Re: [PATCH v2] net: smsc911x: Quieten netif during suspend

From: David Miller
Date: Fri Sep 15 2017 - 17:26:29 EST

From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Date: Wed, 13 Sep 2017 19:42:05 +0200

> If the network interface is kept running during suspend, the net core
> may call net_device_ops.ndo_start_xmit() while the Ethernet device is
> still suspended, which may lead to a system crash.
> E.g. on sh73a0/kzm9g and r8a73a4/ape6evm, the external Ethernet chip is
> driven by a PM controlled clock. If the Ethernet registers are accessed
> while the clock is not running, the system will crash with an imprecise
> external abort.
> As this is a race condition with a small time window, it is not so easy
> to trigger at will. Using pm_test may increase your chances:
> # echo 0 > /sys/module/printk/parameters/console_suspend
> # echo platform > /sys/power/pm_test
> # echo mem > /sys/power/state
> To fix this, make sure the network interface is quietened during
> suspend.
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>