in user space
* knows to use the system call for unlock. If this fails
* either some one else has acquired the lock or it has been
* released.
*/
old = casuword32(&m->m_owner, owner, owner | UMUTEX_CONTESTED);
/* The address was invalid. */
if (old == -1) {
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
error = EFAULT;
break;
}
umtxq_lock(&uq->uq_key);
/*
* We set the contested bit, sleep. Otherwise the lock changed
* and we need to retry or we lost a race to the thread
* unlocking the umtx.
*/
if (old == owner)
error = umtxq_sleep_pi(uq, pi, owner & ~UMUTEX_CONTESTED,
"umtxpi", timo);
else {
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
}
}
umtxq_lock(&uq->uq_key);
umtx_pi_unref(pi);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (error);
}
/*
* Unlock a PI mutex.
*/
static int
do_unlock_pi(struct thread *td, struct umutex *m, uint32_t flags)
{
struct umtx_key key;
struct umtx_q *uq_first, *uq_first2, *uq_me;
struct umtx_pi *pi, *pi2;
uint32_t owner, old, id;
int error;
int count;
int pri;
id = td->td_tid;
/*
* Make sure we own this mtx.
*/
owner = fuword32(__DEVOLATILE(uint32_t *, &m->m_owner));
if (owner == -1)
return (EFAULT);
if ((owner & ~UMUTEX_CONTESTED) != id)
return (EPERM);
/* This should be done in userland */
if ((owner & UMUTEX_CONTESTED) == 0) {
old = casuword32(&m->m_owner, owner, UMUTEX_UNOWNED);
if (old == -1)
return (EFAULT);
if (old == owner)
return (0);
owner = old;
}
/* We should only ever be in here for contested locks */
if ((error = umtx_key_get(m, TYPE_PI_UMUTEX, GET_SHARE(flags),
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
count = umtxq_count_pi(&key, &uq_first);
if (uq_first != NULL) {
mtx_lock_spin(&umtx_lock);
pi = uq_first->uq_pi_blocked;
KASSERT(pi != NULL, ("pi == NULL?"));
if (pi->pi_owner != curthread) {
mtx_unlock_spin(&umtx_lock);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
/* userland messed the mutex */
return (EPERM);
}
uq_me = curthread->td_umtxq;
pi->pi_owner = NULL;
TAILQ_REMOVE(&uq_me->uq_pi_contested, pi, pi_link);
/* get highest priority thread which is still sleeping. */
uq_first = TAILQ_FIRST(&pi->pi_blocked);
while (uq_first != NULL &&
(uq_first->uq_flags & UQF_UMTXQ) == 0) {
uq_first = TAILQ_NEXT(uq_first, uq_lockq);
}
pri = PRI_MAX;
TAILQ_FOREACH(pi2, &uq_me->uq_pi_contested, pi_link) {
uq_first2 = TAILQ_FIRST(&pi2->pi_blocked);
if (uq_first2 != NULL) {
if (pri > UPRI(uq_first2->uq_thread))
pri = UPRI(uq_first2->uq_thread);
}
}
thread_lock(curthread);
sched_unlend_user_prio(curthread, pri);
thread_unlock(curthread);
mtx_unlock_spin(&umtx_lock);
if (uq_first)
umtxq_signal_thread(uq_first);
}
umtxq_unlock(&key);
/*
* When unlocking the umtx, it must be marked as unowned if
* there is zero or one thread only waiting for it.
* Otherwise, it must be marked as contested.
*/
old = casuword32(&m->m_owner, owner,
count <= 1 ? UMUTEX_UNOWNED : UMUTEX_CONTESTED);
umtxq_lock(&key);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
if (old == -1)
return (EFAULT);
if (old != owner)
return (EINVAL);
return (0);
}
/*
* Lock a PP mutex.
*/
static int
_do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags, int timo,
int try)
{
struct umtx_q *uq, *uq2;
struct umtx_pi *pi;
uint32_t ceiling;
uint32_t owner, id;
int error, pri, old_inherited_pri, su;
id = td->td_tid;
uq = td->td_umtxq;
if ((error = umtx_key_get(m, TYPE_PP_UMUTEX, GET_SHARE(flags),
&uq->uq_key)) != 0)
return (error);
su = (priv_check(td, PRIV_SCHED_RTPRIO) == 0);
for (;;) {
old_inherited_pri = uq->uq_inherited_pri;
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
ceiling = RTP_PRIO_MAX - fuword32(&m->m_ceilings[0]);
if (ceiling > RTP_PRIO_MAX) {
error = EINVAL;
goto out;
}
mtx_lock_spin(&umtx_lock);
if (UPRI(td) < PRI_MIN_REALTIME + ceiling) {
mtx_unlock_spin(&umtx_lock);
error = EINVAL;
goto out;
}
if (su && PRI_MIN_REALTIME + ceiling < uq->uq_inherited_pri) {
uq->uq_inherited_pri = PRI_MIN_REALTIME + ceiling;
thread_lock(td);
if (uq->uq_inherited_pri < UPRI(td))
sched_lend_user_prio(td, uq->uq_inherited_pri);
thread_unlock(td);
}
mtx_unlock_spin(&umtx_lock);
owner = casuword32(&m->m_owner,
UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
if (owner == UMUTEX_CONTESTED) {
error = 0;
break;
}
/* The address was invalid. */
if (owner == -1) {
error = EFAULT;
break;
}
if ((flags & UMUTEX_ERROR_CHECK) != 0 &&
(owner & ~UMUTEX_CONTESTED) == id) {
error = EDEADLK;
break;
}
if (try != 0) {
error = EBUSY;
break;
}
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
break;
umtxq_lock(&uq->uq_key);
umtxq_insert(uq);
umtxq_unbusy(&uq->uq_key);
error = umtxq_sleep(uq, "umtxpp", timo);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
mtx_lock_spin(&umtx_lock);
uq->uq_inherited_pri = old_inherited_pri;
pri = PRI_MAX;
TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
uq2 = TAILQ_FIRST(&pi->pi_blocked);
if (uq2 != NULL) {
if (pri > UPRI(uq2->uq_thread))
pri = UPRI(uq2->uq_thread);
}
}
if (pri > uq->uq_inherited_pri)
pri = uq->uq_inherited_pri;
thread_lock(td);
sched_unlend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
}
if (error != 0) {
mtx_lock_spin(&umtx_lock);
uq->uq_inherited_pri = old_inherited_pri;
pri = PRI_MAX;
TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
uq2 = TAILQ_FIRST(&pi->pi_blocked);
if (uq2 != NULL) {
if (pri > UPRI(uq2->uq_thread))
pri = UPRI(uq2->uq_thread);
}
}
if (pri > uq->uq_inherited_pri)
pri = uq->uq_inherited_pri;
thread_lock(td);
sched_unlend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
}
out:
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (error);
}
/*
* Unlock a PP mutex.
*/
static int
do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags)
{
struct umtx_key key;
struct umtx_q *uq, *uq2;
struct umtx_pi *pi;
uint32_t owner, id;
uint32_t rceiling;
int error, pri, new_inherited_pri, su;
id = td->td_tid;
uq = td->td_umtxq;
su = (priv_check(td, PRIV_SCHED_RTPRIO) == 0);
/*
* Make sure we own this mtx.
*/
owner = fuword32(__DEVOLATILE(uint32_t *, &m->m_owner));
if (owner == -1)
return (EFAULT);
if ((owner & ~UMUTEX_CONTESTED) != id)
return (EPERM);
error = copyin(&m->m_ceilings[1], &rceiling, sizeof(uint32_t));
if (error != 0)
return (error);
if (rceiling == -1)
new_inherited_pri = PRI_MAX;
else {
rceiling = RTP_PRIO_MAX - rceiling;
if (rceiling > RTP_PRIO_MAX)
return (EINVAL);
new_inherited_pri = PRI_MIN_REALTIME + rceiling;
}
if ((error = umtx_key_get(m, TYPE_PP_UMUTEX, GET_SHARE(flags),
&key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
umtxq_unlock(&key);
/*
* For priority protected mutex, always set unlocked state
* to UMUTEX_CONTESTED, so that userland always enters kernel
* to lock the mutex, it is necessary because thread priority
* has to be adjusted for such mutex.
*/
error = suword32(__DEVOLATILE(uint32_t *, &m->m_owner),
UMUTEX_CONTESTED);
umtxq_lock(&key);
if (error == 0)
umtxq_signal(&key, 1);
umtxq_unbusy(&key);
umtxq_unlock(&key);
if (error == -1)
error = EFAULT;
else {
mtx_lock_spin(&umtx_lock);
if (su != 0)
uq->uq_inherited_pri = new_inherited_pri;
pri = PRI_MAX;
TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
uq2 = TAILQ_FIRST(&pi->pi_blocked);
if (uq2 != NULL) {
if (pri > UPRI(uq2->uq_thread))
pri = UPRI(uq2->uq_thread);
}
}
if (pri > uq->uq_inherited_pri)
pri = uq->uq_inherited_pri;
thread_lock(td);
sched_unlend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
}
umtx_key_release(&key);
return (error);
}
static int
do_set_ceiling(struct thread *td, struct umutex *m, uint32_t ceiling,
uint32_t *old_ceiling)
{
struct umtx_q *uq;
uint32_t save_ceiling;
uint32_t owner, id;
uint32_t flags;
int error;
flags = fuword32(&m->m_flags);
if ((flags & UMUTEX_PRIO_PROTECT) == 0)
return (EINVAL);
if (ceiling > RTP_PRIO_MAX)
return (EINVAL);
id = td->td_tid;
uq = td->td_umtxq;
if ((error = umtx_key_get(m, TYPE_PP_UMUTEX, GET_SHARE(flags),
&uq->uq_key)) != 0)
return (error);
for (;;) {
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
save_ceiling = fuword32(&m->m_ceilings[0]);
owner = casuword32(&m->m_owner,
UMUTEX_CONTESTED, id | UMUTEX_CONTESTED);
if (owner == UMUTEX_CONTESTED) {
suword32(&m->m_ceilings[0], ceiling);
suword32(__DEVOLATILE(uint32_t *, &m->m_owner),
UMUTEX_CONTESTED);
error = 0;
break;
}
/* The address was invalid. */
if (owner == -1) {
error = EFAULT;
break;
}
if ((owner & ~UMUTEX_CONTESTED) == id) {
suword32(&m->m_ceilings[0], ceiling);
error = 0;
break;
}
/*
* If we caught a signal, we have retried and now
* exit immediately.
*/
if (error != 0)
break;
/*
* We set the contested bit, sleep. Otherwise the lock changed
* and we need to retry or we lost a race to the thread
* unlocking the umtx.
*/
umtxq_lock(&uq->uq_key);
umtxq_insert(uq);
umtxq_unbusy(&uq->uq_key);
error = umtxq_sleep(uq, "umtxpp", 0);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
}
umtxq_lock(&uq->uq_key);
if (error == 0)
umtxq_signal(&uq->uq_key, INT_MAX);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
if (error == 0 && old_ceiling != NULL)
suword32(old_ceiling, save_ceiling);
return (error);
}
static int
_do_lock_umutex(struct thread *td, struct umutex *m, int flags, int timo,
int mode)
{
switch(flags & (UMUTEX_PRIO_INHERIT | UMUTEX_PRIO_PROTECT)) {
case 0:
return (_do_lock_normal(td, m, flags, timo, mode));
case UMUTEX_PRIO_INHERIT:
return (_do_lock_pi(td, m, flags, timo, mode));
case UMUTEX_PRIO_PROTECT:
return (_do_lock_pp(td, m, flags, timo, mode));
}
return (EINVAL);
}
/*
* Lock a userland POSIX mutex.
*/
static int
do_lock_umutex(struct thread *td, struct umutex *m,
struct timespec *timeout, int mode)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
uint32_t flags;
int error;
flags = fuword32(&m->m_flags);
if (flags == -1)
return (EFAULT);
if (timeout == NULL) {
error = _do_lock_umutex(td, m, flags, 0, mode);
/* Mutex locking is restarted if it is interrupted. */
if (error == EINTR && mode != _UMUTEX_WAIT)
error = ERESTART;
} else {
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = _do_lock_umutex(td, m, flags, tvtohz(&tv), mode);
if (error != ETIMEDOUT)
break;
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
/* Timed-locking is not restarted. */
if (error == ERESTART)
error = EINTR;
}
return (error);
}
/*
* Unlock a userland POSIX mutex.
*/
static int
do_unlock_umutex(struct thread *td, struct umutex *m)
{
uint32_t flags;
flags = fuword32(&m->m_flags);
if (flags == -1)
return (EFAULT);
switch(flags & (UMUTEX_PRIO_INHERIT | UMUTEX_PRIO_PROTECT)) {
case 0:
return (do_unlock_normal(td, m, flags));
case UMUTEX_PRIO_INHERIT:
return (do_unlock_pi(td, m, flags));
case UMUTEX_PRIO_PROTECT:
return (do_unlock_pp(td, m, flags));
}
return (EINVAL);
}
static int
do_cv_wait(struct thread *td, struct ucond *cv, struct umutex *m,
struct timespec *timeout, u_long wflags)
{
struct umtx_q *uq;
struct timeval tv;
struct timespec cts, ets, tts;
uint32_t flags;
int error;
uq = td->td_umtxq;
flags = fuword32(&cv->c_flags);
error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &uq->uq_key);
if (error != 0)
return (error);
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_insert(uq);
umtxq_unlock(&uq->uq_key);
/*
* The magic thing is we should set c_has_waiters to 1 before
* releasing user mutex.
*/
suword32(__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 1);
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
error = do_unlock_umutex(td, m);
umtxq_lock(&uq->uq_key);
if (error == 0) {
if ((wflags & UMTX_CHECK_UNPARKING) &&
(td->td_pflags & TDP_WAKEUP)) {
td->td_pflags &= ~TDP_WAKEUP;
error = EINTR;
} else if (timeout == NULL) {
error = umtxq_sleep(uq, "ucond", 0);
} else {
getnanouptime(&ets);
timespecadd(&ets, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = umtxq_sleep(uq, "ucond", tvtohz(&tv));
if (error != ETIMEDOUT)
break;
getnanouptime(&cts);
if (timespeccmp(&cts, &ets, >=)) {
error = ETIMEDOUT;
break;
}
tts = ets;
timespecsub(&tts, &cts);
TIMESPEC_TO_TIMEVAL(&tv, &tts);
}
}
}
if (error != 0) {
if ((uq->uq_flags & UQF_UMTXQ) == 0) {
/*
* If we concurrently got do_cv_signal()d
* and we got an error or UNIX signals or a timeout,
* then, perform another umtxq_signal to avoid
* consuming the wakeup. This may cause supurious
* wakeup for another thread which was just queued,
* but SUSV3 explicitly allows supurious wakeup to
* occur, and indeed a kernel based implementation
* can not avoid it.
*/
if (!umtxq_signal(&uq->uq_key, 1))
error = 0;
}
if (error == ERESTART)
error = EINTR;
}
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
umtx_key_release(&uq->uq_key);
return (error);
}
/*
* Signal a userland condition variable.
*/
static int
do_cv_signal(struct thread *td, struct ucond *cv)
{
struct umtx_key key;
int error, cnt, nwake;
uint32_t flags;
flags = fuword32(&cv->c_flags);
if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
cnt = umtxq_count(&key);
nwake = umtxq_signal(&key, 1);
if (cnt <= nwake) {
umtxq_unlock(&key);
error = suword32(
__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 0);
umtxq_lock(&key);
}
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
return (error);
}
static int
do_cv_broadcast(struct thread *td, struct ucond *cv)
{
struct umtx_key key;
int error;
uint32_t flags;
flags = fuword32(&cv->c_flags);
if ((error = umtx_key_get(cv, TYPE_CV, GET_SHARE(flags), &key)) != 0)
return (error);
umtxq_lock(&key);
umtxq_busy(&key);
umtxq_signal(&key, INT_MAX);
umtxq_unlock(&key);
error = suword32(__DEVOLATILE(uint32_t *, &cv->c_has_waiters), 0);
umtxq_lock(&key);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
return (error);
}
static int
do_rw_rdlock(struct thread *td, struct urwlock *rwlock, long fflag, int timo)
{
struct umtx_q *uq;
uint32_t flags, wrflags;
int32_t state, oldstate;
int32_t blocked_readers;
int error;
uq = td->td_umtxq;
flags = fuword32(&rwlock->rw_flags);
error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
if (error != 0)
return (error);
wrflags = URWLOCK_WRITE_OWNER;
if (!(fflag & URWLOCK_PREFER_READER) && !(flags & URWLOCK_PREFER_READER))
wrflags |= URWLOCK_WRITE_WAITERS;
for (;;) {
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
/* try to lock it */
while (!(state & wrflags)) {
if (__predict_false(URWLOCK_READER_COUNT(state) == URWLOCK_MAX_READERS)) {
umtx_key_release(&uq->uq_key);
return (EAGAIN);
}
oldstate = casuword32(&rwlock->rw_state, state, state + 1);
if (oldstate == state) {
umtx_key_release(&uq->uq_key);
return (0);
}
state = oldstate;
}
if (error)
break;
/* grab monitor lock */
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
/* set read contention bit */
while ((state & wrflags) && !(state & URWLOCK_READ_WAITERS)) {
oldstate = casuword32(&rwlock->rw_state, state, state | URWLOCK_READ_WAITERS);
if (oldstate == state)
goto sleep;
state = oldstate;
}
/* state is changed while setting flags, restart */
if (!(state & wrflags)) {
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
continue;
}
sleep:
/* contention bit is set, before sleeping, increase read waiter count */
blocked_readers = fuword32(&rwlock->rw_blocked_readers);
suword32(&rwlock->rw_blocked_readers, blocked_readers+1);
while (state & wrflags) {
umtxq_lock(&uq->uq_key);
umtxq_insert(uq);
umtxq_unbusy(&uq->uq_key);
error = umtxq_sleep(uq, "urdlck", timo);
umtxq_busy(&uq->uq_key);
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
if (error)
break;
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
}
/* decrease read waiter count, and may clear read contention bit */
blocked_readers = fuword32(&rwlock->rw_blocked_readers);
suword32(&rwlock->rw_blocked_readers, blocked_readers-1);
if (blocked_readers == 1) {
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
for (;;) {
oldstate = casuword32(&rwlock->rw_state, state,
state & ~URWLOCK_READ_WAITERS);
if (oldstate == state)
break;
state = oldstate;
}
}
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
}
umtx_key_release(&uq->uq_key);
return (error);
}
static int
do_rw_rdlock2(struct thread *td, void *obj, long val, struct timespec *timeout)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
int error;
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = do_rw_rdlock(td, obj, val, tvtohz(&tv));
if (error != ETIMEDOUT)
break;
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
if (error == ERESTART)
error = EINTR;
return (error);
}
static int
do_rw_wrlock(struct thread *td, struct urwlock *rwlock, int timo)
{
struct umtx_q *uq;
uint32_t flags;
int32_t state, oldstate;
int32_t blocked_writers;
int error;
uq = td->td_umtxq;
flags = fuword32(&rwlock->rw_flags);
error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
if (error != 0)
return (error);
for (;;) {
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
while (!(state & URWLOCK_WRITE_OWNER) && URWLOCK_READER_COUNT(state) == 0) {
oldstate = casuword32(&rwlock->rw_state, state, state | URWLOCK_WRITE_OWNER);
if (oldstate == state) {
umtx_key_release(&uq->uq_key);
return (0);
}
state = oldstate;
}
if (error)
break;
/* grab monitor lock */
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
while (((state & URWLOCK_WRITE_OWNER) || URWLOCK_READER_COUNT(state) != 0) &&
(state & URWLOCK_WRITE_WAITERS) == 0) {
oldstate = casuword32(&rwlock->rw_state, state, state | URWLOCK_WRITE_WAITERS);
if (oldstate == state)
goto sleep;
state = oldstate;
}
if (!(state & URWLOCK_WRITE_OWNER) && URWLOCK_READER_COUNT(state) == 0) {
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
continue;
}
sleep:
blocked_writers = fuword32(&rwlock->rw_blocked_writers);
suword32(&rwlock->rw_blocked_writers, blocked_writers+1);
while ((state & URWLOCK_WRITE_OWNER) || URWLOCK_READER_COUNT(state) != 0) {
umtxq_lock(&uq->uq_key);
umtxq_insert_queue(uq, UMTX_EXCLUSIVE_QUEUE);
umtxq_unbusy(&uq->uq_key);
error = umtxq_sleep(uq, "uwrlck", timo);
umtxq_busy(&uq->uq_key);
umtxq_remove_queue(uq, UMTX_EXCLUSIVE_QUEUE);
umtxq_unlock(&uq->uq_key);
if (error)
break;
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
}
blocked_writers = fuword32(&rwlock->rw_blocked_writers);
suword32(&rwlock->rw_blocked_writers, blocked_writers-1);
if (blocked_writers == 1) {
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
for (;;) {
oldstate = casuword32(&rwlock->rw_state, state,
state & ~URWLOCK_WRITE_WAITERS);
if (oldstate == state)
break;
state = oldstate;
}
}
umtxq_lock(&uq->uq_key);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
}
umtx_key_release(&uq->uq_key);
return (error);
}
static int
do_rw_wrlock2(struct thread *td, void *obj, struct timespec *timeout)
{
struct timespec ts, ts2, ts3;
struct timeval tv;
int error;
getnanouptime(&ts);
timespecadd(&ts, timeout);
TIMESPEC_TO_TIMEVAL(&tv, timeout);
for (;;) {
error = do_rw_wrlock(td, obj, tvtohz(&tv));
if (error != ETIMEDOUT)
break;
getnanouptime(&ts2);
if (timespeccmp(&ts2, &ts, >=)) {
error = ETIMEDOUT;
break;
}
ts3 = ts;
timespecsub(&ts3, &ts2);
TIMESPEC_TO_TIMEVAL(&tv, &ts3);
}
if (error == ERESTART)
error = EINTR;
return (error);
}
static int
do_rw_unlock(struct thread *td, struct urwlock *rwlock)
{
struct umtx_q *uq;
uint32_t flags;
int32_t state, oldstate;
int error, q, count;
uq = td->td_umtxq;
flags = fuword32(&rwlock->rw_flags);
error = umtx_key_get(rwlock, TYPE_RWLOCK, GET_SHARE(flags), &uq->uq_key);
if (error != 0)
return (error);
state = fuword32(__DEVOLATILE(int32_t *, &rwlock->rw_state));
if (state & URWLOCK_WRITE_OWNER) {
for (;;) {
oldstate = casuword32(&rwlock->rw_state, state,
state & ~URWLOCK_WRITE_OWNER);
if (oldstate != state) {
state = oldstate;
if (!(oldstate & URWLOCK_WRITE_OWNER)) {
error = EPERM;
goto out;
}
} else
break;
}
} else if (URWLOCK_READER_COUNT(state) != 0) {
for (;;) {
oldstate = casuword32(&rwlock->rw_state, state,
state - 1);
if (oldstate != state) {
state = oldstate;
if (URWLOCK_READER_COUNT(oldstate) == 0) {
error = EPERM;
goto out;
}
}
else
break;
}
} else {
error = EPERM;
goto out;
}
count = 0;
if (!(flags & URWLOCK_PREFER_READER)) {
if (state & URWLOCK_WRITE_WAITERS) {
count = 1;
q = UMTX_EXCLUSIVE_QUEUE;
} else if (state & URWLOCK_READ_WAITERS) {
count = INT_MAX;
q = UMTX_SHARED_QUEUE;
}
} else {
if (state & URWLOCK_READ_WAITERS) {
count = INT_MAX;
q = UMTX_SHARED_QUEUE;
} else if (state & URWLOCK_WRITE_WAITERS) {
count = 1;
q = UMTX_EXCLUSIVE_QUEUE;
}
}
if (count) {
umtxq_lock(&uq->uq_key);
umtxq_busy(&uq->uq_key);
umtxq_signal_queue(&uq->uq_key, count, q);
umtxq_unbusy(&uq->uq_key);
umtxq_unlock(&uq->uq_key);
}
out:
umtx_key_release(&uq->uq_key);
return (error);
}
int
_umtx_lock(struct thread *td, struct _umtx_lock_args *uap)
/* struct umtx *umtx */
{
return _do_lock_umtx(td, uap->umtx, td->td_tid, 0);
}
int
_umtx_unlock(struct thread *td, struct _umtx_unlock_args *uap)
/* struct umtx *umtx */
{
return do_unlock_umtx(td, uap->umtx, td->td_tid);
}
static int
__umtx_op_lock_umtx(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout, sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
ts = &timeout;
}
return (do_lock_umtx(td, uap->obj, uap->val, ts));
}
static int
__umtx_op_unlock_umtx(struct thread *td, struct _umtx_op_args *uap)
{
return (do_unlock_umtx(td, uap->obj, uap->val));
}
static int
__umtx_op_wait(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout, sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_wait(td, uap->obj, uap->val, ts, 0, 0);
}
static int
__umtx_op_wait_uint(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout, sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_wait(td, uap->obj, uap->val, ts, 1, 0);
}
static int
__umtx_op_wait_uint_private(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout, sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_wait(td, uap->obj, uap->val, ts, 1, 1);
}
static int
__umtx_op_wake(struct thread *td, struct _umtx_op_args *uap)
{
return (kern_umtx_wake(td, uap->obj, uap->val, 0));
}
static int
__umtx_op_wake_private(struct thread *td, struct _umtx_op_args *uap)
{
return (kern_umtx_wake(td, uap->obj, uap->val, 1));
}
static int
__umtx_op_lock_umutex(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
ts = &timeout;
}
return do_lock_umutex(td, uap->obj, ts, 0);
}
static int
__umtx_op_trylock_umutex(struct thread *td, struct _umtx_op_args *uap)
{
return do_lock_umutex(td, uap->obj, NULL, _UMUTEX_TRY);
}
static int
__umtx_op_wait_umutex(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
ts = &timeout;
}
return do_lock_umutex(td, uap->obj, ts, _UMUTEX_WAIT);
}
static int
__umtx_op_wake_umutex(struct thread *td, struct _umtx_op_args *uap)
{
return do_wake_umutex(td, uap->obj);
}
static int
__umtx_op_unlock_umutex(struct thread *td, struct _umtx_op_args *uap)
{
return do_unlock_umutex(td, uap->obj);
}
static int
__umtx_op_set_ceiling(struct thread *td, struct _umtx_op_args *uap)
{
return do_set_ceiling(td, uap->obj, uap->val, uap->uaddr1);
}
static int
__umtx_op_cv_wait(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
ts = &timeout;
}
return (do_cv_wait(td, uap->obj, uap->uaddr1, ts, uap->val));
}
static int
__umtx_op_cv_signal(struct thread *td, struct _umtx_op_args *uap)
{
return do_cv_signal(td, uap->obj);
}
static int
__umtx_op_cv_broadcast(struct thread *td, struct _umtx_op_args *uap)
{
return do_cv_broadcast(td, uap->obj);
}
static int
__umtx_op_rw_rdlock(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL) {
error = do_rw_rdlock(td, uap->obj, uap->val, 0);
} else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
error = do_rw_rdlock2(td, uap->obj, uap->val, &timeout);
}
return (error);
}
static int
__umtx_op_rw_wrlock(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL) {
error = do_rw_wrlock(td, uap->obj, 0);
} else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
error = do_rw_wrlock2(td, uap->obj, &timeout);
}
return (error);
}
static int
__umtx_op_rw_unlock(struct thread *td, struct _umtx_op_args *uap)
{
return do_rw_unlock(td, uap->obj);
}
typedef int (*_umtx_op_func)(struct thread *td, struct _umtx_op_args *uap);
static _umtx_op_func op_table[] = {
__umtx_op_lock_umtx, /* UMTX_OP_LOCK */
__umtx_op_unlock_umtx, /* UMTX_OP_UNLOCK */
__umtx_op_wait, /* UMTX_OP_WAIT */
__umtx_op_wake, /* UMTX_OP_WAKE */
__umtx_op_trylock_umutex, /* UMTX_OP_MUTEX_TRYLOCK */
__umtx_op_lock_umutex, /* UMTX_OP_MUTEX_LOCK */
__umtx_op_unlock_umutex, /* UMTX_OP_MUTEX_UNLOCK */
__umtx_op_set_ceiling, /* UMTX_OP_SET_CEILING */
__umtx_op_cv_wait, /* UMTX_OP_CV_WAIT*/
__umtx_op_cv_signal, /* UMTX_OP_CV_SIGNAL */
__umtx_op_cv_broadcast, /* UMTX_OP_CV_BROADCAST */
__umtx_op_wait_uint, /* UMTX_OP_WAIT_UINT */
__umtx_op_rw_rdlock, /* UMTX_OP_RW_RDLOCK */
__umtx_op_rw_wrlock, /* UMTX_OP_RW_WRLOCK */
__umtx_op_rw_unlock, /* UMTX_OP_RW_UNLOCK */
__umtx_op_wait_uint_private, /* UMTX_OP_WAIT_UINT_PRIVATE */
__umtx_op_wake_private, /* UMTX_OP_WAKE_PRIVATE */
__umtx_op_wait_umutex, /* UMTX_OP_UMUTEX_WAIT */
__umtx_op_wake_umutex /* UMTX_OP_UMUTEX_WAKE */
};
int
_umtx_op(struct thread *td, struct _umtx_op_args *uap)
{
if ((unsigned)uap->op < UMTX_OP_MAX)
return (*op_table[uap->op])(td, uap);
return (EINVAL);
}
#ifdef COMPAT_IA32
int
freebsd32_umtx_lock(struct thread *td, struct freebsd32_umtx_lock_args *uap)
/* struct umtx *umtx */
{
return (do_lock_umtx32(td, (uint32_t *)uap->umtx, td->td_tid, NULL));
}
int
freebsd32_umtx_unlock(struct thread *td, struct freebsd32_umtx_unlock_args *uap)
/* struct umtx *umtx */
{
return (do_unlock_umtx32(td, (uint32_t *)uap->umtx, td->td_tid));
}
struct timespec32 {
u_int32_t tv_sec;
u_int32_t tv_nsec;
};
static inline int
copyin_timeout32(void *addr, struct timespec *tsp)
{
struct timespec32 ts32;
int error;
error = copyin(addr, &ts32, sizeof(struct timespec32));
if (error == 0) {
tsp->tv_sec = ts32.tv_sec;
tsp->tv_nsec = ts32.tv_nsec;
}
return (error);
}
static int
__umtx_op_lock_umtx_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
ts = &timeout;
}
return (do_lock_umtx32(td, uap->obj, uap->val, ts));
}
static int
__umtx_op_unlock_umtx_compat32(struct thread *td, struct _umtx_op_args *uap)
{
return (do_unlock_umtx32(td, uap->obj, (uint32_t)uap->val));
}
static int
__umtx_op_wait_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_wait(td, uap->obj, uap->val, ts, 1, 0);
}
static int
__umtx_op_lock_umutex_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_lock_umutex(td, uap->obj, ts, 0);
}
static int
__umtx_op_wait_umutex_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_lock_umutex(td, uap->obj, ts, _UMUTEX_WAIT);
}
static int
__umtx_op_cv_wait_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return (do_cv_wait(td, uap->obj, uap->uaddr1, ts, uap->val));
}
static int
__umtx_op_rw_rdlock_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL) {
error = do_rw_rdlock(td, uap->obj, uap->val, 0);
} else {
error = copyin(uap->uaddr2, &timeout,
sizeof(timeout));
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
error = do_rw_rdlock2(td, uap->obj, uap->val, &timeout);
}
return (error);
}
static int
__umtx_op_rw_wrlock_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec timeout;
int error;
/* Allow a null timespec (wait forever). */
if (uap->uaddr2 == NULL) {
error = do_rw_wrlock(td, uap->obj, 0);
} else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0) {
return (EINVAL);
}
error = do_rw_wrlock2(td, uap->obj, &timeout);
}
return (error);
}
static int
__umtx_op_wait_uint_private_compat32(struct thread *td, struct _umtx_op_args *uap)
{
struct timespec *ts, timeout;
int error;
if (uap->uaddr2 == NULL)
ts = NULL;
else {
error = copyin_timeout32(uap->uaddr2, &timeout);
if (error != 0)
return (error);
if (timeout.tv_nsec >= 1000000000 ||
timeout.tv_nsec < 0)
return (EINVAL);
ts = &timeout;
}
return do_wait(td, uap->obj, uap->val, ts, 1, 1);
}
static _umtx_op_func op_table_compat32[] = {
__umtx_op_lock_umtx_compat32, /* UMTX_OP_LOCK */
__umtx_op_unlock_umtx_compat32, /* UMTX_OP_UNLOCK */
__umtx_op_wait_compat32, /* UMTX_OP_WAIT */
__umtx_op_wake, /* UMTX_OP_WAKE */
__umtx_op_trylock_umutex, /* UMTX_OP_MUTEX_LOCK */
__umtx_op_lock_umutex_compat32, /* UMTX_OP_MUTEX_TRYLOCK */
__umtx_op_unlock_umutex, /* UMTX_OP_MUTEX_UNLOCK */
__umtx_op_set_ceiling, /* UMTX_OP_SET_CEILING */
__umtx_op_cv_wait_compat32, /* UMTX_OP_CV_WAIT*/
__umtx_op_cv_signal, /* UMTX_OP_CV_SIGNAL */
__umtx_op_cv_broadcast, /* UMTX_OP_CV_BROADCAST */
__umtx_op_wait_compat32, /* UMTX_OP_WAIT_UINT */
__umtx_op_rw_rdlock_compat32, /* UMTX_OP_RW_RDLOCK */
__umtx_op_rw_wrlock_compat32, /* UMTX_OP_RW_WRLOCK */
__umtx_op_rw_unlock, /* UMTX_OP_RW_UNLOCK */
__umtx_op_wait_uint_private_compat32, /* UMTX_OP_WAIT_UINT_PRIVATE */
__umtx_op_wake_private, /* UMTX_OP_WAKE_PRIVATE */
__umtx_op_wait_umutex_compat32, /* UMTX_OP_UMUTEX_WAIT */
__umtx_op_wake_umutex /* UMTX_OP_UMUTEX_WAKE */
};
int
freebsd32_umtx_op(struct thread *td, struct freebsd32_umtx_op_args *uap)
{
if ((unsigned)uap->op < UMTX_OP_MAX)
return (*op_table_compat32[uap->op])(td,
(struct _umtx_op_args *)uap);
return (EINVAL);
}
#endif
void
umtx_thread_init(struct thread *td)
{
td->td_umtxq = umtxq_alloc();
td->td_umtxq->uq_thread = td;
}
void
umtx_thread_fini(struct thread *td)
{
umtxq_free(td->td_umtxq);
}
/*
* It will be called when new thread is created, e.g fork().
*/
void
umtx_thread_alloc(struct thread *td)
{
struct umtx_q *uq;
uq = td->td_umtxq;
uq->uq_inherited_pri = PRI_MAX;
KASSERT(uq->uq_flags == 0, ("uq_flags != 0"));
KASSERT(uq->uq_thread == td, ("uq_thread != td"));
KASSERT(uq->uq_pi_blocked == NULL, ("uq_pi_blocked != NULL"));
KASSERT(TAILQ_EMPTY(&uq->uq_pi_contested), ("uq_pi_contested is not empty"));
}
/*
* exec() hook.
*/
static void
umtx_exec_hook(void *arg __unused, struct proc *p __unused,
struct image_params *imgp __unused)
{
umtx_thread_cleanup(curthread);
}
/*
* thread_exit() hook.
*/
void
umtx_thread_exit(struct thread *td)
{
umtx_thread_cleanup(td);
}
/*
* clean up umtx data.
*/
static void
umtx_thread_cleanup(struct thread *td)
{
struct umtx_q *uq;
struct umtx_pi *pi;
if ((uq = td->td_umtxq) == NULL)
return;
mtx_lock_spin(&umtx_lock);
uq->uq_inherited_pri = PRI_MAX;
while ((pi = TAILQ_FIRST(&uq->uq_pi_contested)) != NULL) {
pi->pi_owner = NULL;
TAILQ_REMOVE(&uq->uq_pi_contested, pi, pi_link);
}
thread_lock(td);
td->td_flags &= ~TDF_UBORROWING;
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
}
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