[PATCH RFC 05/25] net: Add primitives to update heads of pernet_list sublists

Kirill Tkhai
2017-11-17T18:28:00Z

Currently we have first_device, and device and subsys
sublists. Next patches introduce one more sublist.
So, move the functionality, which will be repeating,
to the primitives.

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
net/core/net_namespace.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index a8ea580885d9..1d9712973695 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -939,6 +939,18 @@ static void __unregister_pernet_operations(struct pernet_operations *ops)

static DEFINE_IDA(net_generic_ids);

+#define update_first_on_add(first, delim, added) \
+ do { \
+ if (first == delim) \
+ first = added; \
+ } while (0)
+
+#define update_first_on_del(first, to_delete) \
+ do { \
+ if (first == to_delete) \
+ first = (to_delete)->next; \
+ } while (0)
+
static int register_pernet_operations(struct list_head *list,
struct pernet_operations *ops)
{
@@ -1045,8 +1057,8 @@ int register_pernet_device(struct pernet_operations *ops)
int error;
down_write(&net_sem);
error = register_pernet_operations(&pernet_list, ops);
- if (!error && (first_device == &pernet_list))
- first_device = &ops->list;
+ if (!error)
+ update_first_on_add(first_device, &pernet_list, &ops->list);
up_write(&net_sem);
return error;
}
@@ -1064,8 +1076,7 @@ EXPORT_SYMBOL_GPL(register_pernet_device);
void unregister_pernet_device(struct pernet_operations *ops)
{
down_write(&net_sem);
- if (&ops->list == first_device)
- first_device = first_device->next;
+ update_first_on_del(first_device, &ops->list);
unregister_pernet_operations(ops);
up_write(&net_sem);
}