[dev.fuzz] internal/fuzz: guard concurrent access to shared memory
This change moves the worker's *sharedMem into a buffered chan that
acts as a mutex. The mutex can be locked by receiving from the chan;
it can be unlocked by sending *sharedMem back to the chan. Multiple
objects (like worker, workerClient, workerServer) may have references
to the chan and may hold the lock across several operations.
This is intended to fix a segfault that occurred when
workerClient.fuzz accessed shared memory after it was already closed
and unmapped by the worker's goroutine. workerClient.fuzz is executed
in a separate goroutine so the worker can still receive messages from
the coordinator (like being told to stop and clean up).
Change-Id: I4eb9079ba9e5bfcfacfecd0fc8ad9bed17b33bba
Reviewed-on: https://go-review.googlesource.com/c/go/+/285054
Run-TryBot: Jay Conrod <jayconrod@google.com>
TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Katie Hockman <katie@golang.org>
Trust: Jay Conrod <jayconrod@google.com>