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From: "bugdal at aerifal dot cx" <sourceware-bugzilla@sourceware.org> To: glibc-bugs@sources.redhat.com Subject: [Bug nptl/14697] New: Behavior of exit is nonconformant with respect to threads and stdio Date: Wed, 10 Oct 2012 18:04:00 -0000 [thread overview] Message-ID: <bug-14697-131@http.sourceware.org/bugzilla/> (raw) http://sourceware.org/bugzilla/show_bug.cgi?id=14697 Bug #: 14697 Summary: Behavior of exit is nonconformant with respect to threads and stdio Product: glibc Version: unspecified Status: NEW Severity: normal Priority: P2 Component: nptl AssignedTo: unassigned@sourceware.org ReportedBy: bugdal@aerifal.cx CC: drepper.fsp@gmail.com Classification: Unclassified Consider the following program: #include <pthread.h> #include <stdio.h> #include <semaphore.h> #include <stdlib.h> void *f(void *p) { flockfile(stdin); sem_post(p); for (;;) pause(); } int main() { sem_t sem; sem_init(&sem, 0, 0); pthread_create(&(pthread_t){0}, 0, f, &sem); while (sem_wait(&sem)); exit(0); } Per Austin Group interpretation for issue #611 (http://austingroupbugs.net/view.php?id=611), this program should deadlock in exit waiting for the lock it will never obtain. Under glibc/NPTL, it exits immediately. If you'd like to make the example more interesting, you could have the thread wake up after 5 seconds and unlock stdin; in that case, the program should run for at least 5 seconds, rather than exiting immediately. To make it even more interesting, have the thread performing a long-running write operation that's intended to be atomic with respect to other threads and also with respect to program termination (such that on normal program termination, either the entire write happened, or no write happened at all). This bug is due to intentional hackery in glibc to avoid hanging on exit() due to locks being held by other threads, under the wrong assumption that exit() "should" immediately exit in this case. There is no language in the standards to support what glibc is doing. -- Configure bugmail: http://sourceware.org/bugzilla/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
next reply other threads:[~2012-10-10 18:04 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-10 18:04 bugdal at aerifal dot cx [this message] 2014-06-25 6:45 ` [Bug nptl/14697] " fweimer at redhat dot com 2014-10-06 17:51 ` bugdal at aerifal dot cx 2023-06-06 9:43 ` fweimer at redhat dot com 2023-07-03 8:03 ` cvs-commit at gcc dot gnu.org 2023-07-03 9:07 ` fweimer at redhat dot com 2024-02-06 14:38 ` gabravier at gmail dot com
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