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 D0DC5C433F5 for ; Wed, 27 Oct 2021 03:09:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2B42610C7 for ; Wed, 27 Oct 2021 03:09:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238908AbhJ0DMD (ORCPT ); Tue, 26 Oct 2021 23:12:03 -0400 Received: from out30-133.freemail.mail.aliyun.com ([115.124.30.133]:54044 "EHLO out30-133.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238941AbhJ0DMC (ORCPT ); Tue, 26 Oct 2021 23:12:02 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R991e4;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=30;SR=0;TI=SMTPD_---0UtqSqrG_1635304169; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UtqSqrG_1635304169) by smtp.aliyun-inc.com(127.0.0.1); Wed, 27 Oct 2021 11:09:31 +0800 Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked 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 , 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: <78c95844-16b7-8904-b48d-3b2ccd76a352@linux.alibaba.com> <20211026225552.72a7ee79@rorschach.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 27 Oct 2021 11:09:29 +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: <20211026225552.72a7ee79@rorschach.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 2021/10/27 上午10:55, Steven Rostedt wrote: > On Wed, 27 Oct 2021 10:34:13 +0800 > 王贇 wrote: > >> +/* >> + * Preemption will be enabled (if it was previously enabled). >> + */ >> static __always_inline void trace_clear_recursion(int bit) >> { >> + WARN_ON_ONCE(bit < 0); > > Can you send a v7 without the WARN_ON. > > This is an extremely hot path, and this will cause noticeable overhead. > > If something were to call this with bit < 0, then it would crash and > burn rather quickly. I see, if the problem will be notified anyway then it's fine, v7 on the way. Regards, Michael Wang > > -- Steve > > >> + >> + preempt_enable_notrace(); >> barrier(); >> trace_recursion_clear(bit); >> } 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 3B26CC433EF for ; Wed, 27 Oct 2021 03:09:52 +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 D2B8161074 for ; Wed, 27 Oct 2021 03:09:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org D2B8161074 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=M/XFLm4wTVqbNfpFwARc4miAhTP8dPhPy6zIAEzorgs=; b=l/gUn38Ly3bcWktETYKQtoKNY8 KhJK6go146Kuazh2TUNJxbtS8ahqDxWdPL0Y0XZU6WQ4u9q8ho49lZ/nFGUBOZQpfELklGB2jFryf cMS8nUBwp+1QXzb56iumROOTote9wFXLZDj+ZUYbWWLPJPFP/7QReWpmI2XKVjzNSD//OK/MRycph GIUR3MkPv2s2BQCSYYLQJV26WNgOlFU8+eZ/pJj8Mp6ZAp886lx3Nl8p3cFH3IKAOqnmL35BWN7of 2BfD13n4oIdD8TanR77hDrmIjCUFnQnddtzuQahDT4oCqxCJAl7jdnCK24T13bmDj3XbCHJI00/9M gtGuoQ7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfZJx-003iVV-Ll; Wed, 27 Oct 2021 03:09:45 +0000 Received: from out30-131.freemail.mail.aliyun.com ([115.124.30.131]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfZJp-003iTv-0b for linux-riscv@lists.infradead.org; Wed, 27 Oct 2021 03:09:38 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R991e4; 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=30; SR=0; TI=SMTPD_---0UtqSqrG_1635304169; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UtqSqrG_1635304169) by smtp.aliyun-inc.com(127.0.0.1); Wed, 27 Oct 2021 11:09:31 +0800 Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked 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 , 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: <78c95844-16b7-8904-b48d-3b2ccd76a352@linux.alibaba.com> <20211026225552.72a7ee79@rorschach.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 27 Oct 2021 11:09:29 +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: <20211026225552.72a7ee79@rorschach.local.home> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211026_200937_291170_C0CAF14E X-CRM114-Status: GOOD ( 12.17 ) 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 CgpPbiAyMDIxLzEwLzI3IOS4iuWNiDEwOjU1LCBTdGV2ZW4gUm9zdGVkdCB3cm90ZToKPiBPbiBX ZWQsIDI3IE9jdCAyMDIxIDEwOjM0OjEzICswODAwCj4g546L6LSHIDx5dW4ud2FuZ0BsaW51eC5h bGliYWJhLmNvbT4gd3JvdGU6Cj4gCj4+ICsvKgo+PiArICogUHJlZW1wdGlvbiB3aWxsIGJlIGVu YWJsZWQgKGlmIGl0IHdhcyBwcmV2aW91c2x5IGVuYWJsZWQpLgo+PiArICovCj4+ICBzdGF0aWMg X19hbHdheXNfaW5saW5lIHZvaWQgdHJhY2VfY2xlYXJfcmVjdXJzaW9uKGludCBiaXQpCj4+ICB7 Cj4+ICsJV0FSTl9PTl9PTkNFKGJpdCA8IDApOwo+IAo+IENhbiB5b3Ugc2VuZCBhIHY3IHdpdGhv dXQgdGhlIFdBUk5fT04uCj4gCj4gVGhpcyBpcyBhbiBleHRyZW1lbHkgaG90IHBhdGgsIGFuZCB0 aGlzIHdpbGwgY2F1c2Ugbm90aWNlYWJsZSBvdmVyaGVhZC4KPiAKPiBJZiBzb21ldGhpbmcgd2Vy ZSB0byBjYWxsIHRoaXMgd2l0aCBiaXQgPCAwLCB0aGVuIGl0IHdvdWxkIGNyYXNoIGFuZAo+IGJ1 cm4gcmF0aGVyIHF1aWNrbHkuCgpJIHNlZSwgaWYgdGhlIHByb2JsZW0gd2lsbCBiZSBub3RpZmll ZCBhbnl3YXkgdGhlbiBpdCdzIGZpbmUsIHY3IG9uIHRoZSB3YXkuCgpSZWdhcmRzLApNaWNoYWVs IFdhbmcKCj4gCj4gLS0gU3RldmUKPiAKPiAKPj4gKwo+PiArCXByZWVtcHRfZW5hYmxlX25vdHJh Y2UoKTsKPj4gIAliYXJyaWVyKCk7Cj4+ICAJdHJhY2VfcmVjdXJzaW9uX2NsZWFyKGJpdCk7Cj4+ ICB9CgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpsaW51 eC1yaXNjdiBtYWlsaW5nIGxpc3QKbGludXgtcmlzY3ZAbGlzdHMuaW5mcmFkZWFkLm9yZwpodHRw Oi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LXJpc2N2Cg== 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 32A66C433F5 for ; Wed, 27 Oct 2021 03:10:24 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 281F460F22 for ; Wed, 27 Oct 2021 03:10:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 281F460F22 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.ozlabs.org Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4HfDG55SYCz3c69 for ; Wed, 27 Oct 2021 14:10:21 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.alibaba.com (client-ip=115.124.30.130; helo=out30-130.freemail.mail.aliyun.com; envelope-from=yun.wang@linux.alibaba.com; receiver=) Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4HfDFc5hNKz2xXf for ; Wed, 27 Oct 2021 14:09:51 +1100 (AEDT) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R991e4; 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=30; SR=0; TI=SMTPD_---0UtqSqrG_1635304169; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UtqSqrG_1635304169) by smtp.aliyun-inc.com(127.0.0.1); Wed, 27 Oct 2021 11:09:31 +0800 Subject: Re: [PATCH v6 1/2] ftrace: disable preemption when recursion locked To: Steven Rostedt References: <78c95844-16b7-8904-b48d-3b2ccd76a352@linux.alibaba.com> <20211026225552.72a7ee79@rorschach.local.home> From: =?UTF-8?B?546L6LSH?= Message-ID: Date: Wed, 27 Oct 2021 11:09:29 +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: <20211026225552.72a7ee79@rorschach.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 , 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 , Paul Mackerras , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 2021/10/27 上午10:55, Steven Rostedt wrote: > On Wed, 27 Oct 2021 10:34:13 +0800 > 王贇 wrote: > >> +/* >> + * Preemption will be enabled (if it was previously enabled). >> + */ >> static __always_inline void trace_clear_recursion(int bit) >> { >> + WARN_ON_ONCE(bit < 0); > > Can you send a v7 without the WARN_ON. > > This is an extremely hot path, and this will cause noticeable overhead. > > If something were to call this with bit < 0, then it would crash and > burn rather quickly. I see, if the problem will be notified anyway then it's fine, v7 on the way. Regards, Michael Wang > > -- Steve > > >> + >> + preempt_enable_notrace(); >> barrier(); >> trace_recursion_clear(bit); >> }