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Unfortunately, the workarounds for the hardware bugs make it pointless to keep fine-grained locking for the MAC Merge state of each port. Our vsc9959_cut_through_fwd() implementation requires ocelot->fwd_domain_lock to be held, in order to serialize with changes to the bridging domains and to port speed changes (which affect which ports can be cut-through). Simultaneously, the traffic classes which can be cut-through cannot be preemptible at the same time, and this will depend on the MAC Merge layer state (which changes from threaded interrupt context). Since vsc9959_cut_through_fwd() would have to hold the mm->lock of all ports for a correct and race-free implementation with respect to ocelot_mm_irq(), in practice it means that any time a port's mm->lock is held, it would potentially block holders of ocelot->fwd_domain_lock. In the interest of simple locking rules, make all MAC Merge layer state changes (and preemptible traffic class changes) be serialized by the ocelot->fwd_domain_lock. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Simon Horman <simon.horman@corigine.com> Reviewed-by: Florian Fainelli <f.fainelli@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 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.