wakeupinterruptible

Wakeupinterruptible, in the context of the Linux kernel, refers to the wake_up_interruptible function and the related mechanism for waking processes that are sleeping in interruptible state on a wait queue.

Overview

wake_up_interruptible wakes up tasks that are sleeping on a wait queue in the TASK_INTERRUPTIBLE state. When invoked, it marks those waiting tasks as runnable (TASK_RUNNING), allowing the scheduler to run them again. The awakened tasks then re-check the condition they were waiting on and continue if the condition is satisfied; otherwise they may go back to sleep.

Details and behavior

- Interruptible sleep vs uninterruptible sleep: Tasks sleeping in TASK_INTERRUPTIBLE can be awakened by events, including explicit wakeups or signals. Tasks in TASK_UNINTERRUPTIBLE are not woken by wake_up_interruptible.

- Scope: The function targets only tasks currently waiting in interruptible sleep on the specified wait queue. It does not affect tasks sleeping in uninterruptible state.

- Synchronization: Wakeups are typically paired with a predicate that is updated under proper locking. The waking function itself is a lightweight operation that schedules the affected tasks to run.

- Relationship to wait queues: wake_up_interruptible is commonly used in conjunction with wait_event_interruptible and related macros to implement sleep-and-wake patterns in drivers and subsystems.

- Signals and interruptions: If a process sleeping interruptibly receives a signal, user-space system calls may return with an interrupt error. The wakeup itself is separate from the signal handling semantics of the sleeping process.

Usage context

wake_up_interruptible is used by device drivers and kernel subsystems to notify waiting processes when a condition changes (for example, data becomes available or a resource becomes free). It is one part of the wait queue API, which also includes mechanisms for putting tasks to sleep and waking them up under different sleep states.

See also

Wait queues, TASK_INTERRUPTIBLE, wait_event_interruptible, wake_up_interruptible_all.

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