Among signal generation syscalls, only sigqueue(2) is allowed by POSIX

to fail due to lack of resources to queue siginfo. Add KSI_SIGQ flag
that allows sigqueue_add() to fail while trying to allocate memory for
new siginfo. When the flag is not set, behaviour is the same as for
KSI_TRAP: if memory cannot be allocated, set bit in sq_kill. KSI_TRAP is
kept to preserve KBI.

Add SI_KERNEL si_code, to be used in siginfo.si_code when signal is
generated by kernel. Deliver siginfo when signal is generated by kill(2)
family of syscalls (SI_USER with properly filled si_uid and si_pid), or
by kernel (SI_KERNEL, mostly job control or SIGIO). Since KSI_SIGQ flag
is not set for the ksi, low memory condition cause old behaviour.

Keep psignal(9) KBI intact, but modify it to generate SI_KERNEL
si_code. Pgsignal(9) and gsignal(9) now take ksi explicitely. Add
pksignal(9) that behaves like psignal but takes ksi, and ddb kill
command implemented as pksignal(..., ksi = NULL) to not do allocation
while in debugger.

While there, remove some register specifiers and use ANSI C prototypes.

Reviewed by:	davidxu
MFC after:	1 month

1 files changed, 5 insertions, 3 deletions

diff --git a/sys/sys/signalvar.h b/sys/sys/signalvar.h
index 65d9cf5..fd0fac3 100644
--- a/sys/sys/signalvar.h
+++ b/sys/sys/signalvar.h
@@ -233,7 +233,8 @@ typedef struct ksiginfo {
 #define KSI_TRAP	0x01	/* Generated by trap. */
 #define	KSI_EXT		0x02	/* Externally managed ksi. */
 #define KSI_INS		0x04	/* Directly insert ksi, not the copy */
-#define	KSI_COPYMASK	KSI_TRAP
+#define	KSI_SIGQ	0x08	/* Generated by sigqueue, might ret EGAIN. */
+#define	KSI_COPYMASK	(KSI_TRAP|KSI_SIGQ)
 
 #define	KSI_ONQ(ksi)	((ksi)->ksi_sigq != NULL)
 
@@ -326,10 +327,11 @@ extern int kern_logsigexit;	/* Sysctl variable kern.logsigexit */
  */
 int	cursig(struct thread *td, int stop_allowed);
 void	execsigs(struct proc *p);
-void	gsignal(int pgid, int sig);
+void	gsignal(int pgid, int sig, ksiginfo_t *ksi);
 void	killproc(struct proc *p, char *why);
+void	pksignal(struct proc *p, int sig, ksiginfo_t *ksi);
 void	pgsigio(struct sigio **, int signum, int checkctty);
-void	pgsignal(struct pgrp *pgrp, int sig, int checkctty);
+void	pgsignal(struct pgrp *pgrp, int sig, int checkctty, ksiginfo_t *ksi);
 int	postsig(int sig);
 void	psignal(struct proc *p, int sig);
 int	psignal_event(struct proc *p, struct sigevent *, ksiginfo_t *);