Date: Wed, 19 Apr 2000 19:32:46 +0200 (CEST) From: cejkar@dcse.fee.vutbr.cz To: FreeBSD-gnats-submit@freebsd.org Subject: bin/18099: Bug-fixes to pthread_cond_*() (uthread_cond.c) Message-ID: <200004191732.e3JHWko12798@kazi.dcse.fee.vutbr.cz>
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>Number: 18099
>Category: bin
>Synopsis: Bug-fixes to pthread_cond_*() (uthread_cond.c)
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Apr 19 10:40:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator: Rudolf Cejka
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
Brno University of Technology, FEE&CS, Czech Republic
>Environment:
5.0-CURRENT and possibly all other branches.
>Description:
Here is small testing program (-pthread):
--
#define _THREAD_SAFE
#include <err.h>
#include <pthread.h>
#include <stdio.h>
pthread_t tid;
pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
/* ARGSUSED */
void *test(void *dummy)
{
if (pthread_cond_broadcast(&cond) != 0)
warnx("pthread_cond_broadcast()");
if (pthread_cond_timedwait(&cond, NULL, NULL) != 0)
warnx("pthread_cond_timedwait()");
return NULL;
}
int main(void)
{
if (pthread_create(&tid, NULL, test, NULL) != 0)
errx(1, "pthread_create()");
if (pthread_join(tid, NULL) != 0)
errx(1, "pthread_join()");
return 0;
}
--
According to standards, pthread_cond_broadcast() should do nothing
without any error. And I think pthread_cond_timedwait() should not
produce a coredump. But if you run it, you get:
--
tst: pthread_cond_broadcast()
Segmentation fault (core dumped)
--
If you apply following patch, you get only:
--
tst: pthread_cond_timedwait()
--
a) pthread_cond_broadcast() will not produce any error: the problem
occurs only when condition is initialized statically and have not
been used (= allocated) before - maybe this is artifical example, but
I had a problem with this in a real situation (on Solaris it works
fine but on FreeBSD before patch it doesn't)
(second and third chunk of patch for pthread_cond_signal() and
pthread_cond_broadcast() functions)
b) pthread_cond_timedwait() will produce error only instead of coredump;
if you look into sources, it really looks as a copy & paste & insert bug
(first chunk of patch)
>How-To-Repeat:
>Fix:
--- src/lib/libc_r/uthread/uthread_cond.c.orig Wed Apr 19 18:52:04 2000
+++ src/lib/libc_r/uthread/uthread_cond.c Wed Apr 19 18:52:04 2000
@@ -308,19 +308,14 @@
if (cond == NULL || abstime == NULL)
rval = EINVAL;
-
- if (abstime->tv_sec < 0 ||
- abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) {
- errno = EINVAL;
- _thread_leave_cancellation_point();
- return (-1);
- }
-
+ else if (abstime->tv_sec < 0 ||
+ abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
+ rval = EINVAL;
/*
* If the condition variable is statically initialized,
* perform the dynamic initialization:
*/
- if (*cond != NULL ||
+ else if (*cond != NULL ||
(rval = pthread_cond_init(cond,NULL)) == 0) {
_thread_enter_cancellation_point();
@@ -473,9 +468,14 @@
int rval = 0;
pthread_t pthread;
- if (cond == NULL || *cond == NULL)
+ if (cond == NULL)
rval = EINVAL;
- else {
+ /*
+ * If the condition variable is statically initialized,
+ * perform the dynamic initialization:
+ */
+ else if (*cond != NULL ||
+ (rval = pthread_cond_init(cond, NULL)) == 0) {
/*
* Defer signals to protect the scheduling queues
* from access by the signal handler:
@@ -525,9 +525,14 @@
int rval = 0;
pthread_t pthread;
- if (cond == NULL || *cond == NULL)
+ if (cond == NULL)
rval = EINVAL;
- else {
+ /*
+ * If the condition variable is statically initialized,
+ * perform the dynamic initialization:
+ */
+ else if (*cond != NULL ||
+ (rval = pthread_cond_init(cond,NULL)) == 0) {
/*
* Defer signals to protect the scheduling queues
* from access by the signal handler:
>Release-Note:
>Audit-Trail:
>Unformatted:
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