netdev - Re: [PATCH net] nfp: flower: avoid taking mutex in atomic context

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Message-ID: <Y9j/Rvi9CSYX2qSk@unreal>
Date:   Tue, 31 Jan 2023 13:45:10 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        oss-drivers@...igine.com, Yanguo Li <yanguo.li@...igine.com>,
        Dan Carpenter <error27@...il.com>
Subject: Re: [PATCH net] nfp: flower: avoid taking mutex in atomic context

On Tue, Jan 31, 2023 at 09:03:13AM +0100, Simon Horman wrote:
> From: Yanguo Li <yanguo.li@...igine.com>
> 
> A mutex may sleep, which is not permitted in atomic context.
> Avoid a case where this may arise by moving the to
> nfp_flower_lag_get_info_from_netdev() in nfp_tun_write_neigh() spinlock.
> 
> Fixes: abc210952af7 ("nfp: flower: tunnel neigh support bond offload")
> Reported-by: Dan Carpenter <error27@...il.com>
> Signed-off-by: Yanguo Li <yanguo.li@...igine.com>
> Signed-off-by: Simon Horman <simon.horman@...igine.com>
> ---
>  drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c b/drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c
> index a8678d5612ee..060a77f2265d 100644
> --- a/drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c
> +++ b/drivers/net/ethernet/netronome/nfp/flower/tunnel_conf.c
> @@ -460,6 +460,7 @@ nfp_tun_write_neigh(struct net_device *netdev, struct nfp_app *app,
>  			    sizeof(struct nfp_tun_neigh_v4);
>  	unsigned long cookie = (unsigned long)neigh;
>  	struct nfp_flower_priv *priv = app->priv;
> +	struct nfp_tun_neigh_lag lag_info;
>  	struct nfp_neigh_entry *nn_entry;
>  	u32 port_id;
>  	u8 mtype;
> @@ -468,6 +469,11 @@ nfp_tun_write_neigh(struct net_device *netdev, struct nfp_app *app,
>  	if (!port_id)
>  		return;
>  
> +	if ((port_id & NFP_FL_LAG_OUT) == NFP_FL_LAG_OUT) {
> +		memset(&lag_info, 0, sizeof(struct nfp_tun_neigh_lag));

This memset can be removed if you initialize lag_info to zero.
struct nfp_tun_neigh_lag lag_info = {};

Thanks

> +		nfp_flower_lag_get_info_from_netdev(app, netdev, &lag_info);
> +	}
> +
>  	spin_lock_bh(&priv->predt_lock);
>  	nn_entry = rhashtable_lookup_fast(&priv->neigh_table, &cookie,
>  					  neigh_table_params);
> @@ -515,7 +521,7 @@ nfp_tun_write_neigh(struct net_device *netdev, struct nfp_app *app,
>  		neigh_ha_snapshot(common->dst_addr, neigh, netdev);
>  
>  		if ((port_id & NFP_FL_LAG_OUT) == NFP_FL_LAG_OUT)
> -			nfp_flower_lag_get_info_from_netdev(app, netdev, lag);
> +			memcpy(lag, &lag_info, sizeof(struct nfp_tun_neigh_lag));
>  		common->port_id = cpu_to_be32(port_id);
>  
>  		if (rhashtable_insert_fast(&priv->neigh_table,
> -- 
> 2.30.2
>