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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Petr Mladek](/assets/img/avatar_default.png)
commit5fa54346ca
upstream. The system might hang with the following backtrace: schedule+0x80/0x100 schedule_timeout+0x48/0x138 wait_for_common+0xa4/0x134 wait_for_completion+0x1c/0x2c kthread_flush_work+0x114/0x1cc kthread_cancel_work_sync.llvm.16514401384283632983+0xe8/0x144 kthread_cancel_delayed_work_sync+0x18/0x2c xxxx_pm_notify+0xb0/0xd8 blocking_notifier_call_chain_robust+0x80/0x194 pm_notifier_call_chain_robust+0x28/0x4c suspend_prepare+0x40/0x260 enter_state+0x80/0x3f4 pm_suspend+0x60/0xdc state_store+0x108/0x144 kobj_attr_store+0x38/0x88 sysfs_kf_write+0x64/0xc0 kernfs_fop_write_iter+0x108/0x1d0 vfs_write+0x2f4/0x368 ksys_write+0x7c/0xec It is caused by the following race between kthread_mod_delayed_work() and kthread_cancel_delayed_work_sync(): CPU0 CPU1 Context: Thread A Context: Thread B kthread_mod_delayed_work() spin_lock() __kthread_cancel_work() spin_unlock() del_timer_sync() kthread_cancel_delayed_work_sync() spin_lock() __kthread_cancel_work() spin_unlock() del_timer_sync() spin_lock() work->canceling++ spin_unlock spin_lock() queue_delayed_work() // dwork is put into the worker->delayed_work_list spin_unlock() kthread_flush_work() // flush_work is put at the tail of the dwork wait_for_completion() Context: IRQ kthread_delayed_work_timer_fn() spin_lock() list_del_init(&work->node); spin_unlock() BANG: flush_work is not longer linked and will never get proceed. The problem is that kthread_mod_delayed_work() checks work->canceling flag before canceling the timer. A simple solution is to (re)check work->canceling after __kthread_cancel_work(). But then it is not clear what should be returned when __kthread_cancel_work() removed the work from the queue (list) and it can't queue it again with the new @delay. The return value might be used for reference counting. The caller has to know whether a new work has been queued or an existing one was replaced. The proper solution is that kthread_mod_delayed_work() will remove the work from the queue (list) _only_ when work->canceling is not set. The flag must be checked after the timer is stopped and the remaining operations can be done under worker->lock. Note that kthread_mod_delayed_work() could remove the timer and then bail out. It is fine. The other canceling caller needs to cancel the timer as well. The important thing is that the queue (list) manipulation is done atomically under worker->lock. Link: https://lkml.kernel.org/r/20210610133051.15337-3-pmladek@suse.com Fixes:9a6b06c8d9
("kthread: allow to modify delayed kthread work") Signed-off-by: Petr Mladek <pmladek@suse.com> Reported-by: Martin Liu <liumartin@google.com> Cc: <jenhaochen@google.com> Cc: Minchan Kim <minchan@google.com> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1214 lines
34 KiB
C
1214 lines
34 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 <uapi/linux/sched/types.h>
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#include <linux/sched.h>
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#include <linux/sched/task.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 <linux/cgroup.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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static inline void set_kthread_struct(void *kthread)
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{
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/*
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* We abuse ->set_child_tid to avoid the new member and because it
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* can't be wrongly copied by copy_process(). We also rely on fact
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* that the caller can't exec, so PF_KTHREAD can't be cleared.
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*/
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current->set_child_tid = (__force void __user *)kthread;
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}
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static inline struct kthread *to_kthread(struct task_struct *k)
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{
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WARN_ON(!(k->flags & PF_KTHREAD));
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return (__force void *)k->set_child_tid;
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}
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void free_kthread_struct(struct task_struct *k)
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{
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/*
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* Can be NULL if this kthread was created by kernel_thread()
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* or if kmalloc() in kthread() failed.
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*/
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kfree(to_kthread(k));
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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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for (;;) {
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set_current_state(TASK_PARKED);
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if (!test_bit(KTHREAD_SHOULD_PARK, &self->flags))
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break;
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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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}
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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 = kmalloc(sizeof(*self), GFP_KERNEL);
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set_kthread_struct(self);
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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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if (!self) {
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create->result = ERR_PTR(-ENOMEM);
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complete(done);
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do_exit(-ENOMEM);
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}
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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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/* 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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cgroup_kthread_ready();
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__kthread_parkme(self);
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ret = threadfn(data);
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}
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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 __printf(4, 0)
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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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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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char name[TASK_COMM_LEN];
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/*
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* task is already visible to other tasks, so updating
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* COMM must be protected.
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*/
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vsnprintf(name, sizeof(name), namefmt, args);
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set_task_comm(task, name);
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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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to_kthread(p)->cpu = cpu;
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return p;
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}
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void kthread_set_per_cpu(struct task_struct *k, int cpu)
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{
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struct kthread *kthread = to_kthread(k);
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if (!kthread)
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return;
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WARN_ON_ONCE(!(k->flags & PF_NO_SETAFFINITY));
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|
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if (cpu < 0) {
|
|
clear_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
|
|
return;
|
|
}
|
|
|
|
kthread->cpu = cpu;
|
|
set_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
|
|
}
|
|
|
|
bool kthread_is_per_cpu(struct task_struct *k)
|
|
{
|
|
struct kthread *kthread = to_kthread(k);
|
|
if (!kthread)
|
|
return false;
|
|
|
|
return test_bit(KTHREAD_IS_PER_CPU, &kthread->flags);
|
|
}
|
|
|
|
/**
|
|
* kthread_unpark - unpark a thread created by kthread_create().
|
|
* @k: thread created by kthread_create().
|
|
*
|
|
* Sets kthread_should_park() for @k to return false, wakes it, and
|
|
* waits for it to return. If the thread is marked percpu then its
|
|
* bound to the cpu again.
|
|
*/
|
|
void kthread_unpark(struct task_struct *k)
|
|
{
|
|
struct kthread *kthread = to_kthread(k);
|
|
|
|
clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags);
|
|
/*
|
|
* We clear the IS_PARKED bit here as we don't wait
|
|
* until the task has left the park code. So if we'd
|
|
* park before that happens we'd see the IS_PARKED bit
|
|
* which might be about to be cleared.
|
|
*/
|
|
if (test_and_clear_bit(KTHREAD_IS_PARKED, &kthread->flags)) {
|
|
/*
|
|
* Newly created kthread was parked when the CPU was offline.
|
|
* The binding was lost and we need to set it again.
|
|
*/
|
|
if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags))
|
|
__kthread_bind(k, kthread->cpu, TASK_PARKED);
|
|
wake_up_state(k, TASK_PARKED);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_unpark);
|
|
|
|
/**
|
|
* kthread_park - park a thread created by kthread_create().
|
|
* @k: thread created by kthread_create().
|
|
*
|
|
* Sets kthread_should_park() for @k to return true, wakes it, and
|
|
* waits for it to return. This can also be called after kthread_create()
|
|
* instead of calling wake_up_process(): the thread will park without
|
|
* calling threadfn().
|
|
*
|
|
* Returns 0 if the thread is parked, -ENOSYS if the thread exited.
|
|
* If called by the kthread itself just the park bit is set.
|
|
*/
|
|
int kthread_park(struct task_struct *k)
|
|
{
|
|
struct kthread *kthread = to_kthread(k);
|
|
|
|
if (WARN_ON(k->flags & PF_EXITING))
|
|
return -ENOSYS;
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
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_kthread(k);
|
|
set_bit(KTHREAD_SHOULD_STOP, &kthread->flags);
|
|
kthread_unpark(k);
|
|
wake_up_process(k);
|
|
wait_for_completion(&kthread->exited);
|
|
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;
|
|
cgroup_init_kthreadd();
|
|
|
|
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)
|
|
{
|
|
memset(worker, 0, sizeof(struct kthread_worker));
|
|
spin_lock_init(&worker->lock);
|
|
lockdep_set_class_and_name(&worker->lock, key, name);
|
|
INIT_LIST_HEAD(&worker->work_list);
|
|
INIT_LIST_HEAD(&worker->delayed_work_list);
|
|
}
|
|
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;
|
|
|
|
if (worker->flags & KTW_FREEZABLE)
|
|
set_freezable();
|
|
|
|
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();
|
|
cond_resched();
|
|
goto repeat;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_worker_fn);
|
|
|
|
static __printf(3, 0) struct kthread_worker *
|
|
__kthread_create_worker(int cpu, unsigned int flags,
|
|
const char namefmt[], va_list args)
|
|
{
|
|
struct kthread_worker *worker;
|
|
struct task_struct *task;
|
|
int node = -1;
|
|
|
|
worker = kzalloc(sizeof(*worker), GFP_KERNEL);
|
|
if (!worker)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
kthread_init_worker(worker);
|
|
|
|
if (cpu >= 0)
|
|
node = cpu_to_node(cpu);
|
|
|
|
task = __kthread_create_on_node(kthread_worker_fn, worker,
|
|
node, namefmt, args);
|
|
if (IS_ERR(task))
|
|
goto fail_task;
|
|
|
|
if (cpu >= 0)
|
|
kthread_bind(task, cpu);
|
|
|
|
worker->flags = flags;
|
|
worker->task = task;
|
|
wake_up_process(task);
|
|
return worker;
|
|
|
|
fail_task:
|
|
kfree(worker);
|
|
return ERR_CAST(task);
|
|
}
|
|
|
|
/**
|
|
* kthread_create_worker - create a kthread worker
|
|
* @flags: flags modifying the default behavior of the 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(unsigned int flags, const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(-1, flags, 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
|
|
* @flags: flags modifying the default behavior of the worker
|
|
* @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, unsigned int flags,
|
|
const char namefmt[], ...)
|
|
{
|
|
struct kthread_worker *worker;
|
|
va_list args;
|
|
|
|
va_start(args, namefmt);
|
|
worker = __kthread_create_worker(cpu, flags, namefmt, args);
|
|
va_end(args);
|
|
|
|
return worker;
|
|
}
|
|
EXPORT_SYMBOL(kthread_create_worker_on_cpu);
|
|
|
|
/*
|
|
* Returns true when the work could not be queued at the moment.
|
|
* It happens when it is already pending in a worker list
|
|
* or when it is being cancelled.
|
|
*/
|
|
static inline bool queuing_blocked(struct kthread_worker *worker,
|
|
struct kthread_work *work)
|
|
{
|
|
lockdep_assert_held(&worker->lock);
|
|
|
|
return !list_empty(&work->node) || work->canceling;
|
|
}
|
|
|
|
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 (!queuing_blocked(worker, work)) {
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
ret = true;
|
|
}
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_queue_work);
|
|
|
|
/**
|
|
* kthread_delayed_work_timer_fn - callback that queues the associated kthread
|
|
* delayed work when the timer expires.
|
|
* @__data: pointer to the data associated with the timer
|
|
*
|
|
* The format of the function is defined by struct timer_list.
|
|
* It should have been called from irqsafe timer with irq already off.
|
|
*/
|
|
void kthread_delayed_work_timer_fn(unsigned long __data)
|
|
{
|
|
struct kthread_delayed_work *dwork =
|
|
(struct kthread_delayed_work *)__data;
|
|
struct kthread_work *work = &dwork->work;
|
|
struct kthread_worker *worker = work->worker;
|
|
|
|
/*
|
|
* This might happen when a pending work is reinitialized.
|
|
* It means that it is used a wrong way.
|
|
*/
|
|
if (WARN_ON_ONCE(!worker))
|
|
return;
|
|
|
|
spin_lock(&worker->lock);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
/* Move the work from worker->delayed_work_list. */
|
|
WARN_ON_ONCE(list_empty(&work->node));
|
|
list_del_init(&work->node);
|
|
if (!work->canceling)
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
|
|
spin_unlock(&worker->lock);
|
|
}
|
|
EXPORT_SYMBOL(kthread_delayed_work_timer_fn);
|
|
|
|
void __kthread_queue_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct timer_list *timer = &dwork->timer;
|
|
struct kthread_work *work = &dwork->work;
|
|
|
|
WARN_ON_ONCE(timer->function != kthread_delayed_work_timer_fn ||
|
|
timer->data != (unsigned long)dwork);
|
|
|
|
/*
|
|
* If @delay is 0, queue @dwork->work immediately. This is for
|
|
* both optimization and correctness. The earliest @timer can
|
|
* expire is on the closest next tick and delayed_work users depend
|
|
* on that there's no such delay when @delay is 0.
|
|
*/
|
|
if (!delay) {
|
|
kthread_insert_work(worker, work, &worker->work_list);
|
|
return;
|
|
}
|
|
|
|
/* Be paranoid and try to detect possible races already now. */
|
|
kthread_insert_work_sanity_check(worker, work);
|
|
|
|
list_add(&work->node, &worker->delayed_work_list);
|
|
work->worker = worker;
|
|
timer->expires = jiffies + delay;
|
|
add_timer(timer);
|
|
}
|
|
|
|
/**
|
|
* kthread_queue_delayed_work - queue the associated kthread work
|
|
* after a delay.
|
|
* @worker: target kthread_worker
|
|
* @dwork: kthread_delayed_work to queue
|
|
* @delay: number of jiffies to wait before queuing
|
|
*
|
|
* If the work has not been pending it starts a timer that will queue
|
|
* the work after the given @delay. If @delay is zero, it queues the
|
|
* work immediately.
|
|
*
|
|
* Return: %false if the @work has already been pending. It means that
|
|
* either the timer was running or the work was queued. It returns %true
|
|
* otherwise.
|
|
*/
|
|
bool kthread_queue_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct kthread_work *work = &dwork->work;
|
|
unsigned long flags;
|
|
bool ret = false;
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
|
|
if (!queuing_blocked(worker, work)) {
|
|
__kthread_queue_delayed_work(worker, dwork, delay);
|
|
ret = true;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_queue_delayed_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);
|
|
|
|
/*
|
|
* Make sure that the timer is neither set nor running and could
|
|
* not manipulate the work list_head any longer.
|
|
*
|
|
* The function is called under worker->lock. The lock is temporary
|
|
* released but the timer can't be set again in the meantime.
|
|
*/
|
|
static void kthread_cancel_delayed_work_timer(struct kthread_work *work,
|
|
unsigned long *flags)
|
|
{
|
|
struct kthread_delayed_work *dwork =
|
|
container_of(work, struct kthread_delayed_work, work);
|
|
struct kthread_worker *worker = work->worker;
|
|
|
|
/*
|
|
* del_timer_sync() must be called to make sure that the timer
|
|
* callback is not running. The lock must be temporary released
|
|
* to avoid a deadlock with the callback. In the meantime,
|
|
* any queuing is blocked by setting the canceling counter.
|
|
*/
|
|
work->canceling++;
|
|
spin_unlock_irqrestore(&worker->lock, *flags);
|
|
del_timer_sync(&dwork->timer);
|
|
spin_lock_irqsave(&worker->lock, *flags);
|
|
work->canceling--;
|
|
}
|
|
|
|
/*
|
|
* This function removes the work from the worker queue.
|
|
*
|
|
* It is called under worker->lock. The caller must make sure that
|
|
* the timer used by delayed work is not running, e.g. by calling
|
|
* kthread_cancel_delayed_work_timer().
|
|
*
|
|
* The work might still be in use when this function finishes. See the
|
|
* current_work proceed by the worker.
|
|
*
|
|
* Return: %true if @work was pending and successfully canceled,
|
|
* %false if @work was not pending
|
|
*/
|
|
static bool __kthread_cancel_work(struct kthread_work *work)
|
|
{
|
|
/*
|
|
* Try to remove the work from a worker list. It might either
|
|
* be from worker->work_list or from worker->delayed_work_list.
|
|
*/
|
|
if (!list_empty(&work->node)) {
|
|
list_del_init(&work->node);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* kthread_mod_delayed_work - modify delay of or queue a kthread delayed work
|
|
* @worker: kthread worker to use
|
|
* @dwork: kthread delayed work to queue
|
|
* @delay: number of jiffies to wait before queuing
|
|
*
|
|
* If @dwork is idle, equivalent to kthread_queue_delayed_work(). Otherwise,
|
|
* modify @dwork's timer so that it expires after @delay. If @delay is zero,
|
|
* @work is guaranteed to be queued immediately.
|
|
*
|
|
* Return: %true if @dwork was pending and its timer was modified,
|
|
* %false otherwise.
|
|
*
|
|
* A special case is when the work is being canceled in parallel.
|
|
* It might be caused either by the real kthread_cancel_delayed_work_sync()
|
|
* or yet another kthread_mod_delayed_work() call. We let the other command
|
|
* win and return %false here. The caller is supposed to synchronize these
|
|
* operations a reasonable way.
|
|
*
|
|
* This function is safe to call from any context including IRQ handler.
|
|
* See __kthread_cancel_work() and kthread_delayed_work_timer_fn()
|
|
* for details.
|
|
*/
|
|
bool kthread_mod_delayed_work(struct kthread_worker *worker,
|
|
struct kthread_delayed_work *dwork,
|
|
unsigned long delay)
|
|
{
|
|
struct kthread_work *work = &dwork->work;
|
|
unsigned long flags;
|
|
int ret = false;
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
|
|
/* Do not bother with canceling when never queued. */
|
|
if (!work->worker)
|
|
goto fast_queue;
|
|
|
|
/* Work must not be used with >1 worker, see kthread_queue_work() */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
/*
|
|
* Temporary cancel the work but do not fight with another command
|
|
* that is canceling the work as well.
|
|
*
|
|
* It is a bit tricky because of possible races with another
|
|
* mod_delayed_work() and cancel_delayed_work() callers.
|
|
*
|
|
* The timer must be canceled first because worker->lock is released
|
|
* when doing so. But the work can be removed from the queue (list)
|
|
* only when it can be queued again so that the return value can
|
|
* be used for reference counting.
|
|
*/
|
|
kthread_cancel_delayed_work_timer(work, &flags);
|
|
if (work->canceling)
|
|
goto out;
|
|
ret = __kthread_cancel_work(work);
|
|
|
|
fast_queue:
|
|
__kthread_queue_delayed_work(worker, dwork, delay);
|
|
out:
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_mod_delayed_work);
|
|
|
|
static bool __kthread_cancel_work_sync(struct kthread_work *work, bool is_dwork)
|
|
{
|
|
struct kthread_worker *worker = work->worker;
|
|
unsigned long flags;
|
|
int ret = false;
|
|
|
|
if (!worker)
|
|
goto out;
|
|
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
/* Work must not be used with >1 worker, see kthread_queue_work(). */
|
|
WARN_ON_ONCE(work->worker != worker);
|
|
|
|
if (is_dwork)
|
|
kthread_cancel_delayed_work_timer(work, &flags);
|
|
|
|
ret = __kthread_cancel_work(work);
|
|
|
|
if (worker->current_work != work)
|
|
goto out_fast;
|
|
|
|
/*
|
|
* The work is in progress and we need to wait with the lock released.
|
|
* In the meantime, block any queuing by setting the canceling counter.
|
|
*/
|
|
work->canceling++;
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
kthread_flush_work(work);
|
|
spin_lock_irqsave(&worker->lock, flags);
|
|
work->canceling--;
|
|
|
|
out_fast:
|
|
spin_unlock_irqrestore(&worker->lock, flags);
|
|
out:
|
|
return ret;
|
|
}
|
|
|
|
/**
|
|
* kthread_cancel_work_sync - cancel a kthread work and wait for it to finish
|
|
* @work: the kthread work to cancel
|
|
*
|
|
* Cancel @work and wait for its execution to finish. This function
|
|
* can be used even if the work re-queues itself. On return from this
|
|
* function, @work is guaranteed to be not pending or executing on any CPU.
|
|
*
|
|
* kthread_cancel_work_sync(&delayed_work->work) must not be used for
|
|
* delayed_work's. Use kthread_cancel_delayed_work_sync() instead.
|
|
*
|
|
* The caller must ensure that the worker on which @work was last
|
|
* queued can't be destroyed before this function returns.
|
|
*
|
|
* Return: %true if @work was pending, %false otherwise.
|
|
*/
|
|
bool kthread_cancel_work_sync(struct kthread_work *work)
|
|
{
|
|
return __kthread_cancel_work_sync(work, false);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_cancel_work_sync);
|
|
|
|
/**
|
|
* kthread_cancel_delayed_work_sync - cancel a kthread delayed work and
|
|
* wait for it to finish.
|
|
* @dwork: the kthread delayed work to cancel
|
|
*
|
|
* This is kthread_cancel_work_sync() for delayed works.
|
|
*
|
|
* Return: %true if @dwork was pending, %false otherwise.
|
|
*/
|
|
bool kthread_cancel_delayed_work_sync(struct kthread_delayed_work *dwork)
|
|
{
|
|
return __kthread_cancel_work_sync(&dwork->work, true);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kthread_cancel_delayed_work_sync);
|
|
|
|
/**
|
|
* 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);
|