diff options
author | Xie He <xie.he.0141@gmail.com> | 2020-08-13 11:17:04 -0700 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2020-08-14 20:41:08 -0700 |
commit | 77b981c82c1df7c7ad32a046f17f007450b46954 (patch) | |
tree | d9f759574656a420590b3efd821dc7e607823aad /drivers/net/wan/hdlc.c | |
parent | 4ca0d9ac3fd8f9f90b72a15d8da2aca3ffb58418 (diff) |
drivers/net/wan/hdlc_x25: Added needed_headroom and a skb->len check
1. Added a skb->len check
This driver expects upper layers to include a pseudo header of 1 byte
when passing down a skb for transmission. This driver will read this
1-byte header. This patch added a skb->len check before reading the
header to make sure the header exists.
2. Added needed_headroom and set hard_header_len to 0
When this driver transmits data,
first this driver will remove a pseudo header of 1 byte,
then the lapb module will prepend the LAPB header of 2 or 3 bytes.
So the value of needed_headroom in this driver should be 3 - 1.
Because this driver has no header_ops, according to the logic of
af_packet.c, the value of hard_header_len should be 0.
Reason of setting needed_headroom and hard_header_len at this place:
This driver is written using the API of the hdlc module, the hdlc
module enables this driver (the protocol driver) to run on any hardware
that has a driver (the hardware driver) written using the API of the
hdlc module.
Two other hdlc protocol drivers - hdlc_ppp and hdlc_raw_eth, also set
things like hard_header_len at this place. In hdlc_ppp, it sets
hard_header_len after attach_hdlc_protocol and before setting dev->type.
In hdlc_raw_eth, it sets hard_header_len by calling ether_setup after
attach_hdlc_protocol and after memcpy the settings.
3. Reset needed_headroom when detaching protocols (in hdlc.c)
When detaching a protocol from a hardware device, the hdlc module will
reset various parameters of the device (including hard_header_len) to
the default values. We add needed_headroom here so that needed_headroom
will also be reset.
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Martin Schiller <ms@dev.tdt.de>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/wan/hdlc.c')
-rw-r--r-- | drivers/net/wan/hdlc.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/net/wan/hdlc.c b/drivers/net/wan/hdlc.c index dfc16770458d..386ed2aa31fd 100644 --- a/drivers/net/wan/hdlc.c +++ b/drivers/net/wan/hdlc.c @@ -230,6 +230,7 @@ static void hdlc_setup_dev(struct net_device *dev) dev->max_mtu = HDLC_MAX_MTU; dev->type = ARPHRD_RAWHDLC; dev->hard_header_len = 16; + dev->needed_headroom = 0; dev->addr_len = 0; dev->header_ops = &hdlc_null_ops; } |