mu.Unlock()
			}
		}(i)
	}
	wg.Wait()

	// We already saw write failures, no need to proceed into read's
	if retError != "" {
		return SpeedTestResult{
			Uploads:     totalBytesWritten,
			Downloads:   totalBytesRead,
			UploadTimes: uploadTimes,
			Error:       retError,
		}, nil
	}

	downloadsCtx, downloadsCancel := context.WithTimeout(ctx, opts.duration)
	defer downloadsCancel()