Re: [cocci] Searching for questionable call pairs (with SmPL)?

[Markus Elfring <Markus.Elfring@web.de>]

> I would think you should do:
> 
> @r exists@
> expression x, y;
> position p1,p2,p3,p4;
> @@
> mutex_lock(x);@p1
>  ...
> mutex_lock(y);@p2
> ...
> mutex_unlock(x);@p3
>  ...
> mutex_unlock(y);@p4
> 
> And then use a python rule to print p1, p2, p3, p4.  That way you will keep
> the different matches separated.

Will the following source code search approach trigger more helpful
development considerations?


@find@
expression x, y;
position l1, l2, ul1, ul2;
@@
 mutex_lock@l1(x);
 ...
 mutex_lock@l2(y);
 <+...
 mutex_unlock@ul1(x);
 ...
 mutex_unlock@ul2(y);
 ...+>

@display@
expression find.x, find.y;
position find.l1, find.l2;
@@
*mutex_lock@l1(x);
 ...
*mutex_lock@l2(y);


Questionable test result (by the software combination “Coccinelle 1.3.0” for example):
Markus_Elfring@Sonne:…/Projekte/Coccinelle/Probe> time /usr/bin/spatch --no-loops ../janitor/show_questionable_unlock_call_order3.cocci qc_audio_offload-handle_uaudio_stream_req-excerpt-20250722.c
…
@@ -70,7 +70,6 @@ static void handle_uaudio_stream_req(str
                goto response;
        }
 
-       mutex_lock(&chip->mutex);
        if (req_msg->enable) {
                if (info_idx < 0 || chip->system_suspend || subs->opened) {
                        ret = -EBUSY;
@@ -103,7 +102,6 @@ static void handle_uaudio_stream_req(str
                        ret = prepare_qmi_response(subs, req_msg, &resp,
                                                   info_idx);
                if (ret < 0) {
-                       mutex_lock(&chip->mutex);
                        subs->opened = 0;
                        mutex_unlock(&chip->mutex);
                }
@@ -136,7 +134,6 @@ static void handle_uaudio_stream_req(str
                }
 
                disable_audio_stream(subs);
-               mutex_lock(&chip->mutex);
                subs->opened = 0;
                mutex_unlock(&chip->mutex);
        }

real    0m0,197s
user    0m0,172s
sys     0m0,024s


Regards,
Markus