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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07818C433F5 for ; Wed, 13 Oct 2021 01:47:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E216C60E09 for ; Wed, 13 Oct 2021 01:47:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236704AbhJMBth (ORCPT ); Tue, 12 Oct 2021 21:49:37 -0400 Received: from out30-56.freemail.mail.aliyun.com ([115.124.30.56]:56803 "EHLO out30-56.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236699AbhJMBtg (ORCPT ); Tue, 12 Oct 2021 21:49:36 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R181e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04400;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=31;SR=0;TI=SMTPD_---0UrdGZW4_1634089648; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UrdGZW4_1634089648) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Oct 2021 09:47:29 +0800 Subject: Re: [PATCH 1/2] ftrace: disable preemption on the testing of recursion To: Steven Rostedt Cc: Guo Ren , Ingo Molnar , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Colin Ian King , Masami Hiramatsu , "Peter Zijlstra (Intel)" , Nicholas Piggin , Jisheng Zhang , linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, live-patching@vger.kernel.org References: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com> <20211012081728.5d357d6c@gandalf.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 13 Oct 2021 09:46:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211012081728.5d357d6c@gandalf.local.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On 2021/10/12 下午8:17, Steven Rostedt wrote: > On Tue, 12 Oct 2021 13:40:08 +0800 > 王贇 wrote: > >> @@ -52,11 +52,6 @@ static void notrace klp_ftrace_handler(unsigned long ip, >> bit = ftrace_test_recursion_trylock(ip, parent_ip); >> if (WARN_ON_ONCE(bit < 0)) >> return; >> - /* >> - * A variant of synchronize_rcu() is used to allow patching functions >> - * where RCU is not watching, see klp_synchronize_transition(). >> - */ > > I have to take a deeper look at this patch set, but do not remove this > comment, as it explains the protection here, that is not obvious with the > changes you made. Will keep that in v2. Regards, Michael Wang > > -- Steve > > >> - preempt_disable_notrace(); >> >> func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, >> stack_node); 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11A08C433EF for ; Wed, 13 Oct 2021 01:47:49 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C0FEA60E52 for ; Wed, 13 Oct 2021 01:47:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org C0FEA60E52 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:Cc:To:Subject:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=3gE+0W7N6U0jtaQgj4IQTD3FOYMhm7mQrov9MCASoAQ=; b=3jZoCTf1mImOOrWYNzD2ipeSlH +PUuzh4/BzyI65UrJe/8MpF08uUaAv4xt80FGEXlqipm5GnijoSEE2l0NdIfO/g6KOHRV11eSLWDb Vpb6d9YWdgTzeETYO87dG7uluZBRgTr9NXQOzG0OdIxns+pAxj8k5I2Bed6YDc2QjpfmgvaFzqFKm 6HT/3/27kyZ6Gm2I/T1ssprZpNqqb4TX3J/ZQ0qYb9XIM2V5Nh1pjEmAMBWkYC2mQMVkkBOcQSiO6 JEVDo31NXf7VRnjehACKbYOS0MQm4VSv04WAS5U3iLSOIiTf2REQ6V9n56ywvTpR8kQ5/M3ELwj5G dJ0nwk9Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1maTMl-00Eao6-HY; Wed, 13 Oct 2021 01:47:35 +0000 Received: from out30-45.freemail.mail.aliyun.com ([115.124.30.45]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1maTMi-00Ean0-Ln for linux-riscv@lists.infradead.org; Wed, 13 Oct 2021 01:47:34 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R181e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04400; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=31; SR=0; TI=SMTPD_---0UrdGZW4_1634089648; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UrdGZW4_1634089648) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Oct 2021 09:47:29 +0800 Subject: Re: [PATCH 1/2] ftrace: disable preemption on the testing of recursion To: Steven Rostedt Cc: Guo Ren , Ingo Molnar , "James E.J. Bottomley" , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Thomas Gleixner , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Colin Ian King , Masami Hiramatsu , "Peter Zijlstra (Intel)" , Nicholas Piggin , Jisheng Zhang , linux-csky@vger.kernel.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, live-patching@vger.kernel.org References: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com> <20211012081728.5d357d6c@gandalf.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 13 Oct 2021 09:46:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211012081728.5d357d6c@gandalf.local.home> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211012_184732_897968_7B6F86D3 X-CRM114-Status: GOOD ( 13.18 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org CgpPbiAyMDIxLzEwLzEyIOS4i+WNiDg6MTcsIFN0ZXZlbiBSb3N0ZWR0IHdyb3RlOgo+IE9uIFR1 ZSwgMTIgT2N0IDIwMjEgMTM6NDA6MDggKzA4MDAKPiDnjovotIcgPHl1bi53YW5nQGxpbnV4LmFs aWJhYmEuY29tPiB3cm90ZToKPiAKPj4gQEAgLTUyLDExICs1Miw2IEBAIHN0YXRpYyB2b2lkIG5v dHJhY2Uga2xwX2Z0cmFjZV9oYW5kbGVyKHVuc2lnbmVkIGxvbmcgaXAsCj4+ICAJYml0ID0gZnRy YWNlX3Rlc3RfcmVjdXJzaW9uX3RyeWxvY2soaXAsIHBhcmVudF9pcCk7Cj4+ICAJaWYgKFdBUk5f T05fT05DRShiaXQgPCAwKSkKPj4gIAkJcmV0dXJuOwo+PiAtCS8qCj4+IC0JICogQSB2YXJpYW50 IG9mIHN5bmNocm9uaXplX3JjdSgpIGlzIHVzZWQgdG8gYWxsb3cgcGF0Y2hpbmcgZnVuY3Rpb25z Cj4+IC0JICogd2hlcmUgUkNVIGlzIG5vdCB3YXRjaGluZywgc2VlIGtscF9zeW5jaHJvbml6ZV90 cmFuc2l0aW9uKCkuCj4+IC0JICovCj4gCj4gSSBoYXZlIHRvIHRha2UgYSBkZWVwZXIgbG9vayBh dCB0aGlzIHBhdGNoIHNldCwgYnV0IGRvIG5vdCByZW1vdmUgdGhpcwo+IGNvbW1lbnQsIGFzIGl0 IGV4cGxhaW5zIHRoZSBwcm90ZWN0aW9uIGhlcmUsIHRoYXQgaXMgbm90IG9idmlvdXMgd2l0aCB0 aGUKPiBjaGFuZ2VzIHlvdSBtYWRlLgoKV2lsbCBrZWVwIHRoYXQgaW4gdjIuCgpSZWdhcmRzLApN aWNoYWVsIFdhbmcKCj4gCj4gLS0gU3RldmUKPiAKPiAKPj4gLQlwcmVlbXB0X2Rpc2FibGVfbm90 cmFjZSgpOwo+Pgo+PiAgCWZ1bmMgPSBsaXN0X2ZpcnN0X29yX251bGxfcmN1KCZvcHMtPmZ1bmNf c3RhY2ssIHN0cnVjdCBrbHBfZnVuYywKPj4gIAkJCQkgICAgICBzdGFja19ub2RlKTsKCl9fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LXJpc2N2IG1h aWxpbmcgbGlzdApsaW51eC1yaXNjdkBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5p bmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtcmlzY3YK 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E3E6C433EF for ; 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Wed, 13 Oct 2021 12:47:36 +1100 (AEDT) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R181e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04400; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=31; SR=0; TI=SMTPD_---0UrdGZW4_1634089648; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UrdGZW4_1634089648) by smtp.aliyun-inc.com(127.0.0.1); Wed, 13 Oct 2021 09:47:29 +0800 Subject: Re: [PATCH 1/2] ftrace: disable preemption on the testing of recursion To: Steven Rostedt References: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com> <20211012081728.5d357d6c@gandalf.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 13 Oct 2021 09:46:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20211012081728.5d357d6c@gandalf.local.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Peter Zijlstra \(Intel\)" , Paul Walmsley , "James E.J. Bottomley" , Guo Ren , Jisheng Zhang , "H. Peter Anvin" , live-patching@vger.kernel.org, linux-riscv@lists.infradead.org, Miroslav Benes , Paul Mackerras , Joe Lawrence , Helge Deller , x86@kernel.org, linux-csky@vger.kernel.org, Ingo Molnar , Petr Mladek , Albert Ou , Jiri Kosina , Nicholas Piggin , Borislav Petkov , Josh Poimboeuf , Thomas Gleixner , linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, Palmer Dabbelt , Masami Hiramatsu , Colin Ian King , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2021/10/12 下午8:17, Steven Rostedt wrote: > On Tue, 12 Oct 2021 13:40:08 +0800 > 王贇 wrote: > >> @@ -52,11 +52,6 @@ static void notrace klp_ftrace_handler(unsigned long ip, >> bit = ftrace_test_recursion_trylock(ip, parent_ip); >> if (WARN_ON_ONCE(bit < 0)) >> return; >> - /* >> - * A variant of synchronize_rcu() is used to allow patching functions >> - * where RCU is not watching, see klp_synchronize_transition(). >> - */ > > I have to take a deeper look at this patch set, but do not remove this > comment, as it explains the protection here, that is not obvious with the > changes you made. Will keep that in v2. Regards, Michael Wang > > -- Steve > > >> - preempt_disable_notrace(); >> >> func = list_first_or_null_rcu(&ops->func_stack, struct klp_func, >> stack_node);