Re: [PATCH 2/2] kprobes: check CONFIG_FREEZER instead of CONFIG_PM

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday 10 February 2009, Ingo Molnar wrote:
> 
> * Masami Hiramatsu <mhiramat@redhat.com> wrote:
> 
> > Ingo Molnar wrote:
> >> * Len Brown <lenb@kernel.org> wrote:
> >>
> >>>>> Check CONFIG_FREEZER instead of CONFIG_PM because kprobe booster
> >>>>> depends on freeze_processes() and thaw_processes() when CONFIG_PREEMPT=y.
> >>>>>
> >>>>> This fixes a linkage error which occurs when CONFIG_PREEMPT=y, CONFIG_PM=y
> >>>>> and CONFIG_FREEZER=n.
> >>>>>
> >>>>> Reported-by: Cheng Renquan <crquan@gmail.com>
> >>>>> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
> >>>>> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> >>>>> ---
> >>>>>  arch/ia64/kernel/kprobes.c |    2 +-
> >>>>>  arch/x86/kernel/kprobes.c  |    2 +-
> >>>>>  kernel/kprobes.c           |    2 +-
> >>>>>  3 files changed, 3 insertions(+), 3 deletions(-)
> >>>> looks good, the x86 bits:
> >>>>
> >>>> Acked-by: Ingo Molnar <mingo@elte.hu>
> >>> man, we have too many config options:-)
> >>
> >> the non-x86 bits (kernel/kprobes.c) are crappy though, and broke -rc4
> >> allnoconfig:
> >>
> >> kernel/built-in.o: In function `collect_garbage_slots':
> >> kprobes.c:(.kprobes.text+0x16e4): undefined reference to `freeze_processes'
> >> kprobes.c:(.kprobes.text+0x16f2): undefined reference to `thaw_processes'
> >> kprobes.c:(.kprobes.text+0x176b): undefined reference to `thaw_processes'
> >
> > Hmm, it seems that kernel/power/built-in.o was not linked to .tmp_vmlinux1.
> >
> >   ld -m elf_i386 --build-id -o .tmp_vmlinux1 -T arch/x86/kernel/vmlinux.lds
> > arch/x86/kernel/head_32.o arch/x86/kernel/head32.o arch/x86/kernel/head.o
> > arch/x86/kernel/init_task.o  init/built-in.o --start-group  usr/built-in.o
> > arch/x86/kernel/built-in.o  arch/x86/mm/built-in.o  arch/x86/mach-default/built-in.o
> > arch/x86/crypto/built-in.o  arch/x86/vdso/built-in.o  kernel/built-in.o
> > mm/built-in.o  fs/built-in.o  ipc/built-in.o  security/built-in.o  crypto/built-in.o
> > block/built-in.o  lib/lib.a  arch/x86/lib/lib.a  lib/built-in.o
> > arch/x86/lib/built-in.o  drivers/built-in.o  sound/built-in.o  firmware/built-in.o
> > arch/x86/pci/built-in.o  net/built-in.o --end-group
> > kernel/built-in.o: In function `collect_garbage_slots':
> > kprobes.c:(.kprobes.text+0x16e4): undefined reference to `freeze_processes'
> > kprobes.c:(.kprobes.text+0x16f2): undefined reference to `thaw_processes'
> > kprobes.c:(.kprobes.text+0x176b): undefined reference to `thaw_processes'
> >
> > At kernel/Makefile:53, I can see
> >
> > obj-$(CONFIG_PM) += power/
> >
> > but CONFIG_PM was not set in config
> 
> Sounds plausible. We need a fix for this - it's broken upstream.

Hmm.  Can || be used under obj-$() ?

Rafael