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From:   "Dawar, Gautam" <gautam.dawar@amd.com>
To:     Dan Carpenter <dan.carpenter@oracle.com>,
        Eugenio Perez Martin <eperezma@redhat.com>
CC:     Stefano Garzarella <sgarzare@redhat.com>,
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        <virtualization@lists.linux-foundation.org>,
        Jason Wang <jasowang@redhat.com>,
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        Wu Zongyong <wuzongyong@linux.alibaba.com>,
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        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
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        "martinpo@xilinx.com" <martinpo@xilinx.com>,
        "pabloc@xilinx.com" <pabloc@xilinx.com>,
        Longpeng <longpeng2@huawei.com>,
        "Piotr.Uminski@intel.com" <Piotr.Uminski@intel.com>,
        "Kamde, Tanuj" <tanuj.kamde@amd.com>,
        Si-Wei Liu <si-wei.liu@oracle.com>,
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        Zhang Min <zhang.min9@zte.com.cn>,
        "hanand@xilinx.com" <hanand@xilinx.com>
Subject: RE: [PATCH v3 2/4] vhost-vdpa: introduce STOP backend feature bit
Thread-Topic: [PATCH v3 2/4] vhost-vdpa: introduce STOP backend feature bit
Thread-Index: AQHYcCaejZ+EcmRq3k6Nyj6LKxIuA60vcvXAgAFp4ICAAALPAIAAPJwAgAAKOgCAAD1RAIAAI1EAgADEoQCAAA0JgIAAbbUA
Date:   Fri, 27 May 2022 14:13:09 +0000
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[AMD Official Use Only - General]

IMHO replacing "return ops->stop;" with "return ops->stop?true:false;" shou=
ld be good enough.

On Fri, May 27, 2022 at 08:50:16AM +0200, Eugenio Perez Martin wrote:
> On Thu, May 26, 2022 at 9:07 PM Dan Carpenter <dan.carpenter@oracle.com> =
wrote:
> >
> > On Thu, May 26, 2022 at 07:00:06PM +0200, Eugenio Perez Martin wrote:
> > > > It feels like returning any literal that isn't 1 or 0 should
> > > > trigger a warning...  I've written that and will check it out tonig=
ht.
> > > >
> > >
> > > I'm not sure this should be so strict, or "literal" does not include =
pointers?
> > >
> >
> > What I mean in exact terms, is that if you're returning a known
> > value and the function returns bool then the known value should be 0 or=
 1.
> > Don't "return 3;".  This new warning will complain if you return a
> > known pointer as in "return &a;".  It won't complain if you return
> > an unknown pointer "return p;".
> >
>
> Ok, thanks for the clarification.
>
> > > As an experiment, can Smatch be used to count how many times a
> > > returned pointer is converted to int / bool before returning vs
> > > not converted?
> >
> > I'm not super excited to write that code...  :/
> >
>
> Sure, I understand. I meant if it was possible or if that is too far
> beyond its scope.

To be honest, I misread what you were asking.  GCC won't let you return a p=
ointer with an implied cast to int.  It has to be explicit.  So there are z=
ero of those.  It's not hard to look for pointers with an implied cast to b=
ool.

static void match_pointer(struct expression *ret_value) {
        struct symbol *type;
        char *name;

        type =3D cur_func_return_type();
        if (!type || sval_type_max(type).value !=3D 1)
                return;

        if (!is_pointer(ret_value))
                return;

        name =3D expr_to_str(ret_value);
        sm_msg("'%s' return pointer cast to bool", name);
        free_string(name);
}

regards,
dan carpenter