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Sometimes we have to be very careful not to allocate underneath a mutex (or spinlock) and yet still want to track activity. Enter i915_active_acquire_for_context(). This raises the activity counter on i915_active prior to use and ensures that the fence-tree contains a slot for the context. v2: Refactor active_lookup() so it can be called again before/after locking to resolve contention. Since we protect the rbtree until we idle, we can do a lockfree lookup, with the caveat that if another thread performs a concurrent insertion, the rotations from the insert may cause us to not find our target. A second pass holding the treelock will find the target if it exists, or the place to perform our insertion. Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200731085015.32368-3-chris@chris-wilson.co.uk Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.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.