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

From: Masami Hiramatsu <[email-masked]>
Date: Mon, 13 Sep 2010 10:06:19 +0900

(2010/09/12 19:49), Felipe Contreras wrote:
> On Thu, Aug 12, 2010 at 10:26 PM, Randy Dunlap <[email-masked]> wrote:
>> From: Randy Dunlap <[email-masked]>
>>
>> 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 <[email-masked]>
>> Cc:     Ananth N Mavinakayanahalli <[email-masked]>
>> Cc:     Anil S Keshavamurthy <[email-masked]>
>> Cc:     "David S. Miller" <[email-masked]>
>> Cc:     Masami Hiramatsu <[email-masked]>
>> ---
>>  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 <[email-masked]>
> 

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.

Thank you,

-- 
Masami HIRAMATSU
2nd Dept. Linux Technology Center
Hitachi, Ltd., Systems Development Laboratory
E-mail: [email-masked]