Re: [PATCH 2/4] generic-smp: remove kmalloc usage

Ingo Molnar
2009-02-18T16:06:36Z

* Rusty Russell <rusty@rustcorp.com.au> wrote:

> On Tuesday 17 February 2009 20:13:59 Ingo Molnar wrote:
> > We should not bend backwards trying to preserve that kmalloc()
> > [and prove that it's safe and race-free] - i.e. the burden of
> > proof is on the person insisting that it's needed, not on the
> > person wanting to remove it.
>
> Respectfully disagree. The kmalloc has been there for a very long time,
> and doing fine AFAICT.

The kmalloc(GFP_ATOMIC) has been in kernel/smp.c for about half
a year, since:

| commit 3d4422332711ef48ef0f132f1fcbfcbd56c7f3d1
| Author: Jens Axboe <jens.axboe@oracle.com>
| Date: Thu Jun 26 11:21:34 2008 +0200
| Subject: [PATCH] Add generic helpers for arch IPI function calls

Which introduced kernel/smp.c to begin with. It got merged on
July 15.

The precedecessor mechanism, smp_call_function*() on x86, used
an on-kernel-stack buffer (and a half-wait mechanism), even in
the async case, not a kmalloc().

I'm not sure where the "kmalloc has been there for a very long
time" statement comes from. Are we talking about the same thing?

Ingo