nvme-tcp: lockdep: use dynamic lockdep keys per socket instance

When NVMe-TCP controller setup and teardown are repeated with lockdep
enabled, lockdep reports false positives WARN for the following locks:

  1) &q->elevator_lock        : IO scheduler change context
  2) &q->q_usage_counter(io)  : SCSI disk probe context
  3) fs_reclaim               : CPU hotplug bring-up context
  4) cpu_hotplug_lock         : socket establishment context
  5) sk_lock-AF_INET-NVME     : MQ sched dispatch context for the socket
  6) set->srcu                : NVMe controller delete context

The lockdep WARN was observed by running blktests test case nvme/005 for
tcp transport on v7.1-rc1 kernel with a patch. Refer to the Link tag for
the details of the WARN.

This is a false positive because lockdep confuses lock 4) (socket
establishment) with lock 5) (socket in use) for different socket
instances. The locks belong to different sockets, but lockdep treats
them as the same due to shared static lockdep keys.

Fix this by using dynamically allocated lockdep keys per socket instance
instead of static keys nvme_tcp_sk_key[] and nvme_tcp_slock_key[]. Add
nvme_tcp_sk_key and nvme_tcp_slock_key fields to struct nvme_tcp_queue
and pass them to sock_lock_init_class_and_name() for proper lockdep
tracking. Change the argument of nvme_tcp_reclassify_socket() from
'struct socket *' to 'struct nvme_tcp_queue *' to pass both the socket
and the keys. Add CONFIG_DEBUG_LOCK_ALLOC guards to nvme_tcp_alloc_queue()
and nvme_tcp_free_queue() to register and unregister the dynamic keys.
Additionally, move nvme_tcp_reclassify_socket() inside these guards since
it's only needed when lockdep is enabled.

Link: https://lore.kernel.org/linux-nvme/afB5syZbUrppgsDQ@shinmob/
Suggested-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>

0 files changed, 0 insertions, 0 deletions