Reading atomic variables in embedded C

Reading atomic variables in embedded C

[Mike Mason]

What's the proper way to read atomic variables in embedded C?  Can we just use kread within a probe handler or is something like atomic_read() still necessary?

Thanks,
Mike

Re: Reading atomic variables in embedded C

[Roland McGrath]

In every machine's asm/atomic.h, atomic_read(v) is actually just defined as
(v->counter) with no other magic.  So, you can just use kread on that, or
use $foo->counter in script code.  This encodes an assumption about the
kernel implementation, though the proper kernel API is to presume the
atomic_read macro might do some magic you need to use.  But, there is no
way to use atomic_read and get the fault-protection of kread.  So it's
improper by systemtap robustness rules to use atomic_read.


Thanks,
Roland