Hello,

My application using musl libc runs into a seg fault if I call pthread_detach after pthread_join on the same thread. From my understanding pthread_detach should return ESRCH if a previous join was called on a particular thread. That’s the correct behavior I see if I run my program with glibc. But on my LEDE based router I run into the seg fault issue.

The cross compiling toolchain I use is arm_cortex-a9+neon_gcc-5.4.0_musl-1.1.16_eabi. Simple example I used for testing is below.

#include <stdio.h>

#include <errno.h>

#include <stdlib.h>

#include <pthread.h>

void *print_message_function( void *ptr );

int main()

{

     pthread_t thread1, thread2;

     const char *message1 = "Thread 1";

     const char *message2 = "Thread 2";

     int  iret1, iret2;

     int dret1, dret2;

     iret1 = pthread_create( &thread1, NULL, &print_message_function, (void*) message1);

     if(iret1)

     {

         fprintf(stderr,"Error - pthread_create() return code: %d\n",iret1);

         exit(EXIT_FAILURE);

     }

     iret2 = pthread_create( &thread2, NULL, &print_message_function, (void*) message2);

     if(iret2)

     {

         fprintf(stderr,"Error - pthread_create() return code: %d\n",iret2);

         exit(EXIT_FAILURE);

     }

     printf("pthread_create() for thread 1 returns: %d\n",iret1);

     printf("pthread_create() for thread 2 returns: %d\n",iret2);

     pthread_join( thread1, NULL);

     pthread_join( thread2, NULL);

     dret1 =  pthread_detach(thread1);

     if (dret1 == EINVAL) {

          printf("got EINVAL when detaching 1\n");

     }

     if (dret1 ==  ESRCH) {

          printf("got ESRCH when detaching 1\n");

     }

     dret2 = pthread_detach(thread2);

     if (dret2 == EINVAL) {

          printf("got EINVAL when detaching 2\n");

     }

     if (dret2 ==  ESRCH) {

          printf("got ESRCH when detaching 2\n");

     }

     return 0;

}

void *print_message_function( void *ptr )

{

     char *message;

     message = (char *) ptr;

     printf("%s \n", message);

}

Output gotten

pthread_create() for thread 1 returns: 0

Thread 1

pthread_create() for thread 2 returns: 0

Thread 2

Segmentation fault (core dumped)

Regards

Salman