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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 EA910CA9EAE for ; Tue, 29 Oct 2019 15:51:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BF17120856 for ; Tue, 29 Oct 2019 15:51:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389836AbfJ2PvG (ORCPT ); Tue, 29 Oct 2019 11:51:06 -0400 Received: from vps-vb.mhejs.net ([37.28.154.113]:40266 "EHLO vps-vb.mhejs.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389319AbfJ2PvG (ORCPT ); Tue, 29 Oct 2019 11:51:06 -0400 Received: from MUA by vps-vb.mhejs.net with esmtps (TLSv1.2:ECDHE-RSA-AES128-GCM-SHA256:128) (Exim 4.92.3) (envelope-from ) id 1iPTlp-0005ru-SO; Tue, 29 Oct 2019 16:50:57 +0100 Subject: Re: [PATCH v3] hwrng: core: Freeze khwrng thread during suspend To: Stephen Boyd Cc: Herbert Xu , linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, Andrey Pronin , Duncan Laurie , Jason Gunthorpe , Arnd Bergmann , Greg Kroah-Hartman , Guenter Roeck , Alexander Steffen References: <20190805233241.220521-1-swboyd@chromium.org> <4a45b3e0-ed3a-61d3-bfc6-957c7ba631bb@maciej.szmigiero.name> <5db85058.1c69fb81.202d7.e3d0@mx.google.com> From: "Maciej S. Szmigiero" Autocrypt: addr=mail@maciej.szmigiero.name; prefer-encrypt=mutual; keydata= mQINBFpGusUBEADXUMM2t7y9sHhI79+2QUnDdpauIBjZDukPZArwD+sDlx5P+jxaZ13XjUQc 6oJdk+jpvKiyzlbKqlDtw/Y2Ob24tg1g/zvkHn8AVUwX+ZWWewSZ0vcwp7u/LvA+w2nJbIL1 N0/QUUdmxfkWTHhNqgkNX5hEmYqhwUPozFR0zblfD/6+XFR7VM9yT0fZPLqYLNOmGfqAXlxY m8nWmi+lxkd/PYqQQwOq6GQwxjRFEvSc09m/YPYo9hxh7a6s8hAP88YOf2PD8oBB1r5E7KGb Fv10Qss4CU/3zaiyRTExWwOJnTQdzSbtnM3S8/ZO/sL0FY/b4VLtlZzERAraxHdnPn8GgxYk oPtAqoyf52RkCabL9dsXPWYQjkwG8WEUPScHDy8Uoo6imQujshG23A99iPuXcWc/5ld9mIo/ Ee7kN50MOXwS4vCJSv0cMkVhh77CmGUv5++E/rPcbXPLTPeRVy6SHgdDhIj7elmx2Lgo0cyh uyxyBKSuzPvb61nh5EKAGL7kPqflNw7LJkInzHqKHDNu57rVuCHEx4yxcKNB4pdE2SgyPxs9 9W7Cz0q2Hd7Yu8GOXvMfQfrBiEV4q4PzidUtV6sLqVq0RMK7LEi0RiZpthwxz0IUFwRw2KS/ 9Kgs9LmOXYimodrV0pMxpVqcyTepmDSoWzyXNP2NL1+GuQtaTQARAQABtDBNYWNpZWogUy4g U3ptaWdpZXJvIDxtYWlsQG1hY2llai5zem1pZ2llcm8ubmFtZT6JAlQEEwEIAD4WIQRyeg1N 257Z9gOb7O+Ef143kM4JdwUCWka6xQIbAwUJA8JnAAULCQgHAgYVCgkICwIEFgIDAQIeAQIX gAAKCRCEf143kM4Jdx4+EACwi1bXraGxNwgFj+KI8T0Xar3fYdaOF7bb7cAHllBCPQkutjnx 8SkYxqGvSNbBhGtpL1TqAYLB1Jr+ElB8qWEV6bJrffbRmsiBPORAxMfu8FF+kVqCYZs3nbku XNzmzp6R/eii40S+XySiscmpsrVQvz7I+xIIYdC0OTUu0Vl3IHf718GBYSD+TodCazEdN96k p9uD9kWNCU1vnL7FzhqClhPYLjPCkotrWM4gBNDbRiEHv1zMXb0/jVIR/wcDIUv6SLhzDIQn Lhre8LyKwid+WQxq7ZF0H+0VnPf5q56990cEBeB4xSyI+tr47uNP2K1kmW1FPd5q6XlIlvh2 WxsG6RNphbo8lIE6sd7NWSY3wXu4/R1AGdn2mnXKMp2O9039ewY6IhoeodCKN39ZR9LNld2w Dp0MU39LukPZKkVtbMEOEi0R1LXQAY0TQO//0IlAehfbkkYv6IAuNDd/exnj59GtwRfsXaVR Nw7XR/8bCvwU4svyRqI4luSuEiXvM9rwDAXbRKmu+Pk5h+1AOV+KjKPWCkBEHaASOxuApouQ aPZw6HDJ3fdFmN+m+vNcRPzST30QxGrXlS5GgY6CJ10W9gt/IJrFGoGxGxYjj4WzO97Rg6Mq WMa7wMPPNcnX5Nc/b8HW67Jhs3trj0szq6FKhqBsACktOU4g/ksV8eEtnLkBjQRaRrtSAQwA 1c8skXiNYGgitv7X8osxlkOGiqvy1WVV6jJsv068W6irDhVETSB6lSc7Qozk9podxjlrae9b vqfaJxsWhuwQjd+QKAvklWiLqw4dll2R3+aanBcRJcdZ9iw0T63ctD26xz84Wm7HIVhGOKsS yHHWJv2CVHjfD9ppxs62XuQNNb3vP3i7LEto9zT1Zwt6TKsJy5kWSjfRr+2eoSi0LIzBFaGN D8UOP8FdpS7MEkqUQPMI17E+02+5XCLh33yXgHFVyWUxChqL2r8y57iXBYE/9XF3j4+58oTD ne/3ef+6dwZGyqyP1C34vWoh/IBq2Ld4cKWhzOUXlqKJno0V6pR0UgnIJN7SchdZy5jd0Mrq yEI5k7fcQHJxLK6wvoQv3mogZok4ddLRJdADifE4+OMyKwzjLXtmjqNtW1iLGc/JjMXQxRi0 ksC8iTXgOjY0f7G4iMkgZkBfd1zqfS+5DfcGdxgpM0m9EZ1mhERRR80U6C+ZZ5VzXga2bj0o ZSumgODJABEBAAGJA/IEGAEIACYWIQRyeg1N257Z9gOb7O+Ef143kM4JdwUCWka7UgIbAgUJ A8JnAAHACRCEf143kM4Jd8D0IAQZAQgAHRYhBOJ3aqugjib/WhtKCVKx1ulR0M4HBQJaRrtS AAoJEFKx1ulR0M4Hc7UL/j0YQlUOylLkDBLzGh/q3NRiGh0+iIG75++2xBtSnd/Y195SQ3cm V61asRcpS7uuK/vZB3grJTPlKv31DPeKHe3FxpLwlu0k9TFBkN4Pv6wH/PBeZfio1My0ocNr MRJT/rIxkBkOMy5b3uTGqxrVeEx+nSZQ12U7ccB6LR2Q4gNm1HiWC5TAIIMCzP6wUvcX8rTD bhZPFNEx0f01cL7t1cpo3ToyZ0nnBcrvYkbJEV3PCwPScag235hE3j4NXT3ocYsIDL3Yt1nW JOAQdcDJdDHZ1NhGtwHY1N51/lHP56TzLw7s2ovWQO/7VRtUWkISBJS/OfgOU29ls5dCKDtZ E2n5GkDQTkrRHjtX4S0s+f9w7fnTjqsae1bsEh6hF2943OloJ8GYophfL7xsxNjzQQLiAMBi LWNn5KRm5W5pjW/6mGRI3W1TY3yV8lcns//0KIlK0JNrAvZzS+82ExDKHLiRTfdGttefIeb3 tagU9I6VMevTpMkfPw8ZwBJo9OFkqGIZD/9gi2tFPcZvQbjuKrRqM/S21CZrI+HfyQTUw/DO OtYqCnhmw7Xcg1YRo9zsp/ffo/OQR1a3d8DryBX9ye8o7uZsd+hshlvLExXHJLvkrGGK5aFA ozlp9hqylIHoCBrWTUuKuuL8Tdxn3qahQiMCpCacULWar/wCYsQvM/SUxosonItS7fShdp7n ObAHB4JToNGS6QfmVWHakeZSmz+vAi/FHjL2+w2RcaPteIcLdGPxcJ9oDMyVv2xKsyA4Xnfp eSWa5mKD1RW1TweWqcPqWlCW5LAUPtOSnexbIQB0ZoYZE6x65BHPgXKlkSqnPstyCp619qLG JOo85L9OCnyKDeQy5+lZEs5YhXy2cmOQ5Ns6kz20IZS/VwIQWBogsBv46OyPE9oaLvngj6ZJ YXqE2pgh2O3rCk6kFPiNwmihCo/EoL73I6HUWUIFeUq9Gm57Z49H+lLrBcXf5k8HcV89CGAU sbn2vAl0pU8oHOwnA/v44D3zJ/Z2agJeYAlb4GgrPqbeIyOt3I99SbCKUZyt7BIB6Uie6GE0 9RGs1+rbnsSDPdIVl+yhV1QhdBLsRc3oOTP+us9V2IMepipsClfkA0nBJ4+dRe2GitjCU9l3 8Cyk96OvgngkkbYJQSrpXvM/BIyWTtTSfzNwhUltQLNoqfw0plDRlA0j6i/jrvrVaoy177kB jQRaRrwiAQwAxnVmJqeP9VUTISps+WbyYFYlMFfIurl7tzK74bc67KUBp+PHuDP9p4ZcJUGC 3UZJP85/GlUVdE1NairYWEJQUB7bpogTuzMI825QXIB9z842HwWfP2RW5eDtJMeujzJeFaUp meTG9snzaYxYN3r0TDKj5dZwSIThIMQpsmhH2zylkT0jH7kBPxb8IkCQ1c6wgKITwoHFjTIO 0B75U7bBNSDpXUaUDvd6T3xd1Fz57ujAvKHrZfWtaNSGwLmUYQAcFvrKDGPB5Z3ggkiTtkmW 3OCQbnIxGJJw/+HefYhB5/kCcpKUQ2RYcYgCZ0/WcES1xU5dnNe4i0a5gsOFSOYCpNCfTHtt VxKxZZTQ/rxjXwTuToXmTI4Nehn96t25DHZ0t9L9UEJ0yxH2y8Av4rtf75K2yAXFZa8dHnQg CkyjA/gs0ujGwD+Gs7dYQxP4i+rLhwBWD3mawJxLxY0vGwkG7k7npqanlsWlATHpOdqBMUiA R22hs02FikAoiXNgWTy7ABEBAAGJAjwEGAEIACYWIQRyeg1N257Z9gOb7O+Ef143kM4JdwUC Wka8IgIbDAUJA8JnAAAKCRCEf143kM4Jd9nXD/9jstJU6L1MLyr/ydKOnY48pSlZYgII9rSn FyLUHzNcW2c/qw9LPMlDcK13tiVRQgKT4W+RvsET/tZCQcap2OF3Z6vd1naTur7oJvgvVM5l VhUia2O60kEZXNlMLFwLSmGXhaAXNBySpzN2xStSLCtbK58r7Vf9QS0mR0PGU2v68Cb8fFWc Yu2Yzn3RXf0YdIVWvaQG9whxZq5MdJm5dknfTcCG+MtmbP/DnpQpjAlgVmDgMgYTBW1W9etU 36YW0pTqEYuv6cmRgSAKEDaYHhFLTR1+lLJkp5fFo3Sjm7XqmXzfSv9JGJGMKzoFOMBoLYv+ VFnMoLX5UJAs0JyFqFY2YxGyLd4J103NI/ocqQeU0TVvOZGVkENPSxIESnbxPghsEC0MWEbG svqA8FwvU7XfGhZPYzTRf7CndDnezEA69EhwpZXKs4CvxbXo5PDTv0OWzVaAWqq8s8aTMJWW AhvobFozJ63zafYHkuEjMo0Xps3o3uvKg7coooH521nNsv4ci+KeBq3mgMCRAy0g/Ef+Ql7m t900RCBHu4tktOhPc3J1ep/e2WAJ4ngUqJhilzyCJnzVJ4cT79VK/uPtlfUCZdUz+jTC88Tm P1p5wlucS31kThy/CV4cqDFB8yzEujTSiRzd7neG3sH0vcxBd69uvSxLZPLGID840k0v5sft PA== Message-ID: Date: Tue, 29 Oct 2019 16:50:52 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <5db85058.1c69fb81.202d7.e3d0@mx.google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On 29.10.2019 15:44, Stephen Boyd wrote: > Quoting Maciej S. Szmigiero (2019-10-28 16:45:31) >> Hi Stephen, >> >> On 06.08.2019 01:32, Stephen Boyd wrote: >>> The hwrng_fill() function can run while devices are suspending and >>> resuming. If the hwrng is behind a bus such as i2c or SPI and that bus >>> is suspended, the hwrng may hang the bus while attempting to add some >>> randomness. It's been observed on ChromeOS devices with suspend-to-idle >>> (s2idle) and an i2c based hwrng that this kthread may run and ask the >>> hwrng device for randomness before the i2c bus has been resumed. >>> >>> Let's make this kthread freezable so that we don't try to touch the >>> hwrng during suspend/resume. This ensures that we can't cause the hwrng >>> backing driver to get into a bad state because the device is guaranteed >>> to be resumed before the hwrng kthread is thawed. >> >> This patch broke suspend with virtio-rng loaded (it hangs). >> >> The problematic call chain is: >> virtrng_freeze() -> remove_common() -> hwrng_unregister() -> >> kthread_stop(). >> >> It looks like kthread_stop() can't finish on a frozen khwrng thread. > > Can you provide the suspend/resume logs? There isn't much in the kernel log, the closest thing I can get is with dyndbg="file drivers/base/power/main.c +p": [ 58.441073][ T3511] virtio-pci 0000:00:06.0: bus freeze [ 58.448744][ T3511] virtio-pci 0000:00:05.0: bus freeze [ 58.454500][ T3511] virtio-pci 0000:00:04.0: bus freeze [ 58.456873][ T3511] virtio-pci 0000:00:03.0: bus freeze And then the VM hangs. The 0000:00:03.0 pci device is virtio-rng. If I add printks around that kthread_stop() in hwrng_unregister() only the first one gets printed. >> >> Reverting this commit makes a VM with virtio-rng driver loaded >> suspend and resume correctly again. > > Which kernel are you testing on? There was a fix to this commit, i.e. > ff296293b353 ("random: Support freezable kthreads in > add_hwgenerator_randomness()"), which was fixed again by 59b569480dc8 > ("random: Use wait_event_freezable() in add_hwgenerator_randomness()"). > There was a problem with suspend/resume that I tried to fix with the > first patch and then the second patch fixed the first one. See this > thread[1] for some more background. You'll want all three. > > [1] https://lkml.kernel.org/r/49fc7c64-88c0-74d0-2cb3-07986490941d@ti.com The kernel under test is current torvalds/master, I can see that it contains both commit ff296293b353 and commit 59b569480dc8. I assume that the third commit you mention is the original one that this e-mail message Subject line refers to (03a3bb7ae63150). Thanks, Maciej