Re: [PATCH 3/4] kmod: Return directly if module name is empty in request_module()

[Tiezhu Yang]

On 04/18/2020 01:48 PM, Luis Chamberlain wrote:
> On Fri, Apr 17, 2020 at 11:45 PM Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote:
> > On Sat, Apr 18, 2020 at 01:19:59PM +0800, Tiezhu Yang wrote:
> > > If module name is empty, it is better to return directly at the beginning
> > > of request_module() without doing the needless call_modprobe() operation.
> > >
> > > Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> > > ---
> > >   kernel/kmod.c | 5 +++++
> > >   1 file changed, 5 insertions(+)
> > >
> > > diff --git a/kernel/kmod.c b/kernel/kmod.c
> > > index 3cd075c..5851444 100644
> > > --- a/kernel/kmod.c
> > > +++ b/kernel/kmod.c
> > > @@ -28,6 +28,8 @@
> > >
> > >   #include <trace/events/module.h>
> > >
> > > +#define MODULE_NOT_FOUND 256
> > > +
> > >   /*
> > >    * Assuming:
> > >    *
> > > @@ -144,6 +146,9 @@ int __request_module(bool wait, const char *fmt, ...)
> > >        if (ret >= MODULE_NAME_LEN)
> > >                return -ENAMETOOLONG;
> > >
> > > +     if (strlen(module_name) == 0)
> > > +             return MODULE_NOT_FOUND;
> > I'd rather we just use something standard like -EINVAL.
> > What do we return if its not found? Then use that value.
> Also, are we testing for this condition yet? If not can we add one?

Yes, kmod_test_0001_driver() in tools/testing/selftests/kmod/kmod.sh tests
this case and expects result MODULE_NOT_FOUND which is 256.