On Mon, 14 May 2007 12:11:37 -0700
Andrew Morton <[email protected]> wrote:
> > This of course raises another question: it is not clear in which context
> > the smp_call_function* functions are supposed to be called. Should it be
> > with preemption disabled or is preemption enabled allowed as well?
> > If calling with preemption enabled is allowed then the powerpc implementation
> > is broken, since smp_processor_id() as well as num_online_cpus() may change
> > while they are accessed.
>
> These are all excellent questions. And important ones.
erk, I see your point. If a caller is calling this with preemption enabled
then the current thread might at any time migrate onto the target CPU,
causing the smp_call_function_single() attempt to fail. So the effects of
that call are basically a random crapshoot.
Often but not always, any code which is hanging onto a variable called
"cpu" while preemption enabled is buggy.
So yes, I'd say that from a sanity-of-implementation POV and for general
defensiveness, we should require that the called of
smp_call_function_single() has disabled preemption.
What a crock.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
