Re: [PATCH net] net: thunder_bgx: Fix netdev structure allocation

Hello Marc,

On Mon, Aug 12, 2024 at 03:13:22PM +0100, Marc Zyngier wrote:

Commit 94833addfaba ("net: thunderx: Unembed netdev structure") had
a go at dynamically allocating the netdev structures for the thunderx_bgx
driver.  This change results in my ThunderX box catching fire (to be fair,
it is what it does best).

Should I be proud of it? :-)

The issues with this change are that:

- bgx_lmac_enable() is called *after* bgx_acpi_register_phy() and
  bgx_init_of_phy(), both expecting netdev to be a valid pointer.

- bgx_init_of_phy() populates the MAC addresses for *all* LMACs
  attached to a given BGX instance, and thus needs netdev for each of
  them to have been allocated.

There is a few things to be said about how the driver mixes LMAC and
BGX states which leads to this sorry state, but that's beside the point.

To address this, go back to a situation where all netdev structures
are allocated before the driver starts relying on them, and move the
freeing of these structures to driver removal. Someone brave enough
can always go and restructure the driver if they want.

Fixes: 94833addfaba ("net: thunderx: Unembed netdev structure")
Signed-off-by: Marc Zyngier <maz@kernel.org>

Reviewed-by: Breno Leitao <leitao@debian.org>

Thanks for taming my fiery commit.