[cocci] Searching for function calls with known parameters (by SmPL)?

[cocci] Searching for function calls with known parameters (by SmPL)?

[Markus Elfring]

Hello!

A function like pm_request_autosuspend() has got the property that it needs
a single input parameter.
https://elixir.bootlin.com/linux/v7.0-rc5/source/include/linux/pm_runtime.h#L460-L483

Such an implementation detail can be easily determined also by the means of
the semantic patch language.
I imagine that corresponding data processing would become more challenging
if it should be determined that a varying number of parameters would be passed
to other function calls at the beginning.
Can function calls be restricted to known parameters accordingly?

Regards,
Markus

Re: [cocci] Searching for function calls with known parameters (by SmPL)?

[Julia Lawall]

On Wed, 25 Mar 2026, Markus Elfring wrote:

> Hello!
>
> A function like pm_request_autosuspend() has got the property that it needs
> a single input parameter.
> https://elixir.bootlin.com/linux/v7.0-rc5/source/include/linux/pm_runtime.h#L460-L483
>
> Such an implementation detail can be easily determined also by the means of
> the semantic patch language.
> I imagine that corresponding data processing would become more challenging
> if it should be determined that a varying number of parameters would be passed
> to other function calls at the beginning.
> Can function calls be restricted to known parameters accordingly?

I still have no idea what you are asking about.  What is the connection
between a function call being placed at the beginning of a function and
the number of parameters that that function call requires?

julia

Re: [cocci] Searching for function calls with known parameters (by SmPL)?

[Markus Elfring]

>> Can function calls be restricted to known parameters accordingly?
> 
> I still have no idea what you are asking about.

???


>                                                  What is the connection
> between a function call being placed at the beginning of a function and

It is usual that a function call can occur at the beginning of a function implementation.
Such a call can occasionally be also repeated before an other call of
the referenced function.


> the number of parameters that that function call requires?

The function signature contains a parameter list.
Would you become interested to determine how many of such parameters
would be passed to a selected function call?

Regards,
Markus

Re: [cocci] Searching for function calls with known parameters (by SmPL)?

[Markus Elfring]

> I still have no idea what you are asking about.  What is the connection
> between a function call being placed at the beginning of a function and
> the number of parameters that that function call requires?

Do you see possibilities to extend an SmPL script (like the following)?

@display@
identifier call, input, name;
type t;
@@
 name(t* input)
 {
*call(input);
 ...
 }


Regards,
Markus

Re: [cocci] Searching for function calls with known parameters (by SmPL)?

[Markus Elfring]

>> Can function calls be restricted to known parameters accordingly?
> 
> I still have no idea what you are asking about.

I hope that communication difficulties can be adjusted also with help of
further (software) users.


>                                                  What is the connection
> between a function call being placed at the beginning of a function and
> the number of parameters that that function call requires?

I hope also that another description approach can influence evolution
in more desirable directions.


Various functions were designed in the way that they handle parameters.
https://cppreference.com/w/c/language/function_definition.html

The Coccinelle software supports the metavariable type “parameter list”
to some degree.
https://gitlab.inria.fr/coccinelle/coccinelle/-/blob/233b5ceb1d5a701fb270ebdf0a9bd6be0a6ce53b/docs/manual/cocci_syntax.tex#L233

Such lists support “special cases” accordingly.

* They can be empty.
  Would you like to exclude this case occasionally?

* More than one entry would be provided.
  The list length can become more interesting then.

  It can occasionally be nice that parameters would explicitly be restricted to
  a fixed number of items by the means of the semantic patch language.

  Data would be assigned to multiple parameters.
  But it is not directly known by this programming interface
  in which order they get passed to a function call.
  The passed data can be handled by the metavariable type “expression list”.
  There are some development challenges remaining for the mapping of contents
  with the mentioned metavariable types.
  Which expressions would refer to identifiers from a specified parameter list?


Regards,
Markus