unlockf is called after the G is put into _Gwaiting, meaning another G
may have readied this one before unlockf is called.
This is implied by the current doc, but add additional notes to call out
this behavior, as it can be quite surprising.
Updates #40641
Change-Id: I60b1ccc6a4dd9ced8ad2aa1f729cb2e973100b59
Reviewed-on: https://go-review.googlesource.com/c/go/+/256058
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com>