xps: add __rcu annotations

Avoid sparse warnings : add __rcu annotations and use
rcu_dereference_protected() where necessary.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 9ae4544..4b0c7f3 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -622,7 +622,7 @@ struct xps_map {
  */
 struct xps_dev_maps {
        struct rcu_head rcu;
-       struct xps_map *cpu_map[0];
+       struct xps_map __rcu *cpu_map[0];
 };
 #define XPS_DEV_MAPS_SIZE (sizeof(struct xps_dev_maps) +               \
     (nr_cpu_ids * sizeof(struct xps_map *)))
@@ -1049,7 +1049,7 @@ struct net_device {
        spinlock_t              tx_global_lock;
 
 #ifdef CONFIG_XPS
-       struct xps_dev_maps     *xps_maps;
+       struct xps_dev_maps __rcu *xps_maps;
 #endif
 
        /* These may be needed for future network-power-down code. */

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 35ef42f..f85cee3 100644 (file)
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -899,6 +899,8 @@ static void xps_dev_maps_release(struct rcu_head *rcu)
 }
 
 static DEFINE_MUTEX(xps_map_mutex);
+#define xmap_dereference(P)            \
+       rcu_dereference_protected((P), lockdep_is_held(&xps_map_mutex))
 
 static ssize_t store_xps_map(struct netdev_queue *queue,
                      struct netdev_queue_attribute *attribute,
@@ -935,11 +937,12 @@ static ssize_t store_xps_map(struct netdev_queue *queue,
 
        mutex_lock(&xps_map_mutex);
 
-       dev_maps = dev->xps_maps;
+       dev_maps = xmap_dereference(dev->xps_maps);
 
        for_each_possible_cpu(cpu) {
-               new_map = map = dev_maps ? dev_maps->cpu_map[cpu] : NULL;
-
+               map = dev_maps ?
+                       xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
+               new_map = map;
                if (map) {
                        for (pos = 0; pos < map->len; pos++)
                                if (map->queues[pos] == index)
@@ -975,13 +978,14 @@ static ssize_t store_xps_map(struct netdev_queue *queue,
                        else
                                new_map = NULL;
                }
-               new_dev_maps->cpu_map[cpu] = new_map;
+               RCU_INIT_POINTER(new_dev_maps->cpu_map[cpu], new_map);
        }
 
        /* Cleanup old maps */
        for_each_possible_cpu(cpu) {
-               map = dev_maps ? dev_maps->cpu_map[cpu] : NULL;
-               if (map && new_dev_maps->cpu_map[cpu] != map)
+               map = dev_maps ?
+                       xmap_dereference(dev_maps->cpu_map[cpu]) : NULL;
+               if (map && xmap_dereference(new_dev_maps->cpu_map[cpu]) != map)
                        call_rcu(&map->rcu, xps_map_release);
                if (new_dev_maps->cpu_map[cpu])
                        nonempty = 1;
@@ -1007,7 +1011,9 @@ error:
 
        if (new_dev_maps)
                for_each_possible_cpu(i)
-                       kfree(new_dev_maps->cpu_map[i]);
+                       kfree(rcu_dereference_protected(
+                               new_dev_maps->cpu_map[i],
+                               1));
        kfree(new_dev_maps);
        free_cpumask_var(mask);
        return -ENOMEM;
@@ -1033,11 +1039,11 @@ static void netdev_queue_release(struct kobject *kobj)
        index = get_netdev_queue_index(queue);
 
        mutex_lock(&xps_map_mutex);
-       dev_maps = dev->xps_maps;
+       dev_maps = xmap_dereference(dev->xps_maps);
 
        if (dev_maps) {
                for_each_possible_cpu(i) {
-                       map  = dev_maps->cpu_map[i];
+                       map = xmap_dereference(dev_maps->cpu_map[i]);
                        if (!map)
                                continue;