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[ Upstream commit2bce1ebed1] When a macsec interface is created, it increases a refcnt to a lower device(real device). when macsec interface is deleted, the refcnt is decreased in macsec_free_netdev(), which is ->priv_destructor() of macsec interface. The problem scenario is this. When nested macsec interfaces are exiting, the exit routine of the macsec module makes refcnt leaks. Test commands: ip link add dummy0 type dummy ip link add macsec0 link dummy0 type macsec ip link add macsec1 link macsec0 type macsec modprobe -rv macsec [ 208.629433] unregister_netdevice: waiting for macsec0 to become free. Usage count = 1 Steps of exit routine of macsec module are below. 1. Calls ->dellink() in __rtnl_link_unregister(). 2. Checks refcnt and wait refcnt to be 0 if refcnt is not 0 in netdev_run_todo(). 3. Calls ->priv_destruvtor() in netdev_run_todo(). Step2 checks refcnt, but step3 decreases refcnt. So, step2 waits forever. This patch makes the macsec module do not hold a refcnt of the lower device because it already holds a refcnt of the lower device with netdev_upper_dev_link(). Fixes:c09440f7dc("macsec: introduce IEEE 802.1AE driver") Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@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 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.