Merge branch 'tcp-coalesce-merge-timestamps'
authorDavid S. Miller <davem@davemloft.net>
Thu, 21 Apr 2016 18:40:56 +0000 (14:40 -0400)
committerDavid S. Miller <davem@davemloft.net>
Thu, 21 Apr 2016 18:40:56 +0000 (14:40 -0400)
commit5bec11cf446eafa4851649db2d53e4086119a36f
tree938326d0b6816e77fcfc232c7f5798dfc780d935
parent3fa88c51c73a67e7eeda1fcafd809f9185790b31
parentcfea5a688eb37bcd1081255df9f9f777f4e61999
Merge branch 'tcp-coalesce-merge-timestamps'

Martin KaFai Lau says:

====================
tcp: Merge timestamp info when coalescing skbs

This series is separated from the RFC series related to
tcp_sendmsg(MSG_EOR) and it is targeting for the net branch.
This patchset is focusing on fixing cases where TCP
timestamp could be lost after coalescing skbs.

A BPF prog is used to kprobe to sock_queue_err_skb()
and print out the value of serr->ee.ee_data.  The BPF
prog (run-able from bcc) is attached here:

BPF prog used for testing:
~~~~~

from __future__ import print_function
from bcc import BPF

bpf_text = """

int trace_err_skb(struct pt_regs *ctx)
{
struct sk_buff *skb = (struct sk_buff *)ctx->si;
struct sock *sk = (struct sock *)ctx->di;
struct sock_exterr_skb *serr;
u32 ee_data = 0;

if (!sk || !skb)
return 0;

serr = SKB_EXT_ERR(skb);
bpf_probe_read(&ee_data, sizeof(ee_data), &serr->ee.ee_data);
bpf_trace_printk("ee_data:%u\\n", ee_data);

return 0;
};
"""

b = BPF(text=bpf_text)
b.attach_kprobe(event="sock_queue_err_skb", fn_name="trace_err_skb")
print("Attached to kprobe")
b.trace_print()
====================

Signed-off-by: David S. Miller <davem@davemloft.net>