X-Git-Url: http://ftp.safe.ca/?p=safe%2Fjmp%2Flinux-2.6;a=blobdiff_plain;f=kernel%2Fkthread.c;h=ab7ae57773e1b41f263407eb4a3bad1c95b41289;hp=1db8c72d0d380c637b18e3951df45f32291ceeda;hb=9a1607071c293e48b08bd703733480b1d55c7b93;hpb=65f27f38446e1976cc98fd3004b110fedcddd189 diff --git a/kernel/kthread.c b/kernel/kthread.c index 1db8c72..ab7ae57 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1,7 +1,7 @@ /* Kernel thread helper functions. * Copyright (C) 2004 IBM Corporation, Rusty Russell. * - * Creation is done via keventd, so that we get a clean environment + * Creation is done via kthreadd, so that we get a clean environment * even if we're invoked from userspace (think modprobe, hotplug cpu, * etc.). */ @@ -9,127 +9,88 @@ #include #include #include +#include #include #include #include #include -#include +#include -/* - * We dont want to execute off keventd since it might - * hold a semaphore our callers hold too: - */ -static struct workqueue_struct *helper_wq; +static DEFINE_SPINLOCK(kthread_create_lock); +static LIST_HEAD(kthread_create_list); +struct task_struct *kthreadd_task; struct kthread_create_info { - /* Information passed to kthread() from keventd. */ + /* Information passed to kthread() from kthreadd. */ int (*threadfn)(void *data); void *data; - struct completion started; - /* Result passed back to kthread_create() from keventd. */ + /* Result passed back to kthread_create() from kthreadd. */ struct task_struct *result; struct completion done; - struct work_struct work; + struct list_head list; }; -struct kthread_stop_info -{ - struct task_struct *k; - int err; - struct completion done; +struct kthread { + int should_stop; + struct completion exited; }; -/* Thread stopping is done by setthing this var: lock serializes - * multiple kthread_stop calls. */ -static DEFINE_MUTEX(kthread_stop_lock); -static struct kthread_stop_info kthread_stop_info; +#define to_kthread(tsk) \ + container_of((tsk)->vfork_done, struct kthread, exited) /** * kthread_should_stop - should this kthread return now? * - * When someone calls kthread_stop on your kthread, it will be woken + * When someone calls kthread_stop() on your kthread, it will be woken * and this will return true. You should then return, and your return * value will be passed through to kthread_stop(). */ int kthread_should_stop(void) { - return (kthread_stop_info.k == current); + return to_kthread(current)->should_stop; } EXPORT_SYMBOL(kthread_should_stop); -static void kthread_exit_files(void) -{ - struct fs_struct *fs; - struct task_struct *tsk = current; - - exit_fs(tsk); /* current->fs->count--; */ - fs = init_task.fs; - tsk->fs = fs; - atomic_inc(&fs->count); - exit_files(tsk); - current->files = init_task.files; - atomic_inc(&tsk->files->count); -} - static int kthread(void *_create) { + /* Copy data: it's on kthread's stack */ struct kthread_create_info *create = _create; - int (*threadfn)(void *data); - void *data; - sigset_t blocked; - int ret = -EINTR; - - kthread_exit_files(); - - /* Copy data: it's on keventd's stack */ - threadfn = create->threadfn; - data = create->data; - - /* Block and flush all signals (in case we're not from keventd). */ - sigfillset(&blocked); - sigprocmask(SIG_BLOCK, &blocked, NULL); - flush_signals(current); + int (*threadfn)(void *data) = create->threadfn; + void *data = create->data; + struct kthread self; + int ret; - /* By default we can run anywhere, unlike keventd. */ - set_cpus_allowed(current, CPU_MASK_ALL); + self.should_stop = 0; + init_completion(&self.exited); + current->vfork_done = &self.exited; /* OK, tell user we're spawned, wait for stop or wakeup */ - __set_current_state(TASK_INTERRUPTIBLE); - complete(&create->started); + __set_current_state(TASK_UNINTERRUPTIBLE); + create->result = current; + complete(&create->done); schedule(); - if (!kthread_should_stop()) + ret = -EINTR; + if (!self.should_stop) ret = threadfn(data); - /* It might have exited on its own, w/o kthread_stop. Check. */ - if (kthread_should_stop()) { - kthread_stop_info.err = ret; - complete(&kthread_stop_info.done); - } - return 0; + /* we can't just return, we must preserve "self" on stack */ + do_exit(ret); } -/* We are keventd: create a thread. */ -static void keventd_create_kthread(struct work_struct *work) +static void create_kthread(struct kthread_create_info *create) { - struct kthread_create_info *create = - container_of(work, struct kthread_create_info, work); int pid; /* We want our own signal handler (we take no signals by default). */ pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD); if (pid < 0) { create->result = ERR_PTR(pid); - } else { - wait_for_completion(&create->started); - read_lock(&tasklist_lock); - create->result = find_task_by_pid(pid); - read_unlock(&tasklist_lock); + complete(&create->done); } - complete(&create->done); } /** @@ -143,7 +104,7 @@ static void keventd_create_kthread(struct work_struct *work) * it. See also kthread_run(), kthread_create_on_cpu(). * * When woken, the thread will run @threadfn() with @data as its - * argument. @threadfn can either call do_exit() directly if it is a + * argument. @threadfn() can either call do_exit() directly if it is a * standalone thread for which noone will call kthread_stop(), or * return when 'kthread_should_stop()' is true (which means * kthread_stop() has been called). The return value should be zero @@ -160,97 +121,106 @@ struct task_struct *kthread_create(int (*threadfn)(void *data), create.threadfn = threadfn; create.data = data; - init_completion(&create.started); init_completion(&create.done); - INIT_WORK(&create.work, keventd_create_kthread); - - /* - * The workqueue needs to start up first: - */ - if (!helper_wq) - create.work.func(&create.work); - else { - queue_work(helper_wq, &create.work); - wait_for_completion(&create.done); - } + + spin_lock(&kthread_create_lock); + list_add_tail(&create.list, &kthread_create_list); + spin_unlock(&kthread_create_lock); + + wake_up_process(kthreadd_task); + wait_for_completion(&create.done); + if (!IS_ERR(create.result)) { + struct sched_param param = { .sched_priority = 0 }; va_list args; + va_start(args, namefmt); vsnprintf(create.result->comm, sizeof(create.result->comm), namefmt, args); va_end(args); + /* + * root may have changed our (kthreadd's) priority or CPU mask. + * The kernel thread should not inherit these properties. + */ + sched_setscheduler_nocheck(create.result, SCHED_NORMAL, ¶m); + set_cpus_allowed_ptr(create.result, cpu_all_mask); } - return create.result; } EXPORT_SYMBOL(kthread_create); /** - * kthread_bind - bind a just-created kthread to a cpu. - * @k: thread created by kthread_create(). - * @cpu: cpu (might not be online, must be possible) for @k to run on. - * - * Description: This function is equivalent to set_cpus_allowed(), - * except that @cpu doesn't need to be online, and the thread must be - * stopped (i.e., just returned from kthread_create(). - */ -void kthread_bind(struct task_struct *k, unsigned int cpu) -{ - BUG_ON(k->state != TASK_INTERRUPTIBLE); - /* Must have done schedule() in kthread() before we set_task_cpu */ - wait_task_inactive(k); - set_task_cpu(k, cpu); - k->cpus_allowed = cpumask_of_cpu(cpu); -} -EXPORT_SYMBOL(kthread_bind); - -/** * kthread_stop - stop a thread created by kthread_create(). * @k: thread created by kthread_create(). * * Sets kthread_should_stop() for @k to return true, wakes it, and - * waits for it to exit. Your threadfn() must not call do_exit() - * itself if you use this function! This can also be called after - * kthread_create() instead of calling wake_up_process(): the thread - * will exit without calling threadfn(). + * waits for it to exit. This can also be called after kthread_create() + * instead of calling wake_up_process(): the thread will exit without + * calling threadfn(). + * + * If threadfn() may call do_exit() itself, the caller must ensure + * task_struct can't go away. * * Returns the result of threadfn(), or %-EINTR if wake_up_process() * was never called. */ int kthread_stop(struct task_struct *k) { + struct kthread *kthread; int ret; - mutex_lock(&kthread_stop_lock); - - /* It could exit after stop_info.k set, but before wake_up_process. */ + trace_sched_kthread_stop(k); get_task_struct(k); - /* Must init completion *before* thread sees kthread_stop_info.k */ - init_completion(&kthread_stop_info.done); - smp_wmb(); + kthread = to_kthread(k); + barrier(); /* it might have exited */ + if (k->vfork_done != NULL) { + kthread->should_stop = 1; + wake_up_process(k); + wait_for_completion(&kthread->exited); + } + ret = k->exit_code; - /* Now set kthread_should_stop() to true, and wake it up. */ - kthread_stop_info.k = k; - wake_up_process(k); put_task_struct(k); - - /* Once it dies, reset stop ptr, gather result and we're done. */ - wait_for_completion(&kthread_stop_info.done); - kthread_stop_info.k = NULL; - ret = kthread_stop_info.err; - mutex_unlock(&kthread_stop_lock); + trace_sched_kthread_stop_ret(ret); return ret; } EXPORT_SYMBOL(kthread_stop); -static __init int helper_init(void) +int kthreadd(void *unused) { - helper_wq = create_singlethread_workqueue("kthread"); - BUG_ON(!helper_wq); + struct task_struct *tsk = current; + + /* Setup a clean context for our children to inherit. */ + set_task_comm(tsk, "kthreadd"); + ignore_signals(tsk); + set_cpus_allowed_ptr(tsk, cpu_all_mask); + set_mems_allowed(node_possible_map); + + current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG; + + for (;;) { + set_current_state(TASK_INTERRUPTIBLE); + if (list_empty(&kthread_create_list)) + schedule(); + __set_current_state(TASK_RUNNING); + + spin_lock(&kthread_create_lock); + while (!list_empty(&kthread_create_list)) { + struct kthread_create_info *create; + + create = list_entry(kthread_create_list.next, + struct kthread_create_info, list); + list_del_init(&create->list); + spin_unlock(&kthread_create_lock); + + create_kthread(create); + + spin_lock(&kthread_create_lock); + } + spin_unlock(&kthread_create_lock); + } return 0; } - -core_initcall(helper_init);