From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D79DFC3F2D1 for ; Mon, 2 Mar 2020 20:46:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 87DFC2173E for ; Mon, 2 Mar 2020 20:46:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="nDLP8Ond" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726971AbgCBUq1 (ORCPT ); Mon, 2 Mar 2020 15:46:27 -0500 Received: from mail-wm1-f68.google.com ([209.85.128.68]:56073 "EHLO mail-wm1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726859AbgCBUqY (ORCPT ); Mon, 2 Mar 2020 15:46:24 -0500 Received: by mail-wm1-f68.google.com with SMTP id 6so557284wmi.5; Mon, 02 Mar 2020 12:46:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=iL8XkZ3bohObdyki9erpkDmWE7PZz8rBVjTwpnCnlK0=; b=nDLP8OndFPvPiuH7XJcsOUk39QK4VKGjamBMl+y9hpzxcppH0mvU+BxkrHvLBO8qzM 05haWkV0UB1KCShVrZVvKXdi8J4FPXBJU/Sq3xksWk9jTWZ82RvcZDTs72OcO/+XVDp9 pxWMw4WPHDcqoqCZBkiUutYqsDemOs/QmZpi/jhI2KoSBTz4OXqkztv9PticdS1CF5Q6 hbnUVjPwMsPgKVuLPwq3k1T+xDSupcTpYbRXhz5yhGXDObQcUHNHdzARg642slqx1DOt 5Qm6yW8IookiZ0gyKZUTwm9yOfTFYCRwdkbENOov4wBm6ciLgf3yokFC5XOy5ik6z4Ia N7lg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=iL8XkZ3bohObdyki9erpkDmWE7PZz8rBVjTwpnCnlK0=; b=KvD0M3OpQ6W6P4dDelzYAULj+/r32rtqTqHlCZ1Wsx0meS6ZvN2NQ8gc+LqgPyZfvh JqMkEo+WtR/nP/LJ++jVv7ZaHQ3Nt+GunC80M3k7/ifGJZJn59OdwomutWl4fvYbW1Fd T5izkVglhilrzJFP6x6lIrIIlYf+rwDt66kNHvwXw20Cd16GkuTcjc0R8k5Ndhs6XXg3 csDUNIwV8MFK5tOXRYIfaLxifAMOZxSuhgmHqdWWeN5L197yXKya5gnkug7Jh1N6IEIu 4Ru7LrStT0t4FOtiYmeEfBgbyimY/5ndxbYdBPc/z0pfhXb+8f7Gsw+dcBNDRFBNk/Hp Tgwg== X-Gm-Message-State: ANhLgQ2TG842TZHWMiHdCv+4ybc19hZktcA+0gPAWCh3oRbmdgv503nx NmB7xS75yhOKe9c/jxG/ScM= X-Google-Smtp-Source: ADFU+vtV9H7d66QDnqCeF4lsAfRdatMO5LB4geo0eceYIkaMjn64qYLHPTsHlOBBKClC75MO0XVvUQ== X-Received: by 2002:a05:600c:291e:: with SMTP id i30mr277777wmd.40.1583181982354; Mon, 02 Mar 2020 12:46:22 -0800 (PST) Received: from localhost.localdomain ([109.126.130.242]) by smtp.gmail.com with ESMTPSA id b14sm20186549wrn.75.2020.03.02.12.46.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Mar 2020 12:46:21 -0800 (PST) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 4/4] io_uring: get next req on subm ref drop Date: Mon, 2 Mar 2020 23:45:19 +0300 Message-Id: <444aef98f849d947d7f10e88f30244fa0bc82360.1583181841.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Get next request when dropping the submission reference. However, if there is an asynchronous counterpart (i.e. read/write, timeout, etc), that would be dangerous to do, so ignore them using new REQ_F_DONT_STEAL_NEXT flag. Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 129 ++++++++++++++++++++++++++------------------------ 1 file changed, 66 insertions(+), 63 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index daf7c2095523..e05710ca63d5 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -488,6 +488,7 @@ enum { REQ_F_NEED_CLEANUP_BIT, REQ_F_OVERFLOW_BIT, REQ_F_POLLED_BIT, + REQ_F_DONT_STEAL_NEXT_BIT, }; enum { @@ -532,6 +533,8 @@ enum { REQ_F_OVERFLOW = BIT(REQ_F_OVERFLOW_BIT), /* already went through poll handler */ REQ_F_POLLED = BIT(REQ_F_POLLED_BIT), + /* don't try to get next req, it's async and racy */ + REQ_F_DONT_STEAL_NEXT = BIT(REQ_F_DONT_STEAL_NEXT_BIT), }; struct async_poll { @@ -1218,6 +1221,27 @@ static void io_cqring_add_event(struct io_kiocb *req, long res) io_cqring_ev_posted(ctx); } +static void io_link_work_cb(struct io_wq_work **workptr) +{ + struct io_wq_work *work = *workptr; + struct io_kiocb *link = work->data; + + io_queue_linked_timeout(link); + io_wq_submit_work(workptr); +} + +static void io_wq_assign_next(struct io_wq_work **workptr, struct io_kiocb *nxt) +{ + struct io_kiocb *link; + + *workptr = &nxt->work; + link = io_prep_linked_timeout(nxt); + if (link) { + nxt->work.func = io_link_work_cb; + nxt->work.data = link; + } +} + static inline bool io_is_fallback_req(struct io_kiocb *req) { return req == (struct io_kiocb *) @@ -1518,25 +1542,35 @@ static void io_free_req(struct io_kiocb *req) io_queue_async_work(nxt); } -/* - * Drop reference to request, return next in chain (if there is one) if this - * was the last reference to this request. - */ -__attribute__((nonnull)) -static void io_put_req_find_next(struct io_kiocb *req, struct io_kiocb **nxtptr) -{ - if (refcount_dec_and_test(&req->refs)) { - io_req_find_next(req, nxtptr); - __io_free_req(req); - } -} - static void io_put_req(struct io_kiocb *req) { if (refcount_dec_and_test(&req->refs)) io_free_req(req); } +__attribute__((warn_unused_result)) +static struct io_kiocb *io_put_req_submission(struct io_kiocb *req) +{ + struct io_kiocb *nxt = NULL; + + /* do it first, while holding a ref */ + if (!(req->flags & REQ_F_DONT_STEAL_NEXT)) + io_req_find_next(req, &nxt); + + io_put_req(req); + return nxt; +} + +static void io_put_req_async_submission(struct io_kiocb *req, + struct io_wq_work **workptr) +{ + static struct io_kiocb *nxt; + + nxt = io_put_req_submission(req); + if (nxt) + io_wq_assign_next(workptr, nxt); +} + /* * Must only be used if we don't need to care about links, usually from * within the completion handling itself. @@ -1979,8 +2013,11 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) { + struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb); + switch (ret) { case -EIOCBQUEUED: + req->flags |= REQ_F_DONT_STEAL_NEXT; break; case -ERESTARTSYS: case -ERESTARTNOINTR: @@ -2526,6 +2563,7 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (unlikely(req->sync.flags & ~IORING_FSYNC_DATASYNC)) return -EINVAL; + req->flags |= REQ_F_DONT_STEAL_NEXT; req->sync.off = READ_ONCE(sqe->off); req->sync.len = READ_ONCE(sqe->len); return 0; @@ -2543,27 +2581,6 @@ static bool io_req_cancelled(struct io_kiocb *req) return false; } -static void io_link_work_cb(struct io_wq_work **workptr) -{ - struct io_wq_work *work = *workptr; - struct io_kiocb *link = work->data; - - io_queue_linked_timeout(link); - io_wq_submit_work(workptr); -} - -static void io_wq_assign_next(struct io_wq_work **workptr, struct io_kiocb *nxt) -{ - struct io_kiocb *link; - - *workptr = &nxt->work; - link = io_prep_linked_timeout(nxt); - if (link) { - nxt->work.func = io_link_work_cb; - nxt->work.data = link; - } -} - static void __io_fsync(struct io_kiocb *req) { loff_t end = req->sync.off + req->sync.len; @@ -2581,14 +2598,11 @@ static void __io_fsync(struct io_kiocb *req) static void io_fsync_finish(struct io_wq_work **workptr) { struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; if (io_req_cancelled(req)) return; __io_fsync(req); - io_put_req(req); /* drop submission reference */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } static int io_fsync(struct io_kiocb *req, bool force_nonblock) @@ -2617,14 +2631,11 @@ static void __io_fallocate(struct io_kiocb *req) static void io_fallocate_finish(struct io_wq_work **workptr) { struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; if (io_req_cancelled(req)) return; __io_fallocate(req); - io_put_req(req); /* drop submission reference */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } static int io_fallocate_prep(struct io_kiocb *req, @@ -2988,13 +2999,10 @@ static void __io_close_finish(struct io_kiocb *req) static void io_close_finish(struct io_wq_work **workptr) { struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; /* not cancellable, don't do io_req_cancelled() */ __io_close_finish(req); - io_put_req(req); /* drop submission reference */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } static int io_close(struct io_kiocb *req, bool force_nonblock) @@ -3016,6 +3024,7 @@ static int io_close(struct io_kiocb *req, bool force_nonblock) */ io_queue_async_work(req); /* submission ref will be dropped, take it for async */ + req->flags |= REQ_F_DONT_STEAL_NEXT; refcount_inc_not_zero(&req->refs); return 0; } @@ -3062,14 +3071,11 @@ static void __io_sync_file_range(struct io_kiocb *req) static void io_sync_file_range_finish(struct io_wq_work **workptr) { struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; if (io_req_cancelled(req)) return; __io_sync_file_range(req); - io_put_req(req); /* put submission ref */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } static int io_sync_file_range(struct io_kiocb *req, bool force_nonblock) @@ -3435,14 +3441,11 @@ static int __io_accept(struct io_kiocb *req, bool force_nonblock) static void io_accept_finish(struct io_wq_work **workptr) { struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; if (io_req_cancelled(req)) return; __io_accept(req, false); - io_put_req(req); /* drop submission reference */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } #endif @@ -3859,9 +3862,10 @@ static void io_poll_task_handler(struct io_kiocb *req, struct io_kiocb **nxt) hash_del(&req->hash_node); io_poll_complete(req, req->result, 0); req->flags |= REQ_F_COMP_LOCKED; - io_put_req_find_next(req, nxt); spin_unlock_irq(&ctx->completion_lock); + req->flags &= ~REQ_F_DONT_STEAL_NEXT; + *nxt = io_put_req_submission(req); io_cqring_ev_posted(ctx); } @@ -3943,7 +3947,10 @@ static int io_poll_add(struct io_kiocb *req) if (mask) { io_cqring_ev_posted(ctx); io_put_req(req); + } else { + req->flags |= REQ_F_DONT_STEAL_NEXT; } + return ipt.error; } @@ -4066,6 +4073,7 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe, if (flags & ~IORING_TIMEOUT_ABS) return -EINVAL; + req->flags |= REQ_F_DONT_STEAL_NEXT; req->timeout.count = READ_ONCE(sqe->off); if (!req->io && io_alloc_async_ctx(req)) @@ -4680,7 +4688,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr) { struct io_wq_work *work = *workptr; struct io_kiocb *req = container_of(work, struct io_kiocb, work); - struct io_kiocb *nxt = NULL; int ret = 0; /* if NO_CANCEL is set, we must still run the work */ @@ -4709,9 +4716,7 @@ static void io_wq_submit_work(struct io_wq_work **workptr) io_put_req(req); } - io_put_req(req); /* drop submission reference */ - if (nxt) - io_wq_assign_next(workptr, nxt); + io_put_req_async_submission(req, workptr); } static int io_req_needs_file(struct io_kiocb *req, int fd) @@ -4935,10 +4940,6 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe) } err: - nxt = NULL; - /* drop submission reference */ - io_put_req_find_next(req, &nxt); - if (linked_timeout) { if (!ret) io_queue_linked_timeout(linked_timeout); @@ -4952,6 +4953,8 @@ static void __io_queue_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe) req_set_fail_links(req); io_put_req(req); } + + nxt = io_put_req_submission(req); if (nxt) { req = nxt; -- 2.24.0