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authorCong Wang <xiyou.wangcong@gmail.com>2020-06-26 11:25:27 -0700
committerDavid S. Miller <davem@davemloft.net>2020-06-28 21:38:27 -0700
commite8280338c778a3f81477624267c9fa47f931477b (patch)
treefb0513375932e0e02b72c82ff61219f6b2300ba0 /net/core
parentbe74294ffa24f5fbc0d6643842e3e095447e17a2 (diff)
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net: explain the lockdep annotations for dev_uc_unsync()
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>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/dev_addr_lists.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/net/core/dev_addr_lists.c b/net/core/dev_addr_lists.c
index 6393ba930097..54cd568e7c2f 100644
--- a/net/core/dev_addr_lists.c
+++ b/net/core/dev_addr_lists.c
@@ -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);