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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 4E694C04AAF for ; Tue, 21 May 2019 19:22:10 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B6294217D7 for ; Tue, 21 May 2019 19:22:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6294217D7 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 457ly70t0yzDqMv for ; Wed, 22 May 2019 05:22:07 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=ftp.linux.org.uk (client-ip=195.92.253.2; helo=zeniv.linux.org.uk; envelope-from=viro@ftp.linux.org.uk; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=zeniv.linux.org.uk Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [195.92.253.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 457lwS250SzDqHL for ; Wed, 22 May 2019 05:20:37 +1000 (AEST) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92 #3 (Red Hat Linux)) id 1hTAIz-0003v8-BX; Tue, 21 May 2019 19:20:09 +0000 Date: Tue, 21 May 2019 20:20:09 +0100 From: Al Viro To: David Howells Subject: Re: [PATCH 1/2] open: add close_range() Message-ID: <20190521192009.GK17978@ZenIV.linux.org.uk> References: <20190521150006.GJ17978@ZenIV.linux.org.uk> <20190521113448.20654-1-christian@brauner.io> <28114.1558456227@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <28114.1558456227@warthog.procyon.org.uk> User-Agent: Mutt/1.11.3 (2019-02-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, oleg@redhat.com, linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org, shuah@kernel.org, linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, miklos@szeredi.hu, x86@kernel.org, torvalds@linux-foundation.org, Christian Brauner , linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, tkjos@android.com, arnd@arndb.de, jannh@google.com, linux-m68k@lists.linux-m68k.org, tglx@linutronix.de, ldv@altlinux.org, linux-arm-kernel@lists.infradead.org, fweimer@redhat.com, linux-parisc@vger.kernel.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, May 21, 2019 at 05:30:27PM +0100, David Howells wrote: > If we can live with close_from(int first) rather than close_range(), then this > can perhaps be done a lot more efficiently by: > > new = alloc_fdtable(first); > spin_lock(&files->file_lock); > old = files_fdtable(files); > copy_fds(new, old, 0, first - 1); > rcu_assign_pointer(files->fdt, new); > spin_unlock(&files->file_lock); > clear_fds(old, 0, first - 1); > close_fdt_from(old, first); > kfree_rcu(old); I really hate to think how that would interact with POSIX locks...