I thought Russia unofficially blocked weapons exports to Pakistan, due to India's insistence? (Recently changed though).
As for China, you can't expect Russia to side against China, we are their partners and the ones they go to when their relations with the West go downhill. We have a shared mutual interest in creating a new multi-polar world, rather than the current American hegemony, and we work together to achieve that goal.
Russia stays neutral in China-India conflicts, as they have all these years.