[PATCH net-next v2] Revert "sh_eth: remove open coded netif_running()"

[PATCH net-next v2] Revert "sh_eth: remove open coded netif_running()"

[Wolfram Sang]

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@omp.ru>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Change since v1:
* added 'net-next' to $subject

 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

Re: [PATCH net-next v2] Revert "sh_eth: remove open coded netif_running()"

[Sergey Shtylyov]

On 3/27/23 6:21 PM, Wolfram Sang wrote:

> 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@omp.ru>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[...]

Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>

MBR, Sergey

Re: [PATCH net-next v2] Revert "sh_eth: remove open coded netif_running()"

[Simon Horman]

On Mon, Mar 27, 2023 at 05:21:12PM +0200, Wolfram Sang wrote:
> 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@omp.ru>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Reviewed-by: Simon Horman <simon.horman@corigine.com>

Re: [PATCH net-next v2] Revert "sh_eth: remove open coded netif_running()"

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Mon, 27 Mar 2023 17:21:12 +0200 you wrote:
> 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@omp.ru>
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> 
> [...]

Here is the summary with links:
  - [net-next,v2] Revert "sh_eth: remove open coded netif_running()"
    https://git.kernel.org/netdev/net-next/c/cdeccd13a03f

You are awesome, thank you!
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