Semaphore Program results in Deadlock - deadlock

Question

I was told to write a program to make two processes which will synchronize with each other to print '00110011...'
I have the following code:
#include"headers.h"
int main(int argc, char* argv[]){
sem_t smid;
if(sem_init(&smid, 1, 1)<0){
perror("sem_init");
exit(EXIT_FAILURE);
}
int pid = fork();
if(pid == 0){
//child process
while(1){
if(sem_wait(&smid)<0){
perror("sem_wait");
exit(EXIT_FAILURE);
}
printf("00");
sleep(1);
if(sem_post(&smid)<0){
perror("sem post");
exit(EXIT_FAILURE);
}
}
}else{
while(1){
if(sem_wait(&smid)<0){
perror("sem_wait");
exit(EXIT_FAILURE);
}
printf("11");
sleep(1);
if(sem_post(&smid)<0){
perror("sem post");
exit(EXIT_FAILURE);
}
}
}
return 0;
}
header.s:
#include<stdlib.h>
#include<stdio.h>
#include<semaphore.h>
#include<unistd.h>
The above code results in a deadlock and I can't understand why.
P.S. I have noticed that the deadlock is removed when I remove both the sleep() function calls.
I need to understand where I am going wrong. Any help is appreciated. Thanks in advance.