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

From: Masami Hiramatsu
Date: Mon Sep 13 2010 - 06:14:25 EST


(2010/09/13 18:41), Felipe Contreras wrote:
> 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: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxx>
>>>>> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@xxxxxxxxx>
>>>>> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
>>>>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
>>>>> ---
>>>>> arch/Kconfig | 2 ++
>>>>> 1 file changed, 2 insertions(+)
>>>>>
>>>>> --- linux-next-20100810.orig/arch/Kconfig
>>>>> +++ linux-next-20100810/arch/Kconfig
>>>>> @@ -45,6 +45,8 @@ config OPTPROBES
>>>>> def_bool y
>>>>> depends on KPROBES && HAVE_OPTPROBES
>>>>> depends on !PREEMPT
>>>>> + depends on DEBUG_KERNEL
>>>>> + select KALLSYMS
>>>>> select KALLSYMS_ALL
>>>>>
>>>>> config HAVE_EFFICIENT_UNALIGNED_ACCESS
>>>>> --
>>>>
>>>> This causes another problem:
>>>>
>>>> arch/Kconfig:33:error: recursive dependency detected!
>>>> arch/Kconfig:33: symbol KPROBES depends on KALLSYMS
>>>> init/Kconfig:825: symbol KALLSYMS is selected by OPTPROBES
>>>> arch/Kconfig:44: 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.

No, what I meant is;
- select KALLSYMS_ALL

:-)



--
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: masami.hiramatsu.pt@xxxxxxxxxxx
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