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To prevent enabling more than one passthrough subsystem per NVMe controller, passthru.c maintains an xarray indexed by cntlid values. Passthrough for a given nvmet subsystem cannot be enabled by configfs if the subsystem's passthru_ctrl->cntlid value is already accounted for in the xarray. However, according to the NVMe spec (rev 2.0c, p.145), "The Controller ID (CNTLID) value returned in the Identify Controller data structure may be used to uniquely identify a controller within an NVM subsystem," meaning that cntlid values are not guaranteed to be globally unique across multiple subsystems. Instead, the cntlid only uniquely identifies multiple controllers _within_ a subsystem. As a result, multiple unique & valid NVMe targets can be blocked from enabling passthrough at the same time if their controllers share cntlid values, a behavior allowed by the spec. Fix this by indexing the xarray with passthru_ctrl->instance values, which are allocated per controller by IDA and thus should be truly unique. Reviewed-by: Sagi Grimberg <sagi@grimberg.me> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Evan Burgess <evan.burgess@seagate.com> Signed-off-by: Keith Busch <kbusch@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.