linux-kernel - Re: [PATCH net] mlxsw: minimal: Fix deadlock in ports creation

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Message-ID: <87wnbf57bw.fsf@nvidia.com>
Date:   Thu, 11 Aug 2022 13:44:17 +0200
From:   Petr Machata <petrm@...dia.com>
To:     Petr Machata <petrm@...dia.com>
CC:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Vadim Pasternak <vadimp@...dia.com>,
        "Ido Schimmel" <idosch@...dia.com>, Jiri Pirko <jiri@...dia.com>
Subject: Re: [PATCH net] mlxsw: minimal: Fix deadlock in ports creation

CC'ing Jiri, which I forgot to do.

Petr Machata <petrm@...dia.com> writes:

> From: Vadim Pasternak <vadimp@...dia.com>
>
> Drop devl_lock() / devl_unlock() from ports creation and removal flows
> since the devlink instance lock is now taken by mlxsw_core.
>
> Fixes: 72a4c8c94efa ("mlxsw: convert driver to use unlocked devlink API during init/fini")
> Signed-off-by: Vadim Pasternak <vadimp@...dia.com>
> Signed-off-by: Ido Schimmel <idosch@...dia.com>
> Signed-off-by: Petr Machata <petrm@...dia.com>
> ---
>  drivers/net/ethernet/mellanox/mlxsw/minimal.c | 7 -------
>  1 file changed, 7 deletions(-)
>
> diff --git a/drivers/net/ethernet/mellanox/mlxsw/minimal.c b/drivers/net/ethernet/mellanox/mlxsw/minimal.c
> index d9bf584234a6..bb1cd4bae82e 100644
> --- a/drivers/net/ethernet/mellanox/mlxsw/minimal.c
> +++ b/drivers/net/ethernet/mellanox/mlxsw/minimal.c
> @@ -328,7 +328,6 @@ static void mlxsw_m_port_module_unmap(struct mlxsw_m *mlxsw_m, u8 module)
>  static int mlxsw_m_ports_create(struct mlxsw_m *mlxsw_m)
>  {
>  	unsigned int max_ports = mlxsw_core_max_ports(mlxsw_m->core);
> -	struct devlink *devlink = priv_to_devlink(mlxsw_m->core);
>  	u8 last_module = max_ports;
>  	int i;
>  	int err;
> @@ -357,7 +356,6 @@ static int mlxsw_m_ports_create(struct mlxsw_m *mlxsw_m)
>  	}
>  
>  	/* Create port objects for each valid entry */
> -	devl_lock(devlink);
>  	for (i = 0; i < mlxsw_m->max_ports; i++) {
>  		if (mlxsw_m->module_to_port[i] > 0) {
>  			err = mlxsw_m_port_create(mlxsw_m,
> @@ -367,7 +365,6 @@ static int mlxsw_m_ports_create(struct mlxsw_m *mlxsw_m)
>  				goto err_module_to_port_create;
>  		}
>  	}
> -	devl_unlock(devlink);
>  
>  	return 0;
>  
> @@ -377,7 +374,6 @@ static int mlxsw_m_ports_create(struct mlxsw_m *mlxsw_m)
>  			mlxsw_m_port_remove(mlxsw_m,
>  					    mlxsw_m->module_to_port[i]);
>  	}
> -	devl_unlock(devlink);
>  	i = max_ports;
>  err_module_to_port_map:
>  	for (i--; i > 0; i--)
> @@ -390,10 +386,8 @@ static int mlxsw_m_ports_create(struct mlxsw_m *mlxsw_m)
>  
>  static void mlxsw_m_ports_remove(struct mlxsw_m *mlxsw_m)
>  {
> -	struct devlink *devlink = priv_to_devlink(mlxsw_m->core);
>  	int i;
>  
> -	devl_lock(devlink);
>  	for (i = 0; i < mlxsw_m->max_ports; i++) {
>  		if (mlxsw_m->module_to_port[i] > 0) {
>  			mlxsw_m_port_remove(mlxsw_m,
> @@ -401,7 +395,6 @@ static void mlxsw_m_ports_remove(struct mlxsw_m *mlxsw_m)
>  			mlxsw_m_port_module_unmap(mlxsw_m, i);
>  		}
>  	}
> -	devl_unlock(devlink);
>  
>  	kfree(mlxsw_m->module_to_port);
>  	kfree(mlxsw_m->ports);