Messages in this thread | | | From | (Eric W. Biederman) | Subject | Re: [PATCH] kthread: Don't depend on work queues (take 2) | Date | Wed, 11 Apr 2007 13:40:23 -0600 |
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Oleg Nesterov <oleg@tv-sign.ru> writes:
> On 04/11, Eric W. Biederman wrote: >> >> @@ -435,8 +436,12 @@ static void __init setup_command_line(char *command_line) >> static void noinline rest_init(void) >> __releases(kernel_lock) >> { >> + int pid; >> kernel_thread(init, NULL, CLONE_FS | CLONE_SIGHAND); >> numa_default_policy(); >> + >> + pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); >> + kthreadd_task = find_task_by_pid(pid); >> unlock_kernel(); > > Just curious. What if kernel/kthread.c declares > > static struct task_struct *kthreadd_task = &init_task; > > an then kthreadd_setup() does kthreadd_task = current. I assume it is always > safe to try_to_wake_up(idle_thread), because it always TASK_RUNNING. This > way we don't need to export kthreadd_task.
I did it this way largely so I could use the export in reparent_to_XXX in daemonize. This way I don't have races in finding kthreadd. Plus I didn't think of the trick of using the idle_thread...
>> + spin_lock(&kthread_create_lock); >> + list_add_tail(&create.list, &kthread_create_list); >> + wake_up_process(kthreadd_task); >> + spin_unlock(&kthread_create_lock); > > Very minor nit, but we don't need to do wake_up under spin_unlock().
I guess that is true. However it doesn't hurt either. I guess I was keeping the form that I used with wait queues where it may have mattered. Either that or I just copied a bad example.
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