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The mirroring selftests work by sending ICMP traffic between two hosts. Along the way, this traffic is mirrored to a gretap netdevice, and counter taps are then installed strategically along the path of the mirrored traffic to verify the mirroring took place. The problem with this is that besides mirroring the primary traffic, any other service traffic is mirrored as well. At the same time, because the tests need to work in HW-offloaded scenarios, the ability of the device to do arbitrary packet inspection should not be taken for granted. Most tests therefore simply use matchall, one uses flower to match on IP address. As a result, the selftests are noisy, because besides the primary ICMP traffic, any amount of other service traffic is mirrored as well. However, often the counter tap is installed at the remote end of the gretap tunnel. Since this is a SW-datapath scenario anyway, we can make the filter arbitrarily accurate. Thus in this patch, add parameters forward_type and backward_type to several mirroring test helpers, as some other helpers already have. Then change do_test_span_dir_ips() to instead of installing one generic tap and using it for test in both directions, install the tap for each direction separately, matching on the ICMP type given by these parameters. Signed-off-by: Petr Machata <petrm@nvidia.com> Reviewed-by: Danielle Ratson <danieller@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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.