tag 2342c8b20a9ff12dd95818c498d47ee4705de6cb
tagger The Android Open Source Project <initial-contribution@android.com> Mon Jan 07 11:12:31 2019 -0800
object 7ac4a30be5d8cbfafc740f9f86d30f37d15f4483

Android 9.0.0 Release 30 (PQ1A.190105.004)

commit 7ac4a30be5d8cbfafc740f9f86d30f37d15f4483
author Bernie Innocenti <codewiz@google.com> Mon May 14 20:40:49 2018 +0900
committer Bernie Innocenti <codewiz@google.com> Wed May 16 14:05:15 2018 +0900
tree abe9305227662edad00cb78d44258d3d7c42da4b
parent cdc003dc8a8ffb418f33518ac545016e6991534a

Avoid spinning endlessly on packet socket errors

In the event the packet socket has an error, it is likely not cleared
and clatd can spin in a tight loop. This may happen when a network is
going down (ENETDOWN, ENETUNREACH, ...). Ordinarily the
ConnectivityService/Nat464Xlat/ClatdController control plane would
tear down clatd in this case.  However, if the control plane is
deadlocked, clatd will chew up CPU indefinitely.

This fix consists of detecting when poll() exits due to a socket error
and trying to clear the error by issuing a no-op recv() on the packet
socket and a 0-byte read() for the /dev/tun socket.

Test: manually, on a marlyn device (kernel 3.18.70)
Bug: 78602493
Change-Id: Ic23f999712a674df11e981a4314ad371e8d5fb6d
(cherry picked from commit 69dc60de5d53488a3c45737ec17b242d703d682b)