0079ad8e8d
This is a re-post of previous patch wrote by David Miller[1]. Phil Karn reported[2] that on busy networks with lots of unresolved multicast routing entries, the creation of new multicast group routes can be extremely slow and unreliable. The reason is we hard-coded multicast route entries with unresolved source addresses(cache_resolve_queue_len) to 10. If some multicast route never resolves and the unresolved source addresses increased, there will be no ability to create new multicast route cache. To resolve this issue, we need either add a sysctl entry to make the cache_resolve_queue_len configurable, or just remove cache_resolve_queue_len limit directly, as we already have the socket receive queue limits of mrouted socket, pointed by David. >From my side, I'd perfer to remove the cache_resolve_queue_len limit instead of creating two more(IPv4 and IPv6 version) sysctl entry. [1] https://lkml.org/lkml/2018/7/22/11 [2] https://lkml.org/lkml/2018/7/21/343 v3: instead of remove cache_resolve_queue_len totally, let's only remove the hard code limit when allocate the unresolved cache, as Eric Dumazet suggested, so we don't need to re-count it in other places. v2: hold the mfc_unres_lock while walking the unresolved list in queue_count(), as Nikolay Aleksandrov remind. Reported-by: Phil Karn <karn@ka9q.net> Signed-off-by: Hangbin Liu <liuhangbin@gmail.com> Reviewed-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.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
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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.