table of contents
|PSIGNAL(9)||Kernel Developer's Manual||PSIGNAL(9)|
post signal to a thread, process, or process group
psignal(struct proc *p, int signum); void
pgsignal(struct pgrp *pgrp, int signum, int checkctty); void
gsignal(int pgid, int signum); void
tdsignal(struct thread *td, int signum);
DESCRIPTION¶These functions post a signal to a thread or one or more processes. The argument signum common to all three functions should be in the range [1-
psignal() 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 to happen. 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).
psignal() behaves as if the target process were taking the default action for signum. This allows the tracing process to be notified of the signal. The
pgsignal() 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.
pgsignal() is implemented by walking along the process list headed by the field
pg_membersof the process group structure pointed at by pgrp and calling
psignal() as appropriate. If pgrp is
NULLno action is taken. The
gsignal() function posts signal number signum to each member of the process group identified by the group id pgid.
gsignal() first finds the group structure associated with pgid, then invokes
pgsignal() with the argument checkctty set to zero. If pgid is zero no action is taken. The
tdsignal() function posts signal number signum to the thread represented by the thread structure td.
SEE ALSO¶sigaction(2), signal(9), tsleep(9)
|October 8, 2011||Debian|