Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757429AbYBDR2y (ORCPT ); Mon, 4 Feb 2008 12:28:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756057AbYBDR2q (ORCPT ); Mon, 4 Feb 2008 12:28:46 -0500 Received: from postfix2-g20.free.fr ([212.27.60.43]:42907 "EHLO postfix2-g20.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755811AbYBDR2q (ORCPT ); Mon, 4 Feb 2008 12:28:46 -0500 Message-ID: <47A74AED.1080806@free.fr> Date: Mon, 04 Feb 2008 18:27:09 +0100 From: Cedric Le Goater User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: Linux Kernel Mailing List CC: Andrew Morton , Pavel Emelianov , Linux Containers Subject: [PATCH 2/2] extend clone_flags using parent_tidptr argument Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2931 Lines: 88 From: Cedric Le Goater We have at least 2 patchsets requiring each a new clone flag and there it is, we've reached the limit, none are left. This patch uses the CLONE_DETACHED flag (unused) as a marker to extend the clone flags through the parent_tidptr argument. Initially, we thought on using the last bit but it has recently been taken by CLONE_IO. Obviously, this hack doesn't work for unshare() for which I don't see any other solution than to add a new syscall : long sys_unshare64(unsigned long clone_flags_high, unsigned long clone_flags_low); Is this the right path to extend the clone flags ? should we add a clone64() rather than hack the extending clone() ? Thanks for any comments ! C. Signed-off-by: Cedric Le Goater --- include/linux/sched.h | 1 + kernel/fork.c | 14 +++++++++++++- 2 files changed, 14 insertions(+), 1 deletion(-) Index: 2.6.24-mm1/include/linux/sched.h =================================================================== --- 2.6.24-mm1.orig/include/linux/sched.h +++ 2.6.24-mm1/include/linux/sched.h @@ -28,6 +28,7 @@ #define CLONE_NEWPID 0x20000000 /* New pid namespace */ #define CLONE_NEWNET 0x40000000 /* New network namespace */ #define CLONE_IO 0x80000000 /* Clone io context */ +#define CLONE_EXTFLAGS CLONE_DETACHED /* use parent_tidptr as an extended set of flags */ /* * Scheduling policies Index: 2.6.24-mm1/kernel/fork.c =================================================================== --- 2.6.24-mm1.orig/kernel/fork.c +++ 2.6.24-mm1/kernel/fork.c @@ -1012,6 +1012,14 @@ static struct task_struct *copy_process( struct task_struct *p; int cgroup_callbacks_done = 0; + /* + * It is not permitted to specify both CLONE_EXTFLAGS and + * CLONE_PARENT_SETTID + */ + if ((clone_flags & (CLONE_EXTFLAGS|CLONE_PARENT_SETTID)) == + (CLONE_EXTFLAGS|CLONE_PARENT_SETTID)) + return ERR_PTR(-EINVAL); + if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS)) return ERR_PTR(-EINVAL); @@ -1455,6 +1463,7 @@ long do_fork(unsigned long clone_flags, struct task_struct *p; int trace = 0; long nr; + u64 clone_flags64 = clone_flags; /* * We hope to recycle these flags after 2.6.26 @@ -1479,7 +1488,10 @@ long do_fork(unsigned long clone_flags, clone_flags |= CLONE_PTRACE; } - p = copy_process(clone_flags, stack_start, regs, stack_size, + if (clone_flags & CLONE_EXTFLAGS) + clone_flags64 = ((u64) (uintptr_t) parent_tidptr << 32) | clone_flags; + + p = copy_process(clone_flags64, stack_start, regs, stack_size, child_tidptr, NULL); /* * Do this prior waking up the new thread - the thread pointer -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/