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From:   Haiyang Zhang <haiyangz@microsoft.com>
To:     Stephen Hemminger <stephen@networkplumber.org>
CC:     "davem@davemloft.net" <davem@davemloft.net>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
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        vkuznets <vkuznets@redhat.com>
Subject: RE: [PATCH net-next, v2, 1/3] hv_netvsc: Add support for LRO/RSC in
 the vSwitch
Thread-Topic: [PATCH net-next, v2, 1/3] hv_netvsc: Add support for LRO/RSC in
 the vSwitch
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Date:   Fri, 21 Sep 2018 18:51:54 +0000
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> -----Original Message-----
> From: Stephen Hemminger <stephen@networkplumber.org>
> Sent: Friday, September 21, 2018 2:37 PM
> To: Haiyang Zhang <haiyangz@linuxonhyperv.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>; davem@davemloft.net;
> netdev@vger.kernel.org; olaf@aepfle.de; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; vkuznets <vkuznets@redhat.com>
> Subject: Re: [PATCH net-next, v2, 1/3] hv_netvsc: Add support for LRO/RSC=
 in
> the vSwitch
>=20
> On Fri, 21 Sep 2018 18:20:35 +0000
> Haiyang Zhang <haiyangz@linuxonhyperv.com> wrote:
>=20
> Overall, this looks good. Some minor suggestions.
>=20
> > +struct nvsc_rsc {
> > +	const struct ndis_pkt_8021q_info *vlan;
> > +	const struct ndis_tcp_ip_checksum_info *csum_info;
> > +	u8 is_last; /* last RNDIS msg in a vmtransfer_page */
> > +	u32 cnt; /* #fragments in an RSC packet */
> > +	u32 pktlen; /* Full packet length */
> > +	void *data[NVSP_RSC_MAX];
> > +	u32 len[NVSP_RSC_MAX];
> > +};
> > +
>=20
> This new state structure is state on a per-channel basis.
> Do you really need this to be persistent across packets?
>=20
> Could this be on stack or do you need it to handle split packets arriving=
 in
> different polls? Or is the stack space a problem?
>=20
> Also, maybe data and length could be in one structure since they are rela=
ted.

The stack space is a problem. NVSP_RSC_MAX is 562, which is defined by host=
.
It will be too large for limited stack space.=20

struct nvsc_rsc includes the data, len, cnt, chksum, vlan for one RSC packe=
t. They
are all related to construction of one SKB and its meta data. So I put them=
 in
one structure.

Thanks,
- Haiyang