Date: Tue, 20 Oct 1998 18:24:42 +0400 From: Dmitrij Tejblum <tejblum@arc.hq.cti.ru> To: "Richard Seaman, Jr." <lists@tar.com> Cc: "HighWind Software Information" <info@highwind.com>, "current@freebsd.org" <current@FreeBSD.ORG> Subject: Re: Another Serious libc_r problem Message-ID: <199810201424.SAA29616@arc.hq.cti.ru> In-Reply-To: Your message of "Tue, 20 Oct 1998 08:30:30 CDT." <199810201330.IAA09508@ns.tar.com>
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> On Tue, 20 Oct 98 08:01:12 -0500, Richard Seaman, Jr. wrote:
>
> >I will try to look at this later, if I have time. However, there are
> >others who know a lot more about this than I do who could probably
> >do a better fix.
>
> You could try the following patch. However, someone else should look at
> it too before its committed.
Heh. I was just about post a very similar patch when received your posting.
I think, howewer, that your patch is slightly wrong, so I will post mine
anyway. As far as I understand, it is better to do pthread_mutex_unlock and
_thread_queue_enc under same _SPINLOCK. (I'm afraid, there is still some
races in this code).
Here is my patch:
*** uthread_cond.c Tue Oct 20 13:55:49 1998
--- uthread_cond.c Tue Oct 20 14:14:55 1998
***************
*** 137,149 ****
*/
else if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
- /* Lock the condition variable structure: */
- _SPINLOCK(&(*cond)->lock);
-
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
/*
* Queue the running thread for the condition
* variable:
--- 137,152 ----
*/
else if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
case COND_TYPE_FAST:
+ /* Wait forever: */
+ _thread_run->wakeup_time.tv_sec = -1;
+
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
/*
* Queue the running thread for the condition
* variable:
***************
*** 151,173 ****
_thread_queue_enq(&(*cond)->c_queue, _thread_run);
/* Unlock the mutex: */
! pthread_mutex_unlock(mutex);
!
! /* Wait forever: */
! _thread_run->wakeup_time.tv_sec = -1;
!
! /* Unlock the condition variable structure: */
! _SPINUNLOCK(&(*cond)->lock);
! /* Schedule the next thread: */
! _thread_kern_sched_state(PS_COND_WAIT,
! __FILE__, __LINE__);
! /* Lock the condition variable structure: */
! _SPINLOCK(&(*cond)->lock);
! /* Lock the mutex: */
! rval = pthread_mutex_lock(mutex);
break;
/* Trap invalid condition variable types: */
--- 154,180 ----
_thread_queue_enq(&(*cond)->c_queue, _thread_run);
/* Unlock the mutex: */
! if ((rval = pthread_mutex_unlock(mutex)) != 0) {
! /*
! * Cannot unlock the mutex, so remove the
! * running thread from the condition
! * variable queue:
! */
! _thread_queue_deq(&(*cond)->c_queue);
! /* Unlock the condition variable structure: */
! _SPINUNLOCK(&(*cond)->lock);
! } else {
! /* Unlock the condition variable structure: */
! _SPINUNLOCK(&(*cond)->lock);
! /* Schedule the next thread: */
! _thread_kern_sched_state(PS_COND_WAIT,
! __FILE__, __LINE__);
! /* Lock the mutex: */
! rval = pthread_mutex_lock(mutex);
! }
break;
/* Trap invalid condition variable types: */
***************
*** 177,184 ****
break;
}
- /* Unlock the condition variable structure: */
- _SPINUNLOCK(&(*cond)->lock);
}
/* Return the completion status: */
--- 184,189 ----
***************
*** 201,209 ****
*/
else if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
- /* Lock the condition variable structure: */
- _SPINLOCK(&(*cond)->lock);
-
/* Process according to condition variable type: */
switch ((*cond)->c_type) {
/* Fast condition variable: */
--- 206,211 ----
***************
*** 215,220 ****
--- 217,225 ----
/* Reset the timeout flag: */
_thread_run->timeout = 0;
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
/*
* Queue the running thread for the condition
* variable:
***************
*** 229,234 ****
--- 234,242 ----
* variable queue:
*/
_thread_queue_deq(&(*cond)->c_queue);
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
} else {
/* Unlock the condition variable structure: */
_SPINUNLOCK(&(*cond)->lock);
***************
*** 237,245 ****
_thread_kern_sched_state(PS_COND_WAIT,
__FILE__, __LINE__);
- /* Lock the condition variable structure: */
- _SPINLOCK(&(*cond)->lock);
-
/* Lock the mutex: */
if ((rval = pthread_mutex_lock(mutex)) != 0) {
}
--- 245,250 ----
***************
*** 258,265 ****
break;
}
- /* Unlock the condition variable structure: */
- _SPINUNLOCK(&(*cond)->lock);
}
/* Return the completion status: */
--- 263,268 ----
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