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[23.128.96.18]) by mx.google.com with ESMTP id b1si4012412edq.592.2020.05.28.07.47.24; Thu, 28 May 2020 07:47:48 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; dkim=pass header.i=@web.de header.s=dbaedf251592 header.b=pVhJ0Qiy; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391132AbgE1OpY (ORCPT + 99 others); Thu, 28 May 2020 10:45:24 -0400 Received: from mout.web.de ([212.227.17.12]:60099 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725922AbgE1OpS (ORCPT ); Thu, 28 May 2020 10:45:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1590677106; bh=Ji+TnI2/l/tfPAhTFGuY2bDQt0RWf1M1u3vwa2F6Hss=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=pVhJ0QiyzrelEonbutiGe/B4RvYYC5lOTafZl0dgU/mK9PBqWKiW5PEcjs4iaEVWs iLnVdOoAjgZEAF2ku8Tc8JMdRVuQBqd90X4J/6vOLy3/lL4jtYmCSuPLYLsThxFJ0R zq/hyJuZgRFc5kkajyywUtbSeuGFPDrujsocoMlk= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [192.168.1.3] ([2.244.30.242]) by smtp.web.de (mrweb105 [213.165.67.124]) with ESMTPSA (Nemesis) id 1MBB3s-1jjHqu0IWc-00CkOR; Thu, 28 May 2020 16:45:06 +0200 Subject: Re: [v5] workqueue: Remove unnecessary kfree() call in rcu_free_wq() To: Tejun Heo , Lai Jiangshan Cc: Dan Carpenter , Zhang Qiang , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org References: <20200527075715.36849-1-qiang.zhang@windriver.com> <284c7851-4e89-a00f-a2e6-aa8e2e1f3fce@web.de> <20200528095703.GH30374@kadam> <20200528122545.GP22511@kadam> <20200528140357.GL83516@mtj.thefacebook.com> From: Markus Elfring Autocrypt: addr=Markus.Elfring@web.de; prefer-encrypt=mutual; keydata= mQINBFg2+xABEADBJW2hoUoFXVFWTeKbqqif8VjszdMkriilx90WB5c0ddWQX14h6w5bT/A8 +v43YoGpDNyhgA0w9CEhuwfZrE91GocMtjLO67TAc2i2nxMc/FJRDI0OemO4VJ9RwID6ltwt mpVJgXGKkNJ1ey+QOXouzlErVvE2fRh+KXXN1Q7fSmTJlAW9XJYHS3BDHb0uRpymRSX3O+E2 lA87C7R8qAigPDZi6Z7UmwIA83ZMKXQ5stA0lhPyYgQcM7fh7V4ZYhnR0I5/qkUoxKpqaYLp YHBczVP+Zx/zHOM0KQphOMbU7X3c1pmMruoe6ti9uZzqZSLsF+NKXFEPBS665tQr66HJvZvY GMDlntZFAZ6xQvCC1r3MGoxEC1tuEa24vPCC9RZ9wk2sY5Csbva0WwYv3WKRZZBv8eIhGMxs rcpeGShRFyZ/0BYO53wZAPV1pEhGLLxd8eLN/nEWjJE0ejakPC1H/mt5F+yQBJAzz9JzbToU 5jKLu0SugNI18MspJut8AiA1M44CIWrNHXvWsQ+nnBKHDHHYZu7MoXlOmB32ndsfPthR3GSv jN7YD4Ad724H8fhRijmC1+RpuSce7w2JLj5cYj4MlccmNb8YUxsE8brY2WkXQYS8Ivse39MX BE66MQN0r5DQ6oqgoJ4gHIVBUv/ZwgcmUNS5gQkNCFA0dWXznQARAQABtCZNYXJrdXMgRWxm cmluZyA8TWFya3VzLkVsZnJpbmdAd2ViLmRlPokCVAQTAQgAPhYhBHDP0hzibeXjwQ/ITuU9 Figxg9azBQJYNvsQAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEOU9Figx g9azcyMP/iVihZkZ4VyH3/wlV3nRiXvSreqg+pGPI3c8J6DjP9zvz7QHN35zWM++1yNek7Ar OVXwuKBo18ASlYzZPTFJZwQQdkZSV+atwIzG3US50ZZ4p7VyUuDuQQVVqFlaf6qZOkwHSnk+ CeGxlDz1POSHY17VbJG2CzPuqMfgBtqIU1dODFLpFq4oIAwEOG6fxRa59qbsTLXxyw+PzRaR LIjVOit28raM83Efk07JKow8URb4u1n7k9RGAcnsM5/WMLRbDYjWTx0lJ2WO9zYwPgRykhn2 sOyJVXk9xVESGTwEPbTtfHM+4x0n0gC6GzfTMvwvZ9G6xoM0S4/+lgbaaa9t5tT/PrsvJiob kfqDrPbmSwr2G5mHnSM9M7B+w8odjmQFOwAjfcxoVIHxC4Cl/GAAKsX3KNKTspCHR0Yag78w i8duH/eEd4tB8twcqCi3aCgWoIrhjNS0myusmuA89kAWFFW5z26qNCOefovCx8drdMXQfMYv g5lRk821ZCNBosfRUvcMXoY6lTwHLIDrEfkJQtjxfdTlWQdwr0mM5ye7vd83AManSQwutgpI q+wE8CNY2VN9xAlE7OhcmWXlnAw3MJLW863SXdGlnkA3N+U4BoKQSIToGuXARQ14IMNvfeKX NphLPpUUnUNdfxAHu/S3tPTc/E/oePbHo794dnEm57LuuQINBFg2+xABEADZg/T+4o5qj4cw nd0G5pFy7ACxk28mSrLuva9tyzqPgRZ2bdPiwNXJUvBg1es2u81urekeUvGvnERB/TKekp25 4wU3I2lEhIXj5NVdLc6eU5czZQs4YEZbu1U5iqhhZmKhlLrhLlZv2whLOXRlLwi4jAzXIZAu 76mT813jbczl2dwxFxcT8XRzk9+dwzNTdOg75683uinMgskiiul+dzd6sumdOhRZR7YBT+xC wzfykOgBKnzfFscMwKR0iuHNB+VdEnZw80XGZi4N1ku81DHxmo2HG3icg7CwO1ih2jx8ik0r riIyMhJrTXgR1hF6kQnX7p2mXe6K0s8tQFK0ZZmYpZuGYYsV05OvU8yqrRVL/GYvy4Xgplm3 DuMuC7/A9/BfmxZVEPAS1gW6QQ8vSO4zf60zREKoSNYeiv+tURM2KOEj8tCMZN3k3sNASfoG fMvTvOjT0yzMbJsI1jwLwy5uA2JVdSLoWzBD8awZ2X/eCU9YDZeGuWmxzIHvkuMj8FfX8cK/ 2m437UA877eqmcgiEy/3B7XeHUipOL83gjfq4ETzVmxVswkVvZvR6j2blQVr+MhCZPq83Ota xNB7QptPxJuNRZ49gtT6uQkyGI+2daXqkj/Mot5tKxNKtM1Vbr/3b+AEMA7qLz7QjhgGJcie qp4b0gELjY1Oe9dBAXMiDwARAQABiQI8BBgBCAAmFiEEcM/SHOJt5ePBD8hO5T0WKDGD1rMF Alg2+xACGwwFCQlmAYAACgkQ5T0WKDGD1rOYSw/+P6fYSZjTJDAl9XNfXRjRRyJSfaw6N1pA Ahuu0MIa3djFRuFCrAHUaaFZf5V2iW5xhGnrhDwE1Ksf7tlstSne/G0a+Ef7vhUyeTn6U/0m +/BrsCsBUXhqeNuraGUtaleatQijXfuemUwgB+mE3B0SobE601XLo6MYIhPh8MG32MKO5kOY hB5jzyor7WoN3ETVNQoGgMzPVWIRElwpcXr+yGoTLAOpG7nkAUBBj9n9TPpSdt/npfok9ZfL /Q+ranrxb2Cy4tvOPxeVfR58XveX85ICrW9VHPVq9sJf/a24bMm6+qEg1V/G7u/AM3fM8U2m tdrTqOrfxklZ7beppGKzC1/WLrcr072vrdiN0icyOHQlfWmaPv0pUnW3AwtiMYngT96BevfA qlwaymjPTvH+cTXScnbydfOQW8220JQwykUe+sHRZfAF5TS2YCkQvsyf7vIpSqo/ttDk4+xc Z/wsLiWTgKlih2QYULvW61XU+mWsK8+ZlYUrRMpkauN4CJ5yTpvp+Orcz5KixHQmc5tbkLWf x0n1QFc1xxJhbzN+r9djSGGN/5IBDfUqSANC8cWzHpWaHmSuU3JSAMB/N+yQjIad2ztTckZY pwT6oxng29LzZspTYUEzMz3wK2jQHw+U66qBFk8whA7B2uAU1QdGyPgahLYSOa4XAEGb6wbI FEE= Message-ID: Date: Thu, 28 May 2020 16:45:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200528140357.GL83516@mtj.thefacebook.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB X-Provags-ID: V03:K1:SEPL94SsTVWqsHP+v75Rc9Xv5QXiVgVLCbgV//JUdIwaxlNCPaM FryG8tBcnSJ2nKvUJ0Q298R4uiDRj2GpN2JuYJK5fnJmCT0SJRjRDrZ5PoId/Vb5VR/p/ul SBeMHiMgviud4J7GPdlwtFFu7fhy1grsOET32MjdqYbiRYVyYOAsZwMKnyes/51T1ZH8NTz Sh80XKB2o1z2opRKBYfXQ== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:axBDLpeRwhk=:DTDhoN+CvquUprReTOYZO3 691D2ldjxpZfqaUfktWxUpIgu5qeeIb6btsUf/12bQIUCvHumYVQ0LrzAoSQuJ2hQlODdWzdT XWryfgpiE7KqhFd88knIQgnaAoDE6bM3PYsUEKgM5PmhLhy1tuVKqYXfZ2+KyV/2cKljkQ5FG +xqpePzcb9nAU+JE44wEnmM1qLgGy2XozW+b+a1NMNNKB/F1G8bE8Vg0aKkh7oxkeMAMRVlc8 WxK3j6ciXy+qrARWQc655TBk+ZWf6kjItA0sJ83rbKt93WHX9tR35uaU1WXH0ApI7WoEyEB2E /2pnB2v+iATuwUUl2YVL16jmuumqkD4PRXrJQm33KmESV0ezRRXh4mbqhBLya3EjKnD8HZH8K ucqoR6LZUe4ABWregE/zD1Q8Z3IiStptujhXcLYi9Tffb2wTmf0e5iU02ETttV8IrOyHVyAbg +tktd9f2XHgnl2Hs+1IULUprxTxg/dli/BM3ChBxcBbUYt1Ysdol8hEmjMhqqetJxWVFhiSdJ F37FXatP3gKnlaBLAQbptt2ataiM/XpopwLkUWUfAJgFiNTjeLVZCO6dXF+u3sxfwaKmPV04q evHDlWhZpALSXBu54NeZEdX0EIJc/a/Iv28VSQHILxz383LZGP5q+IKFGLzqAviTWHsVNeAMG C9NJJD7HO2f0tVbkqWS25tNPrAewj5KVt0OAVtyi0mG5w/kcFYZLMeS1nlZQi9cd4FELOrE9c HGZ+pNrIKNmsJn9g4dJ5SgUzJ+OM3BJpu4DYZuQHIExRADheeVuMK3NiErumYx0le+1y7GuGD ADkx01AtNoogdWfd8Rh+PKaCWfDbCzITr0jde+Yihm8e6nJtlW2KkkkFcjeA3Nkyb9rDeClAx jkUAvXO0h90buw9ovIUEd7i4mXokefHAaF8fh3ctit2SUlgrNfcJN/Zo8d9bBHoz+TNpEiX9p tlVRZ6dOIyq+1XcVPuEX3NbS+qZ7VyN52rLrkilUhQkXnbAU+ioCw6+LYjayCD8RlPmW3ViT8 OWrREZT1MwAorvgRMo2HtYtzQmeZT730nDe3ES0JSsKF7zEnljWtF496l7yJtpwEczByUl5Un YytbiZpE2tH0gSZItJ4zBBpDgrGA0U7RHHSBIt9AK5VZEAlHO+1RQuuur++9qlcXzhqPf2yjY 4bIdnkG9Qkk8qbovC8wCdi1Ooe7cGs6EdGHU1mxRuJRtJZtxkk8FwIQaIt3h9yfZTLudGwMe0 I6NwrcgRUHKa6xr+U Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Yeah, regardless of who puts a wq the last time, the base reference is put > by destroy_workqueue() and thus it's guaranteed that a wq can't be rcu freed > without going through destroy_workqueue(). lol I'm undoing the revert. * Would you like to add such background information to the change description? * How do you think about integrate a following patch version after the extra clarification? Regards, Markus