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The umtx_lock mutex is used by top-half of the kernel, but is

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currently a spin lock.  Apparently, the only reason for this is that
umtx_thread_exit() is called under the process spinlock, which put the
requirement on the umtx_lock.  Note that the witness static order list
is wrong for the umtx_lock, umtx_lock is explicitely before any thread
lock, so it is also before sleepq locks.

Change umtx_lock to be the sleepable mutex.  For the reason above, the
calls to umtx_thread_exit() are moved from thread_exit() earlier in
each caller, when the process spin lock is not yet taken.

Discussed with:	jhb
Tested by:	pho (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	3 weeks
This commit is contained in:
Konstantin Belousov 2015-02-28 04:19:02 +00:00
parent c483877531
commit 13dad10871
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=279390
6 changed files with 42 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/kern/kern_exit.c
View File

@ -71,6 +71,7 @@ __FBSDID("$FreeBSD$");
#include <sys/sdt.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/umtx.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
@ -633,6 +634,7 @@ exit1(struct thread *td, int rv)
wakeup(p->p_pptr);
cv_broadcast(&p->p_pwait);
sched_exit(p->p_pptr, td);
umtx_thread_exit(td);
PROC_SLOCK(p);
p->p_state = PRS_ZOMBIE;
PROC_UNLOCK(p->p_pptr);

2
sys/kern/kern_kthread.c
View File

@ -38,6 +38,7 @@ __FBSDID("$FreeBSD$");
#include <sys/rwlock.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/umtx.h>
#include <sys/unistd.h>
#include <sys/wait.h>
#include <sys/sched.h>
@ -339,6 +340,7 @@ kthread_exit(void)
}
LIST_REMOVE(curthread, td_hash);
rw_wunlock(&tidhash_lock);
umtx_thread_exit(curthread);
PROC_SLOCK(p);
thread_exit();
}

1
sys/kern/kern_thr.c
View File

@ -322,6 +322,7 @@ sys_thr_exit(struct thread *td, struct thr_exit_args *uap)
LIST_REMOVE(td, td_hash);
rw_wunlock(&tidhash_lock);
tdsigcleanup(td);
umtx_thread_exit(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();

2
sys/kern/kern_thread.c
View File

@ -413,7 +413,6 @@ thread_exit(void)
#ifdef AUDIT
AUDIT_SYSCALL_EXIT(0, td);
#endif
umtx_thread_exit(td);
/*
* drop FPU & debug register state storage, or any other
* architecture specific resources that
@ -864,6 +863,7 @@ thread_suspend_check(int return_instead)
tidhash_remove(td);
PROC_LOCK(p);
tdsigcleanup(td);
umtx_thread_exit(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();

62
sys/kern/kern_umtx.c
View File

@ -396,7 +396,7 @@ umtxq_sysinit(void *arg __unused)
#ifdef UMTX_PROFILING
umtx_init_profiling();
#endif
mtx_init(&umtx_lock, "umtx lock", NULL, MTX_SPIN);
mtx_init(&umtx_lock, "umtx lock", NULL, MTX_DEF);
EVENTHANDLER_REGISTER(process_exec, umtx_exec_hook, NULL,
EVENTHANDLER_PRI_ANY);
}
@ -1467,9 +1467,9 @@ 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);
mtx_lock(&umtx_lock);
if (pi->pi_owner == owner) {
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
return (0);
}
@ -1477,7 +1477,7 @@ umtx_pi_claim(struct umtx_pi *pi, struct thread *owner)
/*
* userland may have already messed the mutex, sigh.
*/
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
return (EPERM);
}
umtx_pi_setowner(pi, owner);
@ -1491,7 +1491,7 @@ umtx_pi_claim(struct umtx_pi *pi, struct thread *owner)
sched_lend_user_prio(owner, pri);
thread_unlock(owner);
}
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
return (0);
}
@ -1506,7 +1506,7 @@ umtx_pi_adjust(struct thread *td, u_char oldpri)
struct umtx_pi *pi;
uq = td->td_umtxq;
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
/*
* Pick up the lock that td is blocked on.
*/
@ -1515,7 +1515,7 @@ umtx_pi_adjust(struct thread *td, u_char oldpri)
umtx_pi_adjust_thread(pi, td);
umtx_repropagate_priority(pi);
}
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
}
/*
@ -1537,12 +1537,12 @@ umtxq_sleep_pi(struct umtx_q *uq, struct umtx_pi *pi,
UMTXQ_LOCKED_ASSERT(uc);
KASSERT(uc->uc_busy != 0, ("umtx chain is not busy"));
umtxq_insert(uq);
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (pi->pi_owner == NULL) {
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
/* XXX Only look up thread in current process. */
td1 = tdfind(owner, curproc->p_pid);
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (td1 != NULL) {
if (pi->pi_owner == NULL)
umtx_pi_setowner(pi, td1);
@ -1566,20 +1566,20 @@ umtxq_sleep_pi(struct umtx_q *uq, struct umtx_pi *pi,
td->td_flags |= TDF_UPIBLOCKED;
thread_unlock(td);
umtx_propagate_priority(td);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
umtxq_unbusy(&uq->uq_key);
error = umtxq_sleep(uq, wmesg, timo);
umtxq_remove(uq);
mtx_lock_spin(&umtx_lock);
mtx_lock(&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_repropagate_priority(pi);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
umtxq_unlock(&uq->uq_key);
return (error);
@ -1611,7 +1611,7 @@ umtx_pi_unref(struct umtx_pi *pi)
UMTXQ_LOCKED_ASSERT(uc);
KASSERT(pi->pi_refcount > 0, ("invalid reference count"));
if (--pi->pi_refcount == 0) {
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (pi->pi_owner != NULL) {
TAILQ_REMOVE(&pi->pi_owner->td_umtxq->uq_pi_contested,
pi, pi_link);
@ -1619,7 +1619,7 @@ umtx_pi_unref(struct umtx_pi *pi)
}
KASSERT(TAILQ_EMPTY(&pi->pi_blocked),
("blocked queue not empty"));
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
TAILQ_REMOVE(&uc->uc_pi_list, pi, pi_hashlink);
umtx_pi_free(pi);
}
@ -1873,11 +1873,11 @@ do_unlock_pi(struct thread *td, struct umutex *m, uint32_t flags)
umtxq_busy(&key);
count = umtxq_count_pi(&key, &uq_first);
if (uq_first != NULL) {
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
pi = uq_first->uq_pi_blocked;
KASSERT(pi != NULL, ("pi == NULL?"));
if (pi->pi_owner != curthread) {
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
umtxq_unbusy(&key);
umtxq_unlock(&key);
umtx_key_release(&key);
@ -1903,7 +1903,7 @@ do_unlock_pi(struct thread *td, struct umutex *m, uint32_t flags)
thread_lock(curthread);
sched_lend_user_prio(curthread, pri);
thread_unlock(curthread);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
if (uq_first)
umtxq_signal_thread(uq_first);
} else {
@ -1920,10 +1920,10 @@ do_unlock_pi(struct thread *td, struct umutex *m, uint32_t flags)
* umtx_pi, and unlocked the umtxq.
* If the current thread owns it, it must disown it.
*/
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (pi->pi_owner == td)
umtx_pi_disown(pi);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
}
}
umtxq_unlock(&key);
@ -1986,9 +1986,9 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
goto out;
}
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (UPRI(td) < PRI_MIN_REALTIME + ceiling) {
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
error = EINVAL;
goto out;
}
@ -1999,7 +1999,7 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
sched_lend_user_prio(td, uq->uq_inherited_pri);
thread_unlock(td);
}
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
rv = casueword32(&m->m_owner,
UMUTEX_CONTESTED, &owner, id | UMUTEX_CONTESTED);
@ -2034,7 +2034,7 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
umtxq_remove(uq);
umtxq_unlock(&uq->uq_key);
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
uq->uq_inherited_pri = old_inherited_pri;
pri = PRI_MAX;
TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
@ -2049,11 +2049,11 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
thread_lock(td);
sched_lend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
}
if (error != 0) {
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
uq->uq_inherited_pri = old_inherited_pri;
pri = PRI_MAX;
TAILQ_FOREACH(pi, &uq->uq_pi_contested, pi_link) {
@ -2068,7 +2068,7 @@ do_lock_pp(struct thread *td, struct umutex *m, uint32_t flags,
thread_lock(td);
sched_lend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
}
out:
@ -2140,7 +2140,7 @@ do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags)
if (error == -1)
error = EFAULT;
else {
mtx_lock_spin(&umtx_lock);
mtx_lock(&umtx_lock);
if (su != 0)
uq->uq_inherited_pri = new_inherited_pri;
pri = PRI_MAX;
@ -2156,7 +2156,7 @@ do_unlock_pp(struct thread *td, struct umutex *m, uint32_t flags)
thread_lock(td);
sched_lend_user_prio(td, pri);
thread_unlock(td);
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
}
umtx_key_release(&key);
return (error);
@ -3841,13 +3841,13 @@ umtx_thread_cleanup(struct thread *td)
if ((uq = td->td_umtxq) == NULL)
return;
mtx_lock_spin(&umtx_lock);
mtx_lock(&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);
}
mtx_unlock_spin(&umtx_lock);
mtx_unlock(&umtx_lock);
thread_lock(td);
sched_lend_user_prio(td, PRI_MAX);
thread_unlock(td);

6
sys/kern/subr_witness.c
View File

@ -491,6 +491,11 @@ static struct witness_order_list_entry order_lists[] = {
#endif
{ "time lock", &lock_class_mtx_sleep },
{ NULL, NULL },
/*
* umtx
*/
{ "umtx lock", &lock_class_mtx_sleep },
{ NULL, NULL },
/*
* Sockets
*/
@ -637,7 +642,6 @@ static struct witness_order_list_entry order_lists[] = {
#endif
{ "process slock", &lock_class_mtx_spin },
{ "sleepq chain", &lock_class_mtx_spin },
{ "umtx lock", &lock_class_mtx_spin },
{ "rm_spinlock", &lock_class_mtx_spin },
{ "turnstile chain", &lock_class_mtx_spin },
{ "turnstile lock", &lock_class_mtx_spin },