Commit 1e474b28 authored Feb 05, 2020 by Paul E. McKenney Committed by Thomas Gleixner Feb 07, 2020

smp/up: Make smp_call_function_single() match SMP semantics



In CONFIG_SMP=y kernels, smp_call_function_single() returns -ENXIO when
invoked for a non-existent CPU.  In contrast, in CONFIG_SMP=n kernels,
a splat is emitted and smp_call_function_single() otherwise silently
ignores its "cpu" argument, instead pretending that the caller intended
to have something happen on CPU 0.  Given that there is now code that
expects smp_call_function_single() to return an error if a bad CPU was
specified, this difference in semantics needs to be addressed.

Bring the semantics of the CONFIG_SMP=n version of
smp_call_function_single() into alignment with its CONFIG_SMP=y
counterpart.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200205143409.GA7021@paulmck-ThinkPad-P72

parent 25a3a154

kernel/up.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -14,7 +14,8 @@ int smp_call_function_single(int cpu, void (func) (void info), void *info,
		{
		unsigned long flags;

		WARN_ON(cpu != 0);
		if (cpu != 0)
		return -ENXIO;

		local_irq_save(flags);
		func(info);

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