/*
- * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
+ * Copyright (c) 1998-2016 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
/*!
@class IOCommandGate : public IOEventSource
- @abstract Single-threaded work-loop client request mechanism.
- @discussion An IOCommandGate instance is an extremely light way mechanism
-that executes an action on the driver's work-loop. 'On the work-loop' is
-actually a lie but the work-loop single threaded semantic is maintained for this
-event source. Using the work-loop gate rather than execution by the workloop.
-The command gate tests for a potential self dead lock by checking if the
-runCommand request is made from the work-loop's thread, it doens't check for a
-mutual dead lock though where a pair of work loop's dead lock each other.
+ @abstract Single-threaded work loop client request mechanism.
+ @discussion An IOCommandGate instance is an extremely lightweight mechanism
+that executes an action on the driver's work loop. Although the code does not
+technically execute on the work loop itself, a single-threaded work loop semantic
+is maintained for this event source using the work loop gate. The command gate
+tests for a potential self dead lock by checking if the runCommand request is
+made from the work loop's thread, it doesn't check for a mutual dead lock though
+where a pair of work loop's dead lock each other.
<br><br>
The IOCommandGate is a lighter weight version of the IOCommandQueue and
should be used in preference. Generally use a command queue whenever you need a
queue internal to the device or the device's family. Otherwise if the hardware
is inactive then this request can be acted upon immediately.
<br><br>
- CAUTION: The runAction and runCommand functions can not be called from an interrupt context.
+ CAUTION: The runAction, runCommand, and attemptCommand functions cannot be called from an interrupt context.
*/
class IOCommandGate : public IOEventSource
void *arg2, void *arg3);
protected:
-/*!
- @function checkForWork
- @abstract Not used, $link IOEventSource::checkForWork(). */
- virtual bool checkForWork();
/*! @struct ExpansionData
@discussion This structure will be used to expand the capablilties of the IOWorkLoop in the future.
@result True if inherited classes initialise successfully. */
virtual bool init(OSObject *owner, Action action = 0);
+ // Superclass overrides
+ virtual void free() APPLE_KEXT_OVERRIDE;
+ virtual void setWorkLoop(IOWorkLoop *inWorkLoop) APPLE_KEXT_OVERRIDE;
+
/*! @function runCommand
- @abstract Single thread a command with the target work-loop.
+ @abstract Single thread a command with the target work loop.
@discussion Client function that causes the current action to be called in
-a single threaded manner. Beware the work-loop's gate is recursive and command
+a single threaded manner. Beware the work loop's gate is recursive and command
gates can cause direct or indirect re-entrancy. When the executing on a
-client's thread runCommand will sleep until the work-loop's gate opens for
+client's thread runCommand will sleep until the work loop's gate opens for
execution of client actions, the action is single threaded against all other
-work-loop event sources.
+work loop event sources. If the command is disabled the attempt to run a command will be stalled until enable is called.
@param arg0 Parameter for action of command gate, defaults to 0.
@param arg1 Parameter for action of command gate, defaults to 0.
@param arg2 Parameter for action of command gate, defaults to 0.
@param arg3 Parameter for action of command gate, defaults to 0.
- @result kIOReturnSuccess if successful. kIOReturnNotPermitted if this
-event source is currently disabled, kIOReturnNoResources if no action available.
+ @result kIOReturnSuccess if successful. kIOReturnAborted if a disabled command gate is free()ed before being reenabled, kIOReturnNoResources if no action available.
*/
virtual IOReturn runCommand(void *arg0 = 0, void *arg1 = 0,
void *arg2 = 0, void *arg3 = 0);
/*! @function runAction
- @abstract Single thread a call to an action with the target work-loop.
+ @abstract Single thread a call to an action with the target work loop.
@discussion Client function that causes the given action to be called in
-a single threaded manner. Beware the work-loop's gate is recursive and command
+a single threaded manner. Beware the work loop's gate is recursive and command
gates can cause direct or indirect re-entrancy. When the executing on a
-client's thread runAction will sleep until the work-loop's gate opens for
+client's thread runAction will sleep until the work loop's gate opens for
execution of client actions, the action is single threaded against all other
-work-loop event sources.
- @param action Pointer to function to be executed in work-loop context.
+work loop event sources. If the command is disabled the attempt to run a command will be stalled until enable is called.
+ @param action Pointer to function to be executed in the context of the work loop.
@param arg0 Parameter for action parameter, defaults to 0.
@param arg1 Parameter for action parameter, defaults to 0.
@param arg2 Parameter for action parameter, defaults to 0.
@param arg3 Parameter for action parameter, defaults to 0.
- @result kIOReturnSuccess if successful. kIOReturnBadArgument if action is not defined, kIOReturnNotPermitted if this event source is currently disabled.
+ @result The return value of action if it was called, kIOReturnBadArgument if action is not defined, kIOReturnAborted if a disabled command gate is free()ed before being reenabled.
*/
virtual IOReturn runAction(Action action,
void *arg0 = 0, void *arg1 = 0,
void *arg2 = 0, void *arg3 = 0);
/*! @function attemptCommand
- @abstract Single thread a command with the target work-loop.
+ @abstract Single thread a command with the target work loop.
@discussion Client function that causes the current action to be called in
-a single threaded manner. Beware the work-loop's gate is recursive and command
-gates can cause direct or indirect re-entrancy. When the executing on a
-client's thread attemptCommand will fail if the work-loop's gate is open.
+a single threaded manner. When the executing on a client's thread attemptCommand will fail if the work loop's gate is closed.
@param arg0 Parameter for action of command gate, defaults to 0.
@param arg1 Parameter for action of command gate, defaults to 0.
@param arg2 Parameter for action of command gate, defaults to 0.
void *arg2 = 0, void *arg3 = 0);
/*! @function attemptAction
- @abstract Single thread a call to an action with the target work-loop.
+ @abstract Single thread a call to an action with the target work loop.
@discussion Client function that causes the given action to be called in
-a single threaded manner. Beware the work-loop's gate is recursive and command
+a single threaded manner. Beware the work loop's gate is recursive and command
gates can cause direct or indirect re-entrancy. When the executing on a
-client's thread attemptCommand will fail if the work-loop's gate is open.
- @param action Pointer to function to be executed in work-loop context.
+client's thread attemptCommand will fail if the work loop's gate is closed.
+ @param action Pointer to function to be executed in context of the work loop.
@param arg0 Parameter for action parameter, defaults to 0.
@param arg1 Parameter for action parameter, defaults to 0.
@param arg2 Parameter for action parameter, defaults to 0.
/*! @function commandSleep
@abstract Put a thread that is currently holding the command gate to sleep.
- @discussion Put a thread to sleep waiting for an event but release the gate first. If the event occurs then the commandGate is closed before the returns.
+ @discussion Put a thread to sleep waiting for an event but release the gate first. If the event occurs then the commandGate is closed before the function returns.
@param event Pointer to an address.
- @param interruptible THREAD_UNINT, THREAD_INTERRUPTIBLE or THREAD_ABORTSAFE, defaults to THREAD_ABORTSAFE.
- @result THREAD_AWAKENED - normal wakeup, THREAD_TIMED_OUT - timeout expired, THREAD_INTERRUPTED - interrupted by clear_wait, THREAD_RESTART - restart operation entirely, kIOReturnNotPermitted if the calling thread does not hold the command gate. */
+ @param interruptible THREAD_UNINT, THREAD_INTERRUPTIBLE or THREAD_ABORTSAFE. THREAD_UNINT specifies that the sleep cannot be interrupted by a signal. THREAD_INTERRUPTIBLE specifies that the sleep may be interrupted by a "kill -9" signal. THREAD_ABORTSAFE (the default value) specifies that the sleep may be interrupted by any user signal.
+ @result THREAD_AWAKENED - normal wakeup, THREAD_TIMED_OUT - timeout expired, THREAD_INTERRUPTED - interrupted, THREAD_RESTART - restart operation entirely, kIOReturnNotPermitted if the calling thread does not hold the command gate. */
virtual IOReturn commandSleep(void *event,
UInt32 interruptible = THREAD_ABORTSAFE);
/*! @function commandWakeup
@abstract Wakeup one or more threads that are asleep on an event.
@param event Pointer to an address.
- @param onlyOneThread true to only wake up at most one thread, false otherwise. */
+ @param oneThread true to only wake up at most one thread, false otherwise. */
virtual void commandWakeup(void *event, bool oneThread = false);
+/*! @function disable
+ @abstract Disable the command gate
+ @discussion When a command gate is disabled all future calls to runAction and runCommand will stall until the gate is enable()d later. This can be used to block client threads when a system sleep is requested. The IOWorkLoop thread itself will never stall, even when making runAction/runCommand calls. This call must be made from a gated context, to clear potential race conditions. */
+ virtual void disable() APPLE_KEXT_OVERRIDE;
+
+/*! @function enable
+ @abstract Enable command gate, this will unblock any blocked Commands and Actions.
+ @discussion Enable the command gate. The attemptAction/attemptCommand calls will now be enabled and can succeeed. Stalled runCommand/runAction calls will be woken up. */
+ virtual void enable() APPLE_KEXT_OVERRIDE;
+
+/*! @function commandSleep
+ @abstract Put a thread that is currently holding the command gate to sleep.
+ @discussion Put a thread to sleep waiting for an event but release the gate first. If the event occurs or timeout occurs then the commandGate is closed before the function returns.
+ @param event Pointer to an address.
+ @param deadline Clock deadline to timeout the sleep.
+ @param interruptible THREAD_UNINT, THREAD_INTERRUPTIBLE or THREAD_ABORTSAFE. THREAD_UNINT specifies that the sleep cannot be interrupted by a signal. THREAD_INTERRUPTIBLE specifies that the sleep may be interrupted by a "kill -9" signal. THREAD_ABORTSAFE specifies that the sleep may be interrupted by any user signal.
+ @result THREAD_AWAKENED - normal wakeup, THREAD_TIMED_OUT - timeout expired, THREAD_INTERRUPTED - interrupted, THREAD_RESTART - restart operation entirely, kIOReturnNotPermitted if the calling thread does not hold the command gate. */
+ virtual IOReturn commandSleep(void *event,
+ AbsoluteTime deadline,
+ UInt32 interruptible);
+
private:
+#if __LP64__
OSMetaClassDeclareReservedUnused(IOCommandGate, 0);
+#else
+ OSMetaClassDeclareReservedUsed(IOCommandGate, 0);
+#endif
OSMetaClassDeclareReservedUnused(IOCommandGate, 1);
OSMetaClassDeclareReservedUnused(IOCommandGate, 2);
OSMetaClassDeclareReservedUnused(IOCommandGate, 3);
projects / apple / xnu.git / blobdiff