[Cocci] 答复: Re: [PATCH v2] coccinelle: semantic code search for missingof_node_put

[<wen.yang99@zte.com.cn>]

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> > The counter must be decremented after the last usage of a device node.
> 
> Thanks for your next try to improve the software situation
> also in this area.
> 
> 
> > We find these functions by using the following SmPL:
> 
> Would it be nicer to use the word “script” also here?
> 
OK, we will replace "SmPL" with "scrilt" later.

> 
> > <SmPL>
> > @initialize:ocaml@
> > @@
> 
> How do you think about to describe the chosen algorithm
> in a way for contributors who might not be so familiar with
> this programming language?
> 
> Will any information from previous discussions become relevant
> for a better commit description?
> 

We will also provide an example written in Python later.
> 
> > let relevant_str = "use of_node_put() on it when done"
> 
> Will such a literal need further development and software documentation considerations?
> 
> 
> > let contains s1 s2 =
> >     let re = Str.regexp_string s2
> >     in
> >         try ignore (Str.search_forward re s1 0); true
> >         with Not_found -> false
> >
> > let relevant_functions = ref []
> >
> > let add_function f c =
> >     if not (List.mem f !relevant_functions)
> >     then
> >       begin
> >         let s = String.concat " "
> 
> I find such a concatenation suspicious after the space character
> is used also for a string splitting before.
> Can this delimiter be omitted for the combination?
> 

We first divide the comment by word, then use spaces to concatenate
them into a string, and finally find the substring (use of_node_put() on it when done)
in this string.
> 
> >           (
> >             (List.map String.lowercase_ascii
> >               (List.filter
> >                 (function x ->
> >                   Str.string_match
> >                   (Str.regexp "[a-zA-Z_\\(\\)][-a-zA-Z0-9_\\(\\)]*$")
> >                 x 0) (Str.split (Str.regexp "[ .;\t\n]+") c)))) in
> >              if contains s relevant_str
> 
> I would prefer to use the string constant in the called function directly
> instead of passing it as another parameter.

Thanks. Here the relevant_str is a string constant.

> >              then
> >                Printf.printf "Found relevant function: %s\n" f;
> >                relevant_functions := f :: !relevant_functions;
> >       end
> 
> I find your choice for an output format unclear at the moment.
> I imagine that the corresponding data processing of these function names
> will need fine-tuning.
> I am missing the software component for the conversion of this
> identifier list into a disjunction for the SmPL rule “r1”.

Thanks.
We first use this script to find out all the function names to be processed,
and then copy these function names into r1.

> > And this patch also looks for places where an of_node_put()
> 
> Does a patch or a script perform an action?
> 
OK, Thanks.
We'll fix it soon.

> > call is on some paths but not on others.
> 
> Let us look at mentioned implementation details.
> 
> 
> > +@initialize:python@
> > +@@
> > +
> > +seen = set()
> > +
> > +def add_if_not_present (p1, p2):
> 
> It seems that you would like to use iteration functionality.
> https://github.com/coccinelle/coccinelle/blob/99e081e9b89d49301b7bd2c5e5aac88c66eaaa6a/docs/manual/cocci_syntax.tex#L1826
> 
> How will it matter here?
> 
> 
> > +def display_report(p1, p2):
> > +    if add_if_not_present(p1[0].line, p2[0].line):
> > +       coccilib.report.print_report(p2[0],
> > +                                    "ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line "
> > +                                    + p1[0].line
> > +                                    + ", but without a corresponding object release within this function.")
> > +
> > +def display_org(p1, p2):
> > +    cocci.print_main("acquired a node pointer with refcount incremented", p1)
> > +    cocci.print_secs("needed of_node_put", p2)
> 
> Can it be helpful to specify SmPL dependencies for these functions
> according to the applied operation mode?
> 
> 
> > +x = @p1\(of_find_all_nodes\|
> 
> I would find this SmPL disjunction easier to read without the usage
> of extra backslashes.
> 
> +x =
> +(of_…
> +|of_…
> +)@p1(...);
> 
> 
> Which sort criteria were applied for the generation of the shown
> function name list?

As julia pointed out, your current writing is not compiled.

> > +if (x == NULL || ...) S
> > +... when != e = (T)x
> > +    when != true x == NULL
> 
> I wonder if this code exclusion specification is really required
> after a null pointer was checked before.

Thanks.
Our previous version used the "when any" clause, so we need
"when != true x == NULL". We can delete this code exclusion
specification  for this version. 
We will fix it later.

> > +|
> > +return x;
> > +|
> > +return of_fwnode_handle(x);
> 
> Can a nested SmPL disjunction be helpful at such places?
> 
> +|return
> +(x
> +|of_fwnode_handle(x)
> +);

We are more in agreement with julia's comments:
The original code is much more readable.  The internal representation will be the same.

> > +    when != v4l2_async_notifier_add_fwnode_subdev(<...x...>)
> 
> Would the specification variant “<+... x ...+>” be relevant
> for the parameter selection?

Thanks. 
We use <... x ...> instead of <+... x ...+> here to eliminate the following false positives:

./drivers/media/platform/qcom/camss/camss.c:504:1-7: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 479, but without a corresponding object release within this function.

465 static int camss_of_parse_ports(struct camss *camss)
466 {
...
479                 remote = of_graph_get_remote_port_parent(node);
...
486                 asd = v4l2_async_notifier_add_fwnode_subdev(
487                         &camss->notifier, of_fwnode_handle(remote),              ---> v4l2_async_notifier_add_fwnode_subdev will pass remote to camss->notifier.
488                         sizeof(*csd));
...
504         return num_subdevs;

--
Regards,
Wen

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