Addresses https://bugzilla.kernel.org/show_bug.cgi?id=29252
Addresses https://bugzilla.kernel.org/show_bug.cgi?id=30462
In commit d80bc0fd26 ("ipv6: Always
clone offlink routes.") we forced the kernel to always clone offlink
routes.
The reason we do that is to make sure we never bind an inetpeer to a
prefixed route.
The logic turned on here has existed in the tree for many years,
but was always off due to a protecting CPP define. So perhaps
it's no surprise that there is a logic bug here.
The problem is that we canot clone a route that is already a
host route (ie. has DST_HOST set). Because if we do, an identical
entry already exists in the routing tree and therefore the
ip6_rt_ins() call is going to fail.
This sets off a series of failures and high cpu usage, because when
ip6_rt_ins() fails we loop retrying this operation a few times in
order to handle a race between two threads trying to clone and insert
the same host route at the same time.
Fix this by simply using the route as-is when DST_HOST is set.
Reported-by: slash@ac.auone-net.jp
Reported-by: Ernst Sjöstrand <ernstp@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
7343ff31eb