Re: [RFC, PATCH 3/3] use CLONE_KERNEL_THREAD

Serge E. Hallyn
2007-04-09T16:26:10Z

Quoting Oleg Nesterov (oleg@tv-sign.ru):
> For review only.
>
> Add CLONE_KERNEL_THREAD to kthread_create() and change reparent_to_init()
> to match CLONE_KERNEL_THREAD.
>
> Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
>
> kthread.c | 2 +-
> exit.c | 20 +++++++++-----------
> 2 files changed, 10 insertions(+), 12 deletions(-)
>
> --- 2.6.21-rc5-mm4/kernel/kthread.c~3_USE 2007-04-05 12:18:28.000000000 +0400
> +++ 2.6.21-rc5-mm4/kernel/kthread.c 2007-04-08 19:18:59.000000000 +0400
> @@ -120,7 +120,7 @@ static void keventd_create_kthread(struc
> int pid;
>
> /* We want our own signal handler (we take no signals by default). */
> - pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
> + pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | CLONE_KERNEL_THREAD);
> if (pid < 0) {
> create->result = ERR_PTR(pid);
> } else {
> --- 2.6.21-rc5-mm4/kernel/exit.c~3_USE 2007-04-08 19:06:27.000000000 +0400
> +++ 2.6.21-rc5-mm4/kernel/exit.c 2007-04-08 19:23:18.000000000 +0400
> @@ -279,28 +279,26 @@ static int has_stopped_jobs(struct pid *
> }
>
> /**
> - * reparent_to_init - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
> + * reparent_kthread - Reparent the calling kernel thread to swapper.
> *
> * If a kernel thread is launched as a result of a system call, or if
> - * it ever exits, it should generally reparent itself to init so that
> - * it is correctly cleaned up on exit.
> + * it ever exits, it should generally reparent itself so that it is
> + * correctly cleaned up on exit.
> *
> * The various task state such as scheduling policy and priority may have
> * been inherited from a user process, so we reset them to sane values here.
> *
> - * NOTE that reparent_to_init() gives the caller full capabilities.
> + * NOTE that reparent_kthread() gives the caller full capabilities.
> */
> -static void reparent_to_init(void)
> +static void reparent_kthread(void)

Thanks. The use of 'child_reaper(current)' makes it clear that
'reparent_to_init' had turned into a confusing name in the name
of per-pidspace inits.

-serge

> {
> write_lock_irq(&tasklist_lock);
>
> - /* Reparent to init */
> remove_parent(current);
> - current->parent = child_reaper(current);
> - add_parent(current);
>
> - /* Set the exit signal to SIGCHLD so we signal init on exit */
> - current->exit_signal = SIGCHLD;
> + current->parent = &init_task;
> + add_parent(current);
> + current->exit_signal = -1;
>
> if (!has_rt_policy(current) && (task_nice(current) < 0))
> set_user_nice(current, 0);
> @@ -423,7 +421,7 @@ void daemonize(const char *name, ...)
> current->files = init_task.files;
> atomic_inc(&current->files->count);
>
> - reparent_to_init();
> + reparent_kthread();
> }
>
> EXPORT_SYMBOL(daemonize);
>
> -
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