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Tue, 17 Dec 2019 09:52:41 -0800 (PST) To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <17f7900c-385f-0dfa-11bf-af99d080f894@gmail.com> <76917820-052d-9597-133d-424fee3edade@kernel.dk> <5d4af2f6-26a2-b241-5131-3a0155cbbf22@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 3/3] io_uring: move *queue_link_head() from common path Message-ID: <3b5100a7-2922-a9f2-e4e2-76252318959d@gmail.com> Date: Tue, 17 Dec 2019 20:52:19 +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: <5d4af2f6-26a2-b241-5131-3a0155cbbf22@kernel.dk> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="T7Yvq6wRcCnY2AOcE3cmUZMbLwgNolNvd" 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) --T7Yvq6wRcCnY2AOcE3cmUZMbLwgNolNvd Content-Type: multipart/mixed; boundary="mXySBXItv7iyFXgIaS2oIyByOXi04M0Qs"; protected-headers="v1" From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <3b5100a7-2922-a9f2-e4e2-76252318959d@gmail.com> Subject: Re: [PATCH 3/3] io_uring: move *queue_link_head() from common path References: <17f7900c-385f-0dfa-11bf-af99d080f894@gmail.com> <76917820-052d-9597-133d-424fee3edade@kernel.dk> <5d4af2f6-26a2-b241-5131-3a0155cbbf22@kernel.dk> In-Reply-To: <5d4af2f6-26a2-b241-5131-3a0155cbbf22@kernel.dk> --mXySBXItv7iyFXgIaS2oIyByOXi04M0Qs Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 17/12/2019 20:37, Jens Axboe wrote: > On 12/17/19 9:45 AM, Jens Axboe wrote: >> On 12/16/19 4:38 PM, Pavel Begunkov wrote: >>> On 17/12/2019 02:22, Pavel Begunkov wrote: >>>> Move io_queue_link_head() to links handling code in io_submit_sqe(),= >>>> so it wouldn't need extra checks and would have better data locality= =2E >>>> >>>> Signed-off-by: Pavel Begunkov >>>> --- >>>> fs/io_uring.c | 32 ++++++++++++++------------------ >>>> 1 file changed, 14 insertions(+), 18 deletions(-) >>>> >>>> diff --git a/fs/io_uring.c b/fs/io_uring.c >>>> index bac9e711e38d..a880ed1409cb 100644 >>>> --- a/fs/io_uring.c >>>> +++ b/fs/io_uring.c >>>> @@ -3373,13 +3373,15 @@ static bool io_submit_sqe(struct io_kiocb *r= eq, struct io_submit_state *state, >>>> struct io_kiocb **link) >>>> { >>>> struct io_ring_ctx *ctx =3D req->ctx; >>>> + unsigned int sqe_flags; >>>> int ret; >>>> =20 >>>> + sqe_flags =3D READ_ONCE(req->sqe->flags); >>>> req->user_data =3D READ_ONCE(req->sqe->user_data); >>>> trace_io_uring_submit_sqe(ctx, req->user_data, true, req->in_async= ); >>>> =20 >>>> /* enforce forwards compatibility on users */ >>>> - if (unlikely(req->sqe->flags & ~SQE_VALID_FLAGS)) { >>>> + if (unlikely(sqe_flags & ~SQE_VALID_FLAGS)) { >>>> ret =3D -EINVAL; >>>> goto err_req; >>>> } >>>> @@ -3402,10 +3404,10 @@ static bool io_submit_sqe(struct io_kiocb *r= eq, struct io_submit_state *state, >>>> if (*link) { >>>> struct io_kiocb *head =3D *link; >>>> =20 >>>> - if (req->sqe->flags & IOSQE_IO_DRAIN) >>>> + if (sqe_flags & IOSQE_IO_DRAIN) >>>> head->flags |=3D REQ_F_DRAIN_LINK | REQ_F_IO_DRAIN; >>>> =20 >>>> - if (req->sqe->flags & IOSQE_IO_HARDLINK) >>>> + if (sqe_flags & IOSQE_IO_HARDLINK) >>>> req->flags |=3D REQ_F_HARDLINK; >>>> =20 >>>> if (io_alloc_async_ctx(req)) { >>>> @@ -3421,9 +3423,15 @@ static bool io_submit_sqe(struct io_kiocb *re= q, struct io_submit_state *state, >>>> } >>>> trace_io_uring_link(ctx, req, head); >>>> list_add_tail(&req->link_list, &head->link_list); >>>> - } else if (req->sqe->flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) { >>>> + >>>> + /* last request of a link, enqueue the link */ >>>> + if (!(sqe_flags & IOSQE_IO_LINK)) { >>> >>> This looks suspicious (as well as in the current revision). Returning= back >>> to my questions a few days ago can sqe->flags have IOSQE_IO_HARDLINK,= but not >>> IOSQE_IO_LINK? I don't find any check. >>> >>> In other words, should it be as follows? >>> !(sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) >> >> Yeah, I think that should check for both. I'm fine with either approac= h >> in general: >> >> - IOSQE_IO_HARDLINK must have IOSQE_IO_LINK set >> >> or >> >> - IOSQE_IO_HARDLINK implies IOSQE_IO_LINK >> >> Seems like the former is easier to verify in terms of functionality, >> since we can rest easy if we check this early and -EINVAL if that isn'= t >> the case. >> >> What do you think? >=20 > If you agree, want to send in a patch for that for 5.5? Then I can resp= in > for-5.6/io_uring on top of that, and we can apply your cleanups there. >=20 Yes, that's the idea. Already got a patch, if you haven't done it yet. Just was thinking, whether to add a check for not setting both flags at the same moment in the "imply" case. Would give us 1 state in 2 bits for future use. --=20 Pavel Begunkov --mXySBXItv7iyFXgIaS2oIyByOXi04M0Qs-- --T7Yvq6wRcCnY2AOcE3cmUZMbLwgNolNvd Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEE+6JuPTjTbx479o3OWt5b1Glr+6UFAl35FdMACgkQWt5b1Glr +6WrYA/+J8Ym1qVElDNgFQkxDNdTWjfCuKWNQbigdI+jaKMRuup49skZkF6SHqWE tF4Kv4ONQjEfrMogwUgn35T/vuxYqAN5+7z1Q+5oWgqdQXeSx8ccXzcmY9C6A77F Pj4h/IoWNgT7KkP3waimdICIZ1wLEALuA6ROfqvt9V543XXPlRZGcZlGf090tY3A JPgLjyRJoWgwVMSSkzGlbJFdx51fz+ghZ1Z0nctu3o8vI1wBUqZ0EU9NoxNelLf6 nX5gSRZ5db8Qxg04Me4at8AVVkE0fBouWMQpi42pn6C1QtL/DFnLE79GIWZNvSTw Hfa51OBBoTjsxwKPq1uAaqpJRT4qGBjMDPw2zSmntMhPJ3PD5ojhzEXe2HwWv7dT b4gbv0HIYI43S+zFCYorR1foEJ5utnZMvC1e6HRzrs5EvrRITbuMYYMrtfTXKtBj mJEW5zDet8UKHYE9pT7BcNjNn+zFWHhreX5igG5CEtxAUvHKqThAEjp5cyj22R7/ 4TrpnasIMJr/SrcwRjGQwZVkPv1oZzKj2fdwslfQhMgCCNb6WR6txG1OoVA3xYzQ I49S/34ElGpc4y9+H13675AVw28vqVLAWT1t2q14EEmuNXVgtMzIRMaoHff4DXCO iTaORgg41L9PlmddVn7EyIRC0WWlX/M/7u6bw5mS1IQIRZDWjCc= =Kapw -----END PGP SIGNATURE----- --T7Yvq6wRcCnY2AOcE3cmUZMbLwgNolNvd--