The deadlock can occur when both ends of a connected Unix socket which has
FIOASYNC enabled on at least one end are closed at the same time. One end
notifies that it is closing, calling (*waiter.Queue).Notify which takes
waiter.Queue.mu (as a read lock) and then calls (*FileAsync).Callback, which
takes FileAsync.mu. The other end tries to unregister for notifications by
calling (*FileAsync).Unregister, which takes FileAsync.mu and calls
(*waiter.Queue).EventUnregister which takes waiter.Queue.mu.
This is fixed by moving the calls to waiter.Waitable.EventRegister and
waiter.Waitable.EventUnregister outside of the protection of any mutex used
in (*FileAsync).Callback.
The new test is related, but does not cover this particular situation.
Also fix a data race on FileAsync.e.Callback. (*FileAsync).Callback checked
FileAsync.e.Callback under the protection of FileAsync.mu, but the waiter
calling (*FileAsync).Callback could not and did not. This is fixed by making
FileAsync.e.Callback immutable before passing it to the waiter for the first
time.
Fixes#346
PiperOrigin-RevId: 253138340
Based on the guidelines at
https://opensource.google.com/docs/releasing/authors/.
1. $ rg -l "Google LLC" | xargs sed -i 's/Google LLC.*/The gVisor Authors./'
2. Manual fixup of "Google Inc" references.
3. Add AUTHORS file. Authors may request to be added to this file.
4. Point netstack AUTHORS to gVisor AUTHORS. Drop CONTRIBUTORS.
Fixes#209
PiperOrigin-RevId: 245823212
Change-Id: I64530b24ad021a7d683137459cafc510f5ee1de9
Ian Gudger
Michael Pratt
Nicolas Lacasse
Tamir Duberstein
Brian Geffon