From: Xie He <xie.he.0141@gmail.com>
To: "David S. Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Willem de Bruijn <willemb@google.com>,
Eric Dumazet <edumazet@google.com>,
John Ogness <john.ogness@linutronix.de>,
Tanner Love <tannerlove@google.com>,
Eyal Birger <eyal.birger@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: Xie He <xie.he.0141@gmail.com>
Subject: [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria
Date: Fri, 5 Feb 2021 14:41:24 -0800 [thread overview]
Message-ID: <20210205224124.21345-1-xie.he.0141@gmail.com> (raw)
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
next reply other threads:[~2021-02-06 3:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 22:41 Xie He [this message]
2021-02-06 2:51 ` [PATCH net-next] net/packet: Improve the comment about LL header visibility criteria Willem de Bruijn
2021-02-06 15:42 ` Eyal Birger
2021-02-06 19:29 ` Xie He
2021-02-07 0:57 ` Jakub Kicinski
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