Re: [PATCH v7 20/29] dyndbg: refactor param_set_dyndbg_classes and below

On Tue, Jul 21, 2026 at 3:11=E2=80=AFPM <[email protected]> wrote:
>
> Thank you for your contribution! Sashiko AI review found 1 potential issu=
e(s) to consider:
> - [Medium] The refactored `param_set_dyndbg_module_classes` is structural=
ly incapable of correctly applying existing global classmap settings to new=
ly loaded modules, and it corrupts the global state.
> --
>
> --- Patch [20]: [PATCH v7 20/29] dyndbg: refactor param_set_dyndbg_classe=
s and below ---
> commit fd7e6888285afde6b911cef67e7e2452e7180dba
> Author: Jim Cromie <[email protected]>
>
> dyndbg: refactor param_set_dyndbg_classes and below
>
> This commit refactors the param_set_dyndbg_classes callchain to support
> module-specific classmap updates, primarily intended for modprobe handlin=
g.
> It splits the function into upper and lower parts, threading a modname
> parameter through to ddebug_exec_queries. It also adds a check in
> ddebug_apply_class_bitmap to skip printing if bits haven't changed.
>
> > diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
> > index f66e5373e61e2..a619cefd801f7 100644
> > --- a/lib/dynamic_debug.c
> > +++ b/lib/dynamic_debug.c
> [ ... ]
> > @@ -625,7 +626,9 @@ static int ddebug_apply_class_bitmap(const struct d=
debug_class_param *dcp,
> >       int matches =3D 0;
> >       int bi, ct;
> >
> > -     v2pr_info("apply: 0x%lx to: 0x%lx\n", *new_bits, *old_bits);
> > +     if (*new_bits !=3D *old_bits)
> > +             v2pr_info("apply bitmap: 0x%lx to: 0x%lx for %s\n", *new_=
bits,
> > +                       *old_bits, query_modname ?: "'*'");
> >
> >       for (bi =3D 0; bi < map->length; bi++) {
> >               if (test_bit(bi, new_bits) =3D=3D test_bit(bi, old_bits))
> >                       continue;
>
> [Severity: Medium]
> When applying the current global state to a newly probed module, will thi=
s
> continue statement incorrectly skip all configuration queries?

this is a param callback. the modprobe has finished, and the modprobe
args setting classmaps
are already done.  the param-callback only handles param updates


> Since old_bits represents the global state, test_bit() will evaluate to t=
rue
> when applying the same global configuration to a new module, silently
> skipping required query updates.



>
> >               snprintf(query, QUERY_SIZE, "class %s %c%s", map->class_n=
ames[bi],
> >                        test_bit(bi, new_bits) ? '+' : '-', dcp->flags);
> >
> [ ... ]
> > @@ -683,8 +693,8 @@ int param_set_dyndbg_classes(const char *instr, con=
st struct kernel_param *kp)
> >                               KP_NAME(kp), inrep, CLASSMAP_BITMASK(map-=
>length));
> >                       inrep &=3D CLASSMAP_BITMASK(map->length);
> >               }
> > -             v2pr_info("bits:%lx > %s\n", inrep, KP_NAME(kp));
> > -             totct +=3D ddebug_apply_class_bitmap(dcp, &inrep, dcp->bi=
ts);
> > +             v2pr_info("bits:0x%lx > %s.%s\n", inrep, mod_name ?: "*",=
 KP_NAME(kp));
> > +             totct +=3D ddebug_apply_class_bitmap(dcp, &inrep, dcp->bi=
ts, mod_name);
> >               *dcp->bits =3D inrep;
>
> [Severity: Medium]
> Does this code inadvertently corrupt the global state if a module-specifi=
c
> override is applied?

the param belongs to a module, its not "global".
and I dont know what override means here.
the callback MUST update the internal state, or error out.




> It appears that *dcp->bits (the global parameter state) is unconditionall=
y
> overwritten with inrep, even when a mod_name is provided.

the param belongs to a module. so does the param state.

> Should the state update be conditional on mod_name being NULL, to prevent
> modprobe handling from modifying the global state?
>
> >               break;
> >       case DD_CLASS_TYPE_LEVEL_NUM:
> > @@ -697,7 +707,7 @@ int param_set_dyndbg_classes(const char *instr, con=
st struct kernel_param *kp)
> >               old_bits =3D CLASSMAP_BITMASK(*dcp->lvl);
> >               new_bits =3D CLASSMAP_BITMASK(inrep);
> >               v2pr_info("lvl:%ld bits:0x%lx > %s\n", inrep, new_bits, K=
P_NAME(kp));
> > -             totct +=3D ddebug_apply_class_bitmap(dcp, &new_bits, &old=
_bits);
> > +             totct +=3D ddebug_apply_class_bitmap(dcp, &new_bits, &old=
_bits, mod_name);
> >               *dcp->lvl =3D inrep;
>
> [Severity: Medium]
> Similarly, is the global *dcp->lvl state unconditionally overwritten here
> when a module-specific override is applied for LEVEL_NUM map types?

the state belongs to the module.

>
> >               break;
> >       default:
>
> --
> Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260721-dd-maint=
[email protected]?part=3D20