net: dsa: xrs700x: be compatible with masters which unregister on shutdown
authorVladimir Oltean <vladimir.oltean@nxp.com>
Fri, 17 Sep 2021 13:34:36 +0000 (16:34 +0300)
committerDavid S. Miller <davem@davemloft.net>
Sun, 19 Sep 2021 11:08:37 +0000 (12:08 +0100)
commita68e9da48568a0adf5dc817ef81971c0d1aa0672
tree95ab75ae6b74022bac3b565dfa37d7b1248fe927
parentfe4053078cd0f02a3fa140c43660f327702a9f10
net: dsa: xrs700x: be compatible with masters which unregister on shutdown

Since commit 2f1e8ea726e9 ("net: dsa: link interfaces with the DSA
master to get rid of lockdep warnings"), DSA gained a requirement which
it did not fulfill, which is to unlink itself from the DSA master at
shutdown time.

Since the Arrow SpeedChips XRS700x driver was introduced after the bad
commit, it has never worked with DSA masters which decide to unregister
their net_device on shutdown, effectively hanging the reboot process.
To fix that, we need to call dsa_switch_shutdown.

These devices can be connected by I2C or by MDIO, and if I search for
I2C or MDIO bus drivers that implement their ->shutdown by redirecting
it to ->remove I don't see any, however this does not mean it would not
be possible. To be compatible with that pattern, it is necessary to
implement an "if this then not that" scheme, to avoid ->remove and
->shutdown from being called both for the same struct device.

Fixes: ee00b24f32eb ("net: dsa: add Arrow SpeedChips XRS700x driver")
Link: https://lore.kernel.org/netdev/20210909095324.12978-1-LinoSanfilippo@gmx.de/
Reported-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: George McCollister <george.mccollister@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/dsa/xrs700x/xrs700x.c
drivers/net/dsa/xrs700x/xrs700x.h
drivers/net/dsa/xrs700x/xrs700x_i2c.c
drivers/net/dsa/xrs700x/xrs700x_mdio.c