>Number:         25722
>Category:       lib
>Synopsis:       pthread assertion failure in deadlock situation
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu May 27 07:15:01 UTC 2004
>Closed-Date:
>Last-Modified:
>Originator:     TAMURA Kent
>Release:        NetBSD-current (2.0F)
>Organization:
NetBSD
>Environment:
>Description:
libpthread throws assertion failure when a thread deadlocks by
pthread_mutex_lock() and there are no other threads.

>How-To-Repeat:
--------- mutex.c
#include <pthread.h>

pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

int main() {
    printf("lock 1\n");
    pthread_mutex_lock(&mutex);
    printf("lock 2\n");
    pthread_mutex_lock(&mutex);
    printf("exit\n");
    return 0;
}
--------
% cc -o mutex mutex.c -lpthread
% ./mutex
lock 1
lock 2
assertion "next != 0" failed: file "/usr/src/lib/libpthread/pthread_run.c", line 130, function "pthread__next"
zsh: abort (core dumped)  ./mutex
backtrace is:
#0  0x4808c26b in kill () from /usr/lib/libc.so.12
#1  0x4806b772 in pthread__assertfunc () from /usr/lib/libpthread.so.0
#2  0x48067e4c in pthread__next () from /usr/lib/libpthread.so.0
#3  0x48067cf5 in pthread__block () from /usr/lib/libpthread.so.0
#4  0x480688d6 in pthread_mutex_lock () from /usr/lib/libpthread.so.0
#5  0x48068797 in pthread_mutex_lock () from /usr/lib/libpthread.so.0
#6  0x08048859 in main ()
#7  0x080485b2 in ___start ()


Note that mutex.c is wrong code definitely.  But, according to SUS v3,
the code should cause deadlock at the second pthread_mutex_lock(), and
assertion failure should not occur anyway.

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: