Re: [PATCHES] Networking fixes for -stable.

Hi Ben,

On Tue, Nov 13, 2012 at 8:51 PM, Ben Hutchings [off-list ref] wrote:

On Mon, 2012-11-12 at 00:25 -0500, David Miller wrote:

quoted

Please queue up the following networking bug fixes for
3.0.x, 3.2.x, 3.4.x, and 3.6.x, respectively.

[...]

quoted

From 2204849a85383fbde75680aa199142abe504adbb Mon Sep 17 00:00:00 2001
From: Peter Senna Tschudin <peter.senna@gmail.com>
Date: Sun, 28 Oct 2012 06:12:01 +0000
Subject: [PATCH 7/9] drivers/net/phy/mdio-bitbang.c: Call mdiobus_unregister
 before mdiobus_free

[ Upstream commit aa731872f7d33dcb8b54dad0cfb82d4e4d195d7e ]

Based on commit b27393aecf66199f5ddad37c302d3e0cfadbe6c0

Calling mdiobus_free without calling mdiobus_unregister causes
BUG_ON(). This patch fixes the issue.

[...]

This introduces a regresssion, as mdiobus_unregister() is not safe to
call if the bus isn't registered.  Registration is controlled by the
drivers that use mdio-bitbang, and they should take care of
unregistration too - and most of them do.

Is mdiobus_free() safe to call if the bus isn't registered?

I found calls to free_mdio_bitbang() after call to
mdiobus_unregister() that may be the worst cases for my patch. But I
also found places that call free_mdio_bitbang() without first calling
mdiobus_unregister(). See:

linux-next/arch/powerpc/platforms/82xx/ep8248e.c:152
linux-next/drivers/net/ethernet/8390/ax88796.c:647
linux-next/drivers/net/ethernet/freescale/fs_enet/mii-bitbang.c:197
linux-next/drivers/net/phy/mdio-gpio.c:157
linux-next/drivers/net/phy/mdio-gpio.c:172

Are those calls to free_mdio_bitbang() wrong by not calling
mdiobus_unregister() before?

This should be reverted in mainline and not applied to any stable
series.

Ben.

--
Ben Hutchings
For every complex problem
there is a solution that is simple, neat, and wrong.

Thank you for reviewing,

Peter

--
Peter