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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, 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 CEE81C18DF5 for ; Tue, 20 Nov 2018 14:21:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A29BA206B2 for ; Tue, 20 Nov 2018 14:21:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A29BA206B2 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729789AbeKUAvU (ORCPT ); Tue, 20 Nov 2018 19:51:20 -0500 Received: from szxga06-in.huawei.com ([45.249.212.32]:40552 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726916AbeKUAvU (ORCPT ); Tue, 20 Nov 2018 19:51:20 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id EF78E54F76CEB; Tue, 20 Nov 2018 22:21:55 +0800 (CST) Received: from localhost.localdomain (10.175.124.28) by smtp.huawei.com (10.3.19.204) with Microsoft SMTP Server (TLS) id 14.3.408.0; Tue, 20 Nov 2018 22:21:50 +0800 From: Gao Xiang To: Greg Kroah-Hartman , CC: LKML , , "Chao Yu" , Miao Xie , , Gao Xiang Subject: [PATCH 08/10] staging: erofs: locked before registering for all new workgroups Date: Tue, 20 Nov 2018 22:34:23 +0800 Message-ID: <20181120143425.43637-9-gaoxiang25@huawei.com> X-Mailer: git-send-email 2.14.4 In-Reply-To: <20181120143425.43637-1-gaoxiang25@huawei.com> References: <20181120143425.43637-1-gaoxiang25@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Let's make sure that the one registering a workgroup will also take the primary work lock at first for two reasons: 1) There's no need to introduce such a race window (and consequently overhead) between registering and locking, other tasks could break in by chance, and the race seems unnecessary (no benefit at all); 2) It's better to take the primary work when a workgroup is registered to apply the cache managed policy, for example, if some other tasks break in, it could turn into the in-place decompression rather than use as the cached decompression. Reviewed-by: Chao Yu Signed-off-by: Gao Xiang --- drivers/staging/erofs/unzip_vle.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c index 4e5843e8ee35..a1376f3c6065 100644 --- a/drivers/staging/erofs/unzip_vle.c +++ b/drivers/staging/erofs/unzip_vle.c @@ -420,18 +420,22 @@ z_erofs_vle_work_register(const struct z_erofs_vle_work_finder *f, work = z_erofs_vle_grab_primary_work(grp); work->pageofs = f->pageofs; + /* lock all primary followed works before visible to others */ + if (unlikely(!mutex_trylock(&work->lock))) + /* for a new workgroup, try_lock *never* fails */ + DBG_BUGON(1); + if (gnew) { int err = erofs_register_workgroup(f->sb, &grp->obj, 0); if (err) { + mutex_unlock(&work->lock); kmem_cache_free(z_erofs_workgroup_cachep, grp); return ERR_PTR(-EAGAIN); } } *f->owned_head = *f->grp_ret = grp; - - mutex_lock(&work->lock); return work; } -- 2.14.4