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authorThomas Gleixner <tglx@linutronix.de>2017-04-12 23:07:34 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-04-15 13:20:54 +0300
commit8153f9ac43897f9f4786b30badc134fcc1a4fb11 (patch)
tree94f3d52a87a0e9dec031c899dd568fb0977d4e16 /drivers/acpi/processor_driver.c
parenta5cbdf693a60d5b86d4d21dfedd90f17754eb273 (diff)
downloadlinux-8153f9ac43897f9f4786b30badc134fcc1a4fb11.tar.xz
ACPI/processor: Replace racy task affinity logic
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: Thomas 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.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'drivers/acpi/processor_driver.c')
-rw-r--r--drivers/acpi/processor_driver.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/acpi/processor_driver.c b/drivers/acpi/processor_driver.c
index eab8cdad7dc3..8697a82bd465 100644
--- a/drivers/acpi/processor_driver.c
+++ b/drivers/acpi/processor_driver.c
@@ -262,11 +262,16 @@ err_power_exit:
static int acpi_processor_start(struct device *dev)
{
struct acpi_device *device = ACPI_COMPANION(dev);
+ int ret;
if (!device)
return -ENODEV;
- return __acpi_processor_start(device);
+ /* Protect against concurrent CPU hotplug operations */
+ get_online_cpus();
+ ret = __acpi_processor_start(device);
+ put_online_cpus();
+ return ret;
}
static int acpi_processor_stop(struct device *dev)