ia64/sn/hwperf: Replace racy task affinity logic
authorThomas Gleixner <tglx@linutronix.de>
Thu, 6 Apr 2017 12:56:18 +0000 (14:56 +0200)
committerThomas Gleixner <tglx@linutronix.de>
Sat, 15 Apr 2017 10:20:53 +0000 (12:20 +0200)
commit9feb42ac88b516e378b9782e82b651ca5bed95c4
tree68b28a572dc1735a4b5e0d9be9b751b7d5f854e4
parent67cb85fdcee7fbc61c09c00360d1a4ae37641db4
ia64/sn/hwperf: Replace racy task affinity logic

sn_hwperf_op_cpu() which is invoked from an ioctl requires to run code on
the requested 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.

Replace it by using work_on_cpu_safe() which guarantees to run the code on
the requested CPU or to fail in case the CPU is offline.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: linux-ia64@vger.kernel.org
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: 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/alpine.DEB.2.20.1704122251450.2548@nanos
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
arch/ia64/sn/kernel/sn2/sn_hwperf.c