net: sched: move block device tracking into tcf_block_get/put_ext()

Inserting the device to block xarray in qdisc_create() is not suitable
place to do this. As it requires use of tcf_block() callback, it causes
multiple issues. It is called for all qdisc types, which is incorrect.

So, instead, move it to more suitable place, which is tcf_block_get_ext()
and make sure it is only done for qdiscs that use block infrastructure
and also only for blocks which are shared.

Symmetrically, alter the cleanup path, move the xarray entry removal
into tcf_block_put_ext().

Fixes: 913b47d3

 ("net/sched: Introduce tc block netdev tracking infra")
Reported-by: Ido Schimmel <idosch@nvidia.com>
Closes: https://lore.kernel.org/all/ZY1hBb8GFwycfgvd@shredder/
Reported-by: Kui-Feng Lee <sinquersw@gmail.com>
Closes: https://lore.kernel.org/all/ce8d3e55-b8bc-409c-ace9-5cf1c4f7c88e@gmail.com/
Reported-and-tested-by:  <syzbot+84339b9e7330daae4d66@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/all/0000000000007c85f5060dcc3a28@google.com/
Reported-and-tested-by:  <syzbot+806b0572c8d06b66b234@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/all/00000000000082f2f2060dcc3a92@google.com/
Reported-and-tested-by:  <syzbot+0039110f932d438130f9@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/all/0000000000007fbc8c060dcc3a5c@google.com/
Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
Tested-by: Victor Nogueira <victor@mojatatu.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>