NAME
lwp_create,
lwp_create2 —
spawn a new lwp
LIBRARY
library “libc”
SYNOPSIS
#include
<sys/lwp.h>
int
lwp_create(struct
lwp_params *params);
int
lwp_create2(struct
lwp_params *params, const
cpumask_t *mask);
DESCRIPTION
Thelwp_create()
and the lwp_create2() function spawn a new lwp in the
current process. In a way, lwp_create() and
lwp_create2() are similar to
fork(2). However, lwp_create() and
lwp_create2() do not return twice as parent and child.
Instead, the new lwp will execute a function provided by the
params argument which is a pointer to a
struct lwp_params.
struct lwp_params {
void (*func)(void *); /* Function to start execution */
void *arg; /* Parameter to this function */
void *stack; /* Stack address to use */
lwpid_t *tid1; /* Address to copy out new tid */
lwpid_t *tid2; /* Same */
};
A function pointer func specifies
the function to be executed in the new lwp. It is the duty of
func() to
correctly terminate execution of the lwp, either by calling
extexit(2) or
exit(3). If func() returns, behavior is
unspecified. The only argument passed to func() is
arg.
The new lwp starts with its stack frame set to stack. Note that both func and stack are mandatory. If either is invalid, behavior is unspecified.
The fields tid1 and tid2 point to variables where the tid of the new lwp shall be stored. Two parameters are provided so that storage for both parent and child can be specified separately. Setting any of these to NULL causes the respective tid not to be copied out.
The mask argument to
lwp_create2()
specifies the new lwp's CPU affinity mask. NULL means
no special CPU affinity settings.
RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.
SEE ALSO
HISTORY
The lwp_create() function first appeared
in DragonFly 1.9. The
lwp_create2() function first appeared in
DragonFly 4.7.