0f36ee24cd
For an unbound pool, multiple cpumasks are involved. U: The user-specified cpumask (may be filtered with cpu_possible_mask). A: The actual cpumask filtered by wq_unbound_cpumask. If the filtering leaves no CPU, wq_unbound_cpumask is used. P: Per-pod subsets of #A. wq->attrs stores #U, wq->dfl_pwq->pool->attrs->cpumask #A, and wq->cpu_pwq[CPU]->pool->attrs->cpumask #P. wq_update_pod() is called to update per-pod pwq's during CPU hotplug. To calculate the new #P for each workqueue, it needs to call wq_calc_pod_cpumask() with @attrs that contains #A. Currently, wq_update_pod() achieves this by calling wq_calc_pod_cpumask() with wq->dfl_pwq->pool->attrs. This is rather fragile because we're calling wq_calc_pod_cpumask() with @attrs of a worker_pool rather than the workqueue's actual attrs when what we want to calculate is the workqueue's cpumask on the pod. While this works fine currently, future changes will add fields which are used differently between workqueues and worker_pools and this subtlety will bite us. This patch factors out #U -> #A calculation from apply_wqattrs_prepare() into wqattrs_actualize_cpumask and updates wq_update_pod() to copy wq->unbound_attrs and use the new helper to obtain #A freshly instead of abusing wq->dfl_pwq->pool_attrs. This shouldn't cause any behavior changes in the current code. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: K Prateek Nayak <kprateek.nayak@amd.com> Reference: http://lkml.kernel.org/r/30625cdd-4d61-594b-8db9-6816b017dde3@amd.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.