Linux Kernel Atomic Operations with Memory Barriers - linux-kernel

Question

I am trying to better understand memory barriers in the Linux Kernel. I am wondering if my implementation below would result in valid atomic operations if these threads ran in parallel. I am not focusing on a specific architecture in this implementation...I would want this to work for any architecture. Basically my implementation has a smp_mb() after any write operation and barrier() before any read operation. And if this implementation would not work, would it work for a single writer thread with one or many reader threads?
int a = 0;
int *b = &a;
int c;
#define my_atomic_set(var, val) { \
*var = val; \
smp_mb(); \
}
#define my_atomic_set_ret(var, val) { \
barrier(); \
int ret = *var; \
*var = val; \
smp_mb(); \
ret;
}
#define my_atomic_add(var, val) { \
barrier(); \
int tmp = *var; \
*var = tmp + val; \
smp_mb(); \
}
#define my_atomic_get(var) { \
barrier(); \
*var; \
}
void thread1_func() {
my_atomic_add(b, 1);
my_atomic_set(b, 2);
}
void thread2_func() {
my_atomic_set(b, 3);
my_atomic_add(b, 4);
}
void thread3_func() {
c = my_atomic_get(b);
c = my_atomic_set_ret(b, 10);
}
void thread4_func() {
c = my_atomic_get(b);
c = my_atomic_get(b);
}