SKB_COW_DATA(9) Linux Networking SKB_COW_DATA(9)NAME
skb_cow_data - Check that a socket buffer's data buffers are writable
SYNOPSIS
int skb_cow_data(struct sk_buff * skb, int tailbits, struct sk_buff ** trailer);
ARGUMENTS
skb
The socket buffer to check.
tailbits
Amount of trailing space to be added
trailer
Returned pointer to the skb where the tailbits space begins
DESCRIPTION
Make sure that the data buffers attached to a socket buffer are writable. If they are not, private copies are made of the data buffers and
the socket buffer is set to use these instead.
If tailbits is given, make sure that there is space to write tailbits bytes of data beyond current end of socket buffer. trailer will be
set to point to the skb in which this space begins.
The number of scatterlist elements required to completely map the COW'd and extended socket buffer will be returned.
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 SKB_COW_DATA(9)
Check Out this Related Man Page
STRUCT SK_BUFF(9) Linux Networking STRUCT SK_BUFF(9)NAME
struct_sk_buff - socket buffer
SYNOPSIS
struct sk_buff {
struct sk_buff * next;
struct sk_buff * prev;
ktime_t tstamp;
struct sock * sk;
struct net_device * dev;
char cb[48];
unsigned long _skb_dst;
#ifdef CONFIG_XFRM
struct sec_path * sp;
#endif
unsigned int len;
unsigned int data_len;
__u16 mac_len;
__u16 hdr_len;
union {unnamed_union};
__u16 vlan_tci;
sk_buff_data_t transport_header;
sk_buff_data_t network_header;
sk_buff_data_t mac_header;
sk_buff_data_t tail;
sk_buff_data_t end;
unsigned char * head;
unsigned char * data;
unsigned int truesize;
atomic_t users;
};
MEMBERS
next
Next buffer in list
prev
Previous buffer in list
tstamp
Time we arrived
sk
Socket we are owned by
dev
Device we arrived on/are leaving by
cb[48]
Control buffer. Free for use by every layer. Put private vars here
_skb_dst
destination entry
sp
the security path, used for xfrm
len
Length of actual data
data_len
Data length
mac_len
Length of link layer header
hdr_len
writable header length of cloned skb
{unnamed_union}
anonymous
vlan_tci
vlan tag control information
transport_header
Transport layer header
network_header
Network layer header
mac_header
Link layer header
tail
Tail pointer
end
End pointer
head
Head of buffer
data
Data head pointer
truesize
Buffer size
users
User count - see {datagram,tcp}.c
COPYRIGHT Kernel Hackers Manual 2.6. July 2010 STRUCT SK_BUFF(9)
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