• Thomas Gleixner's avatar
    ACPI/processor: Replace racy task affinity logic · 8153f9ac
    Thomas Gleixner authored
    acpi_processor_get_throttling() requires to invoke the getter function 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. CPU hotplug and concurrent affinity settings for that
    thread resulting in code executing on the wrong CPU and overwriting the
    new affinity setting.
    
    acpi_processor_get_throttling() is invoked in two ways:
    
    1) The CPU online callback, which is already running on the target CPU and
       obviously protected against hotplug and not affected by affinity
       settings.
    
    2) The ACPI driver probe function, which is not protected against hotplug
       during modprobe.
    
    Switch it over to work_on_cpu() and protect the probe function against CPU
    hotplug.
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Herbert Xu <herbert@gondor.apana.org.au>
    Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
    Cc: Sebastian Siewior <bigeasy@linutronix.de>
    Cc: Lai Jiangshan <jiangshanlai@gmail.com>
    Cc: linux-acpi@vger.kernel.org
    Cc: Viresh Kumar <viresh.kumar@linaro.org>
    Cc: Michael Ellerman <mpe@ellerman.id.au>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: "David S. Miller" <davem@davemloft.net>
    Cc: Len Brown <lenb@kernel.org>
    Link: http://lkml.kernel.org/r/20170412201042.785920903@linutronix.deSigned-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    8153f9ac
processor_driver.c 8.79 KB