From patchwork Wed May 4 16:43:54 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 569774 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 929D4C433FE for ; Wed, 4 May 2022 17:04:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349090AbiEDRHo (ORCPT ); Wed, 4 May 2022 13:07:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54976 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355598AbiEDREb (ORCPT ); Wed, 4 May 2022 13:04:31 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E31A84EF52; Wed, 4 May 2022 09:53:10 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 659AE61899; Wed, 4 May 2022 16:53:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B658AC385A4; Wed, 4 May 2022 16:53:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1651683188; bh=NEBsSG0/XWJf6FprfNFMo2p3cGJLwBZ8OJmNqMRtIGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ha7h/MMhWT/k7W9LcRI1xrrIvH6XeIepiF6lTTmnCGeoBGsvT3HKYkTYm8uhzJwoi Iyafm///AApkf3nnLr62/pCEt/OV1ZqnTXg5owavHZ8FH1v1jhLzE5c6LEA5i2ESDm Rjn/SXBXvnGBvCIZci1ANq2XGPQ48JG3toIaD7cE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guo Ren , Guo Ren , Palmer Dabbelt , Masami Hiramatsu Subject: [PATCH 5.15 041/177] riscv: patch_text: Fixup last cpu should be master Date: Wed, 4 May 2022 18:43:54 +0200 Message-Id: <20220504153056.592587620@linuxfoundation.org> X-Mailer: git-send-email 2.36.0 In-Reply-To: <20220504153053.873100034@linuxfoundation.org> References: <20220504153053.873100034@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Guo Ren commit 8ec1442953c66a1d8462cccd8c20b7ba561f5915 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- arch/riscv/kernel/patch.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- 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));