netdev - Re: [PATCH net] net: dsa: lan9303: avoid dsa_switch

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Message-ID: <20240912101556.tvlvf2rq5nmxz7ui@skbuf>
Date: Thu, 12 Sep 2024 13:15:56 +0300
From: Vladimir Oltean <olteanv@...il.com>
To: "A. Sverdlin" <alexander.sverdlin@...mens.com>
Cc: netdev@...r.kernel.org, Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	stable@...r.kernel.org
Subject: Re: [PATCH net] net: dsa: lan9303: avoid dsa_switch_shutdown()

Hi Alexander,

On Wed, Sep 11, 2024 at 04:40:03PM +0200, A. Sverdlin wrote:
> From: Alexander Sverdlin <alexander.sverdlin@...mens.com>
> 
> dsa_switch_shutdown() doesn't bring down any ports, but only disconnects
> slaves from master. Packets still come afterwards into master port and the
> ports are being polled for link status. This leads to crashes:
> 
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
> CPU: 0 PID: 442 Comm: kworker/0:3 Tainted: G O 6.1.99+ #1
> Workqueue: events_power_efficient phy_state_machine
> pc : lan9303_mdio_phy_read
> lr : lan9303_phy_read
> Call trace:
>  lan9303_mdio_phy_read
>  lan9303_phy_read
>  dsa_slave_phy_read
>  __mdiobus_read
>  mdiobus_read
>  genphy_update_link
>  genphy_read_status
>  phy_check_link_status
>  phy_state_machine
>  process_one_work
>  worker_thread
> 
> Call lan9303_remove() instead to really unregister all ports before zeroing
> drvdata and dsa_ptr.
> 
> Fixes: 0650bf52b31f ("net: dsa: be compatible with masters which unregister on shutdown")
> Cc: stable@...r.kernel.org
> Signed-off-by: Alexander Sverdlin <alexander.sverdlin@...mens.com>
> ---

Could you please test this alternative solution (patch attached) for both reported problems?

Thanks.

View attachment "0001-net-dsa-improve-shutdown-sequence.patch" of type "text/x-diff" (3698 bytes)