From: David S. Miller Date: Mon, 28 Sep 2020 22:00:15 +0000 (-0700) Subject: Merge branch 'net-core-fix-a-lockdep-splat-in-the-dev_addr_list' X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0ba56b89fabc139849cf27e475287b0361f550d3;p=linux.git Merge branch 'net-core-fix-a-lockdep-splat-in-the-dev_addr_list' Taehee Yoo says: ==================== net: core: fix a lockdep splat in the dev_addr_list. This patchset is to avoid lockdep splat. When a stacked interface graph is changed, netif_addr_lock() is called recursively and it internally calls spin_lock_nested(). The parameter of spin_lock_nested() is 'dev->lower_level', this is called subclass. The problem of 'dev->lower_level' is that while 'dev->lower_level' is being used as a subclass of spin_lock_nested(), its value can be changed. So, spin_lock_nested() would be called recursively with the same subclass value, the lockdep understands a deadlock. In order to avoid this, a new variable is needed and it is going to be used as a parameter of spin_lock_nested(). The first and second patch is a preparation patch for the third patch. In the third patch, the problem will be fixed. The first patch is to add __netdev_upper_dev_unlink(). An existed netdev_upper_dev_unlink() is renamed to __netdev_upper_dev_unlink(). and netdev_upper_dev_unlink() is added as an wrapper of this function. The second patch is to add the netdev_nested_priv structure. netdev_walk_all_{ upper | lower }_dev() pass both private functions and "data" pointer to handle their own things. At this point, the data pointer type is void *. In order to make it easier to expand common variables and functions, this new netdev_nested_priv structure is added. The third patch is to add a new variable 'nested_level' into the net_device structure. This variable will be used as a parameter of spin_lock_nested() of dev->addr_list_lock. Due to this variable, it can avoid lockdep splat. ==================== Signed-off-by: David S. Miller --- 0ba56b89fabc139849cf27e475287b0361f550d3