From 1e474b28e78897d0d170fab3b28ba683149cb9ea Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Wed, 5 Feb 2020 06:34:09 -0800 Subject: 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 Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20200205143409.GA7021@paulmck-ThinkPad-P72 --- kernel/up.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/up.c b/kernel/up.c index 53144d056252..c6f323dcd45b 100644 --- a/kernel/up.c +++ b/kernel/up.c @@ -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); -- cgit