Question

When I run the following super-simple program, I get errors detected in valgrind drd.
Whose error is it? pthreads? valgrind? me?

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>

pthread_barrier_t barrier1;    

void * wait_for_barrier(void *args)
{
    pthread_barrier_wait(&barrier1);
    return 0;
}

int main (int argc, char *argv[])
{
    pthread_t t;
    pthread_barrier_init(&barrier1, NULL, 2);
    pthread_create(&t, NULL, wait_for_barrier, 0);
    wait_for_barrier(NULL);
    pthread_join(t, NULL);
    return 0;
}

When I compile & profile with:

gcc testbar.c -O3 -g -lpthread && valgrind --tool=drd  ./a.out

I see

…

==28089== Conflicting load by thread 1 at 0x00601088 size 4

==28089==    at 0x4E44E9E: pthread_barrier_wait (pthread_barrier_wait.S:40)

==28089==    by 0x40079B: main (testbar.c:24)

…

I am on Ubuntu 11.10 x86_64. Using valgrind-3.6.1-Debian and gcc 4.6.1-9ubuntu3

Answer 1

It works well. I am using valgrind-3.7.0 and gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 on Linux Mint 13.