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The mmustat_enable sysfs file accessor functions must run code on the target CPU. This is achieved by temporarily setting the affinity of the calling user space thread to the requested CPU and reset it to the original affinity afterwards. That's racy vs. concurrent affinity settings for that thread resulting in code executing on the wrong CPU and overwriting the new affinity setting. Replace it by using work_on_cpu() which guarantees to run the code on the requested CPU. Protection against CPU hotplug is not required as the open sysfs file already prevents the removal from the CPU offline callback. Using the hotplug protected version would actually be wrong because it would deadlock against a CPU hotplug operation of the CPU associated to the sysfs file in progress. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: David S. Miller <davem@davemloft.net> Cc: fenghua.yu@intel.com Cc: tony.luck@intel.com Cc: herbert@gondor.apana.org.au Cc: rjw@rjwysocki.net Cc: peterz@infradead.org Cc: benh@kernel.crashing.org Cc: bigeasy@linutronix.de Cc: jiangshanlai@gmail.com Cc: sparclinux@vger.kernel.org Cc: viresh.kumar@linaro.org Cc: mpe@ellerman.id.au Cc: tj@kernel.org Cc: lenb@kernel.org Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1704131001270.2408@nanos Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. 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.