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Date: Sun, 8 Apr 2007 19:55:13 +0400 From: Oleg Nesterov <oleg@...sign.ru> To: Andrew Morton <akpm@...ux-foundation.org>, "Eric W. Biederman" <ebiederm@...ssion.com>, Davide Libenzi <davidel@...ilserver.org>, Ingo Molnar <mingo@...e.hu>, Linus Torvalds <torvalds@...ux-foundation.org>, Robin Holt <holt@....com>, Roland McGrath <roland@...hat.com> Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org Subject: [RFC, PATCH 2/3] implement CLONE_KERNEL_THREAD flag For review only. We have some problems with the kernel threads parented to /sbin/init, see http://marc.info/?t=117580282200003&r=1 http://marc.info/?t=95299284800003&r=1 A task created with CLONE_KERNEL_THREAD will have swapper as its parent. Note that this is only the first step, we can extend the meaning of this flag to also use init_task for copy_mm/copy_files/etc. arch/sparc/kernel/process.c arch/sparc64/kernel/process.c arch/m68knommu/kernel/process.c arch/m68k/kernel/process.c arch/alpha/kernel/entry.S arch/h8300/kernel/process.c arch/v850/kernel/process.c arch/frv/kernel/kernel_thread.S arch/frv/kernel/kernel_thread.S arch/powerpc/kernel/misc_32.S arch/powerpc/kernel/misc_64.S implement kthread_create() via sys_clone(). This means that these arches can't take advantage of CLONE_KERNEL_THREAD, it will be filtered out by sys_clone(). This patch breaks arch/ia64/, its sys_clone() was not converted by the previous patch, so user-space can do sys_clone(CLONE_KERNEL_THREAD). Signed-off-by: Oleg Nesterov <oleg@...sign.ru> include/linux/sched.h | 5 ++++- kernel/fork.c | 5 ++++- 2 files changed, 8 insertions(+), 2 deletions(-) --- 2.6.21-rc5-mm4/include/linux/sched.h~2_IMPL 2007-04-07 22:07:50.000000000 +0400 +++ 2.6.21-rc5-mm4/include/linux/sched.h 2007-04-08 18:53:51.000000000 +0400 @@ -28,7 +28,10 @@ #define CLONE_NEWIPC 0x08000000 /* New ipcs */ /* user-space visible */ -#define SYS_CLONE_MASK (~0x0) +#define SYS_CLONE_MASK (~(CLONE_KERNEL_THREAD)) + +/* for in kernel use only */ +#define CLONE_KERNEL_THREAD 0x20000000 /* hide from init */ /* * Scheduling policies --- 2.6.21-rc5-mm4/kernel/fork.c~2_IMPL 2007-04-07 23:56:08.000000000 +0400 +++ 2.6.21-rc5-mm4/kernel/fork.c 2007-04-08 18:55:42.000000000 +0400 @@ -1159,7 +1159,8 @@ static struct task_struct *copy_process( p->parent_exec_id = p->self_exec_id; /* ok, now we should be set up.. */ - p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL); + p->exit_signal = (clone_flags & (CLONE_THREAD|CLONE_KERNEL_THREAD)) + ? -1 : (clone_flags & CSIGNAL); p->pdeath_signal = 0; p->exit_state = 0; @@ -1196,6 +1197,8 @@ static struct task_struct *copy_process( /* CLONE_PARENT re-uses the old parent */ if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) p->parent = current->parent; + else if (unlikely(clone_flags & CLONE_KERNEL_THREAD)) + p->parent = &init_task; else p->parent = current; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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