netdev - Re: [PATCH net-next v6] rtnetlink: Support fine-grained netdevice bulk deletion

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Date:   Thu, 6 Jan 2022 21:51:19 +0200
From:   Lahav Schlesinger <lschlesinger@...venets.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <eric.dumazet@...il.com>, netdev@...r.kernel.org,
        idosch@...sch.org, nicolas.dichtel@...nd.com, nikolay@...dia.com
Subject: Re: [PATCH net-next v6] rtnetlink: Support fine-grained netdevice
 bulk deletion

On Tue, Jan 04, 2022 at 05:19:30PM -0700, David Ahern wrote:
> CAUTION: External E-Mail - Use caution with links and attachments
>
>
> On 1/4/22 2:12 PM, Jakub Kicinski wrote:
> > With the dev->bulk_delete flag and raw array instead of attributes you
> > can go back to the version of the code which stores dev pointers in a
> > temp kmalloc'd array, right?
>
> missed this response ... that should work as well once duplicates are
> caught.

I liked the idea that we can avoid increasing sizeof(struct net_device)
for this feature. In this case I see the final implementation as looking
something like this:

dev_list = kmalloc_array(num_devices, sizeof(*dev_list), GFP_KERNEL);

for (i = 0; i < num_devices; i++) {
        dev = __dev_get_by_index(net, ifindices[i]);

        ...

        if (dev->bulk_delete)
                goto cleanup;

        dev->bulk_delete = 1;
        dev_list[i] = dev;
}

for (i = 0; i < num_devices; i++) {
        dev = dev_list[i];
        dev->rtnl_link_ops->dellink(dev, &list_kill);
        dev->bulk_delete = 0;
}

kfree(dev_list);

unregister_netdevice_many(&list_kill);

return 0;

cleanup:
        for (j = 0; j < i; j++) {
                dev_list[j]->bulk_delete = 0;
        }
        kfree(dev_list);


Including the explicit checks in rtnl_setlink() __rtnl_newlink() and
rtnl_getlink() for returning an error if IFLA_IFINDEX_LIST is passed.

If it looks okay I'll send a v7.