Reentrant code / Critical section / Atomic Section

["Daniel Rodrick" <daniel.rodrick@xxxxxxxxx>]

Hi,

Can some body please confirm my understanding?

"Reentrant code" is a piece of code that could be simultaneously
running by multiple threads of execution. (either via SMP, or via
preemption on uniprocessor machines)

"Critical Section" is a piece of code that can be running by only one
thread of execution at a time ( If one thread enters critical section
on one processor, no other thread will enter critical section, even on
another processor).

"Atomic Section" is a piece of code that if starts running on a
processor, then it can't be preempted untill the atomic section is
exited. (it is however possible that the same atomic section is being
run simultaneously on a different processor by a different thread).

In that sense "Reentrant Code" seems to be just the opposite of
"Critical Section". Is this right?

Thanks,

Dan

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