Date: Thu, 24 May 2012 19:40:34 GMT From: Alexis Ballier <aballier@gentoo.org> To: freebsd-gnats-submit@FreeBSD.org Subject: threads/168317: libthr: posix_mutex_trylock does not work with a PTHREAD_MUTEX_ADAPTIVE_NP thread Message-ID: <201205241940.q4OJeYih078251@red.freebsd.org> Resent-Message-ID: <201205241950.q4OJo90g067897@freefall.freebsd.org>
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>Number: 168317
>Category: threads
>Synopsis: libthr: posix_mutex_trylock does not work with a PTHREAD_MUTEX_ADAPTIVE_NP thread
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-threads
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu May 24 19:50:08 UTC 2012
>Closed-Date:
>Last-Modified:
>Originator: Alexis Ballier
>Release: 9.0-RELEASE
>Organization:
Gentoo
>Environment:
FreeBSD fbsd 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue Jan 3 07:46:30 UTC 2012 root@farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64
>Description:
I discovered this running glib-2.32.3 testsuite.
If I feed pthread_mutex_trylock with a PTHREAD_MUTEX_ADAPTIVE_NP thread, it returns EINVAL instead of EBUSY if it fails to lock.
Reduced testcase:
# cat mutex.c
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
int main() {
pthread_mutex_t mutex;
pthread_mutexattr_t attr;
int status;
pthread_mutexattr_init (&attr);
pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_ADAPTIVE_NP);
status = pthread_mutex_init (&mutex, &attr);
printf("status = %i\n", status);
status = pthread_mutex_trylock(&mutex);
printf("status = %i\n", status);
status = pthread_mutex_trylock(&mutex);
printf("status = %i\n", status);
printf("%s\n", strerror(status));
}
# gcc -pthread mutex.c -o mutex
# ./mutex
status = 0
status = 0
status = 22
Invalid argument
However, with a PTHREAD_MUTEX_NORMAL thread it is fine:
# cat mutex2.c
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>
int main() {
pthread_mutex_t mutex;
pthread_mutexattr_t attr;
int status;
pthread_mutexattr_init (&attr);
pthread_mutexattr_settype (&attr, PTHREAD_MUTEX_NORMAL);
status = pthread_mutex_init (&mutex, &attr);
printf("status = %i\n", status);
status = pthread_mutex_trylock(&mutex);
printf("status = %i\n", status);
status = pthread_mutex_trylock(&mutex);
printf("status = %i\n", status);
printf("%s\n", strerror(status));
}
# gcc -pthread mutex2.c -o mutex2
# ./mutex2
status = 0
status = 0
status = 16
Device busy
Some investigation showed that svn rev 173154 got that right but then svn rev 173173 removed this.
>How-To-Repeat:
Try the above testcases, or run glib-2.32.3 testsuite, or watch bailing out any glib based program using trylock.
>Fix:
I'm attaching a patch against head that sould fix this.
Patch attached with submission follows:
Index: lib/libthr/thread/thr_mutex.c
===================================================================
--- lib/libthr/thread/thr_mutex.c (revision 235924)
+++ lib/libthr/thread/thr_mutex.c (working copy)
@@ -538,6 +538,7 @@
switch (PMUTEX_TYPE(m->m_flags)) {
case PTHREAD_MUTEX_ERRORCHECK:
case PTHREAD_MUTEX_NORMAL:
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
ret = EBUSY;
break;
>Release-Note:
>Audit-Trail:
>Unformatted:
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