The core device API performs extra housekeeping bits that are missing
from directly calling cpu_up/down.

See commit a6717c01ddc2 ("powerpc/rtas: use device model APIs and
serialization during LPM") for an example description of what might go
wrong.

This also prepares to make cpu_up/down a private interface for anything
but the cpu subsystem.

Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Qais Yousef <redacted>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <redacted>
CC: Michael Ellerman <mpe@ellerman.id.au>
CC: Enrico Weigelt <info@metux.net>
CC: Ram Pai <redacted>
CC: Nicholas Piggin <npiggin@gmail.com>
CC: Thiago Jung Bauermann <redacted>
CC: Christophe Leroy <redacted>
CC: Thomas Gleixner <redacted>
CC: linuxppc-dev@lists.ozlabs.org
CC: linux-kernel@vger.kernel.org
---

Michael, this now uses add_cpu() which you should be CCed on. I wasn't sure if
I can keep your Ack or remove it in this case. Please let me know if you need
more clarification.

 arch/powerpc/kexec/core_64.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c
index 04a7cba58eff..b4184092172a 100644
--- a/arch/powerpc/kexec/core_64.c
+++ b/arch/powerpc/kexec/core_64.c

@@ -212,7 +212,7 @@ static void wake_offline_cpus(void)
 		if (!cpu_online(cpu)) {
 			printk(KERN_INFO "kexec: Waking offline cpu %d.\n",
 			       cpu);
-			WARN_ON(cpu_up(cpu));
+			WARN_ON(add_cpu(cpu));
 		}
 	}
 }

-- 
2.17.1