linux-kernel - [PATCH] Revert "sh_eth: remove open coded netif

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Message-Id: <20230327081933.5460-1-wsa+renesas@sang-engineering.com>
Date:   Mon, 27 Mar 2023 10:19:33 +0200
From:   Wolfram Sang <wsa+renesas@...g-engineering.com>
To:     netdev@...r.kernel.org
Cc:     linux-renesas-soc@...r.kernel.org,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        Sergey Shtylyov <s.shtylyov@....ru>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] Revert "sh_eth: remove open coded netif_running()"

This reverts commit ce1fdb065695f49ef6f126d35c1abbfe645d62d5. It turned
out this actually introduces a race condition. netif_running() is not a
suitable check for get_stats.

Reported-by: Sergey Shtylyov <s.shtylyov@....ru>
Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
---
 drivers/net/ethernet/renesas/sh_eth.c | 6 +++++-
 drivers/net/ethernet/renesas/sh_eth.h | 1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/sh_eth.c b/drivers/net/ethernet/renesas/sh_eth.c
index 2d9787231099..d8ec729825be 100644
--- a/drivers/net/ethernet/renesas/sh_eth.c
+++ b/drivers/net/ethernet/renesas/sh_eth.c
@@ -2441,6 +2441,8 @@ static int sh_eth_open(struct net_device *ndev)
 
 	netif_start_queue(ndev);
 
+	mdp->is_opened = 1;
+
 	return ret;
 
 out_free_irq:
@@ -2563,7 +2565,7 @@ static struct net_device_stats *sh_eth_get_stats(struct net_device *ndev)
 	if (mdp->cd->no_tx_cntrs)
 		return &ndev->stats;
 
-	if (!netif_running(ndev))
+	if (!mdp->is_opened)
 		return &ndev->stats;
 
 	sh_eth_update_stat(ndev, &ndev->stats.tx_dropped, TROCR);
@@ -2612,6 +2614,8 @@ static int sh_eth_close(struct net_device *ndev)
 	/* Free all the skbuffs in the Rx queue and the DMA buffer. */
 	sh_eth_ring_free(ndev);
 
+	mdp->is_opened = 0;
+
 	pm_runtime_put(&mdp->pdev->dev);
 
 	return 0;
diff --git a/drivers/net/ethernet/renesas/sh_eth.h b/drivers/net/ethernet/renesas/sh_eth.h
index f56dbc8a064a..a5c07c6ff44a 100644
--- a/drivers/net/ethernet/renesas/sh_eth.h
+++ b/drivers/net/ethernet/renesas/sh_eth.h
@@ -560,6 +560,7 @@ struct sh_eth_private {
 
 	unsigned no_ether_link:1;
 	unsigned ether_link_active_low:1;
+	unsigned is_opened:1;
 	unsigned wol_enabled:1;
 };
 
-- 
2.30.2