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

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Date: Sat, 28 Oct 2023 16:26:16 -0700
From: Boqun Feng <boqun.feng@...il.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: Benno Lossin <benno.lossin@...ton.me>,
	FUJITA Tomonori <fujita.tomonori@...il.com>, netdev@...r.kernel.org,
	rust-for-linux@...r.kernel.org, tmgross@...ch.edu,
	miguel.ojeda.sandonis@...il.com, wedsonaf@...il.com
Subject: Re: [PATCH net-next v7 1/5] rust: core abstractions for network PHY
 drivers

On Sat, Oct 28, 2023 at 09:23:25PM +0200, Andrew Lunn wrote:
> > Now let's look back into struct phy_device, it does have a few locks
> > in it, and at least even with phydev->lock held, the content of
> > phydev->lock itself can be changed (e.g tick locks), hence it breaks the
> > requirement of the existence of a `&bindings::phy_device`.
> 
> tick locks appear to be a Rust thing, so are unlikely to appear in a C

Ah, I meant ticket locks... same here a mutex has a wait_lock which can
be implemented by ticket locks or queued spin locks, so the u32 lock
field may change even with lock held.

Regards,
Boqun

> structure. However, kernel C mutex does have a linked list of other
> threads waiting for the mutex. So phydev->lock can change at any time,
> even when held.
> 
> 	Andrew