net: macb: ensure the device is available before accessing GEMGXL control registers

[ Upstream commit 5eff1461a6dec84f04fafa9128548bad51d96147 ]

If runtime power menagement is enabled, the gigabit ethernet PLL would
be disabled after macb_probe(). During this period of time, the system
would hang up if we try to access GEMGXL control registers.

We can't put runtime_pm_get/runtime_pm_put/ there due to the issue of
sleep inside atomic section (7fa2955ff70ce453 ("sh_eth: Fix sleeping
function called from invalid context"). Add netif_running checking to
ensure the device is available before accessing GEMGXL device.

Changed in v2:
 - Use netif_running instead of its own flag

Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/cadence/macb.c b/drivers/net/ethernet/cadence/macb.c
index 78803e7de360ab4c6c71fe98b31c95e2d184319b..d1cdb8540e12fee37889792a447c22dc2492b720 100644 (file)
--- a/drivers/net/ethernet/cadence/macb.c
+++ b/drivers/net/ethernet/cadence/macb.c
@@ -1955,6 +1955,9 @@ static struct net_device_stats *gem_get_stats(struct macb *bp)
        struct gem_stats *hwstat = &bp->hw_stats.gem;
        struct net_device_stats *nstat = &bp->stats;
 
+       if (!netif_running(bp->dev))
+               return nstat;
+
        gem_update_stats(bp);
 
        nstat->rx_errors = (hwstat->rx_frame_check_sequence_errors +