Re: [PATCH -next] optprobes: fix kconfig depends/selects

[Felipe Contreras]

On Mon, Sep 13, 2010 at 10:15 AM, Masami Hiramatsu
<masami.hiramatsu.pt@xxxxxxxxxxx> wrote:
> (2010/09/13 10:06), Masami Hiramatsu wrote:
>> (2010/09/12 19:49), Felipe Contreras wrote:
>>> On Thu, Aug 12, 2010 at 10:26 PM, Randy Dunlap <randy.dunlap@xxxxxxxxxx> wrote:
>>>> From: Randy Dunlap <randy.dunlap@xxxxxxxxxx>
>>>>
>>>> KALLSYMS and KALLSYMS_ALL depend on DEBUG_KERNEL, so add that dependency.
>>>> KALLSYMS_ALL depends on KALLSYMS, so select both of them, not just KALLSYMS_ALL.
>>>>
>>>> warning: (OPTPROBES && KPROBES && HAVE_OPTPROBES && !PREEMPT || MTD_UBI_DEBUG && MTD && SYSFS && MTD_UBI || UBIFS_FS_DEBUG && MISC_FILESYSTEMS && UBIFS_FS || LOCKDEP && DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT || LATENCYTOP && HAVE_LATENCYTOP_SUPPORT) selects KALLSYMS_ALL which has unmet direct dependencies (DEBUG_KERNEL && KALLSYMS)
>>>>
>>>> Signed-off-by: Randy Dunlap <randy.dunlap@xxxxxxxxxx>
>>>> Cc: Â Â Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
>>>> Cc: Â Â Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
>>>> Cc: Â Â "David S. Miller" <davem@xxxxxxxxxxxxx>
>>>> Cc: Â Â Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>>>> ---
>>>> Âarch/Kconfig | Â Â2 ++
>>>> Â1 file changed, 2 insertions(+)
>>>>
>>>> --- linux-next-20100810.orig/arch/Kconfig
>>>> +++ linux-next-20100810/arch/Kconfig
>>>> @@ -45,6 +45,8 @@ config OPTPROBES
>>>> Â Â Â Âdef_bool y
>>>> Â Â Â Âdepends on KPROBES && HAVE_OPTPROBES
>>>> Â Â Â Âdepends on !PREEMPT
>>>> + Â Â Â depends on DEBUG_KERNEL
>>>> + Â Â Â select KALLSYMS
>>>> Â Â Â Âselect KALLSYMS_ALL
>>>>
>>>> Âconfig HAVE_EFFICIENT_UNALIGNED_ACCESS
>>>> --
>>>
>>> This causes another problem:
>>>
>>> arch/Kconfig:33:error: recursive dependency detected!
>>> arch/Kconfig:33: Â Â symbol KPROBES depends on KALLSYMS
>>> init/Kconfig:825: Â Âsymbol KALLSYMS is selected by OPTPROBES
>>> arch/Kconfig:44: Â Â symbol OPTPROBES depends on KPROBES
>>>
>>> The 'select KALLSYMS' is redundant.
>>>
>>> Otherwise: Signed-off-by: Felipe Contreras <felipe.contreras@xxxxxxxxx>
>>>
>>
>> Thanks, let me clear the dependency;
>> Kprobes uses kallsyms_lookup for finding target function and checking
>> instruction boundary, thus CONFIG_KPROBES should select CONFIG_KALLSYMS
>> and CONFIG_KALLSYMS_ALL.
>> Optprobe is a optional feature which is supported on x86 arch, and
>> it also uses kallsyms_lookup for checking instructions in the target
>> function. Anyway, since optprobe itself is depends on kprobes, it doesn't
>> need to select both of KALLSYMS/KALLSYMS_ALL.
>
> Hmm, wait, I might misunderstand something here. I thought
> KALLSYMS_ALL added symbols of static functions.
> But, does KALLSYMS_ALL just add symbols of variables?
> If so, both of KPROBES and OPTPROBES require only KALLSYMS.
> It means that they don't need to care about CONFIG_DEBUG_KERNEL.

So:
-       select KALLSYMS_ALL
+       depends on KALLSYMS_ALL

Because KALLSYMS_ALL depends on DEBUG_KERNEL && KALLSYMS.

-- 
Felipe Contreras
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