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8197b3d43b
Nothing currently prevents a work from queuing for a kthread worker when it is already running on another one. This means that the work might run in parallel on more than one worker. Also some operations are not reliable, e.g. flush. This problem will be even more visible after we add kthread_cancel_work() function. It will only have "work" as the parameter and will use worker->lock to synchronize with others. Well, normally this is not a problem because the API users are sane. But bugs might happen and users also might be crazy. This patch adds a warning when we try to insert the work for another worker. It does not fully prevent the misuse because it would make the code much more complicated without a big benefit. It adds the same warning also into kthread_flush_work() instead of the repeated attempts to get the right lock. A side effect is that one needs to explicitly reinitialize the work if it must be queued into another worker. This is needed, for example, when the worker is stopped and started again. It is a bit inconvenient. But it looks like a good compromise between the stability and complexity. I have double checked all existing users of the kthread worker API and they all seems to initialize the work after the worker gets started. Just for completeness, the patch adds a check that the work is not already in a queue. The patch also puts all the checks into a separate function. It will be reused when implementing delayed works. Link: http://lkml.kernel.org/r/1470754545-17632-8-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Borislav Petkov <bp@suse.de> Cc: Michal Hocko <mhocko@suse.cz> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
861 lines
23 KiB
C
861 lines
23 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) && try_get_task_stack(k))
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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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* kthread_probe_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 *kthread_probe_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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static 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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va_list args)
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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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vsnprintf(task->comm, sizeof(task->comm), namefmt, 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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/**
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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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struct task_struct *task;
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va_list args;
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va_start(args, namefmt);
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task = __kthread_create_on_node(threadfn, data, node, namefmt, args);
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va_end(args);
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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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kthread_bind(p, cpu);
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/* CPU hotplug need to bind once again when unparking the thread. */
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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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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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/*
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* Newly created kthread was parked when the CPU was offline.
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* The binding was lost and we need to set it again.
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*/
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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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put_task_stack(k);
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}
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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;
|
|
|
|
if (kthread) {
|
|
if (!test_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
|
|
set_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
|
|
if (k != current) {
|
|
wake_up_process(k);
|
|
wait_for_completion(&kthread->parked);
|
|
}
|
|
}
|
|
put_task_stack(k);
|
|
ret = 0;
|
|
}
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_park);
|
|
|
|
/**
|
|
* 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. 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;
|
|
|
|
trace_sched_kthread_stop(k);
|
|
|
|
get_task_struct(k);
|
|
kthread = to_live_kthread(k);
|
|
if (kthread) {
|
|
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
|
|
__kthread_unpark(k, kthread);
|
|
wake_up_process(k);
|
|
wait_for_completion(&kthread->exited);
|
|
put_task_stack(k);
|
|
}
|
|
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 __kthread_init_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(__kthread_init_worker);
|
|
|
|
/**
|
|
* kthread_worker_fn - kthread function to process kthread_worker
|
|
* @worker_ptr: pointer to initialized kthread_worker
|
|
*
|
|
* This function implements the main cycle of kthread worker. It processes
|
|
* work_list until it is stopped with kthread_stop(). It sleeps when the queue
|
|
* is empty.
|
|
*
|
|
* The works are not allowed to keep any locks, disable preemption or interrupts
|
|
* when they finish. There is defined a safe point for freezing when one work
|
|
* finishes and before a new one is started.
|
|
*
|
|
* Also the works must not be handled by more than one worker at the same time,
|
|
* see also kthread_queue_work().
|
|
*/
|
|
int kthread_worker_fn(void *worker_ptr)
|
|
{
|
|
struct kthread_worker *worker = worker_ptr;
|
|
struct kthread_work *work;
|
|
|
|
/*
|
|
* FIXME: Update the check and remove the assignment when all kthread
|
|
* worker users are created using kthread_create_worker*() functions.
|
|
*/
|
|
WARN_ON(worker->task && worker->task != current);
|
|
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);
|
|
|
|
static struct kthread_worker *
|
|
__kthread_create_worker(int cpu, const char namefmt[], va_list args)
|
|
{
|
|
struct kthread_worker *worker;
|
|
struct task_struct *task;
|
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
|
|
if (!worker)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
kthread_init_worker(worker);
|
|
|
|
if (cpu >= 0) {
|
|
char name[TASK_COMM_LEN];
|
|
|
|
/*
|
|
* kthread_create_worker_on_cpu() allows to pass a generic
|
|
* namefmt in compare with kthread_create_on_cpu. We need
|
|
* to format it here.
|
|
*/
|
|
vsnprintf(name, sizeof(name), namefmt, args);
|
|
task = kthread_create_on_cpu(kthread_worker_fn, worker,
|
|
cpu, name);
|
|
} else {
|
|
task = __kthread_create_on_node(kthread_worker_fn, worker,
|
|
-1, namefmt, args);
|
|
}
|
|
|
|
if (IS_ERR(task))
|
|
goto fail_task;
|
|
|
|
worker->task = task;
|
|
wake_up_process(task);
|
|
return worker;
|
|
|
|
fail_task:
|
|
kfree(worker);
|
|
return ERR_CAST(task);
|
|
}
|
|
|
|
/**
|
|
* kthread_create_worker - create a kthread worker
|
|
* @namefmt: printf-style name for the kthread worker (task).
|
|
*
|
|
* Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
|
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR)
|
|
* when the worker was SIGKILLed.
|
|
*/
|
|
struct kthread_worker *
|
|
kthread_create_worker(const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(-1, namefmt, args);
|
|
va_end(args);
|
|
|
|
return worker;
|
|
}
|
|
EXPORT_SYMBOL(kthread_create_worker);
|
|
|
|
/**
|
|
* kthread_create_worker_on_cpu - create a kthread worker and bind it
|
|
* it to a given CPU and the associated NUMA node.
|
|
* @cpu: CPU number
|
|
* @namefmt: printf-style name for the kthread worker (task).
|
|
*
|
|
* Use a valid CPU number if you want to bind the kthread worker
|
|
* to the given CPU and the associated NUMA node.
|
|
*
|
|
* A good practice is to add the cpu number also into the worker name.
|
|
* For example, use kthread_create_worker_on_cpu(cpu, "helper/%d", cpu).
|
|
*
|
|
* Returns a pointer to the allocated worker on success, ERR_PTR(-ENOMEM)
|
|
* when the needed structures could not get allocated, and ERR_PTR(-EINTR)
|
|
* when the worker was SIGKILLed.
|
|
*/
|
|
struct kthread_worker *
|
|
kthread_create_worker_on_cpu(int cpu, const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(cpu, namefmt, args);
|
|
va_end(args);
|
|
|
|
return worker;
|
|
}
|
|
EXPORT_SYMBOL(kthread_create_worker_on_cpu);
|
|
|
|
static void kthread_insert_work_sanity_check(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
lockdep_assert_held(&worker->lock);
|
|
WARN_ON_ONCE(!list_empty(&work->node));
|
|
/* Do not use a work with >1 worker, see kthread_queue_work() */
|
|
WARN_ON_ONCE(work->worker && work->worker != worker);
|
|
}
|
|
|
|
/* insert @work before @pos in @worker */
|
|
static void kthread_insert_work(struct kthread_worker *worker,
|
|
struct kthread_work *work,
|
|
struct list_head *pos)
|
|
{
|
|
kthread_insert_work_sanity_check(worker, work);
|
|
|
|
list_add_tail(&work->node, pos);
|
|
work->worker = worker;
|
|
if (!worker->current_work && likely(worker->task))
|
|
wake_up_process(worker->task);
|
|
}
|
|
|
|
/**
|
|
* kthread_queue_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.
|
|
*
|
|
* Reinitialize the work if it needs to be used by another worker.
|
|
* For example, when the worker was stopped and started again.
|
|
*/
|
|
bool kthread_queue_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)) {
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
ret = true;
|
|
}
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_queue_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);
|
|
}
|
|
|
|
/**
|
|
* kthread_flush_work - flush a kthread_work
|
|
* @work: work to flush
|
|
*
|
|
* If @work is queued or executing, wait for it to finish execution.
|
|
*/
|
|
void kthread_flush_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;
|
|
|
|
worker = work->worker;
|
|
if (!worker)
|
|
return;
|
|
|
|
spin_lock_irq(&worker->lock);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
if (!list_empty(&work->node))
|
|
kthread_insert_work(worker, &fwork.work, work->node.next);
|
|
else if (worker->current_work == work)
|
|
kthread_insert_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(kthread_flush_work);
|
|
|
|
/**
|
|
* kthread_flush_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 kthread_flush_worker(struct kthread_worker *worker)
|
|
{
|
|
struct kthread_flush_work fwork = {
|
|
KTHREAD_WORK_INIT(fwork.work, kthread_flush_work_fn),
|
|
COMPLETION_INITIALIZER_ONSTACK(fwork.done),
|
|
};
|
|
|
|
kthread_queue_work(worker, &fwork.work);
|
|
wait_for_completion(&fwork.done);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_flush_worker);
|
|
|
|
/**
|
|
* kthread_destroy_worker - destroy a kthread worker
|
|
* @worker: worker to be destroyed
|
|
*
|
|
* Flush and destroy @worker. The simple flush is enough because the kthread
|
|
* worker API is used only in trivial scenarios. There are no multi-step state
|
|
* machines needed.
|
|
*/
|
|
void kthread_destroy_worker(struct kthread_worker *worker)
|
|
{
|
|
struct task_struct *task;
|
|
|
|
task = worker->task;
|
|
if (WARN_ON(!task))
|
|
return;
|
|
|
|
kthread_flush_worker(worker);
|
|
kthread_stop(task);
|
|
WARN_ON(!list_empty(&worker->work_list));
|
|
kfree(worker);
|
|
}
|
|
EXPORT_SYMBOL(kthread_destroy_worker);
|