linux-kernel - Re: [PATCH 0001/0001] format idle IP output func+offset/length

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Date:   Tue, 7 Nov 2017 00:48:47 +0800
From:   "Liu, Changcheng" <changcheng.liu@...el.com>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Petr Mladek <pmladek@...e.com>, changcheng.liu@...el.com
Cc:     sergey.senozhatsky.work@...il.com,
        Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0001/0001] format idle IP output func+offset/length

Thx Josh. I'll refine the patch.
Answer question as below.

On 07:11 Mon 06 Nov, Josh Poimboeuf wrote:
> On Mon, Nov 06, 2017 at 06:52:03PM +0800, Liu, Changcheng wrote:
> > kaslr feature is enabled in kernel.
> > Remove kernel text address when dumping idle IP info
> > 
> > Signed-off-by: Liu Changcheng <changcheng.liu@...el.com>
> > Signed-off-by: Jerry Liu <primerlink@...il.com>
> > 
> > diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
> > index 0bc0a35..9cc4178 100644
> > --- a/lib/nmi_backtrace.c
> > +++ b/lib/nmi_backtrace.c
> > @@ -92,7 +92,7 @@ bool nmi_cpu_backtrace(struct pt_regs *regs)
> >  	if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
> >  		arch_spin_lock(&lock);
> >  		if (regs && cpu_in_idle(instruction_pointer(regs))) {
> > -			pr_warn("NMI backtrace for cpu %d skipped: idling at pc %#lx\n",
> > +			pr_warn("NMI backtrace for cpu %d skipped: idling at %pS\n",
> >  				cpu, instruction_pointer(regs));
> >  		} else {
> >  			pr_warn("NMI backtrace for cpu %d\n", cpu);
> 
> 1) The patch introduces a compile warning.
I've got the point because the conversion between pointer and unsigned long.
> 
> 2) When posting a new version of the patch, it should have a new version
>    in the subject, e.g. "PATCH v2".
Thx for your guide. I'm on the way to work with community.
> 
> 3) The subject is missing a prefix, like "lib_backtrace: "
> 
> 4) The subject isn't very clear, how about something like:
> 
>    lib_backtrace: fix kernel text address leak
I'll use this subject.
> 
> 5) The description isn't correct.  KASLR isn't always enabled, it
>    depends on the user's config.  But even without KASLR, we don't want
>    to leak kernel text addresses.
That's fine.
> 
> 6) The description should use complete sentences.
Yes.
> 
> 7) I'm not sure the "Signed-off-by:" chain is correct.  Was Jerry Liu
>    the original author of the patch?
This is my personal bad habit. I'll correct it.
> 
> -- 
> Josh