From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org by pdx-caf-mail.web.codeaurora.org (Dovecot) with LMTP id 5OrLBJBEGVt9FAAAmS7hNA ; Thu, 07 Jun 2018 14:43:59 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id C7EA5608BA; Thu, 7 Jun 2018 14:43:58 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on pdx-caf-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by smtp.codeaurora.org (Postfix) with ESMTP id 0B783602FC; Thu, 7 Jun 2018 14:43:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0B783602FC Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934885AbeFGOnz (ORCPT + 25 others); Thu, 7 Jun 2018 10:43:55 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:40696 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934145AbeFGOnx (ORCPT ); Thu, 7 Jun 2018 10:43:53 -0400 Received: from [148.252.241.226] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.84_2) (envelope-from ) id 1fQvbg-0005Zk-Ex; Thu, 07 Jun 2018 15:09:40 +0100 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1fQvb6-0002zs-50; Thu, 07 Jun 2018 15:09:04 +0100 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "" , "Al Viro" , "Willy Tarreau" , "Jens Axboe" , "Vegard Nossum" , "Tetsuo Handa" , "Michael Kerrisk (man-pages)" , "Linus Torvalds" Date: Thu, 07 Jun 2018 15:05:21 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 205/410] pipe: make account_pipe_buffers() return a value, and use it In-Reply-To: X-SA-Exim-Connect-IP: 148.252.241.226 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.57-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "Michael Kerrisk (man-pages)" commit 9c87bcf0a31b338dc8a69a5d251a037565a94e13 upstream. This is an optional patch, to provide a small performance improvement. Alter account_pipe_buffers() so that it returns the new value in user->pipe_bufs. This means that we can refactor too_many_pipe_buffers_soft() and too_many_pipe_buffers_hard() to avoid the costs of repeated use of atomic_long_read() to get the value user->pipe_bufs. Link: http://lkml.kernel.org/r/93e5f193-1e5e-3e1f-3a20-eae79b7e1310@gmail.com Signed-off-by: Michael Kerrisk Reviewed-by: Vegard Nossum Cc: Willy Tarreau Cc: Cc: Tetsuo Handa Cc: Jens Axboe Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Ben Hutchings --- fs/pipe.c | 36 ++++++++++++++++++------------------ 1 file changed, 18 insertions(+), 18 deletions(-) --- a/fs/pipe.c +++ b/fs/pipe.c @@ -590,22 +590,20 @@ pipe_fasync(int fd, struct file *filp, i return retval; } -static void account_pipe_buffers(struct user_struct *user, +static unsigned long account_pipe_buffers(struct user_struct *user, unsigned long old, unsigned long new) { - atomic_long_add(new - old, &user->pipe_bufs); + return atomic_long_add_return(new - old, &user->pipe_bufs); } -static bool too_many_pipe_buffers_soft(struct user_struct *user) +static bool too_many_pipe_buffers_soft(unsigned long user_bufs) { - return pipe_user_pages_soft && - atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_soft; + return pipe_user_pages_soft && user_bufs >= pipe_user_pages_soft; } -static bool too_many_pipe_buffers_hard(struct user_struct *user) +static bool too_many_pipe_buffers_hard(unsigned long user_bufs) { - return pipe_user_pages_hard && - atomic_long_read(&user->pipe_bufs) >= pipe_user_pages_hard; + return pipe_user_pages_hard && user_bufs >= pipe_user_pages_hard; } struct pipe_inode_info *alloc_pipe_info(void) @@ -613,19 +611,20 @@ struct pipe_inode_info *alloc_pipe_info( struct pipe_inode_info *pipe; unsigned long pipe_bufs = PIPE_DEF_BUFFERS; struct user_struct *user = get_current_user(); + unsigned long user_bufs; pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL); if (pipe == NULL) goto out_free_uid; - account_pipe_buffers(user, 0, pipe_bufs); + user_bufs = account_pipe_buffers(user, 0, pipe_bufs); - if (too_many_pipe_buffers_soft(user)) { - account_pipe_buffers(user, pipe_bufs, 1); + if (too_many_pipe_buffers_soft(user_bufs)) { + user_bufs = account_pipe_buffers(user, pipe_bufs, 1); pipe_bufs = 1; } - if (too_many_pipe_buffers_hard(user)) + if (too_many_pipe_buffers_hard(user_bufs)) goto out_revert_acct; pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer), @@ -641,7 +640,7 @@ struct pipe_inode_info *alloc_pipe_info( } out_revert_acct: - account_pipe_buffers(user, pipe_bufs, 0); + (void) account_pipe_buffers(user, pipe_bufs, 0); kfree(pipe); out_free_uid: free_uid(user); @@ -652,7 +651,7 @@ void free_pipe_info(struct pipe_inode_in { int i; - account_pipe_buffers(pipe->user, pipe->buffers, 0); + (void) account_pipe_buffers(pipe->user, pipe->buffers, 0); free_uid(pipe->user); for (i = 0; i < pipe->buffers; i++) { struct pipe_buffer *buf = pipe->bufs + i; @@ -1022,6 +1021,7 @@ static long pipe_set_size(struct pipe_in { struct pipe_buffer *bufs; unsigned int size, nr_pages; + unsigned long user_bufs; long ret = 0; size = round_pipe_size(arg); @@ -1041,11 +1041,11 @@ static long pipe_set_size(struct pipe_in size > pipe_max_size && !capable(CAP_SYS_RESOURCE)) return -EPERM; - account_pipe_buffers(pipe->user, pipe->buffers, nr_pages); + user_bufs = account_pipe_buffers(pipe->user, pipe->buffers, nr_pages); if (nr_pages > pipe->buffers && - (too_many_pipe_buffers_hard(pipe->user) || - too_many_pipe_buffers_soft(pipe->user)) && + (too_many_pipe_buffers_hard(user_bufs) || + too_many_pipe_buffers_soft(user_bufs)) && !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) { ret = -EPERM; goto out_revert_acct; @@ -1096,7 +1096,7 @@ static long pipe_set_size(struct pipe_in return nr_pages * PAGE_SIZE; out_revert_acct: - account_pipe_buffers(pipe->user, nr_pages, pipe->buffers); + (void) account_pipe_buffers(pipe->user, nr_pages, pipe->buffers); return ret; }