[PATCH V4 2/4] riscv: patch_text: Fixup last cpu should be master

[guoren at kernel.org]

From: Guo Ren <guoren at linux.alibaba.com>

These patch_text implementations are using stop_machine_cpuslocked
infrastructure with atomic cpu_count. The original idea: When the
master CPU patch_text, the others should wait for it. But current
implementation is using the first CPU as master, which couldn't
guarantee the remaining CPUs are waiting. This patch changes the
last CPU as the master to solve the potential risk.

Fixes: 043cb41a85de ("riscv: introduce interfaces to patch kernel code")
Signed-off-by: Guo Ren <guoren at linux.alibaba.com>
Signed-off-by: Guo Ren <guoren at kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat at kernel.org>
Cc: <stable at vger.kernel.org>
---
 arch/riscv/kernel/patch.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 0b552873a577..765004b60513 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -104,7 +104,7 @@ static int patch_text_cb(void *data)
 	struct patch_insn *patch = data;
 	int ret = 0;
 
-	if (atomic_inc_return(&patch->cpu_count) == 1) {
+	if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {
 		ret =
 		    patch_text_nosync(patch->addr, &patch->insn,
 					    GET_INSN_LENGTH(patch->insn));
-- 
2.25.1