when sk_buff is allocated while sending packaet

Mr.J · 04-15-2009, 04:07 AM

When a frame is received at NIC, interrupt handler of NIC , allocate sk_buff struct and copy data from Device to struct.
When I send packet (using send function of socket), where this struct is initialized and who allocate this struct....

Thanks
James.

AustinMarton · 04-16-2009, 08:44 PM

I'm not sure exactly where, but the driver receives the skb from the upper layers - so somewhere up there

titan22 · 04-17-2009, 09:37 PM

UDP ip_append_data() user data is copied to SKB
TCP do_tcp_sendpages() user data is copied to SKB
sendfile ip_append_page() zero copy. Update SKB pointers to user data.

They are in L4 layer and sit under net/ipv4 (or ipv6). SKBs are pushed down to L3 IP later.