arm: getpid() when creating a new process with clone, getpid() returns a wrong pid.

[wangyufen]

 Called getpid() When creating a new process with clone(), getpid() returns the father_process's value. 
 It should be child_process's value.


I use that code do test:
#include <errno.h>
#include <stdio.h>
#include <sched.h>
#include <string.h>

#define CHILD_STACK_SIZE 16384

int child_fn(void *test)
{
    printf("child=%d\n", getpid());
    exit(1);
}

int main(int ac, char **av)
{
    int TEST_RETURN;
	void *child_stack;	/* stack for child */
	int child_pid;

	/* Allocate stack for child */
	if ((child_stack = (void *)malloc(CHILD_STACK_SIZE)) == NULL) {
	    exit(1);
    }
        
    TEST_RETURN = clone(child_fn, child_stack + CHILD_STACK_SIZE, 0, NULL);
	printf("clone return=%d\n", TEST_RETURN);
    if (TEST_RETURN == -1) {
        exit(1);
    }
    printf("father=%d\n", getpid());

    return 0;
}

compiled that code with -g -lpthread, run, child pid  is wrong
#arm-linux-uclibceabi-gcc -g -lpthread -o test1 test.c
# ./test1
clone return=406
child=405
father=405

compiled that code with -g , run, child pid  is OK
#arm-linux-uclibceabi-gcc -g -o test test.c
-bash-4.2# ./test
clone return=404
child=404
father=403

I do some strace and gdb on test1 and test, test uses syscall getpid(), test1(compiled with -lpthread) get pid from [r2, #-1060]