linux-hardening - Re: [PATCH -next v3 01/10] coccinelle: Add rules to find str_true

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Message-Id: <466D6A21-0E18-4FC3-9A92-6B3EA58C273D@inria.fr>
Date: Mon, 23 Sep 2024 12:24:04 +0200
From: Julia Lawall <Julia.Lawall@...ia.fr>
To: Hongbo Li <lihongbo22@...wei.com>
Cc: kees@...nel.org, andy@...nel.org, nicolas.palix@...g.fr,
 linux-hardening@...r.kernel.org, cocci@...ia.fr
Subject: Re: [PATCH -next v3 01/10] coccinelle: Add rules to find str_true_false() replacements

Thanks for testing it. I will see if there is some other way to improve the performance.
Sent from my iPhone

> On 23 Sep 2024, at 09:01, Hongbo Li <lihongbo22@...wei.com> wrote:
> 
> 
> 
>> On 2024/9/19 14:25, Julia Lawall wrote:
>>> On Wed, 11 Sep 2024, Hongbo Li wrote:
>>> After str_true_false() has been introduced in the tree,
>>> we can add rules for finding places where str_true_false()
>>> can be used. A simple test can find over 10 locations.
>>> 
>>> Signed-off-by: Hongbo Li <lihongbo22@...wei.com>
>>> ---
>>>  scripts/coccinelle/api/string_choices.cocci | 19 +++++++++++++++++++
>>>  1 file changed, 19 insertions(+)
>>> 
>>> diff --git a/scripts/coccinelle/api/string_choices.cocci b/scripts/coccinelle/api/string_choices.cocci
>>> index 5e729f187f22..6942ad7c4224 100644
>>> --- a/scripts/coccinelle/api/string_choices.cocci
>>> +++ b/scripts/coccinelle/api/string_choices.cocci
>>> @@ -85,3 +85,22 @@ e << str_down_up_r.E;
>>>  @@
>>> 
>>>  coccilib.report.print_report(p[0], "opportunity for str_down_up(%s)" % e)
>>> +
>>> +@..._true_false depends on patch@
>>> +expression E;
>>> +@@
>>> +-      ((E) ? "true" : "false")
>>> ++      str_true_false(E)
>>> +
>>> +@..._true_false_r depends on !patch exists@
>>> +expression E;
>>> +position P;
>>> +@@
>>> +*      ((E@P) ? "true" : "false")
>> Hello,
>> The semantic patch is quite slow.  Actually it tests a large number of
>> cases, eg where the parentheses are present and where they are not.
>> A small optimization is possible in the non-patch case.  The outer
>> parentheses are not needed, because you will already get the same
>> information whether they are there or not.
>> In contrast, for the patch case, the outer parentheses are needed, because
>> if they are there we want to remove them, since they are not needed for
>> the function call.
>> Could you update the depends on !patch cases to remove the outer
>> parentheses?
> 
> You mean in non-patch case, we could just write like the following?:
> 
> +@..._true_false_r depends on !patch exists@
> +expression E;
> +position P;
> +@@
> +*      (E@P) ? "true" : "false"
> 
> I have tested in my machine. The impact of this parenthesis on performance is very minimal.
> 
> With parentheses, the time on driver/ costs:
> 
> real    1m41.696s
> user    85m24.069s
> sys    1m8.891s
> 
> Without parentheses, the time on driver/ costs:
> 
> real    1m40.438s
> user    85m53.987s
> sys    1m7.981s
> 
> 
> Thanks,
> Hongbo
> 
>> Also, just one patch would be fine.  There are many changes, but they are
>> all sort of the same, so it would be easier just to see them all at once.
>> thanks,
>> julia
>>> +
>>> +@...ipt:python depends on report@
>>> +p << str_true_false_r.P;
>>> +e << str_true_false_r.E;
>>> +@@
>>> +
>>> +coccilib.report.print_report(p[0], "opportunity for str_true_false(%s)" % e)
>>> --
>>> 2.34.1
>>> 
>>>