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+rene...@glider.be> --- This is v2 of the series "[PATCH 0/2] net: Fix crashes due to activity during suspend", which degenerated into a single patch after commit ebc8254aeae34226 ("Revert "net: phy: Correctly process PHY_HALTED in phy_stop_machine()"") made "[PATCH 1/2] net: phy: Freeze PHY polling before suspending devices" no longer needed. v2: - Spelling s/quit/quiet/g. No stacktrace is provided, as the imprecise external abort is usually reported from an innocent looking and unrelated function like __loop_delay(), cpu_idle_poll(), or arch_timer_read_counter_long(). --- drivers/net/ethernet/smsc/smsc911x.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/smsc/smsc911x.c b/drivers/net/ethernet/smsc/smsc911x.c index 0b6a39b003a4e188..012fb66eed8dd618 100644 --- a/drivers/net/ethernet/smsc/smsc911x.c +++ b/drivers/net/ethernet/smsc/smsc911x.c @@ -2595,6 +2595,11 @@ static int smsc911x_suspend(struct device *dev) struct net_device *ndev = dev_get_drvdata(dev); struct smsc911x_data *pdata = netdev_priv(ndev); + if (netif_running(ndev)) { + netif_stop_queue(ndev); + netif_device_detach(ndev); + } + /* enable wake on LAN, energy detection and the external PME * signal. */ smsc911x_reg_write(pdata, PMT_CTRL, @@ -2628,7 +2633,15 @@ static int smsc911x_resume(struct device *dev) while (!(smsc911x_reg_read(pdata, PMT_CTRL) & PMT_CTRL_READY_) && --to) udelay(1000); - return (to == 0) ? -EIO : 0; + if (to == 0) + return -EIO; + + if (netif_running(ndev)) { + netif_device_attach(ndev); + netif_start_queue(ndev); + } + + return 0; } static const struct dev_pm_ops smsc911x_pm_ops = { -- 2.7.4