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 X-Spam-Level: X-Spam-Status: No, score=-14.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41537C433E0 for ; Tue, 28 Jul 2020 12:29:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 175512070B for ; Tue, 28 Jul 2020 12:29:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="pxHNeRZM"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="1/iTDsNn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729598AbgG1M3J (ORCPT ); Tue, 28 Jul 2020 08:29:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729399AbgG1M3I (ORCPT ); Tue, 28 Jul 2020 08:29:08 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9867C061794; Tue, 28 Jul 2020 05:29:08 -0700 (PDT) Date: Tue, 28 Jul 2020 12:29:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1595939346; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rI4p+p7PY7+lEZb3eDxP0kJaacGlY/NLIZWz8rMV/U0=; b=pxHNeRZMrsEPfLylenuhN1fExrnCQ0qPz3SaOsEsOZegNt41iewnDDt8ho2OHEYlUn413o k1OUpgqsVaIO0hpVh+PArT0lm2WxdLUuLpx2ZBbMAwIOqkQ7DRCCDI8BahhZ4fXEVlJHou CSw4/VZDrmW2aNYgDi5fhM9JeYrmkeqFVx5yu1NkMEGUsfg0/hbwDP1GQpK99sXjNIZtPw +qR71ssImI9rzvvoxCPjkDyBSCuK/YYHRbC5H0KJnJ2KFSQxT2FLQI9ehvwPuB5OsBuXeZ QJzNkn61Cwdc+IMbUwXJ4+PvWEiSRE90HQJewEe1xJENlR+blz+oohLY8dguFQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1595939346; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=rI4p+p7PY7+lEZb3eDxP0kJaacGlY/NLIZWz8rMV/U0=; b=1/iTDsNn4RKNat2rjRmQFmA+grMMFd6i9da5lBH++p+yMnDeKLH4xGv3LarMjIXRIW0JLk C2vJZpMRT0cSs+DA== From: "tip-bot2 for Masami Hiramatsu" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: perf/core] kprobes: Remove unnecessary module_mutex locking from kprobe_optimizer() Cc: Ingo Molnar , Masami Hiramatsu , Jarkko Sakkinen , x86 , LKML In-Reply-To: <20200728163400.e00b09c594763349f99ce6cb@kernel.org> References: <20200728163400.e00b09c594763349f99ce6cb@kernel.org> MIME-Version: 1.0 Message-ID: <159593934624.4006.4213436208654596958.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the perf/core branch of tip: Commit-ID: 112a0e4171e111e963aada3fe790c71accf4d705 Gitweb: https://git.kernel.org/tip/112a0e4171e111e963aada3fe790c71accf4d705 Author: Masami Hiramatsu AuthorDate: Tue, 28 Jul 2020 16:34:00 +09:00 Committer: Ingo Molnar CommitterDate: Tue, 28 Jul 2020 13:19:05 +02:00 kprobes: Remove unnecessary module_mutex locking from kprobe_optimizer() Since we already lock both kprobe_mutex and text_mutex in the optimizer, text will not be changed and the module unloading will be stopped inside kprobes_module_callback(). The mutex_lock() has originally been introduced to avoid conflict with text modification, at that point we didn't hold text_mutex. But after: f1c6ece23729 ("kprobes: Fix potential deadlock in kprobe_optimizer()") We started holding the text_mutex and don't need the modules mutex anyway. So remove the module_mutex locking. [ mingo: Amended the changelog. ] Suggested-by: Ingo Molnar Signed-off-by: Masami Hiramatsu Signed-off-by: Ingo Molnar Cc: Jarkko Sakkinen Link: https://lore.kernel.org/r/20200728163400.e00b09c594763349f99ce6cb@kernel.org --- kernel/kprobes.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 146c648..e87679a 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -598,8 +598,6 @@ static void kprobe_optimizer(struct work_struct *work) mutex_lock(&kprobe_mutex); cpus_read_lock(); mutex_lock(&text_mutex); - /* Lock modules while optimizing kprobes */ - mutex_lock(&module_mutex); /* * Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed) @@ -624,7 +622,6 @@ static void kprobe_optimizer(struct work_struct *work) /* Step 4: Free cleaned kprobes after quiesence period */ do_free_cleaned_kprobes(); - mutex_unlock(&module_mutex); mutex_unlock(&text_mutex); cpus_read_unlock();