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Ido Schimmel
884dd448f1
There is asymmetry in how the default FDB entry (all-zeroes) is created and destroyed in the VXLAN driver. It is created as part of the driver's newlink() routine, but destroyed as part of its ndo_uninit() routine. This caused multiple problems in the past. First, commit0241b83673("vxlan: fix default fdb entry netlink notify ordering during netdev create") split the notification about the entry from its creation so that it will not be notified to user space before the VXLAN device is registered. Then, commit6db9246871("vxlan: Fix error path in __vxlan_dev_create()") made the error path in __vxlan_dev_create() asymmetric by destroying the FDB entry before unregistering the net device. Otherwise, the FDB entry would have been freed twice: By ndo_uninit() as part of unregister_netdevice() and by vxlan_fdb_destroy() in the error path. Finally, commit7c31e54aee("vxlan: do not destroy fdb if register_netdevice() is failed") split the insertion of the FDB entry into the hash table from its creation, moving the insertion after the registration of the net device. Otherwise, like before, the FDB entry would have been freed twice: By ndo_uninit() as part of register_netdevice()'s error path and by vxlan_fdb_destroy() in the error path of __vxlan_dev_create(). The end result is that the code is unnecessarily complex. In addition, the fixed size hash table cannot be converted to rhashtable as vxlan_fdb_insert() cannot fail, which will no longer be true with rhashtable. Solve this by making the addition and deletion of the default FDB entry completely symmetric. Namely, as part of newlink() routine, create the entry, insert it into to the hash table and send a notification to user space after the net device was registered. Note that at this stage the net device is still administratively down and cannot transmit / receive packets. Move the deletion from ndo_uninit() to the dellink routine(): Flush the default entry together with all the other entries, before unregistering the net device. Reviewed-by: Petr Machata <petrm@nvidia.com> Signed-off-by: Ido Schimmel <idosch@nvidia.com> Link: https://patch.msgid.link/20250415121143.345227-3-idosch@nvidia.com Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.