06220d78f2
Since we would be introducing a new user of the DTL buffer in a subsequent patch, we need a way to gatekeep use of the DTL buffer. The current debugfs interface for DTL allows registering and opening cpu-specific DTL buffers. Cpu specific files are exposed under debugfs 'powerpc/dtl/' node, and changing 'dtl_event_mask' in the same directory enables controlling the event mask used when registering DTL buffer for a particular cpu. Subsequently, we will be introducing a user of the DTL buffers that registers access to the DTL buffers across all cpus with the same event mask. To ensure these two users do not step on each other, we introduce a rwlock to gatekeep DTL buffer access. This fits the requirement of the current debugfs interface wanting to allow multiple independent cpu-specific users (read lock), and the subsequent user wanting exclusive access (write lock). Suggested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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.