Re: [tip:perf/uprobes] uprobes/core: Clean up, refactor andimprove the code

[Srikar Dronamraju]

* Ingo Molnar <mingo@xxxxxxx> [2012-02-20 08:38:23]:

> 
> * Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> wrote:
> 
> > The volatiles were added to arch/x86/kernel/kprobes.c because 
> > of commit 7115e3fcf45 and 315eb8a2a1b. The volatiles are 
> > required because gcc 4.6 gave a warning about the asm operand 
> > for test_bit.  So the same were added to 
> > arch/x86/kernel/uprobes.c.
> 
> Seems like a GCC bug - a bogus warning - or does it generate bad 
> code as well?

Yes it is a gcc bug and was fixed by Jakub.
As per Josh, only the first long is output if compiled on the buggy gcc.

> 
> In any case, kprobes.c did it correctly, it added the volatile 
> *and a comment*, pointing out that it's a GCC bug. No such 
> warning was added to uprobes.c, making the volatile look 
> entirely spurious.

okay. 

> 
> So feel free to re-add the volatile in a followup patch, just 
> make sure the GCC workaround nature is documented.
> 
> Thanks,
> 
> 	Ingo
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/