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

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

On Wednesday 11 February 2009, Masami Hiramatsu wrote:
> Rafael J. Wysocki wrote:
> > On Tuesday 10 February 2009, Masami Hiramatsu wrote:
> >> Rafael J. Wysocki wrote:
> >>> 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-$(CONFIG_PM) += power/
> >>>>>
> >>>>> but CONFIG_PM was not set in config
> >>>> Sounds plausible. We need a fix for this - it's broken upstream.
> >>> Hmm.  Can || be used under obj-$() ?
> >> I think just adding a line "obj-$(CONFIG_FREEZER) += power/" is enough.
> >> (you can see similar lines of "trace/" at the bottom of obj- lines
> >>  in kernel/Makefile )
> > 
> > Indeed, thanks.
> > 
> > So, something like the appended patch should help, I think.
> > 
> > Rafael
> 
> Thank you for fixing. I've tested it.
> 
> Tested-by: Masami Hiramatsu <mhiramat@redhat.com>

Thanks for testing.  I'll send a changelogged version shortly.

Rafael


> > ---
> >  kernel/Makefile       |    1 +
> >  kernel/power/Makefile |    2 +-
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> > 
> > Index: linux-2.6/kernel/Makefile
> > ===================================================================
> > --- linux-2.6.orig/kernel/Makefile
> > +++ linux-2.6/kernel/Makefile
> > @@ -51,6 +51,7 @@ obj-$(CONFIG_UID16) += uid16.o
> >  obj-$(CONFIG_MODULES) += module.o
> >  obj-$(CONFIG_KALLSYMS) += kallsyms.o
> >  obj-$(CONFIG_PM) += power/
> > +obj-$(CONFIG_FREEZER) += power/
> >  obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
> >  obj-$(CONFIG_KEXEC) += kexec.o
> >  obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
> > Index: linux-2.6/kernel/power/Makefile
> > ===================================================================
> > --- linux-2.6.orig/kernel/power/Makefile
> > +++ linux-2.6/kernel/power/Makefile
> > @@ -3,7 +3,7 @@ ifeq ($(CONFIG_PM_DEBUG),y)
> >  EXTRA_CFLAGS	+=	-DDEBUG
> >  endif
> >  
> > -obj-y				:= main.o
> > +obj-$(CONFIG_PM)		+= main.o
> >  obj-$(CONFIG_PM_SLEEP)		+= console.o
> >  obj-$(CONFIG_FREEZER)		+= process.o
> >  obj-$(CONFIG_HIBERNATION)	+= swsusp.o disk.o snapshot.o swap.o user.o