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=-9.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 4F4A5C433B4 for ; Wed, 7 Apr 2021 13:34:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18D34610CF for ; Wed, 7 Apr 2021 13:34:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344356AbhDGNe2 (ORCPT ); Wed, 7 Apr 2021 09:34:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35736 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235738AbhDGNeZ (ORCPT ); Wed, 7 Apr 2021 09:34:25 -0400 Received: from mail-ej1-x62a.google.com (mail-ej1-x62a.google.com [IPv6:2a00:1450:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B8D01C061756 for ; Wed, 7 Apr 2021 06:34:14 -0700 (PDT) Received: by mail-ej1-x62a.google.com with SMTP id r9so5177365ejj.3 for ; Wed, 07 Apr 2021 06:34:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=vDUwuylMSr1p1egrzfXRzNG099y7Eed6Or0fAEsvKCQ=; b=LtgPaaonNNQMSIoZlawOawV0mxA9TDZPXNqlhX51QLfqd5ArIwap8xrVoblByK6NWB vyifvRY2F1kuQMuvqBdcAqC6wUZmZWyhWQYz8+pmEy0ctl2JYrsv3i4vHlF0IlanjKIn qhQTdw1Se38tnbvw+8oEaaleXs/S3NTe42vfF0+Hq6kAg5gOosmRsw5kVwxETiWYmEmz BTi6qaabwxGdmAjBxN2TL0XUT5UawZXLD7jXXqnLqkwtY45ZhzCHcJSz7dENEQNvw7h4 Sk/n2EqszSsLXZlBfad+CG7ICzQPpXOCzbRVxdc0PkCtJ79G4ellWXaUqH9+Vn7K/JEt vp+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=vDUwuylMSr1p1egrzfXRzNG099y7Eed6Or0fAEsvKCQ=; b=MprsGmZa0T3GlN1MH3h1/xFHAO9ABEGHflvrUwaUU3+aWTleSHjJIPrGQ1iaEY4T/B X2w03GmxnGfRD7+5A50hHEyLX3KCT+HYDW4EJnPua+j94UGyohTMoGf/nnIybXYlD1+h I5w3J6vgwrTquRxAn4z4JmnqVu60VRLyW2gsWIDrvByThx5W1wOyYq2sbaKw4+cAd3PV Q/j+4hf4Nv/mSEIjyCxC3o1JZv7lL2tAS0ebtyTqy/Ao4Kq1JsFKHg0TWT1o8wgkD2xL npHH3YOCz5YUaLjNmLDUV1BPSfRViJ0aqs7gDhG/D9Rx27QlynRDGAuzWsJqg4dB1pcq k2Lw== X-Gm-Message-State: AOAM532Mw9d4i+WTIvP/NNcpB3qDEaXRVJersNIbS7bwbi2C0/vJZjJT a6x1z6zOgr3zjHfSvPeoCtU= X-Google-Smtp-Source: ABdhPJwezZfm8hhIsdQiRShili47FGXBhTKNC2TWW/LSV90FHHW4Rx7SxjaupD6OQQX3JlwGrWTnYw== X-Received: by 2002:a17:906:29d4:: with SMTP id y20mr3792013eje.461.1617802453544; Wed, 07 Apr 2021 06:34:13 -0700 (PDT) Received: from [192.168.0.109] ([95.87.199.133]) by smtp.gmail.com with ESMTPSA id m1sm9213522ejl.35.2021.04.07.06.34.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Apr 2021 06:34:13 -0700 (PDT) Subject: Re: [PATCH v2 4/5] tracing: Unify the logic for function tracing options To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org References: <20210329130533.199507-1-y.karadz@gmail.com> <20210329130533.199507-5-y.karadz@gmail.com> <20210405181525.0d4a724e@gandalf.local.home> From: "Yordan Karadzhov (VMware)" Message-ID: <3eb21018-d10d-6f05-cd91-e514d260f924@gmail.com> Date: Wed, 7 Apr 2021 16:34:11 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210405181525.0d4a724e@gandalf.local.home> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steven, Hi Steven, On 6.04.21 г. 1:15, Steven Rostedt wrote: >> >> @@ -235,30 +248,31 @@ static struct tracer function_trace; >> static int >> func_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) >> { >> - switch (bit) { >> - case TRACE_FUNC_OPT_STACK: >> - /* do nothing if already set */ >> - if (!!set == !!(func_flags.val & TRACE_FUNC_OPT_STACK)) >> - break; >> + ftrace_func_t func; >> + u32 new_flags_val; > Nit, but the variable should just be "new_flags", which is consistent with > old_flags. In the kernel we don't need to the variable names to be so > verbose. > >> >> - /* We can change this flag when not running. */ >> - if (tr->current_trace != &function_trace) >> - break; >> + /* Do nothing if already set. */ >> + if (!!set == !!(func_flags.val & bit)) >> + return 0; >> >> - unregister_ftrace_function(tr->ops); >> + /* We can change this flag only when not running. */ >> + if (tr->current_trace != &function_trace) >> + return 0; >> >> - if (set) { >> - tr->ops->func = function_stack_trace_call; >> - register_ftrace_function(tr->ops); >> - } else { >> - tr->ops->func = function_trace_call; >> - register_ftrace_function(tr->ops); >> - } >> + new_flags_val = (func_flags.val & ~(1UL << (bit - 1))); >> + new_flags_val |= (set << (bit - 1)); > bit is already the mask, no need to shift it, nor there's no reason for the > extra set of parenthesis. And the above can be done in one line. > > new_flags = (func_flags.val & ~bit) | (set ? bit : 0); > OK, I totally misinterpreted the meaning of the "bit" argument of the function. I did not realized it is a mask. I was thinking the argument gives only the number of the bit that changes (like 5 for the 5-th bit inside the mask). Thanks! Yordan