linux-kernel - Re: [PATCH net v3] net: phy: mscc: fix deadlock in vsc85xx_default

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Message-ID: <20181123180358.GC5273@lunn.ch>
Date:   Fri, 23 Nov 2018 19:03:58 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Quentin Schulz <quentin.schulz@...tlin.com>
Cc:     davem@...emloft.net, f.fainelli@...il.com,
        allan.nielsen@...rochip.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, thomas.petazzoni@...tlin.com,
        alexandre.belloni@...tlin.com
Subject: Re: [PATCH net v3] net: phy: mscc: fix deadlock in
 vsc85xx_default_config

On Fri, Nov 23, 2018 at 07:01:51PM +0100, Quentin Schulz wrote:
> The vsc85xx_default_config function called in the vsc85xx_config_init
> function which is used by VSC8530, VSC8531, VSC8540 and VSC8541 PHYs
> mistakenly calls phy_read and phy_write in-between phy_select_page and
> phy_restore_page.
> 
> phy_select_page and phy_restore_page actually take and release the MDIO
> bus lock and phy_write and phy_read take and release the lock to write
> or read to a PHY register.
> 
> Let's fix this deadlock by using phy_modify_paged which handles
> correctly a read followed by a write in a non-standard page.
> 
> Fixes: 6a0bfbbe20b0 ("net: phy: mscc: migrate to phy_select/restore_page functions")
> 
> Signed-off-by: Quentin Schulz <quentin.schulz@...tlin.com>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew