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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Andrew Morton](/assets/img/avatar_default.png)
- Make it clear that the `node' arg refers to memory allocations only: kthread_create_on_node() does not pin the new thread to that node's CPUs. - Encourage the use of NUMA_NO_NODE. [nzimmer@sgi.com: use NUMA_NO_NODE in kthread_create() also] Cc: Nathan Zimmer <nzimmer@sgi.com> Cc: Tejun Heo <tj@kernel.org> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
711 lines
19 KiB
C
711 lines
19 KiB
C
/* Kernel thread helper functions.
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* Copyright (C) 2004 IBM Corporation, Rusty Russell.
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*
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* Creation is done via kthreadd, so that we get a clean environment
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* even if we're invoked from userspace (think modprobe, hotplug cpu,
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* etc.).
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*/
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#include <linux/sched.h>
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#include <linux/kthread.h>
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#include <linux/completion.h>
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#include <linux/err.h>
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#include <linux/cpuset.h>
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#include <linux/unistd.h>
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#include <linux/file.h>
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#include <linux/export.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/freezer.h>
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#include <linux/ptrace.h>
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#include <linux/uaccess.h>
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#include <trace/events/sched.h>
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static DEFINE_SPINLOCK(kthread_create_lock);
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static LIST_HEAD(kthread_create_list);
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struct task_struct *kthreadd_task;
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struct kthread_create_info
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{
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/* Information passed to kthread() from kthreadd. */
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int (*threadfn)(void *data);
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void *data;
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int node;
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/* Result passed back to kthread_create() from kthreadd. */
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struct task_struct *result;
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struct completion *done;
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struct list_head list;
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};
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struct kthread {
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unsigned long flags;
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unsigned int cpu;
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void *data;
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struct completion parked;
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struct completion exited;
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};
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enum KTHREAD_BITS {
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KTHREAD_IS_PER_CPU = 0,
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KTHREAD_SHOULD_STOP,
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KTHREAD_SHOULD_PARK,
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KTHREAD_IS_PARKED,
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};
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#define __to_kthread(vfork) \
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container_of(vfork, struct kthread, exited)
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static inline struct kthread *to_kthread(struct task_struct *k)
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{
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return __to_kthread(k->vfork_done);
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}
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static struct kthread *to_live_kthread(struct task_struct *k)
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{
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struct completion *vfork = ACCESS_ONCE(k->vfork_done);
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if (likely(vfork))
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return __to_kthread(vfork);
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return NULL;
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}
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/**
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* kthread_should_stop - should this kthread return now?
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*
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* When someone calls kthread_stop() on your kthread, it will be woken
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* and this will return true. You should then return, and your return
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* value will be passed through to kthread_stop().
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*/
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bool kthread_should_stop(void)
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{
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return test_bit(KTHREAD_SHOULD_STOP, &to_kthread(current)->flags);
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}
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EXPORT_SYMBOL(kthread_should_stop);
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/**
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* kthread_should_park - should this kthread park now?
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*
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* When someone calls kthread_park() on your kthread, it will be woken
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* and this will return true. You should then do the necessary
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* cleanup and call kthread_parkme()
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*
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* Similar to kthread_should_stop(), but this keeps the thread alive
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* and in a park position. kthread_unpark() "restarts" the thread and
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* calls the thread function again.
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*/
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bool kthread_should_park(void)
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{
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return test_bit(KTHREAD_SHOULD_PARK, &to_kthread(current)->flags);
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}
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EXPORT_SYMBOL_GPL(kthread_should_park);
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/**
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* kthread_freezable_should_stop - should this freezable kthread return now?
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* @was_frozen: optional out parameter, indicates whether %current was frozen
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*
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* kthread_should_stop() for freezable kthreads, which will enter
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* refrigerator if necessary. This function is safe from kthread_stop() /
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* freezer deadlock and freezable kthreads should use this function instead
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* of calling try_to_freeze() directly.
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*/
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bool kthread_freezable_should_stop(bool *was_frozen)
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{
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bool frozen = false;
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might_sleep();
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if (unlikely(freezing(current)))
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frozen = __refrigerator(true);
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if (was_frozen)
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*was_frozen = frozen;
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return kthread_should_stop();
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}
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EXPORT_SYMBOL_GPL(kthread_freezable_should_stop);
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/**
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* kthread_data - return data value specified on kthread creation
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* @task: kthread task in question
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*
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* Return the data value specified when kthread @task was created.
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* The caller is responsible for ensuring the validity of @task when
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* calling this function.
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*/
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void *kthread_data(struct task_struct *task)
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{
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return to_kthread(task)->data;
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}
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/**
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* probe_kthread_data - speculative version of kthread_data()
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* @task: possible kthread task in question
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*
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* @task could be a kthread task. Return the data value specified when it
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* was created if accessible. If @task isn't a kthread task or its data is
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* inaccessible for any reason, %NULL is returned. This function requires
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* that @task itself is safe to dereference.
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*/
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void *probe_kthread_data(struct task_struct *task)
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{
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struct kthread *kthread = to_kthread(task);
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void *data = NULL;
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probe_kernel_read(&data, &kthread->data, sizeof(data));
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return data;
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}
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static void __kthread_parkme(struct kthread *self)
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{
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__set_current_state(TASK_PARKED);
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while (test_bit(KTHREAD_SHOULD_PARK, &self->flags)) {
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if (!test_and_set_bit(KTHREAD_IS_PARKED, &self->flags))
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complete(&self->parked);
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schedule();
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__set_current_state(TASK_PARKED);
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}
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clear_bit(KTHREAD_IS_PARKED, &self->flags);
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__set_current_state(TASK_RUNNING);
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}
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void kthread_parkme(void)
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{
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__kthread_parkme(to_kthread(current));
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}
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EXPORT_SYMBOL_GPL(kthread_parkme);
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static int kthread(void *_create)
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{
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/* Copy data: it's on kthread's stack */
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struct kthread_create_info *create = _create;
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int (*threadfn)(void *data) = create->threadfn;
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void *data = create->data;
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struct completion *done;
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struct kthread self;
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int ret;
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self.flags = 0;
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self.data = data;
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init_completion(&self.exited);
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init_completion(&self.parked);
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current->vfork_done = &self.exited;
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/* If user was SIGKILLed, I release the structure. */
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done = xchg(&create->done, NULL);
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if (!done) {
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kfree(create);
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do_exit(-EINTR);
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}
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/* OK, tell user we're spawned, wait for stop or wakeup */
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__set_current_state(TASK_UNINTERRUPTIBLE);
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create->result = current;
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complete(done);
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schedule();
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ret = -EINTR;
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if (!test_bit(KTHREAD_SHOULD_STOP, &self.flags)) {
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__kthread_parkme(&self);
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ret = threadfn(data);
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}
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/* we can't just return, we must preserve "self" on stack */
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do_exit(ret);
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}
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/* called from do_fork() to get node information for about to be created task */
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int tsk_fork_get_node(struct task_struct *tsk)
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{
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#ifdef CONFIG_NUMA
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if (tsk == kthreadd_task)
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return tsk->pref_node_fork;
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#endif
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return NUMA_NO_NODE;
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}
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static void create_kthread(struct kthread_create_info *create)
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{
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int pid;
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#ifdef CONFIG_NUMA
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current->pref_node_fork = create->node;
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#endif
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/* We want our own signal handler (we take no signals by default). */
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pid = kernel_thread(kthread, create, CLONE_FS | CLONE_FILES | SIGCHLD);
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if (pid < 0) {
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/* If user was SIGKILLed, I release the structure. */
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struct completion *done = xchg(&create->done, NULL);
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if (!done) {
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kfree(create);
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return;
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}
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create->result = ERR_PTR(pid);
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complete(done);
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}
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}
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/**
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* kthread_create_on_node - create a kthread.
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* @threadfn: the function to run until signal_pending(current).
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* @data: data ptr for @threadfn.
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* @node: task and thread structures for the thread are allocated on this node
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* @namefmt: printf-style name for the thread.
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*
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* Description: This helper function creates and names a kernel
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* thread. The thread will be stopped: use wake_up_process() to start
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* it. See also kthread_run(). The new thread has SCHED_NORMAL policy and
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* is affine to all CPUs.
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*
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* If thread is going to be bound on a particular cpu, give its node
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* in @node, to get NUMA affinity for kthread stack, or else give NUMA_NO_NODE.
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* When woken, the thread will run @threadfn() with @data as its
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* argument. @threadfn() can either call do_exit() directly if it is a
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* standalone thread for which no one will call kthread_stop(), or
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* return when 'kthread_should_stop()' is true (which means
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* kthread_stop() has been called). The return value should be zero
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* or a negative error number; it will be passed to kthread_stop().
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*
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* Returns a task_struct or ERR_PTR(-ENOMEM) or ERR_PTR(-EINTR).
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*/
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struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
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void *data, int node,
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const char namefmt[],
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...)
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{
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DECLARE_COMPLETION_ONSTACK(done);
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struct task_struct *task;
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struct kthread_create_info *create = kmalloc(sizeof(*create),
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GFP_KERNEL);
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if (!create)
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return ERR_PTR(-ENOMEM);
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create->threadfn = threadfn;
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create->data = data;
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create->node = node;
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create->done = &done;
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spin_lock(&kthread_create_lock);
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list_add_tail(&create->list, &kthread_create_list);
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spin_unlock(&kthread_create_lock);
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wake_up_process(kthreadd_task);
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/*
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* Wait for completion in killable state, for I might be chosen by
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* the OOM killer while kthreadd is trying to allocate memory for
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* new kernel thread.
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*/
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if (unlikely(wait_for_completion_killable(&done))) {
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/*
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* If I was SIGKILLed before kthreadd (or new kernel thread)
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* calls complete(), leave the cleanup of this structure to
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* that thread.
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*/
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if (xchg(&create->done, NULL))
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return ERR_PTR(-EINTR);
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/*
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* kthreadd (or new kernel thread) will call complete()
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* shortly.
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*/
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wait_for_completion(&done);
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}
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task = create->result;
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if (!IS_ERR(task)) {
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static const struct sched_param param = { .sched_priority = 0 };
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va_list args;
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va_start(args, namefmt);
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vsnprintf(task->comm, sizeof(task->comm), namefmt, args);
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va_end(args);
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/*
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* root may have changed our (kthreadd's) priority or CPU mask.
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* The kernel thread should not inherit these properties.
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*/
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sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m);
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set_cpus_allowed_ptr(task, cpu_all_mask);
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}
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kfree(create);
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return task;
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}
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EXPORT_SYMBOL(kthread_create_on_node);
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static void __kthread_bind_mask(struct task_struct *p, const struct cpumask *mask, long state)
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{
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unsigned long flags;
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if (!wait_task_inactive(p, state)) {
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WARN_ON(1);
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return;
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}
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/* It's safe because the task is inactive. */
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raw_spin_lock_irqsave(&p->pi_lock, flags);
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do_set_cpus_allowed(p, mask);
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p->flags |= PF_NO_SETAFFINITY;
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raw_spin_unlock_irqrestore(&p->pi_lock, flags);
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}
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static void __kthread_bind(struct task_struct *p, unsigned int cpu, long state)
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{
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__kthread_bind_mask(p, cpumask_of(cpu), state);
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}
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void kthread_bind_mask(struct task_struct *p, const struct cpumask *mask)
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{
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__kthread_bind_mask(p, mask, TASK_UNINTERRUPTIBLE);
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}
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/**
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* kthread_bind - bind a just-created kthread to a cpu.
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* @p: thread created by kthread_create().
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* @cpu: cpu (might not be online, must be possible) for @k to run on.
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*
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* Description: This function is equivalent to set_cpus_allowed(),
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* except that @cpu doesn't need to be online, and the thread must be
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* stopped (i.e., just returned from kthread_create()).
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*/
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void kthread_bind(struct task_struct *p, unsigned int cpu)
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{
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__kthread_bind(p, cpu, TASK_UNINTERRUPTIBLE);
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}
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EXPORT_SYMBOL(kthread_bind);
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/**
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* kthread_create_on_cpu - Create a cpu bound kthread
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* @threadfn: the function to run until signal_pending(current).
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* @data: data ptr for @threadfn.
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* @cpu: The cpu on which the thread should be bound,
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* @namefmt: printf-style name for the thread. Format is restricted
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* to "name.*%u". Code fills in cpu number.
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*
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* Description: This helper function creates and names a kernel thread
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* The thread will be woken and put into park mode.
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*/
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struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
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void *data, unsigned int cpu,
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const char *namefmt)
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{
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struct task_struct *p;
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p = kthread_create_on_node(threadfn, data, cpu_to_node(cpu), namefmt,
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cpu);
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if (IS_ERR(p))
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return p;
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set_bit(KTHREAD_IS_PER_CPU, &to_kthread(p)->flags);
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to_kthread(p)->cpu = cpu;
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/* Park the thread to get it out of TASK_UNINTERRUPTIBLE state */
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kthread_park(p);
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return p;
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}
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static void __kthread_unpark(struct task_struct *k, struct kthread *kthread)
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{
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clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
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/*
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* We clear the IS_PARKED bit here as we don't wait
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* until the task has left the park code. So if we'd
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* park before that happens we'd see the IS_PARKED bit
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* which might be about to be cleared.
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*/
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if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
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if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
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__kthread_bind(k, kthread->cpu, TASK_PARKED);
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wake_up_state(k, TASK_PARKED);
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}
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}
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/**
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* kthread_unpark - unpark a thread created by kthread_create().
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* @k: thread created by kthread_create().
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*
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* Sets kthread_should_park() for @k to return false, wakes it, and
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* waits for it to return. If the thread is marked percpu then its
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* bound to the cpu again.
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*/
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void kthread_unpark(struct task_struct *k)
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{
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struct kthread *kthread = to_live_kthread(k);
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if (kthread)
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__kthread_unpark(k, kthread);
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}
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EXPORT_SYMBOL_GPL(kthread_unpark);
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/**
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* kthread_park - park a thread created by kthread_create().
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* @k: thread created by kthread_create().
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*
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* Sets kthread_should_park() for @k to return true, wakes it, and
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* waits for it to return. This can also be called after kthread_create()
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* instead of calling wake_up_process(): the thread will park without
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* calling threadfn().
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*
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* Returns 0 if the thread is parked, -ENOSYS if the thread exited.
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* If called by the kthread itself just the park bit is set.
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*/
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int kthread_park(struct task_struct *k)
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{
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struct kthread *kthread = to_live_kthread(k);
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int ret = -ENOSYS;
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if (kthread) {
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if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
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set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
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if (k != current) {
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wake_up_process(k);
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wait_for_completion(&kthread->parked);
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}
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}
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ret = 0;
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}
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return ret;
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}
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EXPORT_SYMBOL_GPL(kthread_park);
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/**
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* kthread_stop - stop a thread created by kthread_create().
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* @k: thread created by kthread_create().
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*
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* Sets kthread_should_stop() for @k to return true, wakes it, and
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* waits for it to exit. This can also be called after kthread_create()
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* instead of calling wake_up_process(): the thread will exit without
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* calling threadfn().
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*
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* If threadfn() may call do_exit() itself, the caller must ensure
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* task_struct can't go away.
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*
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* Returns the result of threadfn(), or %-EINTR if wake_up_process()
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* was never called.
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*/
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int kthread_stop(struct task_struct *k)
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{
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struct kthread *kthread;
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int ret;
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trace_sched_kthread_stop(k);
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get_task_struct(k);
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kthread = to_live_kthread(k);
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if (kthread) {
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set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
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__kthread_unpark(k, kthread);
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wake_up_process(k);
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wait_for_completion(&kthread->exited);
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}
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ret = k->exit_code;
|
|
put_task_struct(k);
|
|
|
|
trace_sched_kthread_stop_ret(ret);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL(kthread_stop);
|
|
|
|
int kthreadd(void *unused)
|
|
{
|
|
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_states[N_MEMORY]);
|
|
|
|
current->flags |= PF_NOFREEZE;
|
|
|
|
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;
|
|
}
|
|
|
|
void __init_kthread_worker(struct kthread_worker *worker,
|
|
const char *name,
|
|
struct lock_class_key *key)
|
|
{
|
|
spin_lock_init(&worker->lock);
|
|
lockdep_set_class_and_name(&worker->lock, key, name);
|
|
INIT_LIST_HEAD(&worker->work_list);
|
|
worker->task = NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(__init_kthread_worker);
|
|
|
|
/**
|
|
* kthread_worker_fn - kthread function to process kthread_worker
|
|
* @worker_ptr: pointer to initialized kthread_worker
|
|
*
|
|
* This function can be used as @threadfn to kthread_create() or
|
|
* kthread_run() with @worker_ptr argument pointing to an initialized
|
|
* kthread_worker. The started kthread will process work_list until
|
|
* the it is stopped with kthread_stop(). A kthread can also call
|
|
* this function directly after extra initialization.
|
|
*
|
|
* Different kthreads can be used for the same kthread_worker as long
|
|
* as there's only one kthread attached to it at any given time. A
|
|
* kthread_worker without an attached kthread simply collects queued
|
|
* kthread_works.
|
|
*/
|
|
int kthread_worker_fn(void *worker_ptr)
|
|
{
|
|
struct kthread_worker *worker = worker_ptr;
|
|
struct kthread_work *work;
|
|
|
|
WARN_ON(worker->task);
|
|
worker->task = current;
|
|
repeat:
|
|
set_current_state(TASK_INTERRUPTIBLE); /* mb paired w/ kthread_stop */
|
|
|
|
if (kthread_should_stop()) {
|
|
__set_current_state(TASK_RUNNING);
|
|
spin_lock_irq(&worker->lock);
|
|
worker->task = NULL;
|
|
spin_unlock_irq(&worker->lock);
|
|
return 0;
|
|
}
|
|
|
|
work = NULL;
|
|
spin_lock_irq(&worker->lock);
|
|
if (!list_empty(&worker->work_list)) {
|
|
work = list_first_entry(&worker->work_list,
|
|
struct kthread_work, node);
|
|
list_del_init(&work->node);
|
|
}
|
|
worker->current_work = work;
|
|
spin_unlock_irq(&worker->lock);
|
|
|
|
if (work) {
|
|
__set_current_state(TASK_RUNNING);
|
|
work->func(work);
|
|
} else if (!freezing(current))
|
|
schedule();
|
|
|
|
try_to_freeze();
|
|
goto repeat;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_worker_fn);
|
|
|
|
/* insert @work before @pos in @worker */
|
|
static void insert_kthread_work(struct kthread_worker *worker,
|
|
struct kthread_work *work,
|
|
struct list_head *pos)
|
|
{
|
|
lockdep_assert_held(&worker->lock);
|
|
|
|
list_add_tail(&work->node, pos);
|
|
work->worker = worker;
|
|
if (!worker->current_work && likely(worker->task))
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
/**
|
|
* queue_kthread_work - queue a kthread_work
|
|
* @worker: target kthread_worker
|
|
* @work: kthread_work to queue
|
|
*
|
|
* Queue @work to work processor @task for async execution. @task
|
|
* must have been created with kthread_worker_create(). Returns %true
|
|
* if @work was successfully queued, %false if it was already pending.
|
|
*/
|
|
bool queue_kthread_work(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
bool ret = false;
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
if (list_empty(&work->node)) {
|
|
insert_kthread_work(worker, work, &worker->work_list);
|
|
ret = true;
|
|
}
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(queue_kthread_work);
|
|
|
|
struct kthread_flush_work {
|
|
struct kthread_work work;
|
|
struct completion done;
|
|
};
|
|
|
|
static void kthread_flush_work_fn(struct kthread_work *work)
|
|
{
|
|
struct kthread_flush_work *fwork =
|
|
container_of(work, struct kthread_flush_work, work);
|
|
complete(&fwork->done);
|
|
}
|
|
|
|
/**
|
|
* flush_kthread_work - flush a kthread_work
|
|
* @work: work to flush
|
|
*
|
|
* If @work is queued or executing, wait for it to finish execution.
|
|
*/
|
|
void flush_kthread_work(struct kthread_work *work)
|
|
{
|
|
struct kthread_flush_work fwork = {
|
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
|
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done),
|
|
};
|
|
struct kthread_worker *worker;
|
|
bool noop = false;
|
|
|
|
retry:
|
|
worker = work->worker;
|
|
if (!worker)
|
|
return;
|
|
|
|
spin_lock_irq(&worker->lock);
|
|
if (work->worker != worker) {
|
|
spin_unlock_irq(&worker->lock);
|
|
goto retry;
|
|
}
|
|
|
|
if (!list_empty(&work->node))
|
|
insert_kthread_work(worker, &fwork.work, work->node.next);
|
|
else if (worker->current_work == work)
|
|
insert_kthread_work(worker, &fwork.work, worker->work_list.next);
|
|
else
|
|
noop = true;
|
|
|
|
spin_unlock_irq(&worker->lock);
|
|
|
|
if (!noop)
|
|
wait_for_completion(&fwork.done);
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_kthread_work);
|
|
|
|
/**
|
|
* flush_kthread_worker - flush all current works on a kthread_worker
|
|
* @worker: worker to flush
|
|
*
|
|
* Wait until all currently executing or pending works on @worker are
|
|
* finished.
|
|
*/
|
|
void flush_kthread_worker(struct kthread_worker *worker)
|
|
{
|
|
struct kthread_flush_work fwork = {
|
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
|
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done),
|
|
};
|
|
|
|
queue_kthread_work(worker, &fwork.work);
|
|
wait_for_completion(&fwork.done);
|
|
}
|
|
EXPORT_SYMBOL_GPL(flush_kthread_worker);
|