On Mon, Feb 8, 2021 at 9:19 AM Antoine Tenart <aten...@kernel.org> wrote:
>
> Most of the xps_cpus_show and xps_rxqs_show functions share the same
> logic. Having it in two different functions does not help maintenance.
> This patch moves their common logic into a new function, xps_queue_show,
> to improve this.
>
> Signed-off-by: Antoine Tenart <aten...@kernel.org>
> ---
> net/core/net-sysfs.c | 98 ++++++++++++++------------------------------
> 1 file changed, 31 insertions(+), 67 deletions(-)
>
> diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
> index 6ce5772e799e..984c15248483 100644
> --- a/net/core/net-sysfs.c
> +++ b/net/core/net-sysfs.c
> @@ -1314,35 +1314,31 @@ static const struct attribute_group dql_group = {
> #endif /* CONFIG_BQL */
>
> #ifdef CONFIG_XPS
> -static ssize_t xps_cpus_show(struct netdev_queue *queue,
> - char *buf)
> +static ssize_t xps_queue_show(struct net_device *dev, unsigned int index,
> + char *buf, enum xps_map_type type)
> {
> - struct net_device *dev = queue->dev;
> struct xps_dev_maps *dev_maps;
> - unsigned int index, nr_ids;
> - int j, len, ret, tc = 0;
> unsigned long *mask;
> -
> - if (!netif_is_multiqueue(dev))
> - return -ENOENT;
> -
> - index = get_netdev_queue_index(queue);
> -
> - /* If queue belongs to subordinate dev use its map */
> - dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
> + unsigned int nr_ids;
> + int j, len, tc = 0;
>
> tc = netdev_txq_to_tc(dev, index);
> if (tc < 0)
> return -EINVAL;
>
> rcu_read_lock();
> - dev_maps = rcu_dereference(dev->xps_maps[XPS_CPUS]);
> - nr_ids = dev_maps ? dev_maps->nr_ids : nr_cpu_ids;
> + dev_maps = rcu_dereference(dev->xps_maps[type]);
> +
> + /* Default to nr_cpu_ids/dev->num_rx_queues and do not just return 0
> + * when dev_maps hasn't been allocated yet, to be backward compatible.
> + */
> + nr_ids = dev_maps ? dev_maps->nr_ids :
> + (type == XPS_CPUS ? nr_cpu_ids : dev->num_rx_queues);
>
> mask = bitmap_zalloc(nr_ids, GFP_KERNEL);
> if (!mask) {
> - ret = -ENOMEM;
> - goto err_rcu_unlock;
> + rcu_read_unlock();
> + return -ENOMEM;
> }
>
> if (!dev_maps || tc >= dev_maps->num_tc)
> @@ -1368,11 +1364,24 @@ static ssize_t xps_cpus_show(struct netdev_queue
> *queue,
>
> len = bitmap_print_to_pagebuf(false, buf, mask, nr_ids);
> bitmap_free(mask);
> +
> return len < PAGE_SIZE ? len : -EINVAL;
> +}
>
> -err_rcu_unlock:
> - rcu_read_unlock();
> - return ret;
> +static ssize_t xps_cpus_show(struct netdev_queue *queue, char *buf)
> +{
> + struct net_device *dev = queue->dev;
> + unsigned int index;
> +
> + if (!netif_is_multiqueue(dev))
> + return -ENOENT;
> +
> + index = get_netdev_queue_index(queue);
> +
> + /* If queue belongs to subordinate dev use its map */
> + dev = netdev_get_tx_queue(dev, index)->sb_dev ? : dev;
> +
> + return xps_queue_show(dev, index, buf, XPS_CPUS);
> }
>
> static ssize_t xps_cpus_store(struct netdev_queue *queue,
So this patch has the same issue as the one that was removing the
rtnl_lock. Basically the sb_dev needs to still be protected by the
rtnl_lock. We might need to take the rtnl_lock and maybe make use of
the get_device/put_device logic to make certain the device cannot be
freed while you are passing it to xps_queue_show.
