Subject: Re: [PATCH net-next] net: phy: Add driver for Motorcomm yt8531 gigabit ethernet phy

From: "Russell King (Oracle)" <[email-masked]>
Date: Wed, 30 Nov 2022 17:33:15 +0000

Hi Andrew,

On Wed, Nov 30, 2022 at 06:10:42PM +0100, Andrew Lunn wrote:
> This is not the first time Russell has pointed out your locking is
> wrong.
> 
> How about adding a check in functions which should be called with the
> lock taken really do have the lock taken?

They already do:

        lockdep_assert_held_once(&bus->mdio_lock);

but I guess people just aren't testing their code with lockdep enabled.

The only other thing I can think of trying is to use mutex_trylock():

	if (WARN_ON_ONCE(mutex_trylock(&bus->mdio_lock)))
		mutex_unlock(&bus->mdio_lock);

scattered throughout.

However, if the author does have lockdep enabled but ignores the
warnings, that isn't going to help.

-- 
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