93d03d0418
This commit adds VFS docmentation, and details about the VFS interface. Signed-off-by: Saurav Pal <resyfer.dev@gmail.com>
98 lines
2.9 KiB
ReStructuredText
98 lines
2.9 KiB
ReStructuredText
.. _notifier_chain:
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==============
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Notifier Chain
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==============
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NuttX provides a callback list mechanism called *Notifier Chain*.
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Notifier chain is essentially a list of callbacks used at certain times,
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such as system asserting, powering off and restarting.
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**Notifier chain** is very much like the Linux notifier chains, except
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for some implementation differences.
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Classes of Notifier Chain
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=========================
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There are currently two different classes of notifier.
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Atomic notifier chains
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----------------------
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Atomic notifier chains: Chain callbacks run in interrupt/atomic context.
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In Nuttx, callouts are allowed to block(In Linux, callouts in atomic
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notifier chain are not allowed to block). One example of an Atomic notifier
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chain is turning off FPU when asserting.
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Blocking notifier chains
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------------------------
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Blocking notifier chains: Chain callbacks run in process context.
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Callouts are allowed to block. One example of a blocking notifier chain
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is when an orderly powering off is needed.
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Common Notifier Chain Interfaces
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================================
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Notifier Block Types
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--------------------
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- ``struct notifier_block``. Defines one notifier callback entry.
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Notifier Chain Interfaces
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-------------------------
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.. c:function:: void panic_notifier_chain_register(FAR struct notifier_block *nb)
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Add notifier to the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param nb: New entry in notifier chain.
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.. c:function:: void panic_notifier_chain_unregister(FAR struct notifier_block *nb)
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Remove notifier from the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param nh: Entry to remove from notifier chain.
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.. c:function:: void panic_notifier_call_chain(unsigned long action, FAR void *data)
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Call functions in the panic notifier chain.
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The panic notifier chain is an atomic notifier chain. It will be called
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when asserting.
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:param action: Value passed unmodified to notifier function.
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:param data: Pointer passed unmodified to notifier function.
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.. c:function:: void register_reboot_notifier(FAR struct notifier_block *nb)
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Add notifier to the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param nb: New entry in notifier chain.
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.. c:function:: void unregister_reboot_notifier(FAR struct notifier_block *nb)
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Remove notifier from the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param nh: Entry to remove from notifier chain.
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.. c:function:: void reboot_notifier_call_chain(unsigned long action, FAR void *data)
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Call functions in the reboot notifier chain.
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The reboot notifier chain is an atomic notifier chain.
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:param action: Value passed unmodified to notifier function.
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:param data: Pointer passed unmodified to notifier function.
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