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#include <sys/interrupt.h>extern struct intr_event *tty_intr_event;
The swi_add() function is used to add a new software interrupt handler to a specified interrupt event. The eventp argument is an optional pointer to a struct intr_event pointer. If this argument points to an existing event that holds a list of interrupt handlers, then this handler will be attached to that event. Otherwise a new event will be created, and if eventp is not NULL, then the pointer at that address to will be modified to point to the newly created event. The name argument is used to associate a name with a specific handler. This name is appended to the name of the software interrupt thread that this handler is attached to. The handler argument is the function that will be executed when the handler is scheduled to run. The arg parameter will be passed in as the only parameter to handler when the function is executed. The pri value specifies the priority of this interrupt handler relative to other software interrupt handlers. If an interrupt event is created, then this value is used as the vector, and the flags argument is used to specify the attributes of a handler such as INTR_MPSAFE. The cookiep argument points to a void * cookie. This cookie will be set to a value that uniquely identifies this handler, and is used to schedule the handler for execution later on.
The swi_remove() function is used to teardown an interrupt handler pointed to by the cookie argument. It detaches the interrupt handler from the associated interrupt event and frees its memory.
The swi_sched() function is used to schedule an interrupt handler and its associated thread to run. The cookie argument specifies which software interrupt handler should be scheduled to run. The flags argument specifies how and when the handler should be run and is a mask of one or more of the following flags:
|Specifies that the kernel should mark the specified handler as needing to run, but the kernel should not schedule the software interrupt thread to run. Instead, handler will be executed the next time that the software interrupt thread runs after being scheduled by another event. Attaching a handler to the clock software interrupt thread and using this flag when scheduling a software interrupt handler can be used to implement the functionality performed by setdelayed() in earlier versions of FreeBSD .|
The tty_intr_event and clk_intr_event variables contain pointers to the software interrupt handlers for the tty and clock software interrupts, respectively. tty_intr_event is used to hang tty software interrupt handlers off of the same thread. clk_intr_event is used to hang delayed handlers off of the clock software interrupt thread so that the functionality of setdelayed() can be obtained in conjunction with SWI_DELAY. The vm_ih handler cookie is used to schedule software interrupt threads to run for the VM subsystem.
|The system-imposed limit on the total number of processes under execution would be exceeded. The limit is given by the sysctl(3) MIB variable KERN_MAXPROC.|
|The flags argument specifies INTR_ENTROPY.|
|The eventp argument points to a hardware interrupt thread.|
|Either of the name or handler arguments are NULL.|
|The INTR_EXCL flag is specified and the interrupt event pointed to by eventp already has at least one handler, or the interrupt event already has an exclusive handler.|
The swi_remove() function will fail if:
|A software interrupt handler pointed to by cookie is NULL.|
|SWI (9)||April 19, 2012|
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