smp_processor_id.c 1.34 KB
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// SPDX-License-Identifier: GPL-2.0
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/*
 * lib/smp_processor_id.c
 *
 * DEBUG_PREEMPT variant of smp_processor_id().
 */
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#include <linux/export.h>
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#include <linux/sched.h>
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notrace static unsigned int check_preemption_disabled(const char *what1,
							const char *what2)
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{
	int this_cpu = raw_smp_processor_id();

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	if (likely(preempt_count()))
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		goto out;

	if (irqs_disabled())
		goto out;

	/*
	 * Kernel threads bound to a single CPU can safely use
	 * smp_processor_id():
	 */
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	if (cpumask_equal(&current->cpus_allowed, cpumask_of(this_cpu)))
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		goto out;

	/*
	 * It is valid to assume CPU-locality during early bootup:
	 */
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	if (system_state < SYSTEM_SCHEDULING)
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		goto out;

	/*
	 * Avoid recursion:
	 */
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	preempt_disable_notrace();
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	if (!printk_ratelimit())
		goto out_enable;

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	printk(KERN_ERR "BUG: using %s%s() in preemptible [%08x] code: %s/%d\n",
		what1, what2, preempt_count() - 1, current->comm, current->pid);

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	printk("caller is %pS\n", __builtin_return_address(0));
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	dump_stack();

out_enable:
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	preempt_enable_no_resched_notrace();
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out:
	return this_cpu;
}

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notrace unsigned int debug_smp_processor_id(void)
{
	return check_preemption_disabled("smp_processor_id", "");
}
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EXPORT_SYMBOL(debug_smp_processor_id);

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notrace void __this_cpu_preempt_check(const char *op)
{
	check_preemption_disabled("__this_cpu_", op);
}
EXPORT_SYMBOL(__this_cpu_preempt_check);