Re: [PATCH net-next v2 12/12] net-sysfs: move the xps cpus/rxqs retrieval in a common function

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 <atenart@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,