[LTP] [PATCH v2] pthread_detach_1-2: Fix failure on modern glibc

[Martin Doucha]

Hi,
this looks like trying to hide a glibc bug to me. I've looked at both 
the POSIX standard and Linux man pages and there is no mention that 
already exited threads may be left joinable. I think we should report 
this as a bug and wait for response from glibc maintainers.

On 5/9/26 09:39, Wei Gao via ltp wrote:
> Latest test in our openqa setup (Linux 7.1-rc2, Glibc 2.43) show following error:
> Test FAILED: We were able to join a detached thread.
> 
> This is triggered by glibc commit 5da15b15adab661c80e373b6af89be0b5fa5b3ad
> ("nptl: Do not use pthread set_tid_address as state synchronization (BZ #19951)").
> 
> New logic remove the logic of check whether valid thread handle in __pthread_clockjoin_ex().
> -  /* Make sure the descriptor is valid.  */
> -  if (INVALID_NOT_TERMINATED_TD_P (pd))
> -    /* Not a valid thread handle.  */
> -    return ESRCH;
> 
> So add a second synchronization semaphore to ensure the child thread remains
> alive until the main thread has completed its checks. This forces glibc
> to see the THREAD_STATE_DETACHED status and correctly return EINVAL.
> 
> Signed-off-by: Wei Gao <wegao@suse.com>
> ---
> v1->v2:
> - Update commit message for root cause detail
> 
>   .../interfaces/pthread_detach/1-2.c           | 25 +++++++++++++++++++
>   1 file changed, 25 insertions(+)
> 
> diff --git a/testcases/open_posix_testsuite/conformance/interfaces/pthread_detach/1-2.c b/testcases/open_posix_testsuite/conformance/interfaces/pthread_detach/1-2.c
> index dc5ed39d3..1a9650f49 100644
> --- a/testcases/open_posix_testsuite/conformance/interfaces/pthread_detach/1-2.c
> +++ b/testcases/open_posix_testsuite/conformance/interfaces/pthread_detach/1-2.c
> @@ -92,6 +92,7 @@
>   /********************************************************************************************/
>   
>   static unsigned int sc;
> +static sem_t sem_exit;
>   
>   static void *threaded(void *arg)
>   {
> @@ -113,6 +114,15 @@ static void *threaded(void *arg)
>   		UNRESOLVED(errno, "Failed to post the semaphore");
>   	}
>   
> +	/* Wait for the main thread to allow exit */
> +	do {
> +		ret = sem_wait(&sem_exit);
> +	}
> +	while ((ret == -1) && (errno == EINTR));
> +	if (ret == -1) {
> +		UNRESOLVED(errno, "Failed to wait for the exit semaphore");
> +	}
> +
>   	return arg;
>   }
>   
> @@ -125,6 +135,11 @@ int test_main(int argc PTS_ATTRIBUTE_UNUSED, char **argv PTS_ATTRIBUTE_UNUSED)
>   
>   	scenar_init();
>   
> +	ret = sem_init(&sem_exit, 0, 0);
> +	if (ret != 0) {
> +		UNRESOLVED(errno, "Failed to init the exit semaphore");
> +	}
> +
>   	for (sc = 0; sc < NSCENAR; sc++) {
>   #if VERBOSE > 0
>   		output("-----\n");
> @@ -202,11 +217,21 @@ int test_main(int argc PTS_ATTRIBUTE_UNUSED, char **argv PTS_ATTRIBUTE_UNUSED)
>   				    ("We were able to join a detached thread.");
>   			}
>   
> +			/* Allow the thread to exit */
> +			do {
> +				ret = sem_post(&sem_exit);
> +			}
> +			while ((ret == -1) && (errno == EINTR));
> +			if (ret == -1) {
> +				UNRESOLVED(errno, "Failed to post the exit semaphore");
> +			}
> +
>   			/* Let the thread an additionnal row to cleanup */
>   			sched_yield();
>   		}
>   	}
>   
> +	sem_destroy(&sem_exit);
>   	scenar_fini();
>   #if VERBOSE > 0
>   	output("-----\n");


-- 
Martin Doucha   mdoucha@suse.cz
SW Quality Engineer
SUSE LINUX, s.r.o.
CORSO IIa
Krizikova 148/34
186 00 Prague 8
Czech Republic