kernel_isrthread(9r)kernel_isrthread(9r)NAME
kernel_isrthread - General: Starts a fixed priority kernel thread dedicated to interrupt service
SYNOPSIS
thread_t kernel_isrthread(
task_t task,
void (*start) (void),
int pri );
ARGUMENTS
Specifies a pointer to a task structure. This pointer identifies the task in which the kernel_isrthread routine starts the newly created
kernel thread dedicated to interrupt service handling. Specifies a pointer to an routine that is the entry point for the newly created
kernel thread. Specifies the scheduling priority level for the newly created kernel thread. See the DESCRIPTION section for the priority
usage table that describes the possible scheduling priorities.
DESCRIPTION
The kernel_isrthread routine creates and starts a kernel thread at the specified entry point. This kernel thread handles only interrupt
service requests in the specified task and at the specified priority level. A kernel module should always attach a kernel thread to the
``first task.''
The following priority usage table describes the possible scheduling priorities. The first column shows a range of priorities. The second
column shows an associated scheduling priority constant defined in <src/kernel/kern/sched.h> (if applicable). The third column describes
the usage of the priority ranges. To specify a scheduling priority of 38, you pass the constant BASEPRI_SYSTEM. To specify a scheduling
priority of 33, you can pass the following: BASEPRI_HIGHEST + 1.
--------------------------------------------------------------
Priority Constant Usage
--------------------------------------------------------------
0--31 N/A Realtime kernel threads
32--38 BASEPRI_HIGHEST -- Operating system kernel
BASEPRI_SYSTEM threads
44--64 BASEPRI_USER -- User kernel threads
BASEPRI_LOWEST
--------------------------------------------------------------
RETURN VALUES
Upon successful completion, kernel_isrthread returns a pointer to the thread structure associated with the kernel thread started at the
specified entry point. Kernel modules can use this pointer as a handle to a specific kernel thread in calls to other kernel threads-related
routines.
SEE ALSO
Routines: kernel_thread_w_arg(9r)
Data Structures: task(9s), thread(9s)kernel_isrthread(9r)
Check Out this Related Man Page
thread_terminate(9r)thread_terminate(9r)NAME
thread_terminate - General: Prepares to stop or stops execution of the specified kernel thread
SYNOPSIS
kern_return_t thread_terminate(
thread_t thread_to_terminate );
ARGUMENTS
Specifies a pointer to the thread structure associated with the kernel thread that you want to terminate. This pointer was returned in a
previous call to the kernel_isrthread or kernel_thread_w_arg routine.
DESCRIPTION
The thread_terminate routine prepares to stop or permanently stops execution of the specified kernel thread. You created and started this
kernel thread in a previous call to the kernel_isrthread or kernel_thread_w_arg routine. These routines return a pointer to the thread
structure associated with the newly created and started kernel thread. Kernel modules use this pointer as a handle to identify the specific
kernel thread that thread_terminate stops executing.
Typically, a kernel thread terminates itself. However, one kernel thread can terminate another kernel thread. A kernel thread that termi-
nates itself must call thread_halt_self immediately after the call to thread_terminate. The reason for this is that thread_terminate only
prepares the self-terminating kernel thread to stop execution. The thread_halt_self routine completes the work needed to stop execution
(by performing the appropriate cleanup work) of the self-terminating kernel thread.
Specifically, the thread_terminate routine works as follows: For terminating other kernel threads
The thread_terminate routine stops execution of the specified kernel thread, frees any resources associated with that kernel thread,
and thus makes the kernel thread unavailable. To make the kernel thread available again, you need to create it by calling ker-
nel_isrthread or kernel_thread_w_arg. A kernel thread terminates itself
The thread_terminate routine prepares to stop execution of the kernel thread that needs to terminate itself. The thread_halt_self
routine completes the work needed to stop execution of the self-terminating kernel thread by performing the appropriate cleanup
work. After you call these routines, the self-terminating kernel thread becomes unavailable until you create it again by calling
kernel_isrthread or kernel_thread_w_arg.
NOTES
You do not need to terminate every kernel thread that you create. You should not terminate a kernel thread that is waiting for some event.
The basic rule is that you should terminate only those kernel threads that you do not need anymore. For example, if a dynamically config-
ured kernel module uses kernel threads, you should terminate them in the CFG_OP_UNCONFIGURE entry point of the loadable module's configure
routine. The kernel threads are no longer needed after the module is unconfigured.
Note that the thread_terminate routine (for kernel threads that terminate other kernel threads) not only permanently stops execution of the
specified kernel thread, but it also frees any resources associated with that kernel thread; thus, this kernel thread can no longer be
used.
RETURN VALUES
Upon successfully terminating the specified kernel thread, thread_terminate returns the constant KERN_SUCCESS. If the thread structure
pointer passed to the thread_to_terminate argument does not identify a valid kernel thread, thread_terminate returns the constant
KERN_INVALID_ARGUMENT. On any other error, thread_terminate returns the constant KERN_FAILURE.
SEE ALSO
Data Structures: thread(9s)
Routines: kernel_isrthread(9r), kernel_thread_w_arg(9r), thread_halt_self(9r)thread_terminate(9r)