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36df6e3dbd
To make css_rstat_updated() able to safely run in nmi context, let's move the rstat update tree creation at the flush side and use per-cpu lockless lists in struct cgroup_subsys to track the css whose stats are updated on that cpu. The struct cgroup_subsys_state now has per-cpu lnode which needs to be inserted into the corresponding per-cpu lhead of struct cgroup_subsys. Since we want the insertion to be nmi safe, there can be multiple inserters on the same cpu for the same lnode. Here multiple inserters are from stacked contexts like softirq, hardirq and nmi. The current llist does not provide function to protect against the scenario where multiple inserters can use the same lnode. So, using llist_node() out of the box is not safe for this scenario. However we can protect against multiple inserters using the same lnode by using the fact llist node points to itself when not on the llist and atomically reset it and select the winner as the single inserter. Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev> Tested-by: JP Kobryn <inwardvessel@gmail.com> Signed-off-by: Tejun Heo <tj@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 reStructuredText 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.