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>

1 files changed, 15 insertions, 9 deletions

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index 35ef42fa0cf3..f85cee3d869e 100644
--- 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;