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commitaf8aab7137upstream. All threads queuing CQ entries on different CQs are unnecessarily synchronized by a spin lock to check if the CQ kthread worker hasn't been destroyed before queuing an CQ entry. The lock used in6efaf10f16("IB/rdmavt: Avoid queuing work into a destroyed cq kthread worker") is a device global lock and will have poor performance at scale as completions are entered from a large number of CPUs. Convert to use RCU where the read side of RCU is rvt_cq_enter() to determine that the worker is alive prior to triggering the completion event. Apply write side RCU semantics in rvt_driver_cq_init() and rvt_cq_exit(). Fixes:6efaf10f16("IB/rdmavt: Avoid queuing work into a destroyed cq kthread worker") Cc: <stable@vger.kernel.org> # 4.14.x Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com> Signed-off-by: Doug Ledford <dledford@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.