Messages in this thread | | | Date | Thu, 13 Jun 2013 22:46:02 -0700 | Subject | Re: [PATCH] smp.h: Use local_irq_{save,restore}() in !SMP version of on_each_cpu(). | From | Linus Torvalds <> |
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On Thu, Jun 13, 2013 at 6:07 PM, David Daney <ddaney.cavm@gmail.com> 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
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