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=-14.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, UNWANTED_LANGUAGE_BODY,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 718E8C4320A for ; Sun, 8 Aug 2021 13:54:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35EAA61040 for ; Sun, 8 Aug 2021 13:54:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229504AbhHHNzA (ORCPT ); Sun, 8 Aug 2021 09:55:00 -0400 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:41946 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229923AbhHHNzA (ORCPT ); Sun, 8 Aug 2021 09:55:00 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R141e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UiIyDWG_1628430874; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UiIyDWG_1628430874) by smtp.aliyun-inc.com(127.0.0.1); Sun, 08 Aug 2021 21:54:39 +0800 From: Hao Xu To: Jens Axboe Cc: io-uring@vger.kernel.org, Pavel Begunkov , Joseph Qi Subject: [PATCH 2/2] io-wq: fix IO_WORKER_F_FIXED issue in create_io_worker() Date: Sun, 8 Aug 2021 21:54:34 +0800 Message-Id: <20210808135434.68667-3-haoxu@linux.alibaba.com> X-Mailer: git-send-email 2.24.4 In-Reply-To: <20210808135434.68667-1-haoxu@linux.alibaba.com> References: <20210808135434.68667-1-haoxu@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org There may be cases like: A B spin_lock(wqe->lock) nr_workers is 0 nr_workers++ spin_unlock(wqe->lock) spin_lock(wqe->lock) nr_wokers is 1 nr_workers++ spin_unlock(wqe->lock) create_io_worker() acct->worker is 1 create_io_worker() acct->worker is 1 There should be one worker marked IO_WORKER_F_FIXED, but no one is. Fix this by introduce a new agrument for create_io_worker() to indicate if it is the first worker. Fixes: 3d4e4face9c1 ("io-wq: fix no lock protection of acct->nr_worker") Signed-off-by: Hao Xu --- fs/io-wq.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/io-wq.c b/fs/io-wq.c index 5536b2a008d1..660625ac02d7 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -129,7 +129,7 @@ struct io_cb_cancel_data { bool cancel_all; }; -static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index); +static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first); static void io_wqe_dec_running(struct io_worker *worker); static bool io_worker_get(struct io_worker *worker) @@ -248,10 +248,12 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct) rcu_read_unlock(); if (!ret) { - bool do_create = false; + bool do_create = false, first = false; raw_spin_lock_irq(&wqe->lock); if (acct->nr_workers < acct->max_workers) { + if (!acct->nr_workers) + first = true; acct->nr_workers++; do_create = true; } @@ -259,7 +261,7 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct) if (do_create) { atomic_inc(&acct->nr_running); atomic_inc(&wqe->wq->worker_refs); - create_io_worker(wqe->wq, wqe, acct->index); + create_io_worker(wqe->wq, wqe, acct->index, first); } } } @@ -283,7 +285,7 @@ static void create_worker_cb(struct callback_head *cb) struct io_wq *wq; struct io_wqe *wqe; struct io_wqe_acct *acct; - bool do_create = false; + bool do_create = false, first = false; cwd = container_of(cb, struct create_worker_data, work); wqe = cwd->wqe; @@ -291,12 +293,14 @@ static void create_worker_cb(struct callback_head *cb) acct = &wqe->acct[cwd->index]; raw_spin_lock_irq(&wqe->lock); if (acct->nr_workers < acct->max_workers) { + if (!acct->nr_workers) + first = true; acct->nr_workers++; do_create = true; } raw_spin_unlock_irq(&wqe->lock); if (do_create) { - create_io_worker(wq, cwd->wqe, cwd->index); + create_io_worker(wq, wqe, cwd->index, first); } else { atomic_dec(&acct->nr_running); io_worker_ref_put(wq); @@ -638,7 +642,7 @@ void io_wq_worker_sleeping(struct task_struct *tsk) raw_spin_unlock_irq(&worker->wqe->lock); } -static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index) +static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first) { struct io_wqe_acct *acct = &wqe->acct[index]; struct io_worker *worker; @@ -679,7 +683,7 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index) worker->flags |= IO_WORKER_F_FREE; if (index == IO_WQ_ACCT_BOUND) worker->flags |= IO_WORKER_F_BOUND; - if ((acct->nr_workers == 1) && (worker->flags & IO_WORKER_F_BOUND)) + if (first && (worker->flags & IO_WORKER_F_BOUND)) worker->flags |= IO_WORKER_F_FIXED; raw_spin_unlock_irq(&wqe->lock); wake_up_new_task(tsk); -- 2.24.4