linux-kernel - [PATCH v2] net: macb: ensure the device is available before accessing GEMGXL control registers

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Date:   Sat, 22 May 2021 17:16:11 +0800
From:   Zong Li <zong.li@...ive.com>
To:     nicolas.ferre@...rochip.com, claudiu.beznea@...rochip.com,
        davem@...emloft.net, kuba@...nel.org, f.fainelli@...il.com,
        palmer@...belt.com, paul.walmsley@...ive.com,
        schwab@...ux-m68k.org, sboyd@...nel.org, aou@...s.berkeley.edu,
        mturquette@...libre.com, geert@...ux-m68k.org, yixun.lan@...il.com,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org
Cc:     Zong Li <zong.li@...ive.com>
Subject: [PATCH v2] net: macb: ensure the device is available before accessing GEMGXL control registers

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@...ive.com>
---
 drivers/net/ethernet/cadence/macb_main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 6bc7d41d519b..a0c7b1167dbb 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2867,6 +2867,9 @@ 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->dev->stats;
 
+	if (!netif_running(bp->dev))
+		return nstat;
+
 	gem_update_stats(bp);
 
 	nstat->rx_errors = (hwstat->rx_frame_check_sequence_errors +
-- 
2.31.1