Re: Fix quilt merge error in acpi-cpufreq.c

Linus Torvalds
2009-04-15T15:31:58Z

On Wed, 15 Apr 2009, Rusty Russell wrote:
>
> The API is screwy. It excludes the current CPU from the mask,
> unconditionally. It's a tlb flush helper masquerading as a general function.
>
> (smp_call_function has the same issue).
>
> Something like this?
>
> Subject: smp_call_function_many: add explicit exclude_self flag

No. This just makes the API even screwier. It fixes the
"smp_processor_id()" thing, but it is

(a) horribly buggy

See the 'return' without any put_cpu()

(b) horribly buggy

Those

if (exclude_self && cpu == this_cpu)
cpu = cpumask_next_and(cpu, mask, cpu_online_mask);

things are wrong - we need to do that "jump over our own CPU" thing
regardless of whether 'exclude_self' is set or not, since we're going
to special-case our own CPU anyway.

(c) Wrong, even if it wasn't (horribly buggy)^2

Adding "flags" to an interface doesn't make it better. Quite the
reverse. It makes it worse. It also makes it even MORE different from
all the other smp_call_function's, which just do the 'self' cpu
without any stupid conditionals and flags.

IOW, it would make things worse even if it worked. Which it doesn't.

> Impact: clarify and extend confusing API

And what the hell is up with these bogus "Impact:" things? Who started
doing that, and why? If your single-line explanation at the top is not
good enough, and your multi-line explanation isn't clear enough, then you
should fix the OTHER parts, not add that _idiotic_ "Impact" statement.

The thing has spread like wildfire, and it's STUPID.

Linus