linux-kernel - [PATCH net-next 4/5] net/mlx5e: Don't drop RTNL during firmware flash

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Message-ID: <1747829342-1018757-5-git-send-email-tariqt@nvidia.com>
Date: Wed, 21 May 2025 15:09:01 +0300
From: Tariq Toukan <tariqt@...dia.com>
To: "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, Eric Dumazet <edumazet@...gle.com>, "Andrew
 Lunn" <andrew+netdev@...n.ch>
CC: Jason Gunthorpe <jgg@...pe.ca>, Leon Romanovsky <leon@...nel.org>, "Saeed
 Mahameed" <saeedm@...dia.com>, Tariq Toukan <tariqt@...dia.com>, "Richard
 Cochran" <richardcochran@...il.com>, Alexei Starovoitov <ast@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>, Jesper Dangaard Brouer
	<hawk@...nel.org>, John Fastabend <john.fastabend@...il.com>,
	<linux-rdma@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<netdev@...r.kernel.org>, <bpf@...r.kernel.org>, Moshe Shemesh
	<moshe@...dia.com>, Mark Bloch <mbloch@...dia.com>, Gal Pressman
	<gal@...dia.com>, Cosmin Ratiu <cratiu@...dia.com>
Subject: [PATCH net-next 4/5] net/mlx5e: Don't drop RTNL during firmware flash

From: Cosmin Ratiu <cratiu@...dia.com>

There's no explanation in the original commit of why that was done, but
presumably flashing takes a long time and holding RTNL for so long
blocks other interactions with the netdev layer.

However, the stack is moving towards netdev instance locking and
dropping and reacquiring RTNL in the context of flashing introduces
locking ordering issues: RTNL must be acquired before the netdev
instance lock and released after it.

This patch therefore takes the simpler approach by no longer dropping
and reacquiring the RTNL, as soon RTNL for ethtool will be removed,
leaving only the instance lock to protect against races.

Signed-off-by: Cosmin Ratiu <cratiu@...dia.com>
Reviewed-by: Carolina Jubran <cjubran@...dia.com>
Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>
Signed-off-by: Tariq Toukan <tariqt@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
index e399d7a3d6cb..ea078c9f5d15 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c
@@ -2060,14 +2060,9 @@ int mlx5e_ethtool_flash_device(struct mlx5e_priv *priv,
 	if (err)
 		return err;
 
-	dev_hold(dev);
-	rtnl_unlock();
-
 	err = mlx5_firmware_flash(mdev, fw, NULL);
 	release_firmware(fw);
 
-	rtnl_lock();
-	dev_put(dev);
 	return err;
 }
 
-- 
2.31.1