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Tue, 19 Nov 2019 12:51:55 -0800 (PST) Subject: Re: [PATCH 7/8] io_uring: fix sequencing issues with linked timeouts To: Jens Axboe , io-uring@vger.kernel.org References: <20191116015314.24276-1-axboe@kernel.dk> <20191116015314.24276-8-axboe@kernel.dk> 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== Message-ID: Date: Tue, 19 Nov 2019 23:51:35 +0300 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: <20191116015314.24276-8-axboe@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="j5BCWOu37USg5bmp0hS8QSlMwUTWgEjjN" Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --j5BCWOu37USg5bmp0hS8QSlMwUTWgEjjN Content-Type: multipart/mixed; boundary="ygcMyst8zW4r6TVbws0FtkBA37Eox8xCp"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Message-ID: Subject: Re: [PATCH 7/8] io_uring: fix sequencing issues with linked timeouts References: <20191116015314.24276-1-axboe@kernel.dk> <20191116015314.24276-8-axboe@kernel.dk> In-Reply-To: <20191116015314.24276-8-axboe@kernel.dk> --ygcMyst8zW4r6TVbws0FtkBA37Eox8xCp Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 16/11/2019 04:53, Jens Axboe wrote: > We have an issue with timeout links that are deeper in the submit chain= , > because we only handle it upfront, not from later submissions. Move the= > prep + issue of the timeout link to the async work prep handler, and do= > it normally for non-async queue. If we validate and prepare the timeout= > links upfront when we first see them, there's nothing stopping us from > supporting any sort of nesting. >=20 > Fixes: 2665abfd757f ("io_uring: add support for linked SQE timeouts") > Reported-by: Pavel Begunkov > Signed-off-by: Jens Axboe > --- > @@ -923,6 +942,7 @@ static void io_fail_links(struct io_kiocb *req) > io_cqring_fill_event(link, -ECANCELED); > __io_double_put_req(link); > } > + kfree(sqe_to_free); > } > =20 > io_commit_cqring(ctx); > @@ -2668,8 +2688,12 @@ static void io_wq_submit_work(struct io_wq_work = **workptr) > =20 > /* if a dependent link is ready, pass it back */ > if (!ret && nxt) { > - io_prep_async_work(nxt); > + struct io_kiocb *link; > + > + io_prep_async_work(nxt, &link); > *workptr =3D &nxt->work; Are we safe here without synchronisation? Probably io_link_timeout_fn() may miss the new value (doing io-wq cancel). > + if (link) > + io_queue_linked_timeout(link); > } > } > =20 --=20 Pavel Begunkov --ygcMyst8zW4r6TVbws0FtkBA37Eox8xCp-- --j5BCWOu37USg5bmp0hS8QSlMwUTWgEjjN Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl3UVdsACgkQWt5b1Glr +6UMYRAAplVrHGTJ4MqDqvC3Iz9mEZEe4LuwUI4gCOuFGFk5mRDUlG4NglPjlp36 NzU1F88jmbOWJZiBBWVW4Cu4M73/pCPj5n8gmQACnNJtJ4eJrcGuva0RFCFma39I RuCt3CanIHk6F8niiwshP+dpArrYocTS71bX9MTZ7zbmQOLYNycyK1OyQ3odoZxu 7noEh/8/67E37xxOWLWWQpBuT8qGo3l3tsZG6xmYmcQ5xnRlf8Xc/ZeKZWSuuvme 75nhDQXyBJ0JdiHp5WIfbM7xHyiDrZBaVlm/kcKnjAEcjWIkgdJwHxI+W0HxYZ38 QrKbX9aTsMs6NIVGs8a4NC5yZ+QYCPIOPWHgHWh1jLi4xyvEUoNV+1LoNkT9Dlvz 6Q6YaFCo1hmgcWF8xtozPbdSWBu06Xboy+pbzNnaiK1B7gjvhsj3/LlN5VCQmkHY dPmOUWuHY2+0n8Rqqwed0QXsWFnmp/i021mG4HcvTIjK0ke78FkjQ1B543y7RWUr dJd0UlAyMMai7XC864zoY4kCsuBmmWclx5g1dMjqmjyPTfrQNrICbfKxGn80epf/ jbF1gTR9fpQA0xLP5Taw8FY+LRjU245qStdqLLG7FTElgyTMqQoSoqFFmtbaounh OG5tHChpuE9fWtWrT2vqSjfj30LLvc1vYhyeu0Z8paOW8U48jNM= =V2dm -----END PGP SIGNATURE----- --j5BCWOu37USg5bmp0hS8QSlMwUTWgEjjN--