Re: [LAD] a *simple* ring buffer, comments pls?

Yes, the hardware would be allowed to reorder them, so pthread_mutex_lock() has memory barriers. I think everyone knew that much :) However my point to Fons was that, because pthread_mutex_lock() is an external function, the compiler is not allowed to make any assumptions about the global variable x (both functions might modify it): it cannot re-read x after unlock(), or read x before lock(). This was the missing ingredient. So it's a cooperation of sequence point-rules and memory barriers that achieves the effects of a critical section in C. So in 10 years we will be able to rely on a conformant compiler being available on all relevant platforms :) -- Dan