Re: [patch 1/6] x86, ftrace, hw-branch-tracer: support hotplug cpus

[Ingo Molnar]

* Markus Metzger <markus.t.metzger@xxxxxxxxx> wrote:

> Support hotplug cpus.

> +static int __cpuinit bts_hotcpu_handler(struct notifier_block *nfb,
> +				     unsigned long action, void *hcpu)
> +{
> +	unsigned int cpu = (unsigned long)hcpu;
> +
> +	mutex_lock(&bts_tracer_mutex);

This is buggy: CPU hotplug handlers must not sleep (they are 
called with irqs disabled), while this code does a mutex_lock() 
which can sleep.

	Ingo
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