net: core: netlink: add helper refcount dec and lock function (6f99528e) · Commits · 戴 / test

Rtnl lock is encapsulated in netlink and cannot be accessed by other modules directly. This means that reference counted objects that rely on rtnl lock cannot use it with refcounter helper function that atomically releases decrements reference and obtains mutex. This patch implements simple wrapper function around refcount_dec_and_lock that obtains rtnl lock if reference counter value reached 0. Signed-off-by:

Vlad Buslov <vladbu@mellanox.com> Acked-by:

Jiri Pirko <jiri@mellanox.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

include/linux/rtnetlink.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		#include <linux/mutex.h>
		#include <linux/netdevice.h>
		#include <linux/wait.h>
		#include <linux/refcount.h>
		#include <uapi/linux/rtnetlink.h>

		extern int rtnetlink_send(struct sk_buff skb, struct net net, u32 pid, u32 group, int echo);
		@@ -34,6 +35,7 @@ extern void rtnl_unlock(void);
		extern int rtnl_trylock(void);
		extern int rtnl_is_locked(void);
		extern int rtnl_lock_killable(void);
		extern bool refcount_dec_and_rtnl_lock(refcount_t *r);

		extern wait_queue_head_t netdev_unregistering_wq;
		extern struct rw_semaphore pernet_ops_rwsem;

net/core/rtnetlink.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -130,6 +130,12 @@ int rtnl_is_locked(void)
		}
		EXPORT_SYMBOL(rtnl_is_locked);

		bool refcount_dec_and_rtnl_lock(refcount_t *r)
		{
		return refcount_dec_and_mutex_lock(r, &rtnl_mutex);
		}
		EXPORT_SYMBOL(refcount_dec_and_rtnl_lock);

		#ifdef CONFIG_PROVE_LOCKING
		bool lockdep_rtnl_is_held(void)
		{

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