netdev - Re: [PATCH net-next v7 1/5] rust: core abstractions for network PHY drivers

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Message-ID: <b69b2ac0-752b-42ea-a729-9efdee503602@lunn.ch>
Date: Fri, 17 Nov 2023 14:53:44 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Alice Ryhl <aliceryhl@...gle.com>
Cc: fujita.tomonori@...il.com, benno.lossin@...ton.me,
	miguel.ojeda.sandonis@...il.com, netdev@...r.kernel.org,
	rust-for-linux@...r.kernel.org, tmgross@...ch.edu,
	wedsonaf@...il.com
Subject: Re: [PATCH net-next v7 1/5] rust: core abstractions for network PHY
 drivers

> I would change this to "it's okay to call phy_drivers_unregister from a
> different thread than the one in which phy_drivers_register was called".

This got me thinking about 'threads'. For register and unregister, we
are talking abut the kernel modules module_init() and module_exit()
function. module_init() can be called before user space is even
started, but it could also be called by insmod. module_exit() could be
called by rmmod, but it could also be the kernel, after user space has
gone away on shutdown. We are always in a context which can block, but
i never really think of this being threads. You can start a kernel
thread, and have some data structure exclusively used by that kernel
thread, but that is pretty unusual.

So i would probably turn this commenting around. Only comment like
this in the special case that a kernel thread exists, and it is
expected to have exclusive access.

	 Andrew