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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Zong Li <zong.li@sifive.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 23/84] net: macb: ensure the device is available before accessing GEMGXL control registers
Date:   Mon, 14 Jun 2021 12:27:01 +0200
Message-Id: <20210614102647.147526287@linuxfoundation.org>
In-Reply-To: <20210614102646.341387537@linuxfoundation.org>
References: <20210614102646.341387537@linuxfoundation.org>
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From: Zong Li <zong.li@sifive.com>

[ 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>
---
 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 377668465535..ebd0853a6f31 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -2536,6 +2536,9 @@ 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 +
-- 
2.30.2