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Fri, 28 Feb 2020 16:44:16 -0800 (PST) To: Jens Axboe , io-uring@vger.kernel.org Cc: andres@anarazel.de References: <20200228203053.25023-1-axboe@kernel.dk> <20200228203053.25023-3-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== Subject: Re: [PATCH 2/6] io_uring: add IORING_OP_PROVIDE_BUFFERS Message-ID: <7671b196-99cc-d0a9-3b7e-86769c304b10@gmail.com> Date: Sat, 29 Feb 2020 03:43:28 +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: <20200228203053.25023-3-axboe@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LEOHR2eu8yoA0oFNpuKHVaTpwoS9asdc5" 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) --LEOHR2eu8yoA0oFNpuKHVaTpwoS9asdc5 Content-Type: multipart/mixed; boundary="356vW6CkIAHNBM5vE8YoUz3l5pTd18Tda"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Cc: andres@anarazel.de Message-ID: <7671b196-99cc-d0a9-3b7e-86769c304b10@gmail.com> Subject: Re: [PATCH 2/6] io_uring: add IORING_OP_PROVIDE_BUFFERS References: <20200228203053.25023-1-axboe@kernel.dk> <20200228203053.25023-3-axboe@kernel.dk> In-Reply-To: <20200228203053.25023-3-axboe@kernel.dk> --356vW6CkIAHNBM5vE8YoUz3l5pTd18Tda Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 28/02/2020 23:30, Jens Axboe wrote: > IORING_OP_PROVIDE_BUFFERS uses the buffer registration infrastructure t= o > support passing in an addr/len that is associated with a buffer ID and > buffer group ID. The group ID is used to index and lookup the buffers, > while the buffer ID can be used to notify the application which buffer > in the group was used. The addr passed in is the starting buffer addres= s, > and length is each buffer length. A number of buffers to add with can b= e > specified, in which case addr is incremented by length for each additio= n, > and each buffer increments the buffer ID specified. >=20 > No validation is done of the buffer ID. If the application provides > buffers within the same group with identical buffer IDs, then it'll hav= e > a hard time telling which buffer ID was used. The only restriction is > that the buffer ID can be a max of 16-bits in size, so USHRT_MAX is the= > maximum ID that can be used. >=20 > Signed-off-by: Jens Axboe > + > +static int io_add_buffers(struct io_provide_buf *pbuf, struct list_hea= d *list) > +{ > + struct io_buffer *buf; > + u64 addr =3D pbuf->addr; > + int i, bid =3D pbuf->bid; > + > + for (i =3D 0; i < pbuf->nbufs; i++) { > + buf =3D kmalloc(sizeof(*buf), GFP_KERNEL); > + if (!buf) > + break; > + > + buf->addr =3D addr; > + buf->len =3D pbuf->len; > + buf->bid =3D bid; > + list_add(&buf->list, list); > + addr +=3D pbuf->len; So, it chops a linear buffer into pbuf->nbufs chunks of size pbuf->len. Did you consider iovec? I'll try to think about it after getting some sle= ep > + bid++; > + } > + > + return i; > +} > + > +static int io_provide_buffers(struct io_kiocb *req, struct io_kiocb **= nxt, > + bool force_nonblock) > +{ > + struct io_provide_buf *p =3D &req->pbuf; > + struct io_ring_ctx *ctx =3D req->ctx; > + struct list_head *list; > + int ret =3D 0; > + > + /* > + * "Normal" inline submissions always hold the uring_lock, since we > + * grab it from the system call. Same is true for the SQPOLL offload.= > + * The only exception is when we've detached the request and issue it= > + * from an async worker thread, grab the lock for that case. > + */ > + if (!force_nonblock) > + mutex_lock(&ctx->uring_lock); io_poll_task_handler() calls it with force_nonblock=3D=3Dtrue, but it doe= sn't hold the mutex AFAIK. > + > + lockdep_assert_held(&ctx->uring_lock); > + > + list =3D idr_find(&ctx->io_buffer_idr, p->gid); > + if (!list) { > + list =3D kmalloc(sizeof(*list), GFP_KERNEL); > + if (!list) { > + ret =3D -ENOMEM; > + goto out; > + } > + INIT_LIST_HEAD(list); > + ret =3D idr_alloc(&ctx->io_buffer_idr, list, p->gid, p->gid + 1, > + GFP_KERNEL); > + if (ret < 0) { > + kfree(list); > + goto out; > + } > + } > + > + ret =3D io_add_buffers(p, list); Isn't it better to not do partial registration? i.e. it may return ret < pbuf->nbufs > + if (!ret) { > + /* no buffers added and list empty, remove entry */ > + if (list_empty(list)) { > + idr_remove(&ctx->io_buffer_idr, p->gid); > + kfree(list); > + } > + ret =3D -ENOMEM; > + } > +out: > + if (!force_nonblock) > + mutex_unlock(&ctx->uring_lock); > + if (ret < 0) > + req_set_fail_links(req); > + io_cqring_add_event(req, ret); > + io_put_req_find_next(req, nxt); > + return 0; > +} > + --=20 Pavel Begunkov --356vW6CkIAHNBM5vE8YoUz3l5pTd18Tda-- --LEOHR2eu8yoA0oFNpuKHVaTpwoS9asdc5 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl5Zs7QACgkQWt5b1Glr +6UCvBAAiH0euzxJUzW6M8vjZR0Mo0tduhsFdx3lk1NaWDpj4lZvJ19Odjw/nZ64 z4/WkEIijCeOCvdK3AIH7hC1/o7ZF+fnFHpAAbmyjE32ayAuEvtbVLj+8oUwhQNY CSiNva8fJUp9YY4luOJ8zwOQ2VY34BrYZxhZJVmzDkYtyOno68fXk4t/IxBMTkM6 4ZNk9iryhSGSLC2BvrcPfGMK0AO3ANAM7DxXvfOJ1+eLHaWyQdW3+lz1nUjN8Q6b ZCc9v/7+c8qNhq3fVSsizEpeETwK6hSgIsiCg8SACKKxyvBAVuaf0cEsxQXr27PE hqgwxwzoD2KwbDjxFWVtHBMDGq59JUtffTzavXLqQT7wZNepneYjgZIx/KxovBim eZF6xquGBWkr/b19XRX4gEdFdlbnBdmdQ6hA5ZqhSNsOycMVWKiKoG59ldFCrBHV wEPc5XJVc0LM+jUCnz8Hp8/G3C9waThl8gLdKK/jwZovuD33QwaSvYmSZ8E2FIf8 RJ4XoSvC3aA1VxcEHwXNC96QWaFwBesk80Wv5xjBo7OEVQf/5kGglcqZSSH1dTlb V5mOoOq1t9M0f96tUg9j/q+/bRugahpmrlDcCrvmuZFWNl2BMPNp82kF3+FdqHrq 793r1iJCBcq2NByPj5CTplqWBiv1HBb865rB8iVnxzL6mhBayaw= =ywtm -----END PGP SIGNATURE----- --LEOHR2eu8yoA0oFNpuKHVaTpwoS9asdc5--