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 and runCommand functions can not be called from an interrupt context. But attemptCommand can, though it may return an error
*/
class IOCommandGate : public IOEventSource
@result True if inherited classes initialise successfully. */
virtual bool init(OSObject *owner, Action action = 0);
+ // Superclass overrides
+ virtual void free();
+ virtual void setWorkLoop(IOWorkLoop *inWorkLoop);
+
/*! @function runCommand
@abstract Single thread a command with the target work-loop.
@discussion Client function that causes the current action to be called in
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
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);
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
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 action Pointer to function to be executed in work-loop context.
@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 kIOReturnSuccess if successful. 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,
/*! @function attemptCommand
@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.
@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
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.
+client's thread attemptCommand will fail if the work-loop's gate is closed.
@param action Pointer to function to be executed in work-loop context.
@param arg0 Parameter for action parameter, defaults to 0.
@param arg1 Parameter for action parameter, defaults to 0.
@param onlyOneThread 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();
+
+/*! @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();
+
private:
OSMetaClassDeclareReservedUnused(IOCommandGate, 0);
OSMetaClassDeclareReservedUnused(IOCommandGate, 1);
projects / apple / xnu.git / blobdiff