Re: [PATCH RFC 2/2] nvmet-rdma: use a separate lockdep class for the listening cm_id

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Low] nvmet-rdma: wildcard listener child cm_ids keep default lockdep
  class
--

commit a129fce174ee6d77cacc5458875c55e53aa41b7e
Author: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>

nvmet-rdma: use a separate lockdep class for the listening cm_id

This commit calls rdma_reclassify_id_for_listen() on the port's listening
cm_id in nvmet_rdma_enable_port() to give its handler_mutex a separate
lockdep class from connected queue cm_ids.

Link: https://lore.kernel.org/linux-nvme/at36um4zrsfOr3kh@shinmob/

> diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
> index b9e39d1657d29..94f6d8edb517f 100644
> --- a/drivers/nvme/target/rdma.c
> +++ b/drivers/nvme/target/rdma.c
> @@ -1914,6 +1914,8 @@ static int nvmet_rdma_enable_port(struct nvmet_rdma_port *port)
>  		return PTR_ERR(cm_id);
>  	}
>  
> +	rdma_reclassify_id_for_listen(cm_id);
> +
>  	/*
>  	 * Allow both IPv4 and IPv6 sockets to bind a single port
>  	 * at the same time.

[Severity: Low]
Does this still leave the per-device child listening cm_ids in the default
handler_mutex lockdep class when port->addr is a wildcard address?

For a wildcard address, rdma_bind_addr() leaves id_priv->cma_dev NULL, so
rdma_listen() calls cma_listen_on_all() -> cma_listen_on_dev(), which
creates a per-device child dev_id_priv via __rdma_create_id() without
reclassifying its handler_mutex:

drivers/infiniband/core/cma.c:cma_listen_on_dev() {
	...
	dev_id_priv =
		__rdma_create_id(net, cma_listen_handler, id_priv,
				 id_priv->id.ps, id_priv->id.qp_type, id_priv);
	...
}

When nvmet_rdma_disable_port() later calls rdma_destroy_id(cm_id) under
nvmet_config_sem, _cma_cancel_listens() calls
rdma_destroy_id(&dev_id_priv->id) and takes dev_id_priv->handler_mutex,
triggering the same false-positive lockdep warning.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261108120154.148824-1-shinichiro.kawasaki@wdc.com?part=2