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Mon, 30 Sep 2019 01:29:22 -0700 (PDT) Received: from [192.168.43.187] ([109.126.142.9]) by smtp.gmail.com with ESMTPSA id a7sm25567078wra.43.2019.09.30.01.29.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 30 Sep 2019 01:29:21 -0700 (PDT) To: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, josef@toxicpanda.com, Tejun Heo , cgroups@vger.kernel.org References: From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [RESEND RFC PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency Message-ID: <276a02f3-3b1a-0580-54fb-497f85103ae3@gmail.com> Date: Mon, 30 Sep 2019 11:29:21 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="vpDpuljOak4VUjubg0p6HLJIDCCP6aiBm" Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --vpDpuljOak4VUjubg0p6HLJIDCCP6aiBm Content-Type: multipart/mixed; boundary="iwCQfC1143W97Fjrsn5ILXvfBDPud4pYO"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, josef@toxicpanda.com, Tejun Heo , cgroups@vger.kernel.org Message-ID: <276a02f3-3b1a-0580-54fb-497f85103ae3@gmail.com> Subject: Re: [RESEND RFC PATCH 0/2] Fix misuse of blk_rq_stats in blk-iolatency References: In-Reply-To: --iwCQfC1143W97Fjrsn5ILXvfBDPud4pYO Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi, I claim, that there is a bug, that hopefully doesn't show itself apart from a minor disabled optimisation. It's _too_ easy to misuse, and if somebody try to reuse, this could lead to quite interesting issues. Could somebody at last take a look? Thanks On 25/07/2019 00:35, Pavel Begunkov (Silence) wrote: > From: Pavel Begunkov >=20 > There are implicit assumptions about struct blk_rq_stats, which make > it's very easy to misuse. The first patch fixes consequences, and the > second employs type-system to prevent recurrences. >=20 > Acked-by: Josef Bacik >=20 > Pavel Begunkov (2): > blk-iolatency: Fix zero mean in previous stats > blk-stats: Introduce explicit stat staging buffers >=20 > block/blk-iolatency.c | 60 ++++++++++++++++++++++++++++++---------= > block/blk-stat.c | 48 +++++++++++++++++++++++-------- > block/blk-stat.h | 9 ++++-- > include/linux/blk_types.h | 6 ++++ > 4 files changed, 94 insertions(+), 29 deletions(-) >=20 --=20 Yours sincerely, Pavel Begunkov --iwCQfC1143W97Fjrsn5ILXvfBDPud4pYO-- --vpDpuljOak4VUjubg0p6HLJIDCCP6aiBm Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl2RvOEACgkQWt5b1Glr +6UKiBAAgW2BL4yvqLYVizbAQnkdFQG/KreGrf5vyKZhcv2UHjoMvO2EUQzpwX2v FMaHbFAx5tOnjeoWmwXjYuAJLAnu3qT1+tGtVUFxWcDbyTnrnqAEMB9dItDr2Ga5 K6smdf9rZhnFufPiJfJ0dFqBlfqJ1YhY3L5PG8as5/9Um9B/JCCb0Hjft5yoG2Gs lsVh+RFzw8hHSptJOru/Fz6oKVDiMloqRSCWhiS7hXquMUhcPusAJLzGPhQ8Kv7o W8bZOcs99Ijp8Ye5xlgLtohBtpN1C/+ZFMHVxv4UH+JrPvwFzLDCD/mCfGLWTbUK N8ypzi5AW4KmlBAbzUs8HjQk7FvswcazyWRRm9bg4JWEE1TLgUMrrWmUsHxLlnDO knNWMjD9+PO7BrYtQm6OUX4+0Jz9wUtYBGSZF7IXLCutJ9/NloHRTFIQWXnp2NX8 WWhB1x590ljZ1REULO1312qztHOQyEOgI9vGV1jlMMQPp5RzRAHeJyC2Ay0JSt43 RZBkbjkG5tcSZ/atpzi/LhXW4PIN3IBvto9F1WYpf465ISjFhmHfEk7K+Tcfa+S1 QfHO3/t2dmFEH/2vm2/foff0av4HedV3gtulofAjpH7c4SVFWJGRjGDewrsap/C2 zMKGPSyJnh8D+boNOMkiLV8qI0juyFQD7MTybazl6u8vHqVssVQ= =CxFQ -----END PGP SIGNATURE----- --vpDpuljOak4VUjubg0p6HLJIDCCP6aiBm--