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The dpaa2 architecture permits dynamic connections between objects on the fsl-mc bus, specifically between a DPNI object (represented by a struct net_device) and a DPMAC object (represented by a struct phylink). The DPNI driver is notified when those connections are created/broken through the dpni_irq0_handler_thread() method. To ensure that ethtool operations, as well as netdev up/down operations serialize with the connection/disconnection of the DPNI with a DPMAC, dpni_irq0_handler_thread() takes the rtnl_lock() to block those other operations from taking place. There is code called by dpaa2_mac_connect() which wants to acquire the rtnl_mutex once again, see phylink_create() -> phylink_register_sfp() -> sfp_bus_add_upstream() -> rtnl_lock(). So the strategy doesn't quite work out, even though it's fairly simple. Create a different strategy, where all code paths in the dpaa2-eth driver access priv->mac only while they are holding priv->mac_lock. The phylink instance is not created or connected to the PHY under the priv->mac_lock, but only assigned to priv->mac then. This will eliminate the reliance on the rtnl_mutex. Add lockdep annotations and put comments where holding the lock is not necessary, and priv->mac can be dereferenced freely. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com> Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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.
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.