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From:   Parav Pandit <parav@mellanox.com>
To:     Alex Williamson <alex.williamson@redhat.com>,
        Kirti Wankhede <kwankhede@nvidia.com>
CC:     "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH 4/8] vfio/mdev: Drop redundant extern for exported symbols
Thread-Topic: [PATCH 4/8] vfio/mdev: Drop redundant extern for exported
 symbols
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Date:   Mon, 25 Mar 2019 21:27:16 +0000
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> -----Original Message-----
> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Monday, March 25, 2019 2:50 PM
> To: Kirti Wankhede <kwankhede@nvidia.com>
> Cc: Parav Pandit <parav@mellanox.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Subject: Re: [PATCH 4/8] vfio/mdev: Drop redundant extern for exported
> symbols
>=20
> On Tue, 26 Mar 2019 00:37:04 +0530
> Kirti Wankhede <kwankhede@nvidia.com> wrote:
>=20
> > On 3/23/2019 4:50 AM, Parav Pandit wrote:
> > > There is no need use 'extern' for exported functions.
> > >
> > > Signed-off-by: Parav Pandit <parav@mellanox.com>
> > > ---
> > >  include/linux/mdev.h | 21 ++++++++++-----------
> > >  1 file changed, 10 insertions(+), 11 deletions(-)
> > >
> > > diff --git a/include/linux/mdev.h b/include/linux/mdev.h index
> > > b6e048e..0924c48 100644
> > > --- a/include/linux/mdev.h
> > > +++ b/include/linux/mdev.h
> > > @@ -118,21 +118,20 @@ struct mdev_driver {
> > >
> > >  #define to_mdev_driver(drv)	container_of(drv, struct mdev_driver,
> driver)
> > >
> > > -extern void *mdev_get_drvdata(struct mdev_device *mdev); -extern
> > > void mdev_set_drvdata(struct mdev_device *mdev, void *data); -extern
> > > uuid_le mdev_uuid(struct mdev_device *mdev);
> > > +void *mdev_get_drvdata(struct mdev_device *mdev); void
> > > +mdev_set_drvdata(struct mdev_device *mdev, void *data); uuid_le
> > > +mdev_uuid(struct mdev_device *mdev);
> > >
> > >  extern struct bus_type mdev_bus_type;
> > >
> > > -extern int  mdev_register_device(struct device *dev,
> > > -				 const struct mdev_parent_ops *ops);
> > > -extern void mdev_unregister_device(struct device *dev);
> > > +int mdev_register_device(struct device *dev, const struct
> > > +mdev_parent_ops *ops); void mdev_unregister_device(struct device
> > > +*dev);
> > >
> > > -extern int  mdev_register_driver(struct mdev_driver *drv, struct
> > > module *owner); -extern void mdev_unregister_driver(struct
> > > mdev_driver *drv);
> > > +int mdev_register_driver(struct mdev_driver *drv, struct module
> > > +*owner); void mdev_unregister_driver(struct mdev_driver *drv);
> > >
> > > -extern struct device *mdev_parent_dev(struct mdev_device *mdev);
> > > -extern struct device *mdev_dev(struct mdev_device *mdev); -extern
> > > struct mdev_device *mdev_from_dev(struct device *dev);
> > > +struct device *mdev_parent_dev(struct mdev_device *mdev); struct
> > > +device *mdev_dev(struct mdev_device *mdev); struct mdev_device
> > > +*mdev_from_dev(struct device *dev);
> > >
> > >  #endif /* MDEV_H */
> > >
> >
> > Adding 'extern' to exported symbols is inline to other exported
> > functions from device's core module like device_register(),
> > device_unregister(), get_device(), put_device()
>=20
> Right, I'd be inclined to leave this as a style choice, but...
>=20
> commit 3fe5dbfef47e992b810cbe82af1df02d8255fb8c
> Author: Alexey Dobriyan <adobriyan@gmail.com>
> Date:   Thu Jan 3 15:26:16 2019 -0800
>=20
>     Documentation/process/coding-style.rst: don't use "extern" with funct=
ion
> prototypes
>=20
>     `extern' with function prototypes makes lines longer and creates more
>     characters on the screen.
>=20
>     Do not bug people with checkpatch.pl warnings for now as fallout can =
be
>     devastating.
>=20
> So it's a new decision and rather weakly imposed new standard.  Thanks,
>=20
We always improve the kernel, sometimes in pieces, sometime at subsystem le=
vel or sometimes tree wide.
This is done mdev level.
device core is not good example to point that they use 'extern' so its fine=
 here...
That was written more than 10 years ago.
So we should be open to improvements.. silly or large..