post signal to a process
proc *p, int
pgrp *pgrp, int
sigio_ref *sir, int
These functions post a signal to one or more processes. The
argument signum common to all three functions should
be in the range [1-
function posts signal number signum to the process
represented by the process structure p. With a few
exceptions noted below, the target process signal disposition is updated and
is marked as runnable, so further handling of the signal is done in the
context of the target process after a context switch. Note that
psignal() does not by itself cause a context switch
The target process is not marked as runnable in the following cases:
- The target process is sleeping uninterruptibly. The signal will be noticed when the process returns from the system call or trap.
- The target process is currently ignoring the signal.
- If a stop signal is sent to a sleeping process that takes the default action (see sigaction(2)), the process is stopped without awakening it.
SIGCONTrestarts a stopped process (or puts them back to sleep) regardless of the signal action (e.g., blocked or ignored).
If the target process is being traced,
behaves as if the target process were taking the default action for
signum. This allows the tracing process to be notified
of the signal.
function posts signal number signum to each member of
the process group described by pgrp. If
checkctty is non-zero, the signal will be posted only
to processes that have a controlling terminal. If pgrp
NULL, no action is taken.
function posts signal number signum to the process or
each member of the process group indicated by reference
sir. If checkctty is non-zero,
the signal will be posted only to processes that have a controlling
These functions are implemented in the file sys/kern/kern_sig.c.
sigaction(2), sigio_setown(9), tsleep(9)