From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 16 Apr 2005 15:20:36 -0700 Subject: Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip! --- kernel/kthread.c | 202 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 202 insertions(+) create mode 100644 kernel/kthread.c (limited to 'kernel/kthread.c') diff --git a/kernel/kthread.c b/kernel/kthread.c new file mode 100644 index 0000000..e377e22 --- /dev/null +++ b/kernel/kthread.c @@ -0,0 +1,202 @@ +/* Kernel thread helper functions. + * Copyright (C) 2004 IBM Corporation, Rusty Russell. + * + * Creation is done via keventd, so that we get a clean environment + * even if we're invoked from userspace (think modprobe, hotplug cpu, + * etc.). + */ +#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; + +struct kthread_create_info +{ + /* Information passed to kthread() from keventd. */ + int (*threadfn)(void *data); + void *data; + struct completion started; + + /* Result passed back to kthread_create() from keventd. */ + struct task_struct *result; + struct completion done; +}; + +struct kthread_stop_info +{ + struct task_struct *k; + int err; + struct completion done; +}; + +/* Thread stopping is done by setthing this var: lock serializes + * multiple kthread_stop calls. */ +static DECLARE_MUTEX(kthread_stop_lock); +static struct kthread_stop_info kthread_stop_info; + +int kthread_should_stop(void) +{ + return (kthread_stop_info.k == current); +} +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) +{ + 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); + + /* By default we can run anywhere, unlike keventd. */ + set_cpus_allowed(current, CPU_MASK_ALL); + + /* OK, tell user we're spawned, wait for stop or wakeup */ + __set_current_state(TASK_INTERRUPTIBLE); + complete(&create->started); + schedule(); + + if (!kthread_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 are keventd: create a thread. */ +static void keventd_create_kthread(void *_create) +{ + struct kthread_create_info *create = _create; + 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); + create->result = find_task_by_pid(pid); + } + complete(&create->done); +} + +struct task_struct *kthread_create(int (*threadfn)(void *data), + void *data, + const char namefmt[], + ...) +{ + struct kthread_create_info create; + DECLARE_WORK(work, keventd_create_kthread, &create); + + create.threadfn = threadfn; + create.data = data; + init_completion(&create.started); + init_completion(&create.done); + + /* + * The workqueue needs to start up first: + */ + if (!helper_wq) + work.func(work.data); + else { + queue_work(helper_wq, &work); + wait_for_completion(&create.done); + } + if (!IS_ERR(create.result)) { + va_list args; + va_start(args, namefmt); + vsnprintf(create.result->comm, sizeof(create.result->comm), + namefmt, args); + va_end(args); + } + + return create.result; +} +EXPORT_SYMBOL(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); + +int kthread_stop(struct task_struct *k) +{ + int ret; + + down(&kthread_stop_lock); + + /* It could exit after stop_info.k set, but before wake_up_process. */ + get_task_struct(k); + + /* Must init completion *before* thread sees kthread_stop_info.k */ + init_completion(&kthread_stop_info.done); + wmb(); + + /* 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; + up(&kthread_stop_lock); + + return ret; +} +EXPORT_SYMBOL(kthread_stop); + +static __init int helper_init(void) +{ + helper_wq = create_singlethread_workqueue("kthread"); + BUG_ON(!helper_wq); + + return 0; +} +core_initcall(helper_init); + -- cgit v1.1