Commit 1e474b28 authored by Paul E. McKenney's avatar Paul E. McKenney Committed by Thomas Gleixner

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: default avatarPaul E. McKenney <paulmck@kernel.org>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200205143409.GA7021@paulmck-ThinkPad-P72
parent 25a3a154
...@@ -14,7 +14,8 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info, ...@@ -14,7 +14,8 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
{ {
unsigned long flags; unsigned long flags;
WARN_ON(cpu != 0); if (cpu != 0)
return -ENXIO;
local_irq_save(flags); local_irq_save(flags);
func(info); func(info);
......
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