This is a note to let you know that I've just added the patch titled
cpufreq/sh: Replace racy task affinity logic
to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: cpufreq-sh-replace-racy-task-affinity-logic.patch and it can be found in the queue-4.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Thu Mar 22 14:40:23 CET 2018
From: Thomas Gleixner tglx@linutronix.de Date: Wed, 12 Apr 2017 22:07:36 +0200 Subject: cpufreq/sh: Replace racy task affinity logic
From: Thomas Gleixner tglx@linutronix.de
[ Upstream commit 205dcc1ecbc566cbc20acf246e68de3b080b3ecf ]
The target() callback must run on the affected cpu. This is achieved by temporarily setting the affinity of the calling 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.
Replace it by work_on_cpu(). All call pathes which invoke the callbacks are already protected against CPU hotplug.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Acked-by: Viresh Kumar viresh.kumar@linaro.org 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: linux-pm@vger.kernel.org Cc: Lai Jiangshan jiangshanlai@gmail.com 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/20170412201042.958216363@linutronix.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cpufreq/sh-cpufreq.c | 45 +++++++++++++++++++++++++------------------ 1 file changed, 27 insertions(+), 18 deletions(-)
--- a/drivers/cpufreq/sh-cpufreq.c +++ b/drivers/cpufreq/sh-cpufreq.c @@ -30,54 +30,63 @@
static DEFINE_PER_CPU(struct clk, sh_cpuclk);
+struct cpufreq_target { + struct cpufreq_policy *policy; + unsigned int freq; +}; + static unsigned int sh_cpufreq_get(unsigned int cpu) { return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000; }
-/* - * Here we notify other drivers of the proposed change and the final change. - */ -static int sh_cpufreq_target(struct cpufreq_policy *policy, - unsigned int target_freq, - unsigned int relation) +static long __sh_cpufreq_target(void *arg) { - unsigned int cpu = policy->cpu; + struct cpufreq_target *target = arg; + struct cpufreq_policy *policy = target->policy; + int cpu = policy->cpu; struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu); - cpumask_t cpus_allowed; struct cpufreq_freqs freqs; struct device *dev; long freq;
- cpus_allowed = current->cpus_allowed; - set_cpus_allowed_ptr(current, cpumask_of(cpu)); - - BUG_ON(smp_processor_id() != cpu); + if (smp_processor_id() != cpu) + return -ENODEV;
dev = get_cpu_device(cpu);
/* Convert target_freq from kHz to Hz */ - freq = clk_round_rate(cpuclk, target_freq * 1000); + freq = clk_round_rate(cpuclk, target->freq * 1000);
if (freq < (policy->min * 1000) || freq > (policy->max * 1000)) return -EINVAL;
- dev_dbg(dev, "requested frequency %u Hz\n", target_freq * 1000); + dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);
freqs.old = sh_cpufreq_get(cpu); freqs.new = (freq + 500) / 1000; freqs.flags = 0;
- cpufreq_freq_transition_begin(policy, &freqs); - set_cpus_allowed_ptr(current, &cpus_allowed); + cpufreq_freq_transition_begin(target->policy, &freqs); clk_set_rate(cpuclk, freq); - cpufreq_freq_transition_end(policy, &freqs, 0); + cpufreq_freq_transition_end(target->policy, &freqs, 0);
dev_dbg(dev, "set frequency %lu Hz\n", freq); - return 0; }
+/* + * Here we notify other drivers of the proposed change and the final change. + */ +static int sh_cpufreq_target(struct cpufreq_policy *policy, + unsigned int target_freq, + unsigned int relation) +{ + struct cpufreq_target data = { .policy = policy, .freq = target_freq }; + + return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data); +} + static int sh_cpufreq_verify(struct cpufreq_policy *policy) { struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
Patches currently in stable-queue which might be from tglx@linutronix.de are
queue-4.9/acpi-processor-fix-error-handling-in-__acpi_processor_start.patch queue-4.9/x86-reboot-turn-off-kvm-when-halting-a-cpu.patch queue-4.9/acpi-processor-replace-racy-task-affinity-logic.patch queue-4.9/time-change-posix-clocks-ops-interfaces-to-use-timespec64.patch queue-4.9/genirq-use-irqd_get_trigger_type-to-compare-the-trigger-type-for-shared-irqs.patch queue-4.9/cpufreq-sh-replace-racy-task-affinity-logic.patch queue-4.9/irqchip-mips-gic-separate-ipi-reservation-usage-tracking.patch queue-4.9/x86-kaslr-fix-kexec-kernel-boot-crash-when-kaslr-randomization-fails.patch