Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6;
Message-ID: <1ef6c0a0-4d82-4fdc-8007-87e054a4c08d@suse.com>
Date:   Tue, 28 Nov 2023 16:06:03 +0100
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 2/2] tracing: Disable events in reverse order of their
 enable operation
Content-Language: en-US
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     mhiramat@kernel.org, mathieu.desnoyers@efficios.com,
        zhengyejian1@huawei.com, linux-trace-kernel@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20231127151248.7232-1-petr.pavlu@suse.com>
 <20231127151248.7232-3-petr.pavlu@suse.com>
 <20231127125815.4a4d06c6@gandalf.local.home>
From:   Petr Pavlu <petr.pavlu@suse.com>
In-Reply-To: <20231127125815.4a4d06c6@gandalf.local.home>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?U2RDWkwyYVVxRkdNUUEvMG16a0NwcHgxWUI2MHhFVkdiYnRZYmJqcVJ6L2ZQ?=
 =?utf-8?B?U0RPSmVsSjY4MkExNHhwUUg5MGhzeC9TNU8rMVhyUmxDUnhpQTN2RS9nSkk2?=
 =?utf-8?B?WU10dzVNeEdia01wc2pRZldzNUI1L2ExVWlYZzhrOWJUTEdhYkF0NWpJMmJs?=
 =?utf-8?B?cjQyaWNLVXN6Zmx4TG9nQUFGVCtXZ2ZYSHhRcjBUeEZtUStoVHZ5dTJrMVlV?=
 =?utf-8?B?KytkQmdjcHliNnJkK2ZSc1pxNGdmK3dxelMxaDRmV3ZJUWhxY3ptNXpDeEdk?=
 =?utf-8?B?dU5mdXFwSnA4MVZHYXF4Tm1MV3laU0c1eVBlRWppWnRQeUIwSWIrUElhRGpH?=
 =?utf-8?B?TWFFR0xSTFozN2I2ZjVzWS9SWkFNQkFicW5aRzBQbVlBS29GYURHZlF2bytP?=
 =?utf-8?B?T2FOL3JYZ21tdzM1akgvVGRWWHJaa3lxaGpwemVITHJ0Z1drT2dvdDRJMzJu?=
 =?utf-8?B?ZTZpN01EbTdOak9XeE1ja1lWekhVWHFXUnlmd2FsUmc1WUI3dTJ4NFRHcjNN?=
 =?utf-8?B?M1BsZC9zQlFJcit2NHlPRW9HTVFlNTJ3QnpXQ2JkVkZxUFIwQmR1QkkwZDBB?=
 =?utf-8?B?ZWg2K0QvUnVSQ1dtcHhVUGlnWHFuT3BDTE1idVYreFViY3NlVGpDYUVDN1pk?=
 =?utf-8?B?YWNvQ3F6cytHQno5RHovWmdVL1lFNWhreFRFZWI0bmlieXo0SCsxbVhpdTdE?=
 =?utf-8?B?OFpKSWdQTmtXK1BMdDlOUEJzK0ZFS0ZGY25hdzVkSU0wUDdnVHltQXUwZ0Fj?=
 =?utf-8?B?cERoL0w0QVBqRThiNlNpRGZqRlV3Qmh5M2hFWHFRV05kOXloWElDZWpUdFQv?=
 =?utf-8?B?UzlwN2FxT1BGUzFnU2liWWx4R3dpM01XRE5XRWQvc0tOSnVlS09ucUxJS3lC?=
 =?utf-8?B?NVJ2MDFqQVU5cmtPSW4wTC9hbVNuL1E1bTBYN2lPd2JxUXVDL29pVmhHOGZj?=
 =?utf-8?B?RmhQUitoQTJEWnlnOHd1SFU0VzdBcWpQWnpIb3JNQXIyeUVEWDIvRVBWc0pP?=
 =?utf-8?B?dkhrK2xMaXdkT05pZ3F1VVJVTytIWDFyQlBHbVVJSmFVMEpUZFI4dzVSTURZ?=
 =?utf-8?B?cFBHeVVOcDJYTUJSMzdMY2FGZnVja3BDV1hiZno1UkZwN1RIYnh1RnZXN24w?=
 =?utf-8?B?ZlVseHpNaTFzK1dEOE1hNlFoRlBNOUxMT3J3NnFKdXdXSU1PWGg5RHF1aTRp?=
 =?utf-8?B?S0ZMNk5td2gyNXVRWjhkT01MSUovZVIvckVkNkRtSStka3Z3WHBrT0Mwa20v?=
 =?utf-8?B?dEozamZwaVJnRlo5UnFDdzNuU1drdTdJcEkvTDdXTnd6eXBSTzN3UExEb3lK?=
 =?utf-8?B?dSt2ZUF3K1YycmhxUFg1eXN6QzdROGgwUm5nRThlMUZ3WGx2V0xMQzlHWGlB?=
 =?utf-8?B?SlBOYTBzR0pEK2lrSXdQY1J2SWlFbG9YMUhON0VpdW9rUVh2WHlPRzBTQWRo?=
 =?utf-8?B?K3RCbFd5bm81YVVtY2NBZmt3MmF6eUcxQm1LeXUzVzhEcmppQVZOMVF1MGU5?=
 =?utf-8?B?WWI1d2JXL1VtOWppNWQzY1NpekZVVU5MQWdHUFpsNjYySUJxQ1JzQXp6NVRN?=
 =?utf-8?B?RWdaQ2ZpSXcwNUs0NDRvbHViWnVmblVxTFgwdTNndVVUQlA1NmZHTVEvSVJC?=
 =?utf-8?B?czdOY2o5UFJiVlZxK1JCdDNWUG5GZEF2Q0lidEp5akpiLytubkhrWFJuVTky?=
 =?utf-8?B?SEQ3YzVUelZ1a0hheEF5L25odmx6cDBqOVdiTzdIOE5KOURSc25nMVNqdGt3?=
 =?utf-8?B?ZlZQazRYSjdVRUFLWFNqRHk0OHJDbmRpMjE5OHV5dDNOMzBDUW05dUxwQytM?=
 =?utf-8?B?YXBBUjV6NGQvTEpOT1kwZnNwUnJKR3JDMkMzeW9XR0RRazFjN1NHRWRBU2hT?=
 =?utf-8?B?OUszaU9sSTJaK3IwaUwwT0VkMTA4WmEzVGhVNk10bllWcXVOVlMvSGkzQ3Ey?=
 =?utf-8?B?MnFrWUZ2N0xHRDhPSXIxSWdzTjQvM01IdFdyYmgyc1pSUjdteklhdy9IV1lz?=
 =?utf-8?B?WlJ1b2xjcXV6cVJURHNSMHZiZ3B6amFlOWZYN2dIQXdoM3QxbC83ZzMvRVpm?=
 =?utf-8?B?RDQzS0h6eWVwZ3RJenA0cHV6NDJ2T1orOEoxN3FsQUp2TlVpbTdqdmF0ak9O?=
 =?utf-8?Q?glhx7e6DLLsJW7YSoQ1qTLfn3?=
X-OriginatorOrg: suse.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 93bfbb58-c0b2-4635-f032-08dbf0238a47
X-MS-Exchange-CrossTenant-AuthSource: AM0PR0402MB3395.eurprd04.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Nov 2023 15:06:03.9756
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: f7a17af6-1c5c-4a36-aa8b-f5be247aa4ba
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: tBVLvvAMNOsrVkvRcg8jZFL64mRIQxnrty/muBm1qG4yBaTPm9A9ni2Cw1NhsDCoMDGFJ6G8Mmg3RmtdH5J9DQ==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAXPR04MB8672
X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIM_SIGNED,DKIM_VALID,
	DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,
	SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable
	autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on pete.vger.email
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (pete.vger.email [0.0.0.0]); Tue, 28 Nov 2023 07:06:23 -0800 (PST)

On 11/27/23 18:58, Steven Rostedt wrote:
> On Mon, 27 Nov 2023 16:12:48 +0100
> Petr Pavlu <petr.pavlu@suse.com> wrote:
> 
>> Make the disable operation in __ftrace_event_enable_disable() use the
>> reverse order of the respective enable operation.
>>
>> This has two minor benefits:
>> * Disabling of buffered events via trace_buffered_event_disable() is
>>   done after unregistering the trace event. It closes a small window
>>   where an event would be still registered and could be hit, but would
>>   unnecessarily go directly to a ring buffer.
> 
> There's little benefit to the above. Going to the ring buffer and reverting
> it is just a bit more expensive, but should not be an issue with this small
> window.
> 
>> * The SOFT_DISABLED flag is now consistently set only when SOFT_MODE is
>>   also set.
> 
> This code is a bit fragile, and I rather not change the logic. There's a
> lot of corner cases.
> 
> I'm not saying that this is a bad change, I just don't want to add it and
> find out later it broke one of the corner cases. To add this would require
> an analysis that every input produces the same output with and without this
> change.
> 
> If you want to make a table showing all inputs between soft_disable and the
> flags, and show that the result produces the same updates, I'll then
> reconsidered applying this.

Ok, that is fair. It looked to me as a reasonable change but I don't
feel strongly about it and I understand your concern. I guess I'll drop
it in v2.

Thanks,
Petr