From patchwork Tue Nov 8 05:05:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Lemon X-Patchwork-Id: 13035893 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12227C4332F for ; Tue, 8 Nov 2022 05:05:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232896AbiKHFFp convert rfc822-to-8bit (ORCPT ); Tue, 8 Nov 2022 00:05:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38932 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233095AbiKHFFl (ORCPT ); Tue, 8 Nov 2022 00:05:41 -0500 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87F6913DC2 for ; Mon, 7 Nov 2022 21:05:39 -0800 (PST) Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 2A7LKpss010010 for ; Mon, 7 Nov 2022 21:05:39 -0800 Received: from maileast.thefacebook.com ([163.114.130.3]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3knq54wajv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 07 Nov 2022 21:05:39 -0800 Received: from twshared2001.03.ash8.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Mon, 7 Nov 2022 21:05:37 -0800 Received: by devvm2494.atn0.facebook.com (Postfix, from userid 172786) id 46E1F23B26025; Mon, 7 Nov 2022 21:05:22 -0800 (PST) From: Jonathan Lemon To: CC: Subject: [PATCH v1 15/15] io_uring: Notify the application as the fillq is drained. Date: Mon, 7 Nov 2022 21:05:21 -0800 Message-ID: <20221108050521.3198458-16-jonathan.lemon@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20221108050521.3198458-1-jonathan.lemon@gmail.com> References: <20221108050521.3198458-1-jonathan.lemon@gmail.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: t0aHdp26enFR9ERwmHglAucZKqu-VipG X-Proofpoint-GUID: t0aHdp26enFR9ERwmHglAucZKqu-VipG X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-11-07_11,2022-11-07_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Userspace maintains a free count of space available in the fillq, and only returns entries based on the available space. As the kernel removes these entries, it needs to notify the application so more buffers can be queued. Only one outstanding notifier per queue is used, and it provides the most recent count of entries removed from the queue. Also post a notifier when the NIC is unable to obtain any buffers. When this happens, the NIC may just drop packets or stall. Signed-off-by: Jonathan Lemon --- io_uring/zctap.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) diff --git a/io_uring/zctap.c b/io_uring/zctap.c index c7897fe2ccf6..e6c7ed85d4ee 100644 --- a/io_uring/zctap.c +++ b/io_uring/zctap.c @@ -15,6 +15,7 @@ #include "zctap.h" #include "rsrc.h" #include "kbuf.h" +#include "refs.h" #define NR_ZCTAP_IFQS 1 @@ -26,7 +27,9 @@ struct ifq_region { int cache_count; int free_count; int nr_pages; + int taken; u16 id; + bool empty; spinlock_t freelist_lock; struct delayed_work release_work; @@ -44,8 +47,14 @@ struct ifq_region { struct io_zctap_ifq_priv { struct io_zctap_ifq ifq; struct ubuf_info uarg; + struct io_kiocb req; }; +static struct io_kiocb *io_zctap_ifq_notifier(struct io_zctap_ifq *ifq) +{ + return &((struct io_zctap_ifq_priv *)ifq)->req; +} + static void io_zctap_ifq_put(struct io_zctap_ifq *ifq); typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf); @@ -131,6 +140,34 @@ static void io_zctap_recycle_buf(struct ifq_region *ifr, } } +struct io_zctap_notif { + struct file *file; + u64 udata; + int res; + int cflags; +}; + +static void io_zctap_post_notify(struct io_kiocb *req, bool *locked) +{ + struct io_zctap_notif *n = io_kiocb_to_cmd(req, struct io_zctap_notif); + + io_post_aux_cqe(req->ctx, n->udata, n->res, n->cflags, true); + io_req_task_complete(req, locked); +} + +static void io_zctap_notify(struct io_kiocb *req, int bgid, int count) +{ + struct io_zctap_notif *n = io_kiocb_to_cmd(req, struct io_zctap_notif); + + n->udata = 0xface0000; /* XXX */ + n->res = (bgid << 16) | count; + n->cflags = IORING_CQE_F_BUFFER|IORING_CQE_F_NOTIF; + + req_ref_get(req); + req->io_task_work.func = io_zctap_post_notify; + io_req_task_work_add(req); +} + /* gets a user-supplied buffer from the fill queue * note: may drain N entries, but still have no usable buffers * XXX add retry limit? @@ -159,6 +196,7 @@ static struct io_zctap_buf *io_zctap_get_buffer(struct io_zctap_ifq *ifq, if (!addr) return NULL; + ifr->taken++; pgid = addr & 0xffff; region_id = (addr >> 16) & 0xffff; if (region_id) { @@ -196,6 +234,7 @@ struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq, int refc) { struct io_zctap_buf *buf; struct ifq_region *ifr; + struct io_kiocb *req; int count; u16 pgid; @@ -218,6 +257,12 @@ struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq, int refc) count = io_zctap_get_buffers(ifq, ifr->cache, REGION_REFILL_COUNT); ifr->cache_count += count; + req = io_zctap_ifq_notifier(ifq); + if (ifr->taken && atomic_read(&req->refs) == 1) { + io_zctap_notify(req, ifq->fill_bgid, ifr->taken); + ifr->taken = 0; + } + if (ifr->cache_count) goto out; @@ -234,11 +279,17 @@ struct io_zctap_buf *io_zctap_get_buf(struct io_zctap_ifq *ifq, int refc) if (ifr->cache_count) goto out; + if (!ifr->empty && atomic_read(&req->refs) == 1) { + io_zctap_notify(req, ifq->fill_bgid, 0); + ifr->empty = true; + } + return NULL; out: pgid = ifr->cache[--ifr->cache_count]; buf = &ifr->buf[pgid]; + ifr->empty = false; WARN_RATELIMIT(atomic_read(&buf->refcount), "pgid:%d refc:%d cache_count:%d\n", @@ -445,6 +496,8 @@ int io_provide_ifq_region(struct io_zctap_ifq *ifq, u16 id) ifr->id = id; ifr->ifq = ifq; ifr->delay_end = 0; + ifr->taken = 0; + ifr->empty = false; ifr->cache_count = 0; err = io_zctap_map_region(ifr, imu); @@ -533,6 +586,11 @@ static struct io_zctap_ifq *io_zctap_ifq_alloc(struct io_ring_ctx *ctx) priv->ifq.ctx = ctx; priv->ifq.queue_id = -1; priv->ifq.uarg = &priv->uarg; + + priv->req.ctx = ctx; + priv->req.task = current; + io_req_set_refcount(&priv->req); + return &priv->ifq; }