在 2016年12月15日 01:24, Cong Wang 写道:
On Tue, Dec 13, 2016 at 11:49 PM, Du, Fan <fan...@intel.com> wrote:
Hi
I'm interested to one Docker issue[1] which looks like related to kernel vxlan
socket creation
as described in the thread. From my limited knowledge here, socket creation is
synchronous ,
and after the *socket* syscall, the sock handle will be valid and ready to
linkup.
You need to read the code. vxlan tunnel is a UDP tunnel, it needs a kernel
socket (and a port) to setup UDP communication, unlike GRE tunnel etc.
I check the fix is merged in 4.0, my code base is pretty new,
so somehow I failed to see the work queue stuff in drver/net/vxlan.c
Somehow I'm not sure the detailed scenario here, and which/how possible commit
fix?
Thanks!
Quoted analysis:
--------------------------------------------------------------------------
(Found in kernel 3.13)
The issue happens because in older kernels when a vxlan interface is created,
the socket creation is queued up in a worker thread which actually creates
the socket. But this needs to happen before we bring up the link on the vxlan
interface.
If for some chance, the worker thread hasn't completed the creation of the
socket
before we did link up then when we do link up the kernel checks if the socket
was
created and if not it will return ENOTCONN. This was a bug in the kernel which
got fixed
in later kernels. That is why retrying with a timer fixes the issue.
This was introduced by commit 1c51a9159ddefa5119724a4c7da3fd3ef44b68d5
and later fixed by commit 56ef9c909b40483d2c8cb63fcbf83865f162d5ec.
信聪哥，得永生。
Thanks for the offending commit id！
