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From: Florian Fainelli <f.fainelli@gmail.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
	"David S . Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	netdev@vger.kernel.org
Cc: Eric Dumazet <edumazet@google.com>,
	Paolo Abeni <pabeni@redhat.com>,
	Stephen Rothwell <sfr@canb.auug.org.au>,
	Andrew Lunn <andrew@lunn.ch>,
	Heiner Kallweit <hkallweit1@gmail.com>,
	Russell King <linux@armlinux.org.uk>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] net: mdio: unexport __init-annotated mdio_bus_init()
Date: Mon, 6 Jun 2022 10:09:25 +0200	[thread overview]
Message-ID: <53818857-18b8-c7d8-8003-43452c9aa003@gmail.com> (raw)
In-Reply-To: <20220606045355.4160711-2-masahiroy@kernel.org>



On 6/6/2022 6:53 AM, Masahiro Yamada wrote:
> EXPORT_SYMBOL and __init is a bad combination because the .init.text
> section is freed up after the initialization. Hence, modules cannot
> use symbols annotated __init. The access to a freed symbol may end up
> with kernel panic.
> 
> modpost used to detect it, but it has been broken for a decade.
> 
> Recently, I fixed modpost so it started to warn it again, then this
> showed up in linux-next builds.
> 
> There are two ways to fix it:
> 
>    - Remove __init
>    - Remove EXPORT_SYMBOL
> 
> I chose the latter for this case because the only in-tree call-site,
> drivers/net/phy/phy_device.c is never compiled as modular.
> (CONFIG_PHYLIB is boolean)
> 
> Fixes: 90eff9096c01 ("net: phy: Allow splitting MDIO bus/device support from PHYs")
> Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian

  reply	other threads:[~2022-06-06  8:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-06  4:53 [PATCH 0/3] net: unexport some symbols that are annotated __init Masahiro Yamada
2022-06-06  4:53 ` [PATCH 1/3] net: mdio: unexport __init-annotated mdio_bus_init() Masahiro Yamada
2022-06-06  8:09   ` Florian Fainelli [this message]
2022-06-06  8:25   ` Russell King (Oracle)
2022-06-06  4:53 ` [PATCH 2/3] net: xfrm: unexport __init-annotated xfrm4_protocol_init() Masahiro Yamada
2022-06-07 11:18   ` Paolo Abeni
2022-06-08  5:39     ` Steffen Klassert
2022-06-06  4:53 ` [PATCH 3/3] net: ipv6: unexport __init-annotated seg6_hmac_init() Masahiro Yamada
2022-06-08 17:20 ` [PATCH 0/3] net: unexport some symbols that are annotated __init patchwork-bot+netdevbpf

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