Re: [PATCH 3/3] selftests/livepatch: filter 'taints' from dmesg comparison

[Joe Lawrence <joe.lawrence@redhat.com>]

On 6/12/20 8:57 AM, Kamalesh Babulal wrote:
> On 6/12/20 5:17 PM, Petr Mladek wrote:
>> On Thu 2020-06-11 09:10:38, Joe Lawrence wrote:
>>> On 6/11/20 3:39 AM, Miroslav Benes wrote:
>>>> On Wed, 10 Jun 2020, Joe Lawrence wrote:
>>>>
>>>>> The livepatch selftests currently filter out "tainting kernel with
>>>>> TAINT_LIVEPATCH" messages which may be logged when loading livepatch
>>>>> modules.
>>>>>
>>>>> Further filter the log to drop "loading out-of-tree module taints
>>>>> kernel" in the rare case the klp_test modules have been built
>>>>> out-of-tree.
>>>>>
>>>>> Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
>>>>> ---
>>>>>    tools/testing/selftests/livepatch/functions.sh | 3 ++-
>>>>>    1 file changed, 2 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/tools/testing/selftests/livepatch/functions.sh b/tools/testing/selftests/livepatch/functions.sh
>>>>> index 83560c3df2ee..f5d4ef12f1cb 100644
>>>>> --- a/tools/testing/selftests/livepatch/functions.sh
>>>>> +++ b/tools/testing/selftests/livepatch/functions.sh
>>>>> @@ -260,7 +260,8 @@ function check_result {
>>>>>    	local result
>>>>>    	result=$(dmesg --notime | diff --changed-group-format='%>' --unchanged-group-format='' "$SAVED_DMESG" - | \
>>>>> -		 grep -v 'tainting' | grep -e '^livepatch:' -e 'test_klp')
>>>>> +		 grep -e '^livepatch:' -e 'test_klp' | \
>>>>> +		 grep -ve '\<taints\>' -ve '\<tainting\>')
>>>>
>>>> or make it just 'grep -v 'taint' ? It does not matter much though.
>>>>
>>>
>>> I don't know of any larger words* that may hit a partial match on "taint",
>>> but I figured the two word bounded regexes would be more specific.
>>
>> I do not have strong opinion. I am fine with both current and Mirek's proposal.
>>
>> I am just curious where \< and \> regexp substitutions are documented.
>> I see the following at the very end of "man re_syntax":
>>
>>     \< and \> are synonyms for  “[[:<:]]� and “[[:>:]]� respectively
>>
>> But I am not able to find documentation for “[[:<:]]� and “[[:>:]].
>> Even google looks helpless ;-)
>>
> 
> AFAIK, using \< and \> matches exact word.  Whereas when used individually,
> \< matches beginning and \> matches end of the word.
> 

 From 
https://www.gnu.org/software/grep/manual/grep.html#The-Backslash-Character-and-Special-Expressions 
:

The ‘\’ character, when followed by certain ordinary characters, takes a 
special meaning:

...

‘\<’

     Match the empty string at the beginning of word.
‘\>’

     Match the empty string at the end of word.


I'd be happy to use any other (more readable!) whole-word matching grep 
trick, this \<one\> just happens to be committed to my cmdline muscle 
memory.

-- Joe