net: explain the lockdep annotations for dev_uc_unsync() (e8280338) · Commits · 戴 / test

The lockdep annotations for dev_uc_unsync() and dev_mc_unsync() are not easy to understand, so add some comments to explain why they are correct. Similar for the rest netif_addr_lock_bh() cases, they don't need nested version. Cc: Taehee Yoo <ap420073@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by:

Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/dev_addr_lists.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -690,6 +690,15 @@ void dev_uc_unsync(struct net_device to, struct net_device from)
		if (to->addr_len != from->addr_len)
		return;

		/* netif_addr_lock_bh() uses lockdep subclass 0, this is okay for two
		* reasons:
		* 1) This is always called without any addr_list_lock, so as the
		* outermost one here, it must be 0.
		* 2) This is called by some callers after unlinking the upper device,
		* so the dev->lower_level becomes 1 again.
		* Therefore, the subclass for 'from' is 0, for 'to' is either 1 or
		* larger.
		*/
		netif_addr_lock_bh(from);
		netif_addr_lock_nested(to);
		__hw_addr_unsync(&to->uc, &from->uc, to->addr_len);
		@@ -911,6 +920,7 @@ void dev_mc_unsync(struct net_device to, struct net_device from)
		if (to->addr_len != from->addr_len)
		return;

		/* See the above comments inside dev_uc_unsync(). */
		netif_addr_lock_bh(from);
		netif_addr_lock_nested(to);
		__hw_addr_unsync(&to->mc, &from->mc, to->addr_len);

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