linux-kernel - Re: [PATCH 3/4] kmod: Return directly if module name is empty in request

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Message-ID: <CAB=NE6XD7XCmsTAg3+mw=b8WZnKJiwha5t4DBJFt5w+b_DsNkg@mail.gmail.com>
Date:   Fri, 17 Apr 2020 23:48:46 -0600
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Shuah Khan <shuah@...nel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH 3/4] kmod: Return directly if module name is empty in request_module()

On Fri, Apr 17, 2020 at 11:45 PM Luis Chamberlain <mcgrof@...nel.org> 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@...ngson.cn>
> > ---
> >  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?