Don't hold baseEndpoint.mu while calling EventUpdate().

This removes a three-lock deadlock between fdnotifier.notifier.mu,
epoll.EventPoll.listsMu, and baseEndpoint.mu.

A lock order comment was added to epoll/epoll.go.

Also fix unsafe access of baseEndpoint.connected/receiver.

PiperOrigin-RevId: 358515191

1 files changed, 6 insertions, 0 deletions

diff --git a/pkg/sentry/kernel/epoll/epoll.go b/pkg/sentry/kernel/epoll/epoll.go
index 61aeca044..407b6e917 100644
--- a/pkg/sentry/kernel/epoll/epoll.go
+++ b/pkg/sentry/kernel/epoll/epoll.go
@@ -14,6 +14,12 @@
 
 // Package epoll provides an implementation of Linux's IO event notification
 // facility. See epoll(7) for more details.
+//
+// Lock order:
+// EventPoll.mu
+//   fdnotifier.notifier.mu
+//     EventPoll.listsMu
+//       unix.baseEndpoint.Mutex
 package epoll
 
 import (