If a single 32-bit variable is shared between multiple threads, should I put a mutex lock around the variable? For example, suppose 1 thread writes to a 32-bit counter and a 2nd thread reads it. Is there any chance the 2nd thread could read a corrupted value?
I'm working on a 32-bit ARM embedded system. The compiler always seems to align 32-bit variables so they can be read or written with a single instruction. If the 32-bit variable was not aligned, then the read or write would be broken down into multiple instructions and the 2nd thread could read a corrupted value.
Does the answer to this question change if I move to a multiple-core system in the future and the variable is shared between cores? (assuming a shared cache between cores)
Thanks!