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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84C42C433F5 for ; Fri, 22 Apr 2022 16:03:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356127AbiDVQGV (ORCPT ); Fri, 22 Apr 2022 12:06:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357065AbiDVQGO (ORCPT ); Fri, 22 Apr 2022 12:06:14 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75E475E149 for ; Fri, 22 Apr 2022 09:03:20 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id j8so11778036pll.11 for ; Fri, 22 Apr 2022 09:03:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UGK3iOLOSq8b+uW93AKentNVyqK1drmrSS6mX3tmCK4=; b=jREOmp2tBNoX9/1JSC70rEEUVIFeaV48CD7qYFaDgDafU4SAaf9LhxP1k+Rn6vpleM cskZCEoTYLEONhvD7sDXgIeb2ay/1zuHkkkpPeZNSbjJTGucqwNKlNwqA3EhplbzG7G4 ZRoCWXpI8nSjzPsLjVHRNaL+ul/CBEs/833AqNI7BftoMXQzaXCNU4ereRAdqn5K6AEO CvAsxDdmuZRoKIGuKOonyNOEGdtlIoLyBKZgaXs6SPBR9VyJuo+AOSSuKZi47KF9WFdf 7t6riDyt8vTj76MOUivasvnNMNXEqA2dE0lteUO1dl08saMJWervfiaLvH+0A6JLnbHP UiUQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=UGK3iOLOSq8b+uW93AKentNVyqK1drmrSS6mX3tmCK4=; b=cNxj8Mqfq7xRwOmFLdnjuMK4jUpg0ppzDCeCKGjdg1hJidNFEjcw9wR1V4V6uBvX30 w3VgmWeQpaz1zjqMuemkjyxQp9EQT7bdrW/P5zLFvz24mNBgWdzC0uMpILZpS+VE+NWv wfsViJkyZUaZnmLD/C0T1qeNtcmdLNC2Zqaag1yRm+Iftg0phEhdqdrh3KDIWD33Q9G8 PRzDvwXNvsHzT9gc9IJgMXcvgrrRaDABD/4EMok1Ywi/x6vGyLRPEJ3j+jbDvmgGE6nD Rr4I49z5ee+vPZXZYtju3NiqrO8UQ9mXk9LA+lHYCYe/Jm5+DcvMVNCDMrHZebpTW9Vq iV7Q== X-Gm-Message-State: AOAM531IV5zMtv8Ao626kIYEbPUZzKJMIBsYGfOvIw8aK+mfzUAe+QVt 5DuPHjC1SRwW1wrLLz8PBsg= X-Google-Smtp-Source: ABdhPJx5XKcoaoRaemeTrLmz3cPHtWUeo+5F4Miz7i1lYIRFTpqzShSr3m+CgLrJ9DV3A/AMZs5J+g== X-Received: by 2002:a17:902:c9d2:b0:15b:e021:8bcc with SMTP id q18-20020a170902c9d200b0015be0218bccmr4149894pld.40.1650643399714; Fri, 22 Apr 2022 09:03:19 -0700 (PDT) Received: from localhost ([2620:10d:c090:400::5:b5ae]) by smtp.gmail.com with ESMTPSA id g17-20020a625211000000b005056a6313a7sm2927881pfb.87.2022.04.22.09.03.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 Apr 2022 09:03:19 -0700 (PDT) Sender: Tejun Heo Date: Fri, 22 Apr 2022 06:03:17 -1000 From: Tejun Heo To: Imran Khan Cc: viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org, ebiederm@xmission.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 01/10] kernfs: Remove reference counting for kernfs_open_node. Message-ID: References: <20220410023719.1752460-1-imran.f.khan@oracle.com> <20220410023719.1752460-2-imran.f.khan@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220410023719.1752460-2-imran.f.khan@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 10, 2022 at 12:37:10PM +1000, Imran Khan wrote: > @@ -768,15 +765,15 @@ void kernfs_drain_open_files(struct kernfs_node *kn) > if (!(kn->flags & (KERNFS_HAS_MMAP | KERNFS_HAS_RELEASE))) > return; > > - spin_lock_irq(&kernfs_open_node_lock); > on = kn->attr.open; > - if (on) > - atomic_inc(&on->refcnt); > - spin_unlock_irq(&kernfs_open_node_lock); > if (!on) > return; > > mutex_lock(&kernfs_open_file_mutex); > + if (!kn->attr.open) { > + mutex_unlock(&kernfs_open_file_mutex); > + return; > + } What if @on got freed and new one got allocated between the lockless check and the locked check? Is there a reason to keep the lockless check at all? > list_for_each_entry(of, &on->files, list) { > struct inode *inode = file_inode(of->file); Thanks. -- tejun