linux-kernel - Re: [PATCH 2/2] kprobes: check CONFIG_FREEZER instead of CONFIG

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Message-Id: <200902102240.34313.rjw@sisk.pl>
Date:	Tue, 10 Feb 2009 22:40:33 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Masami Hiramatsu <mhiramat@...hat.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Len Brown <lenb@...nel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Pavel Machek <pavel@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>,
	Cheng Renquan <crquan@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/2] kprobes: check CONFIG_FREEZER instead of CONFIG_PM

On Tuesday 10 February 2009, Masami Hiramatsu wrote:
> Rafael J. Wysocki wrote:
> > On Tuesday 10 February 2009, Ingo Molnar wrote:
> >> * Masami Hiramatsu <mhiramat@...hat.com> wrote:
> >>
> >>> Ingo Molnar wrote:
> >>>> * Len Brown <lenb@...nel.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@...il.com>
> >>>>>>> Signed-off-by: Masami Hiramatsu <mhiramat@...hat.com>
> >>>>>>> Signed-off-by: Rafael J. Wysocki <rjw@...k.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@...e.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

---
 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
--
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