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From: Valentin Schneider <valentin.schneider@arm.com>
To: Julia Lawall <julia.lawall@lip6.fr>
Cc: Markus Elfring <Markus.Elfring@web.de>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	dm-devel@redhat.com, linux-block@vger.kernel.org,
	rcu@vger.kernel.org, linux-kernel@vger.kernel.org,
	Andrea Arcangeli <aarcange@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: sched: make struct task_struct::state 32-bit
Date: Mon, 23 Sep 2019 12:26:44 +0100	[thread overview]
Message-ID: <d529c390-546e-a8a4-f475-c3ee41f97645@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.21.1909231228200.2272@hadrien>

On 23/09/2019 11:34, Julia Lawall wrote:
>> // FIXME: current not recognized as task_struct*, fixhack with regexp
>> identifier current =~ "^current$";
> 
> Please don't do this.  Just use the word current.  It doesn't have to be a
> metavariable.  You will though get a warning about it.  To eliminate the
> warning, you can say symbol current;
> 

Didn't know about that way to get rid of the warning, thanks!

>> identifier task_state =~ "^TASK_";
> 
> Are there a lot of options?  You can also enumerate them in {}, ie
> 
> identifier task_state = {TASK_BLAH, TASK_BLAHBLAH};
> 

Around a dozen, can be enumerated easily and is indeed probably better than
a regexp.

>> identifier state_var;
>> position pos;
>> @@
>>
>> (
>>   p->state & state_var@pos
>> |
>>   current->state & state_var@pos
>> |
>>   p->state | state_var@pos
>> |
>>   current->state | state_var@pos
>> |
>>   p->state < state_var@pos
>> |
>>   current->state < state_var@pos
>> |
>>   p->state > state_var@pos
>> |
>>   current->state > state_var@pos
>> |
>>   state_var@pos = p->state
>> |
>>   state_var@pos = current->state
>> |
>>   p->state == state_var@pos
>> |
>>   current->state == state_var@pos
>> |
>>   p->state != state_var@pos
>> |
>>   current->state != state_var@pos
>> |
>> // FIXME: match functions that do something with state_var underneath?
>> // How to do recursive rules?
> 
> You want to look at the definitions of called functions?  Coccinelle
> doesn't really support that, but there are hackish ways to add that.  How
> many function calls would you expect have to be unrolled?
> 

I wouldn't expect more than a handful (~5). I suppose this has to do with
injecting some Python/Ocaml code? I have some examples bookmarked but
haven't gotten to stare at them long enough.

>>   set_current_state(state_var@pos)
>> |
>>   set_special_state(state_var@pos)
>> |
>>   signal_pending_state(state_var@pos, p)
>> |
>>   signal_pending_state(state_var@pos, current)
>> |
>>   state_var@pos & task_state
>> |
>>   state_var@pos | task_state
>> )
>>
>> // Fixup local variables
>> @depends on patch && state_access@
>> identifier state_var = state_access.state_var;
>> @@
>> (
>> - long
>> + int
>> |
>> - unsigned long
>> + unsigned int
>> )
>> state_var;
>>
>> // Fixup function parameters
>> @depends on patch && state_access@
>> identifier fn;
>> identifier state_var = state_access.state_var;
>> @@
>>
>> fn(...,
>> - long state_var
>> + int state_var
>> ,...)
>> {
>> 	...
>> }
>>
>> // FIXME: find a way to squash that with the above?
> 
> I think that you can make a disjunction on a function parameter
> 
> fn(...,
> (
> - T1 x1
> + T2 x2
> |
> - T3 x3
> + T4 x4
> )
> , ...) { ... }
> 

My attempt at this gives me "minus: parse error", which is why I went
with the split.

Something simple like this works:
---
virtual patch
virtual report

@@
identifier fn;
identifier p;
@@

fn(...,
- long
+ int
p
,...)
{
	...
}
---

but this doesn't:
---
virtual patch
virtual report

@@
identifier fn;
identifier p;
@@

fn(...,
(
- long p
+ int p
|
- unsigned long p
+ unsigned int p
)
,...)
{
	...
}
---

> julia
> 

  reply	other threads:[~2019-09-23 11:26 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-02 21:05 [PATCH] sched: make struct task_struct::state 32-bit Alexey Dobriyan
2019-09-02 23:02 ` Valentin Schneider
2019-09-03 16:23   ` Alexey Dobriyan
2019-09-03 16:31     ` Valentin Schneider
2019-09-03  6:51 ` [dm-devel] " Christoph Hellwig
2019-09-03  7:13   ` Peter Zijlstra
2019-09-03 17:29 ` Valentin Schneider
2019-09-03 18:19   ` Alexey Dobriyan
2019-09-03 21:51     ` Valentin Schneider
2019-09-04 12:07       ` Valentin Schneider
2019-09-04 17:48         ` Valentin Schneider
2019-09-05 15:51         ` Markus Elfring
2019-09-05 16:52           ` Valentin Schneider
2019-09-23 10:26             ` Valentin Schneider
2019-09-23 10:34               ` Julia Lawall
2019-09-23 11:26                 ` Valentin Schneider [this message]
2019-09-23 11:43                   ` Julia Lawall
2019-09-23 13:23                     ` Valentin Schneider
2019-09-24  8:28                   ` Markus Elfring
2019-09-24  8:07               ` Markus Elfring
2019-09-04  9:43     ` [PATCH] " David Laight
2019-09-04 10:25       ` Valentin Schneider

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