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Sun, 23 Feb 2020 10:04:46 -0800 (PST) To: Jens Axboe , io-uring@vger.kernel.org Cc: glauber@scylladb.com, peterz@infradead.org, Jann Horn References: <20200220203151.18709-1-axboe@kernel.dk> <20200220203151.18709-8-axboe@kernel.dk> <862fb96f-cebe-dfd8-0042-3284985d8704@gmail.com> <3c9a3fca-a780-6d04-65cb-c08ef382a2eb@kernel.dk> <2d869361-18d0-a0fa-cc53-970078d8b826@kernel.dk> <08564f4e-8dd1-d656-a22a-325cc1c3e38f@kernel.dk> <231dc76e-697f-d8dd-46cb-53776bdc920d@kernel.dk> <18d38bb6-70e2-24ce-a668-d279b8e3ce4c@kernel.dk> <3d4aa255-f333-573c-e806-a3e79a28f3c6@kernel.dk> <48e81bbf-89c7-f84d-cefc-86d26baeae07@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== Subject: Re: [PATCH 7/9] io_uring: add per-task callback handler Message-ID: <3e51d59a-f856-0491-1e51-faed95b3af20@gmail.com> Date: Sun, 23 Feb 2020 21:04:02 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <48e81bbf-89c7-f84d-cefc-86d26baeae07@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 23/02/2020 18:07, Jens Axboe wrote: > On 2/23/20 7:58 AM, Jens Axboe wrote: >> On 2/23/20 7:49 AM, Jens Axboe wrote: >>>> Anyway, creds handling is too scattered across the code, and this do a >>>> lot of useless refcounting and bouncing. It's better to find it a >>>> better place in the near future. >>> >>> I think a good cleanup on top of this would be to move the personality >>> lookup to io_req_defer_prep(), and kill it from io_submit_sqe(). Now >>> __io_issue_sqe() does the right thing, and it'll just fall out nicely >>> with that as far as I can tell. >>> >>> Care to send a patch for that? >> >> Since we also need it for non-deferral, how about just leaving the >> lookup in there and removing the assignment? That means we only do that >> juggling in one spot, which makes more sense. I think this should just >> be folded into the previous patch. > > Tested, we need a ref grab on the creds when assigning since we're > dropped at the other end. Nice, this looks much better. > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index cead1a0602b4..d83f113f22fd 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -4923,7 +4923,6 @@ static inline void io_queue_link_head(struct io_kiocb *req) > static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, > struct io_submit_state *state, struct io_kiocb **link) > { > - const struct cred *old_creds = NULL; > struct io_ring_ctx *ctx = req->ctx; > unsigned int sqe_flags; > int ret, id; > @@ -4938,14 +4937,12 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, > > id = READ_ONCE(sqe->personality); > if (id) { > - const struct cred *personality_creds; > - > - personality_creds = idr_find(&ctx->personality_idr, id); > - if (unlikely(!personality_creds)) { > + req->work.creds = idr_find(&ctx->personality_idr, id); > + if (unlikely(!req->work.creds)) { > ret = -EINVAL; > goto err_req; > } > - old_creds = override_creds(personality_creds); > + get_cred(req->work.creds); > } > > /* same numerical values with corresponding REQ_F_*, safe to copy */ > @@ -4957,8 +4954,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, > err_req: > io_cqring_add_event(req, ret); > io_double_put_req(req); > - if (old_creds) > - revert_creds(old_creds); > return false; > } > > @@ -5019,8 +5014,6 @@ static bool io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe, > } > } > > - if (old_creds) > - revert_creds(old_creds); > return true; > } > > -- Pavel Begunkov