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We currently have two code paths for broadcast packets: A) self-generated, via batadv_interface_tx()-> batadv_send_bcast_packet(). B) received/forwarded, via batadv_recv_bcast_packet()-> batadv_forw_bcast_packet(). For A), self-generated broadcast packets: The only modifications to the skb data is the ethernet header which is added/pushed to the skb in batadv_send_broadcast_skb()->batadv_send_skb_packet(). However before doing so, batadv_skb_head_push() is called which calls skb_cow_head() to unshare the space for the to be pushed ethernet header. So for this case, it is safe to use skb clones. For B), received/forwarded packets: The same applies as in A) for the to be forwarded packets. Only the ethernet header is added. However after (queueing for) forwarding the packet in batadv_recv_bcast_packet()->batadv_forw_bcast_packet(), a packet is additionally decapsulated and is sent up the stack through batadv_recv_bcast_packet()->batadv_interface_rx(). Protocols higher up the stack are already required to check if the packet is shared and create a copy for further modifications. When the next (protocol) layer works correctly, it cannot happen that it tries to operate on the data behind the skb clone which is still queued up for forwarding. Co-authored-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Sven Eckelmann <sven@narfation.org> Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue> Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
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 Restructured Text 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.