From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754985Ab2HOPZK (ORCPT ); Wed, 15 Aug 2012 11:25:10 -0400 Received: from mail-lpp01m010-f46.google.com ([209.85.215.46]:46559 "EHLO mail-lpp01m010-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753810Ab2HOPZI (ORCPT ); Wed, 15 Aug 2012 11:25:08 -0400 Date: Wed, 15 Aug 2012 19:25:04 +0400 From: Cyrill Gorcunov To: "H. Peter Anvin" Cc: LKML , Pavel Emelyanov Subject: Q: On restoring terminal with hinted index Message-ID: <20120815152504.GG23657@moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, that happened that in a sake of restoring ptys after checkpoint we need to create them with predefined indices, as they were at moment of dumping. So we have two options -- 1) Open terminals in sequence until needed index reached 2) Use some other way to say the kernel that some index is preferred. So I thought, would it be acceptible to provide such hint via sysctl, as in patch below (note I've not even compiled it yet, but would like to know your opinion early). (Maybe even make it one shot, thus once ida_get_new_above called the pty_next reset to zero). --- fs/devpts/inode.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) Index: linux-2.6.git/fs/devpts/inode.c =================================================================== --- linux-2.6.git.orig/fs/devpts/inode.c +++ linux-2.6.git/fs/devpts/inode.c @@ -45,6 +45,7 @@ static int pty_reserve = NR_UNIX98_PTY_R static int pty_limit_min; static int pty_limit_max = INT_MAX; static int pty_count; +static int pty_next; static struct ctl_table pty_table[] = { { @@ -69,6 +70,12 @@ static struct ctl_table pty_table[] = { .mode = 0444, .data = &pty_count, .proc_handler = proc_dointvec, + }, { + .procname = "next", + .maxlen = sizeof(int), + .mode = 0644, + .data = &pty_next, + .proc_handler = proc_dointvec, }, {} }; @@ -516,7 +523,7 @@ retry: return -ENOSPC; } - ida_ret = ida_get_new(&fsi->allocated_ptys, &index); + ida_ret = ida_get_new_above(&fsi->allocated_ptys, pty_next, &index); if (ida_ret < 0) { mutex_unlock(&allocated_ptys_lock); if (ida_ret == -EAGAIN)