#include <linux/spinlock.h> #include <linux/task_work.h> #include <linux/tracehook.h> int task_work_add(struct task_struct *task, struct task_work *twork, bool notify) { unsigned long flags; int err = -ESRCH; #ifndef TIF_NOTIFY_RESUME if (notify) return -ENOTSUPP; #endif /* * We must not insert the new work if the task has already passed * exit_task_work(). We rely on do_exit()->raw_spin_unlock_wait() * and check PF_EXITING under pi_lock. */ raw_spin_lock_irqsave(&task->pi_lock, flags); if (likely(!(task->flags & PF_EXITING))) { hlist_add_head(&twork->hlist, &task->task_works); err = 0; } raw_spin_unlock_irqrestore(&task->pi_lock, flags); /* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */ if (likely(!err) && notify) set_notify_resume(task); return err; } struct task_work * task_work_cancel(struct task_struct *task, task_work_func_t func) { unsigned long flags; struct task_work *twork; struct hlist_node *pos; raw_spin_lock_irqsave(&task->pi_lock, flags); hlist_for_each_entry(twork, pos, &task->task_works, hlist) { if (twork->func == func) { hlist_del(&twork->hlist); goto found; } } twork = NULL; found: raw_spin_unlock_irqrestore(&task->pi_lock, flags); return twork; } void task_work_run(void) { struct task_struct *task = current; struct hlist_head task_works; struct hlist_node *pos; raw_spin_lock_irq(&task->pi_lock); hlist_move_list(&task->task_works, &task_works); raw_spin_unlock_irq(&task->pi_lock); if (unlikely(hlist_empty(&task_works))) return; /* * We use hlist to save the space in task_struct, but we want fifo. * Find the last entry, the list should be short, then process them * in reverse order. */ for (pos = task_works.first; pos->next; pos = pos->next) ; for (;;) { struct hlist_node **pprev = pos->pprev; struct task_work *twork = container_of(pos, struct task_work, hlist); twork->func(twork); if (pprev == &task_works.first) break; pos = container_of(pprev, struct hlist_node, next); } }