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 4FF11C433F5 for ; Tue, 26 Oct 2021 09:48:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35B4161039 for ; Tue, 26 Oct 2021 09:48:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233011AbhJZJum (ORCPT ); Tue, 26 Oct 2021 05:50:42 -0400 Received: from out30-132.freemail.mail.aliyun.com ([115.124.30.132]:46166 "EHLO out30-132.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234310AbhJZJul (ORCPT ); Tue, 26 Oct 2021 05:50:41 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R151e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=30;SR=0;TI=SMTPD_---0Utm5zog_1635241690; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0Utm5zog_1635241690) by smtp.aliyun-inc.com(127.0.0.1); Tue, 26 Oct 2021 17:48:12 +0800 Subject: Re: [PATCH v5 1/2] ftrace: disable preemption when recursion locked To: Miroslav Benes Cc: Guo Ren , Steven Rostedt , 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 , 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: <3ca92dc9-ea04-ddc2-71cd-524bfa5a5721@linux.alibaba.com> <333cecfe-3045-8e0a-0c08-64ff590845ab@linux.alibaba.com> From: =?UTF-8?B?546L6LSH?= Message-ID: <18ba2a71-e12d-33f7-63fe-2857b2db022c@linux.alibaba.com> Date: Tue, 26 Oct 2021 17:48:10 +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: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org Hi, Miroslav On 2021/10/26 下午5:35, Miroslav Benes wrote: > Hi, > >> diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h >> index abe1a50..2bc1522 100644 >> --- a/include/linux/trace_recursion.h >> +++ b/include/linux/trace_recursion.h >> @@ -135,6 +135,9 @@ static __always_inline int trace_get_context_bit(void) >> # define do_ftrace_record_recursion(ip, pip) do { } while (0) >> #endif >> >> +/* >> + * Preemption is promised to be disabled when return bit > 0. >> + */ >> static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip, >> int start) >> { >> @@ -162,11 +165,17 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign >> current->trace_recursion = val; >> barrier(); >> >> + preempt_disable_notrace(); >> + >> return bit; >> } >> >> +/* >> + * Preemption will be enabled (if it was previously enabled). >> + */ >> static __always_inline void trace_clear_recursion(int bit) >> { >> + preempt_enable_notrace(); >> barrier(); >> trace_recursion_clear(bit); >> } > > The two comments should be updated too since Steven removed the "bit == 0" > trick. Could you please give more hint on how will it be correct? I get the point that bit will no longer be 0, there are only -1 or > 0 now so trace_test_and_set_recursion() will disable preemption on bit > 0 and trace_clear_recursion() will enabled it since it should only be called when bit > 0 (I remember we could use a WARN_ON here now :-P). > >> @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit) >> * tracing recursed in the same context (normal vs interrupt), >> * >> * Returns: -1 if a recursion happened. >> - * >= 0 if no recursion >> + * > 0 if no recursion. >> */ >> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip, >> unsigned long parent_ip) > > And this change would not be correct now. I thought it will no longer return 0 so I change it to > 0, isn't that correct? Regards, Michael Wang > > Regards > Miroslav > 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 1AFE9C433EF for ; Tue, 26 Oct 2021 09:48:39 +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 6DCB960EC0 for ; Tue, 26 Oct 2021 09:48:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 6DCB960EC0 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=YU/KtiytaNfhiGADdcnIMDo6NgNn6KSn/dDPpXzj34I=; b=Lj/NNdVswyvmNtiHh+qKynaWKo hNnJSrRoDnFkWYOkczXBh7sGvwigbSMuNjDJwqM6IgML1TXN+bYEezC7snS06R1c+w2TqkYa5mnLF PH75ED1lq55ddyhV0C49Bu8lM+4+Y0r/JEmFfvAJKKa+HXhtnypg7stYtvsuXdeHKeDW7EVwtiAtI 9l90KMhIDAHvvrmibSqKcRJ0OZFA3ugDCSIbCYGWre/TTBqHRbQRZhGaG/9A29vgQTtHu6zupgc7x 14O4iF6F81iLyyVUSi4EPYfldtCsH2phOfzhWVUUPBlpzLNIVI89GC3FU/lF0B8x30jG6pWKA4F2o s8Kq7SLQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfJ4G-001MKj-JX; Tue, 26 Oct 2021 09:48:28 +0000 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfJ44-001MCm-HG for linux-riscv@lists.infradead.org; Tue, 26 Oct 2021 09:48:18 +0000 X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R151e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04357; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=30; SR=0; TI=SMTPD_---0Utm5zog_1635241690; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0Utm5zog_1635241690) by smtp.aliyun-inc.com(127.0.0.1); Tue, 26 Oct 2021 17:48:12 +0800 Subject: Re: [PATCH v5 1/2] ftrace: disable preemption when recursion locked To: Miroslav Benes Cc: Guo Ren , Steven Rostedt , 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 , 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: <3ca92dc9-ea04-ddc2-71cd-524bfa5a5721@linux.alibaba.com> <333cecfe-3045-8e0a-0c08-64ff590845ab@linux.alibaba.com> From: =?UTF-8?B?546L6LSH?= Message-ID: <18ba2a71-e12d-33f7-63fe-2857b2db022c@linux.alibaba.com> Date: Tue, 26 Oct 2021 17:48:10 +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: Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211026_024816_767926_EA6BADB7 X-CRM114-Status: GOOD ( 17.46 ) 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 SGksIE1pcm9zbGF2CgpPbiAyMDIxLzEwLzI2IOS4i+WNiDU6MzUsIE1pcm9zbGF2IEJlbmVzIHdy b3RlOgo+IEhpLAo+IAo+PiBkaWZmIC0tZ2l0IGEvaW5jbHVkZS9saW51eC90cmFjZV9yZWN1cnNp b24uaCBiL2luY2x1ZGUvbGludXgvdHJhY2VfcmVjdXJzaW9uLmgKPj4gaW5kZXggYWJlMWE1MC4u MmJjMTUyMiAxMDA2NDQKPj4gLS0tIGEvaW5jbHVkZS9saW51eC90cmFjZV9yZWN1cnNpb24uaAo+ PiArKysgYi9pbmNsdWRlL2xpbnV4L3RyYWNlX3JlY3Vyc2lvbi5oCj4+IEBAIC0xMzUsNiArMTM1 LDkgQEAgc3RhdGljIF9fYWx3YXlzX2lubGluZSBpbnQgdHJhY2VfZ2V0X2NvbnRleHRfYml0KHZv aWQpCj4+ICAjIGRlZmluZSBkb19mdHJhY2VfcmVjb3JkX3JlY3Vyc2lvbihpcCwgcGlwKQlkbyB7 IH0gd2hpbGUgKDApCj4+ICAjZW5kaWYKPj4KPj4gKy8qCj4+ICsgKiBQcmVlbXB0aW9uIGlzIHBy b21pc2VkIHRvIGJlIGRpc2FibGVkIHdoZW4gcmV0dXJuIGJpdCA+IDAuCj4+ICsgKi8KPj4gIHN0 YXRpYyBfX2Fsd2F5c19pbmxpbmUgaW50IHRyYWNlX3Rlc3RfYW5kX3NldF9yZWN1cnNpb24odW5z aWduZWQgbG9uZyBpcCwgdW5zaWduZWQgbG9uZyBwaXAsCj4+ICAJCQkJCQkJaW50IHN0YXJ0KQo+ PiAgewo+PiBAQCAtMTYyLDExICsxNjUsMTcgQEAgc3RhdGljIF9fYWx3YXlzX2lubGluZSBpbnQg dHJhY2VfdGVzdF9hbmRfc2V0X3JlY3Vyc2lvbih1bnNpZ25lZCBsb25nIGlwLCB1bnNpZ24KPj4g IAljdXJyZW50LT50cmFjZV9yZWN1cnNpb24gPSB2YWw7Cj4+ICAJYmFycmllcigpOwo+Pgo+PiAr CXByZWVtcHRfZGlzYWJsZV9ub3RyYWNlKCk7Cj4+ICsKPj4gIAlyZXR1cm4gYml0Owo+PiAgfQo+ Pgo+PiArLyoKPj4gKyAqIFByZWVtcHRpb24gd2lsbCBiZSBlbmFibGVkIChpZiBpdCB3YXMgcHJl dmlvdXNseSBlbmFibGVkKS4KPj4gKyAqLwo+PiAgc3RhdGljIF9fYWx3YXlzX2lubGluZSB2b2lk IHRyYWNlX2NsZWFyX3JlY3Vyc2lvbihpbnQgYml0KQo+PiAgewo+PiArCXByZWVtcHRfZW5hYmxl X25vdHJhY2UoKTsKPj4gIAliYXJyaWVyKCk7Cj4+ICAJdHJhY2VfcmVjdXJzaW9uX2NsZWFyKGJp dCk7Cj4+ICB9Cj4gCj4gVGhlIHR3byBjb21tZW50cyBzaG91bGQgYmUgdXBkYXRlZCB0b28gc2lu Y2UgU3RldmVuIHJlbW92ZWQgdGhlICJiaXQgPT0gMCIgCj4gdHJpY2suCgpDb3VsZCB5b3UgcGxl YXNlIGdpdmUgbW9yZSBoaW50IG9uIGhvdyB3aWxsIGl0IGJlIGNvcnJlY3Q/CgpJIGdldCB0aGUg cG9pbnQgdGhhdCBiaXQgd2lsbCBubyBsb25nZXIgYmUgMCwgdGhlcmUgYXJlIG9ubHkgLTEgb3Ig PiAwIG5vdwpzbyB0cmFjZV90ZXN0X2FuZF9zZXRfcmVjdXJzaW9uKCkgd2lsbCBkaXNhYmxlIHBy ZWVtcHRpb24gb24gYml0ID4gMCBhbmQKdHJhY2VfY2xlYXJfcmVjdXJzaW9uKCkgd2lsbCBlbmFi bGVkIGl0IHNpbmNlIGl0IHNob3VsZCBvbmx5IGJlIGNhbGxlZCB3aGVuCmJpdCA+IDAgKEkgcmVt ZW1iZXIgd2UgY291bGQgdXNlIGEgV0FSTl9PTiBoZXJlIG5vdyA6LVApLgoKPiAKPj4gQEAgLTE3 OCw3ICsxODcsNyBAQCBzdGF0aWMgX19hbHdheXNfaW5saW5lIHZvaWQgdHJhY2VfY2xlYXJfcmVj dXJzaW9uKGludCBiaXQpCj4+ICAgKiB0cmFjaW5nIHJlY3Vyc2VkIGluIHRoZSBzYW1lIGNvbnRl eHQgKG5vcm1hbCB2cyBpbnRlcnJ1cHQpLAo+PiAgICoKPj4gICAqIFJldHVybnM6IC0xIGlmIGEg cmVjdXJzaW9uIGhhcHBlbmVkLgo+PiAtICogICAgICAgICAgID49IDAgaWYgbm8gcmVjdXJzaW9u Cj4+ICsgKiAgICAgICAgICAgPiAwIGlmIG5vIHJlY3Vyc2lvbi4KPj4gICAqLwo+PiAgc3RhdGlj IF9fYWx3YXlzX2lubGluZSBpbnQgZnRyYWNlX3Rlc3RfcmVjdXJzaW9uX3RyeWxvY2sodW5zaWdu ZWQgbG9uZyBpcCwKPj4gIAkJCQkJCQkgdW5zaWduZWQgbG9uZyBwYXJlbnRfaXApCj4gCj4gQW5k IHRoaXMgY2hhbmdlIHdvdWxkIG5vdCBiZSBjb3JyZWN0IG5vdy4KCkkgdGhvdWdodCBpdCB3aWxs IG5vIGxvbmdlciByZXR1cm4gMCBzbyBJIGNoYW5nZSBpdCB0byA+IDAsIGlzbid0IHRoYXQgY29y cmVjdD8KClJlZ2FyZHMsCk1pY2hhZWwgV2FuZwoKPiAKPiBSZWdhcmRzCj4gTWlyb3NsYXYKPiAK Cl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LXJp c2N2IG1haWxpbmcgbGlzdApsaW51eC1yaXNjdkBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9s aXN0cy5pbmZyYWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtcmlzY3YK 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 18986C433F5 for ; Tue, 26 Oct 2021 09:48:52 +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 56E1861039 for ; Tue, 26 Oct 2021 09:48:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 56E1861039 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 4Hdn8K5tH5z2ymZ for ; Tue, 26 Oct 2021 20:48:49 +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 4Hdn7s219Bz2xvf for ; Tue, 26 Oct 2021 20:48:22 +1100 (AEDT) X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R151e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=e01e04357; MF=yun.wang@linux.alibaba.com; NM=1; PH=DS; RN=30; SR=0; TI=SMTPD_---0Utm5zog_1635241690; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0Utm5zog_1635241690) by smtp.aliyun-inc.com(127.0.0.1); Tue, 26 Oct 2021 17:48:12 +0800 Subject: Re: [PATCH v5 1/2] ftrace: disable preemption when recursion locked To: Miroslav Benes References: <3ca92dc9-ea04-ddc2-71cd-524bfa5a5721@linux.alibaba.com> <333cecfe-3045-8e0a-0c08-64ff590845ab@linux.alibaba.com> From: =?UTF-8?B?546L6LSH?= Message-ID: <18ba2a71-e12d-33f7-63fe-2857b2db022c@linux.alibaba.com> Date: Tue, 26 Oct 2021 17:48:10 +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: 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, Joe Lawrence , Helge Deller , x86@kernel.org, linux-csky@vger.kernel.org, Ingo Molnar , Petr Mladek , Albert Ou , Jiri Kosina , Nicholas Piggin , Borislav Petkov , Steven Rostedt , 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" Hi, Miroslav On 2021/10/26 下午5:35, Miroslav Benes wrote: > Hi, > >> diff --git a/include/linux/trace_recursion.h b/include/linux/trace_recursion.h >> index abe1a50..2bc1522 100644 >> --- a/include/linux/trace_recursion.h >> +++ b/include/linux/trace_recursion.h >> @@ -135,6 +135,9 @@ static __always_inline int trace_get_context_bit(void) >> # define do_ftrace_record_recursion(ip, pip) do { } while (0) >> #endif >> >> +/* >> + * Preemption is promised to be disabled when return bit > 0. >> + */ >> static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsigned long pip, >> int start) >> { >> @@ -162,11 +165,17 @@ static __always_inline int trace_test_and_set_recursion(unsigned long ip, unsign >> current->trace_recursion = val; >> barrier(); >> >> + preempt_disable_notrace(); >> + >> return bit; >> } >> >> +/* >> + * Preemption will be enabled (if it was previously enabled). >> + */ >> static __always_inline void trace_clear_recursion(int bit) >> { >> + preempt_enable_notrace(); >> barrier(); >> trace_recursion_clear(bit); >> } > > The two comments should be updated too since Steven removed the "bit == 0" > trick. Could you please give more hint on how will it be correct? I get the point that bit will no longer be 0, there are only -1 or > 0 now so trace_test_and_set_recursion() will disable preemption on bit > 0 and trace_clear_recursion() will enabled it since it should only be called when bit > 0 (I remember we could use a WARN_ON here now :-P). > >> @@ -178,7 +187,7 @@ static __always_inline void trace_clear_recursion(int bit) >> * tracing recursed in the same context (normal vs interrupt), >> * >> * Returns: -1 if a recursion happened. >> - * >= 0 if no recursion >> + * > 0 if no recursion. >> */ >> static __always_inline int ftrace_test_recursion_trylock(unsigned long ip, >> unsigned long parent_ip) > > And this change would not be correct now. I thought it will no longer return 0 so I change it to > 0, isn't that correct? Regards, Michael Wang > > Regards > Miroslav >