Author: kib
Date: Sat Feb 28 04:19:02 2015
New Revision: 279390
URL: https://svnweb.freebsd.org/changeset/base/279390
Log:
The umtx_lock mutex is used by top-half of the kernel, but is
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
Modified:
head/sys/kern/kern_exit.c
head/sys/kern/kern_kthread.c
head/sys/kern/kern_thr.c
head/sys/kern/kern_thread.c
head/sys/kern/kern_umtx.c
head/sys/kern/subr_witness.c
Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c Sat Feb 28 00:31:01 2015 (r279389)
+++ head/sys/kern/kern_exit.c Sat Feb 28 04:19:02 2015 (r279390)
@@ -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);
Modified: head/sys/kern/kern_kthread.c
==============================================================================
--- head/sys/kern/kern_kthread.c Sat Feb 28 00:31:01 2015
(r279389)
+++ head/sys/kern/kern_kthread.c Sat Feb 28 04:19:02 2015
(r279390)
@@ -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();
}
Modified: head/sys/kern/kern_thr.c
==============================================================================
--- head/sys/kern/kern_thr.c Sat Feb 28 00:31:01 2015 (r279389)
+++ head/sys/kern/kern_thr.c Sat Feb 28 04:19:02 2015 (r279390)
@@ -322,6 +322,7 @@ sys_thr_exit(struct thread *td, struct t
LIST_REMOVE(td, td_hash);
rw_wunlock(&tidhash_lock);
tdsigcleanup(td);
+ umtx_thread_exit(td);
PROC_SLOCK(p);
thread_stopped(p);
thread_exit();
Modified: head/sys/kern/kern_thread.c
==============================================================================
--- head/sys/kern/kern_thread.c Sat Feb 28 00:31:01 2015 (r279389)
+++ head/sys/kern/kern_thread.c Sat Feb 28 04:19:02 2015 (r279390)
@@ -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();
Modified: head/sys/kern/kern_umtx.c
==============================================================================
--- head/sys/kern/kern_umtx.c Sat Feb 28 00:31:01 2015 (r279389)
+++ head/sys/kern/kern_umtx.c Sat Feb 28 04:19:02 2015 (r279390)
@@ -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
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
/*
* 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
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
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
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
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
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 u
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 u
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 u
* 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 umu
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 umu
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 umu
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 umu
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 umu
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 u
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 u
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);
Modified: head/sys/kern/subr_witness.c
==============================================================================
--- head/sys/kern/subr_witness.c Sat Feb 28 00:31:01 2015
(r279389)
+++ head/sys/kern/subr_witness.c Sat Feb 28 04:19:02 2015
(r279390)
@@ -492,6 +492,11 @@ static struct witness_order_list_entry o
{ "time lock", &lock_class_mtx_sleep },
{ NULL, NULL },
/*
+ * umtx
+ */
+ { "umtx lock", &lock_class_mtx_sleep },
+ { NULL, NULL },
+ /*
* Sockets
*/
{ "accept", &lock_class_mtx_sleep },
@@ -637,7 +642,6 @@ static struct witness_order_list_entry o
#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 },
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