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Notification Mechanism

  • Built on top of the standard pipe driver

  • can be enabled by CONFIG_WATCH_QUEUE

  • splicing is disabled on these pipes to prevent inter-leaving of kernel messages

  • owner of the pipe has to tell the kernel, the sources from which it would like to get notifications

  • a message will be discarded if there isn’t a slot available in the ring or if no preallocated message buffer is available. In both of these cases

  • the kernel does not wait for the consumers to collect it, but rather just continues on.

    • This means that notifications can be generated whilst spinlocks are held and also protects the kernel from being held up indefinitely by a userspace malfunction.

Please refer General notification mechanism - Kernel Docs for information on Mesage Structure, Watch Queue, Watch List and Event Filtering.

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