Re: [PATCH] selftests/livepatch: filter 'taints' from dmesg comparison

[Miroslav Benes <mbenes@suse.cz>]

On Thu, 7 Nov 2019, Joe Lawrence wrote:

> On 11/7/19 3:42 AM, Miroslav Benes wrote:
> > On Wed, 6 Nov 2019, Joe Lawrence wrote:
> > 
> >> The livepatch selftests compare expected dmesg output to verify kernel
> >> behavior.  They currently filter out "tainting kernel with
> >> TAINT_LIVEPATCH" messages which may be logged when loading livepatch
> >> modules.
> >>
> >> Further filter the log to also drop "loading out-of-tree module taints
> >> kernel" messages in case the klp_test modules have been build without
> >> the in-tree module flag.
> > 
> > That is true, but "tainting kernel with TAINT_LIVEPATCH" should be printed
> > out even in this case. check_modinfo_livepatch() is called for all modules
> > and relies on MODINFO(livepatch, Y).
> >  > So either the bug is elsewhere or I need one more cup of tea.

Ok, the above is not relevant here.

I'm only wondering about the execution steps, because supporting modules 
lib/livepatch/ should be built as in-tree. No?
 
> I'm only half a cup in this morning myself, but...
> 
> In my scenario, I saw in the kernel log:
> 
>   % modprobe test_klp_livepatch
>   test_klp_livepatch: loading out-of-tree module taints kernel.
>   test_klp_livepatch: module verification failed: signature and/or 
> required key missing - tainting kernel
>   ...

So modprobe here should not print anything like this.

> and because check_result() only removes 'tainting' with grep -v, the expected
> log message failed to match with the actual filtered message because of the
> first 'taints' message.
> 
> So this change just adds more to the filtered out strings:
> 
>   result = dmesg | grep -v <filtered out strings> | grep <interesting 
> strings>

The code is definitely correct. You can add my 

Acked-by: Miroslav Benes <mbenes@suse.cz>

M