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

From: Rafael J. Wysocki
Date: Tue Feb 10 2009 - 08:57:17 EST


On Tuesday 10 February 2009, Ingo Molnar wrote:
>
> * Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:
>
> > Ingo Molnar wrote:
> >> * Len Brown <lenb@xxxxxxxxxx> 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@xxxxxxxxx>
> >>>>> Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> >>>>> Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
> >>>>> ---
> >>>>> 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@xxxxxxx>
> >>> 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
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