073-pppoe-Use-workqueue-to-die-properly-when-a-PADT-is-r.patch@45653

在PPP的連線裡，當收到PADT的封包時，表示對方想要結束這個PPP連線，所以在收到PADT之後，主機也必須停止本身的PPP連線，並透過PPPoE daemon回應PADT封包。

在kernel中處理PADT封包時，並未能讓上層立即知道收到PADT封包，以至於PPPoE daemon必須等echo request timeout後，才自行送出PADT封包，這樣會造成PADT封包延後送出，解決方法就是使用這個patch。

When a PADT frame is received, the socket may not be in a good state to
close down the PPP interface. The current implementation handles this by
simply blocking all further PPP traffic, and hoping that the lack of traffic
will trigger the user to investigate.

Use schedule_work to get to a process context from which we clear down the
PPP interface, in a fashion analogous to hangup on a TTY-based PPP
interface. This causes pppd to disconnect immediately, and allows tools to
take immediate corrective action.

Note that pppd's rp_pppoe.so plugin has code in it to disable the session
when it disconnects; however, as a consequence of this patch, the session is
already disabled before rp_pppoe.so is asked to disable the session. The
result is a harmless error message:

Failed to disconnect PPPoE socket: 114 Operation already in progress

This message is safe to ignore, as long as the error is 114 Operation
already in progress; in that specific case, it means that the PPPoE session
has already been disabled before pppd tried to disable it.

drivers/net/ppp/pppoe.c

include/linux/if_pppox.h

參考來源
https://dev.openwrt.org/browser/trunk/target/linux/generic/patches-4.0/073-pppoe-Use-workqueue-to-die-properly-when-a-PADT-is-r.patch?rev=45653