From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934039AbcLHBac (ORCPT ); Wed, 7 Dec 2016 20:30:32 -0500 Received: from mail-wm0-f42.google.com ([74.125.82.42]:37465 "EHLO mail-wm0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932372AbcLHBab (ORCPT ); Wed, 7 Dec 2016 20:30:31 -0500 From: Rasmus Villemoes To: Tejun Heo , Andrew Morton Cc: linux-kernel@vger.kernel.org, Lai Jiangshan , Jens Axboe , Greg Kroah-Hartman , Rasmus Villemoes Subject: [RFC 10/10] fs/devpts: use tida for id allocation Date: Thu, 8 Dec 2016 02:23:05 +0100 Message-Id: <1481160187-9652-11-git-send-email-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1481160187-9652-1-git-send-email-linux@rasmusvillemoes.dk> References: <1481160187-9652-1-git-send-email-linux@rasmusvillemoes.dk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using the newly introduced tida for allocating pty indexes saves around 16KB of runtime memory. Since tida does it's own internal locking, we don't need to protect it with the &allocated_ptys_lock and do the whole "preallocate outside lock, loop if we're extremely unlucky", thus allowing us simplify devpts_new_index somewhat. Signed-off-by: Rasmus Villemoes --- fs/devpts/inode.c | 28 ++++++++++------------------ 1 file changed, 10 insertions(+), 18 deletions(-) diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 108df2e3602c..ea40437f246a 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -22,7 +22,7 @@ #include #include #include -#include +#include #include #include #include @@ -122,7 +122,7 @@ static const match_table_t tokens = { }; struct pts_fs_info { - struct ida allocated_ptys; + struct tida allocated_ptys; struct pts_mount_opts mount_opts; struct super_block *sb; struct dentry *ptmx_dentry; @@ -377,7 +377,7 @@ static void *new_pts_fs_info(struct super_block *sb) if (!fsi) return NULL; - ida_init(&fsi->allocated_ptys); + tida_init(&fsi->allocated_ptys); fsi->mount_opts.mode = DEVPTS_DEFAULT_MODE; fsi->mount_opts.ptmxmode = DEVPTS_DEFAULT_PTMX_MODE; fsi->sb = sb; @@ -453,7 +453,7 @@ static void devpts_kill_sb(struct super_block *sb) struct pts_fs_info *fsi = DEVPTS_SB(sb); if (fsi) - ida_destroy(&fsi->allocated_ptys); + tida_destroy(&fsi->allocated_ptys); kfree(fsi); kill_litter_super(sb); } @@ -473,29 +473,21 @@ static struct file_system_type devpts_fs_type = { int devpts_new_index(struct pts_fs_info *fsi) { int index; - int ida_ret; -retry: - if (!ida_pre_get(&fsi->allocated_ptys, GFP_KERNEL)) - return -ENOMEM; + index = tida_get(&fsi->allocated_ptys, GFP_KERNEL); + if (index < 0) + return index; mutex_lock(&allocated_ptys_lock); if (pty_count >= (pty_limit - (fsi->mount_opts.reserve ? 0 : pty_reserve))) { + tida_put(&fsi->allocated_ptys, index); mutex_unlock(&allocated_ptys_lock); return -ENOSPC; } - ida_ret = ida_get_new(&fsi->allocated_ptys, &index); - if (ida_ret < 0) { - mutex_unlock(&allocated_ptys_lock); - if (ida_ret == -EAGAIN) - goto retry; - return -EIO; - } - if (index >= fsi->mount_opts.max) { - ida_remove(&fsi->allocated_ptys, index); + tida_put(&fsi->allocated_ptys, index); mutex_unlock(&allocated_ptys_lock); return -ENOSPC; } @@ -507,7 +499,7 @@ int devpts_new_index(struct pts_fs_info *fsi) void devpts_kill_index(struct pts_fs_info *fsi, int idx) { mutex_lock(&allocated_ptys_lock); - ida_remove(&fsi->allocated_ptys, idx); + tida_put(&fsi->allocated_ptys, idx); pty_count--; mutex_unlock(&allocated_ptys_lock); } -- 2.1.4