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Kuniyuki Iwashima
1767bb2d47
In __ipv6_sock_mc_join(), per-socket mld data is protected by lock_sock(), and only __dev_get_by_index() requires RTNL. Let's use dev_get_by_index() and drop RTNL for IPV6_ADD_MEMBERSHIP and MCAST_JOIN_GROUP. Note that we must call rt6_lookup() and dev_hold() under RCU. If rt6_lookup() returns an entry from the exception table, dst_dev_put() could change rt->dev.dst to loopback concurrently, and the original device could lose the refcount before dev_hold() and unblock device registration. dst_dev_put() is called from NETDEV_UNREGISTER and synchronize_net() follows it, so as long as rt6_lookup() and dev_hold() are called within the same RCU critical section, the dev is alive. Even if the race happens, they are synchronised by idev->dead and mcast addresses are cleaned up. For the racy access to rt->dst.dev, we use dst_dev(). Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://patch.msgid.link/20250702230210.3115355-7-kuni1840@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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.