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From:   Dexuan Cui <decui@microsoft.com>
To:     David Miller <davem@davemloft.net>
CC:     "kuba@kernel.org" <kuba@kernel.org>,
        KY Srinivasan <kys@microsoft.com>,
        Haiyang Zhang <haiyangz@microsoft.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>
Subject: RE: [PATCH v3 net-next] net: mana: Add a driver for Microsoft Azure
 Network Adapter (MANA)
Thread-Topic: [PATCH v3 net-next] net: mana: Add a driver for Microsoft Azure
 Network Adapter (MANA)
Thread-Index: AQHXLNFkZWy01RJh1EWXtFcKc+4EuqqrT01QgAAJMACAAADqQA==
Date:   Fri, 9 Apr 2021 00:47:52 +0000
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> From: David Miller <davem@davemloft.net>
> Sent: Thursday, April 8, 2021 5:41 PM
> > ...
> > In the driver code, all the structs/unions marked by __packed are used =
to
> > talk with the hardware, so I think __packed is necessary here?
>=20
> It actually isan't in many cases, check with and without the __packed dir=
ective
> and see if anything chasnges.

Will do.

> > Do you think if it's better if we remove all the __packed, and add
> > static_assert(sizeof(struct XXX) =3D=3D YYY) instead? e.g.
> >
> > @@ -105,7 +105,8 @@ struct gdma_msg_hdr {
> >         u16 msg_version;
> >         u16 hwc_msg_id;
> >         u32 msg_size;
> > -} __packed;
> > +};
> > +static_assert(sizeof(struct gdma_msg_hdr) =3D=3D 16);
>=20
> This won't make sure the structure member offsets are what you expect.
>=20
> I think you'll have to go through the structures one-by-one by hand to
> figure out which ones really require the __packed attribute and which do =
not.

Got it. Let me see if I can remove all the __packed.