Re: [PATCH] nvmet: protect nvmet_ports_list with nvmet_config_sem

[Keith Busch <kbusch@kernel.org>]

On Fri, Oct 23, 2026 at 07:36:28PM +0800, Qing Zhang wrote:
> >From 554233f4165842a0a104896c30ed4d2e89c11931 Mon Sep 17 00:00:00 2001
> From: Qing Zhang <diasyzhang@tencent.com>
> Date: Fri, 23 Oct 2026 19:29:28 +0800
> Subject: [PATCH] nvmet: protect nvmet_ports_list with nvmet_config_sem
> 
> Readers of nvmet_ports_list (e.g. nvmet_subsys_disc_changed()) hold
> nvmet_config_sem and assert it via lockdep.  The writers --
> nvmet_ports_make() and nvmet_port_release() -- do not take the lock;
> they rely on the parent directory's VFS inode lock for serialization,
> which is an implementation detail of configfs and not a guaranteed
> contract.  Align the writers with the lock the readers already require.
> 
> Also move list_add() in nvmet_ports_make() to after the port is fully
> initialized: the old position published the port on the global list
> before INIT_LIST_HEAD(&port->subsystems), so a concurrent reader
> could traverse uninitialized list heads.
> 
> flush_workqueue() in nvmet_port_release() stays outside the semaphore
> to avoid a lock dependency on nvmet_wq.

Thanks, applied to nvme-7.4.