On Tue, Dec 08, 2020 at 07:01:01PM +0100, Pablo Neira Ayuso wrote:
> Add an explicit comment in the code to describe the indirect
> serialization of the holders of the commit_mutex with the rtnl_mutex.
> Commit 90d2723c6d4c ("netfilter: nf_tables: do not hold reference on
> netdevice from preparation phase") already describes this, but a comment
> in this case if better for reference.
>
> Reported-by: Vladimir Oltean <olteanv@xxxxxxxxx>
> Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> ---
> net/netfilter/nf_tables_api.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index c2f59879a48d..9a080767667b 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -1723,6 +1723,10 @@ static struct nft_hook *nft_netdev_hook_alloc(struct net *net,
> }
>
> nla_strlcpy(ifname, attr, IFNAMSIZ);
> + /* nf_tables_netdev_event() is called under rtnl_mutex, this is
> + * indirectly serializing all the other holders of the commit_mutex with
> + * the rtnl_mutex.
> + */
> dev = __dev_get_by_name(net, ifname);
> if (!dev) {
> err = -ENOENT;
> --
> 2.20.1
>
Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>
Thanks!
