Subject: [PATCH 2/3] powerpc/cpuhp: BUG -> WARN conversion in offline path

From: Nathan Lynch <[email-masked]>
Date: Mon, 20 Sep 2021 08:55:03 -0500

If, due to bugs elsewhere, we get into unregister_cpu_online() with a CPU
that isn't marked hotpluggable, we can emit a warning and return an
appropriate error instead of crashing.

Signed-off-by: Nathan Lynch <[email-masked]>
---
 arch/powerpc/kernel/sysfs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index defecb3b1b15..08d8072d6e7a 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -928,7 +928,8 @@ static int unregister_cpu_online(unsigned int cpu)
 	struct device_attribute *attrs, *pmc_attrs;
 	int i, nattrs;
 
-	BUG_ON(!c->hotpluggable);
+	if (WARN_RATELIMIT(!c->hotpluggable, "cpu %d can't be offlined\n", cpu))
+		return -EBUSY;
 
 #ifdef CONFIG_PPC64
 	if (cpu_has_feature(CPU_FTR_SMT))
-- 
2.31.1