From mboxrd@z Thu Jan 1 00:00:00 1970 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 7C728C433FE for ; Wed, 26 Oct 2022 13:21:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233167AbiJZNVz (ORCPT ); Wed, 26 Oct 2022 09:21:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52460 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233914AbiJZNVe (ORCPT ); Wed, 26 Oct 2022 09:21:34 -0400 Received: from mail-pj1-x102d.google.com (mail-pj1-x102d.google.com [IPv6:2607:f8b0:4864:20::102d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A05D7B7A6 for ; Wed, 26 Oct 2022 06:20:44 -0700 (PDT) Received: by mail-pj1-x102d.google.com with SMTP id m2so9990466pjr.3 for ; Wed, 26 Oct 2022 06:20:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=vTJtDcKCzm+jxcTMpjvVR3+lgYBiwIQNYP+cqOJzgwI=; b=nwONDDCrf87pEAToQfsQ2TDMlnRvjovexwXk8PXMC34Iix1wraRwmcBkYM1hjXi3+E /SIqgCroxG7m3K7s55njxuAn2SvT1QpmUekAZ00C9yVRYfmJHdJIhweQCzcvAsFnsMNQ UUv1FBQ+CRLI5ZKudnqYRGD/q+9acy2Phqw5HXo5V4G9WXuqJ3TBI9vB+VmAqd2jLtVP h8tsZsz7UgxmP8GXyPy2BFzL6sGd6kw0uM3TK1CjrVkCJIylc88Vqt0niRBR4lvdVQwc cessoCfudM4DSddxMtcT5IuQCmMhjIeccgGOirfEKnP/pLCDnKWgCGLL2oKv7gQetFdY Wrcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=vTJtDcKCzm+jxcTMpjvVR3+lgYBiwIQNYP+cqOJzgwI=; b=QcDZ2nlyO/pW9ssBEY+aSiqT0sYuVY/dUeYpDJ6X83pmCtZi0dSq4Dl2juGrEzQwCf +ZIh/79YCt15B19Wg4UZLKrWGVQOWaj7/VbM6azGuaYl8AKELf0RGUl1Ta+rkT124LKm hQNRRj9sr/WogKO3Xz0MNDwKHTT/jUC89GNvw3sZuHdvZMZaw29I88qyE95HfGnkYYnz TDsZtwTTHtjJvKnEkaCa7pwHttxAWJS2ZpYXEF3cdOugbIGK+6kg2GnNaW3/wd/23MIF hGAeV6oR1RYPHu3k3KEFnHefTCTg07puvOJ2hwkOaBr5a50KYW0C7J/xx17w5KMmESOu llfg== X-Gm-Message-State: ACrzQf2E9Kv4sAJ+lFH0mhxfI3aVV0klOQW8+kko2S3VReQl/Os3u0jF DKBhtzEkW4rY6fbT5vXaxLk= X-Google-Smtp-Source: AMsMyM69xhZxgKyfjn+sFTG7xtAteBalwuiy+sxSOBBtcjCpmMwTIhnf/V7w21lJBOCC+O/JkJOqZA== X-Received: by 2002:a17:902:f68c:b0:186:dfca:a444 with SMTP id l12-20020a170902f68c00b00186dfcaa444mr2184514plg.151.1666790444124; Wed, 26 Oct 2022 06:20:44 -0700 (PDT) Received: from localhost.localdomain ([221.226.144.218]) by smtp.gmail.com with ESMTPSA id v12-20020a170902b7cc00b00186b04776b0sm2880131plz.118.2022.10.26.06.20.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Oct 2022 06:20:43 -0700 (PDT) From: Song Shuai To: rostedt@goodmis.org, mingo@redhat.com Cc: linux-kernel@vger.kernel.org, Song Shuai Subject: [PATCH] ftrace: avoid replacing the list func with itself Date: Wed, 26 Oct 2022 21:20:39 +0800 Message-Id: <20221026132039.2236233-1-suagrfillet@gmail.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The list func (ftrace_ops_list_func) will be patched first before the transition between old and new calls are set, which fixed the race described in this commit `59338f75`. While ftrace_trace_function changes from the list func to a ftrace_ops func, like unregistering the klp_ops to leave the only global_ops in ftrace_ops_list, the ftrace_[regs]_call will be replaced with the list func although it already exists. So there should be a condition to avoid this. This patch backups saved_ftrace_func by saved_ftrace_func_old which will be compared with the list func before trying to patch it. Signed-off-by: Song Shuai --- kernel/trace/ftrace.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index bc921a3f7ea8..56b1a42e1937 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -2755,6 +2755,8 @@ void __weak ftrace_arch_code_modify_post_process(void) { } +static ftrace_func_t saved_ftrace_func_old; + void ftrace_modify_all_code(int command) { int update = command & FTRACE_UPDATE_TRACE_FUNC; @@ -2774,7 +2776,7 @@ void ftrace_modify_all_code(int command) * to make sure the ops are having the right functions * traced. */ - if (update) { + if (update && saved_ftrace_func_old != ftrace_ops_list_func) { err = ftrace_update_ftrace_func(ftrace_ops_list_func); if (FTRACE_WARN_ON(err)) return; @@ -2918,6 +2920,7 @@ static void ftrace_trampoline_free(struct ftrace_ops *ops) static void ftrace_startup_enable(int command) { if (saved_ftrace_func != ftrace_trace_function) { + saved_ftrace_func_old = saved_ftrace_func; saved_ftrace_func = ftrace_trace_function; command |= FTRACE_UPDATE_TRACE_FUNC; } @@ -3007,6 +3010,7 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command) ops->flags &= ~FTRACE_OPS_FL_ENABLED; if (saved_ftrace_func != ftrace_trace_function) { + saved_ftrace_func_old = saved_ftrace_func; saved_ftrace_func = ftrace_trace_function; command |= FTRACE_UPDATE_TRACE_FUNC; } @@ -8321,6 +8325,7 @@ static void ftrace_startup_sysctl(void) /* Force update next time */ saved_ftrace_func = NULL; + saved_ftrace_func_old = NULL; /* ftrace_start_up is true if we want ftrace running */ if (ftrace_start_up) { command = FTRACE_UPDATE_CALLS; -- 2.20.1