linux-kernel - Re: [PATCH v6 7/8] dynamic_debug: add asm-generic implementation for DYNAMIC_DEBUG_RELATIVE

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Date:   Thu, 27 Jun 2019 11:03:23 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jason Baron <jbaron@...mai.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 7/8] dynamic_debug: add asm-generic implementation for DYNAMIC_DEBUG_RELATIVE_POINTERS

On Wed, Jun 26, 2019 at 4:52 PM Rasmus Villemoes
<linux@...musvillemoes.dk> wrote:
>
> On 27/06/2019 01.16, Nick Desaulniers wrote:
> > On Tue, Jun 25, 2019 at 3:18 PM Nick Desaulniers
> > <ndesaulniers@...gle.com> wrote:
> >
> > The prints should show up in dmesg right, assuming you do something to
> > trigger them?  Can you provide more details for a test case that's
> > easy to trip? What's an easy case to reproduce from a limited
> > buildroot env (basic shell/toybox)?
> >
>
> Hm, I seemed to remember that those kobject events triggered all the
> time. Oh well, try this one:
>
> echo 'file ping.c +p' > control
> ping localhost
> dmesg | grep ping

I don't have guest networking setup from QEMU to host, so there's no
network available to ping. :(

but:

(initramfs) echo 'file drivers/tty/*.c +p' > /dfs/dynamic_debug/control
(initramfs) grep tty /dfs/dynamic_debug/control
...
drivers/tty/serial/8250/8250_core.c:113 [8250]serial8250_interrupt =p
"%s(%d): start\012"
drivers/tty/serial/8250/8250_core.c:139 [8250]serial8250_interrupt =p
"%s(%d): end\012"
...
(initramfs) dmesg
...
[  134.895846] serial8250_interrupt(4): start
[  134.895967] serial8250_interrupt(4): end
[  134.895970] serial8250_interrupt(4): start
[  134.895981] serial8250_interrupt(4): end
[  134.895998] serial8250_interrupt(4): start
[  134.896053] serial8250_interrupt(4): end

I then verified that nothing new appears in dmesg related to these
traces after running:
(initramfs) echo 'file drivers/tty/*.c -p' > /dfs/dynamic_debug/control

so if that's good enough, then for the series:
Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>

Thanks,
~Nick Desaulniers