linux-kernel - Re: [PATCH net-next 6/6] net: phy: dp83869: Fix link up reporting in SGMII bridge mode

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Message-ID: <289c5122-759f-408a-a48a-a3719f0331f9@lunn.ch>
Date: Mon, 1 Jul 2024 19:09:40 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Romain Gantois <romain.gantois@...tlin.com>
Cc: Heiner Kallweit <hkallweit1@...il.com>,
	Russell King <linux@...linux.org.uk>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 6/6] net: phy: dp83869: Fix link up reporting in
 SGMII bridge mode

> +			if (dp83869->mod_phy) {
> +				ret = phy_read_status(dp83869->mod_phy);
> +				if (ret)
> +					return ret;

Locking? When phylib does this in phy_check_link_status(), we have:

	lockdep_assert_held(&phydev->lock);

I don't see anything which takes the downstreams PHY lock.

Is this also introducing race conditions? What happens if the link
just went down? phy_check_link_status() takes actions. Will they still
happen when phylib next talks to the downstream PHY? It is probably
safer to call phy_check_link_status() than phy_read_status().

   Andrew