* [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
@ 2021-02-05 22:41 Xie He
2021-02-06 2:51 ` Willem de Bruijn
0 siblings, 1 reply; 5+ messages in thread
From: Xie He @ 2021-02-05 22:41 UTC (permalink / raw)
To: David S. Miller, Jakub Kicinski, Willem de Bruijn, Eric Dumazet,
John Ogness, Tanner Love, Eyal Birger, netdev, linux-kernel
Cc: Xie He
The "dev_has_header" function, recently added in
commit d549699048b4 ("net/packet: fix packet receive on L3 devices
without visible hard header"),
is more accurate as criteria for determining whether a device exposes
the LL header to upper layers, because in addition to dev->header_ops,
it also checks for dev->header_ops->create.
When transmitting an skb on a device, dev_hard_header can be called to
generate an LL header. dev_hard_header will only generate a header if
dev->header_ops->create is present.
Signed-off-by: Xie He <xie.he.0141@gmail.com>
---
net/packet/af_packet.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 6bbc7a448593..e24b2841c643 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -132,17 +132,17 @@ Resume
because it is invisible to us.
On transmit:
------------
-dev->header_ops != NULL
+dev_has_header(dev) == true
mac_header -> ll header
data -> ll header
-dev->header_ops == NULL (ll header is invisible to us)
+dev_has_header(dev) == false (ll header is invisible to us)
mac_header -> data
data -> data
We should set network_header on output to the correct position,
packet classifier depends on it.
*/
--
2.27.0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
2021-02-05 22:41 [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria Xie He
@ 2021-02-06 2:51 ` Willem de Bruijn
2021-02-06 15:42 ` Eyal Birger
2021-02-07 0:57 ` Jakub Kicinski
0 siblings, 2 replies; 5+ messages in thread
From: Willem de Bruijn @ 2021-02-06 2:51 UTC (permalink / raw)
To: Xie He
Cc: David S. Miller, Jakub Kicinski, Eric Dumazet, John Ogness,
Tanner Love, Eyal Birger, Network Development, linux-kernel
On Fri, Feb 5, 2021 at 5:42 PM Xie He <xie.he.0141@gmail.com> wrote:
>
> The "dev_has_header" function, recently added in
> commit d549699048b4 ("net/packet: fix packet receive on L3 devices
> without visible hard header"),
> is more accurate as criteria for determining whether a device exposes
> the LL header to upper layers, because in addition to dev->header_ops,
> it also checks for dev->header_ops->create.
>
> When transmitting an skb on a device, dev_hard_header can be called to
> generate an LL header. dev_hard_header will only generate a header if
> dev->header_ops->create is present.
>
> Signed-off-by: Xie He <xie.he.0141@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Indeed, existence of dev->header_ops->create is the deciding factor. Thanks Xie.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
2021-02-06 2:51 ` Willem de Bruijn
@ 2021-02-06 15:42 ` Eyal Birger
2021-02-06 19:29 ` Xie He
2021-02-07 0:57 ` Jakub Kicinski
1 sibling, 1 reply; 5+ messages in thread
From: Eyal Birger @ 2021-02-06 15:42 UTC (permalink / raw)
To: Xie He
Cc: David S. Miller, Jakub Kicinski, Willem de Bruijn, Eric Dumazet,
John Ogness, Tanner Love, Network Development, linux-kernel
Hi,
On Sat, Feb 6, 2021 at 4:52 AM Willem de Bruijn
<willemdebruijn.kernel@gmail.com> wrote:
>
> On Fri, Feb 5, 2021 at 5:42 PM Xie He <xie.he.0141@gmail.com> wrote:
> >
> > The "dev_has_header" function, recently added in
> > commit d549699048b4 ("net/packet: fix packet receive on L3 devices
> > without visible hard header"),
> > is more accurate as criteria for determining whether a device exposes
> > the LL header to upper layers, because in addition to dev->header_ops,
> > it also checks for dev->header_ops->create.
> >
> > When transmitting an skb on a device, dev_hard_header can be called to
> > generate an LL header. dev_hard_header will only generate a header if
> > dev->header_ops->create is present.
> >
> > Signed-off-by: Xie He <xie.he.0141@gmail.com>
>
> Acked-by: Willem de Bruijn <willemb@google.com>
>
> Indeed, existence of dev->header_ops->create is the deciding factor. Thanks Xie.
As such, may I suggest making this explicit by making
dev_hard_header() use dev_has_header()?
Eyal.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
2021-02-06 15:42 ` Eyal Birger
@ 2021-02-06 19:29 ` Xie He
0 siblings, 0 replies; 5+ messages in thread
From: Xie He @ 2021-02-06 19:29 UTC (permalink / raw)
To: Eyal Birger
Cc: David S. Miller, Jakub Kicinski, Willem de Bruijn, Eric Dumazet,
John Ogness, Tanner Love, Network Development, linux-kernel
On Sat, Feb 6, 2021 at 7:43 AM Eyal Birger <eyal.birger@gmail.com> wrote:
>
> As such, may I suggest making this explicit by making
> dev_hard_header() use dev_has_header()?
That is a good idea. We may submit another patch for that.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
2021-02-06 2:51 ` Willem de Bruijn
2021-02-06 15:42 ` Eyal Birger
@ 2021-02-07 0:57 ` Jakub Kicinski
1 sibling, 0 replies; 5+ messages in thread
From: Jakub Kicinski @ 2021-02-07 0:57 UTC (permalink / raw)
To: Willem de Bruijn
Cc: Xie He, David S. Miller, Eric Dumazet, John Ogness, Tanner Love,
Eyal Birger, Network Development, linux-kernel
On Fri, 5 Feb 2021 21:51:36 -0500 Willem de Bruijn wrote:
> On Fri, Feb 5, 2021 at 5:42 PM Xie He <xie.he.0141@gmail.com> wrote:
> >
> > The "dev_has_header" function, recently added in
> > commit d549699048b4 ("net/packet: fix packet receive on L3 devices
> > without visible hard header"),
> > is more accurate as criteria for determining whether a device exposes
> > the LL header to upper layers, because in addition to dev->header_ops,
> > it also checks for dev->header_ops->create.
> >
> > When transmitting an skb on a device, dev_hard_header can be called to
> > generate an LL header. dev_hard_header will only generate a header if
> > dev->header_ops->create is present.
> >
> > Signed-off-by: Xie He <xie.he.0141@gmail.com>
>
> Acked-by: Willem de Bruijn <willemb@google.com>
>
> Indeed, existence of dev->header_ops->create is the deciding factor. Thanks Xie.
Applied, thanks!
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-02-05 22:41 [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria Xie He
2021-02-06 2:51 ` Willem de Bruijn
2021-02-06 15:42 ` Eyal Birger
2021-02-06 19:29 ` Xie He
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