ipv4: Fix fib_trie rebalancing, part 3
ipv4: Fix fib_trie rebalancing, part 3

Alas current delaying of freeing old tnodes by RCU in trie_rebalance
is still not enough because we can free a top tnode before updating a
t->trie pointer.

Reported-by: Pawel Staszewski <ac265502104f804d1ff242e3dd0f2ea78dc60fd1@itcare.pl>
Tested-by: Pawel Staszewski <ac265502104f804d1ff242e3dd0f2ea78dc60fd1@itcare.pl>
Signed-off-by: Jarek Poplawski <85e4e0cd35fdfcbe234be29b330d591ff9717625@gmail.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs