[PATCH] riscv: BUG_ON() for no cpu nodes in setup_smp

[Song Shuai]

When booting with ACPI tables, the tiny devictree created by
EFI Stub doesn't provide cpu nodes.

In setup_smp(), of_parse_and_init_cpus() will bug on !found_boot_cpu
if acpi_disabled. That's unclear, so bug for no cpu nodes before
of_parse_and_init_cpus().

Signed-off-by: Song Shuai <suagrfillet at gmail.com>
---
 arch/riscv/kernel/smpboot.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index 6ca2b5309aab..243a7b533ad7 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -187,8 +187,13 @@ static void __init of_parse_and_init_cpus(void)
 
 void __init setup_smp(void)
 {
-	if (acpi_disabled)
+	if (acpi_disabled) {
+		/* When booting with ACPI tables, the devictree created by EFI Stub
+		 * doesn't provide cpu nodes. So BUG here for any acpi_disabled.
+		 */
+		BUG_ON(!of_get_next_cpu_node(NULL));
 		of_parse_and_init_cpus();
+	}
 	else
 		acpi_parse_and_init_cpus();
 }
-- 
2.20.1