From: Guo Ren Date: Wed, 6 Apr 2022 14:16:49 +0000 (+0800) Subject: riscv: patch_text: Fixup last cpu should be master X-Git-Tag: v5.18-rc5~17^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=8ec1442953c66a1d8462cccd8c20b7ba561f5915;p=thirdparty%2Fkernel%2Flinux.git riscv: patch_text: Fixup last cpu should be master 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. Signed-off-by: Guo Ren Signed-off-by: Guo Ren Acked-by: Palmer Dabbelt Reviewed-by: Masami Hiramatsu Fixes: 043cb41a85de ("riscv: introduce interfaces to patch kernel code") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt --- diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 0b552873a5778..765004b605132 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));