internal/poll: use fdMutex to provide read/write locking on Windows

On Windows it is not possible to do concurrent I/O on file handles due
to the way FD.Pread and FD.Pwrite are implemented. This serialization is
achieved by having a dedicated mutex locked in the affected FD methods.

This makes the code difficult to reason about, as there is another
layer of locking introduced by the fdMutex. For example, it is not
obvious that concurrent I/O operations are serialized.

This CL removed the dedicated mutex and uses the fdMutex to provide
read/write locking.

Change-Id: I00389662728ce29428a587c3189bab90a0399215
Reviewed-on: https://go-review.googlesource.com/c/go/+/698096
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>

0 files changed, 0 insertions, 0 deletions