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net: explain the lockdep annotations for dev_uc_unsync()

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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>
This commit is contained in:
Cong Wang 2020-06-26 11:25:27 -07:00 committed by David S. Miller
parent be74294ffa
commit e8280338c7
1 changed files with 10 additions and 0 deletions
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10
net/core/dev_addr_lists.c
View file

@ -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);