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Fanout uses a per net global namespace. A process that intends to create a new fanout group can accidentally join an existing group. It is not possible to detect this. Add socket option PACKET_FANOUT_FLAG_UNIQUEID. When specified the supplied fanout group id must be set to 0, and the kernel chooses an id that is not already in use. This is an ephemeral flag so that other sockets can be added to this group using setsockopt, but NOT specifying this flag. The current getsockopt(..., PACKET_FANOUT, ...) can be used to retrieve the new group id. We assume that there are not a lot of fanout groups and that this is not a high frequency call. The method assigns ids starting at zero and increases until it finds an unused id. It keeps track of the last assigned id, and uses it as a starting point to find new ids. Signed-off-by: Mike Maloney <maloney@google.com> Acked-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.