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, 1 insertions, 0 deletions

diff --git a/sys/sys/signal.h b/sys/sys/signal.h
index e90b107..81d45a9 100644
--- a/sys/sys/signal.h
+++ b/sys/sys/signal.h
@@ -338,6 +338,7 @@ struct sigaction {
 					/* an asynchronous I/O request.*/
 #define	SI_MESGQ	0x10005		/* Signal generated by arrival of a */
 					/* message on an empty message queue. */
+#define	SI_KERNEL	0x10006
 #endif
 #if __BSD_VISIBLE
 #define	SI_UNDEFINED	0