On Thu, Jun 13, 2013 at 6:07 PM, David Daney <ddaney.cavm@xxxxxxxxx> wrote:
>
> Suggested fix: Do what we already do in the SMP version of
> on_each_cpu(), and use local_irq_save/local_irq_restore.
I was going to apply this, but started looking a bit more.
Using "flags" as a variable name inside a macro like this is a
*really* bad idea.
Lookie here:
[torvalds@pixel linux]$ git grep on_each_cpu.*flags
arch/s390/kernel/perf_cpum_cf.c: on_each_cpu(setup_pmc_cpu,
&flags, 1);
arch/s390/kernel/perf_cpum_cf.c: on_each_cpu(setup_pmc_cpu,
&flags, 1);
and ask yourself what happens when the "info" argument expands to
"&flags", and it all compiles perfectly fine, but the "&flags" takes
the address of the new _inner_ variable called "flags" from the macro
expansion. Not the one that the caller actually intends..
Oops.
Not a good idea.
So I would suggest trivially renaming "flags" as "__flags" or
something, or perhaps even just making it a real function and avoiding
the whole namespace issue.
And rather than doing that blindly by editing the patch at after -rc5,
I'm just going to ask you to re-send a tested patch. Ok?
Linus
