kern/45421: kernel should log and inform user when it uses SIGKILL because of RLIMIT_CPU

["Greg A. Woods" <woods%planix.com@localhost>]

>Number:         45421
>Category:       kern
>Synopsis:       kernel should log and inform user when it uses SIGKILL because 
>of RLIMIT_CPU
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 04 18:40:00 +0000 2011
>Originator:     Greg A. Woods
>Release:        NetBSD-current 2011/10/04
>Organization:
Planix, Inc.; Kelowna, BC; Canada
>Environment:
System: NetBSD
Architecture: all
Machine: all
>Description:

        the kernel should log, and inform the user, when it uses SIGKILL
        to terminate a process because it has exceeded RLIMIT_CPU.

        also, fix a nearby errant use of printf() instead of log().

>How-To-Repeat:

        try to make actual use of CPU limits without confusing and
        angering users

>Fix:

Index: sys/kern/kern_synch.c
===================================================================
RCS file: /cvs/master/m-NetBSD/main/src/sys/kern/kern_synch.c,v
retrieving revision 1.291
diff -u -r1.291 kern_synch.c
--- sys/kern/kern_synch.c       27 Sep 2011 01:02:38 -0000      1.291
+++ sys/kern/kern_synch.c       4 Oct 2011 17:59:40 -0000
@@ -1250,9 +1250,11 @@
                rlim = &p->p_rlimit[RLIMIT_CPU];
                sig = 0;
                if (__predict_false(runtm >= rlim->rlim_cur)) {
-                       if (runtm >= rlim->rlim_max)
+                       if (runtm >= rlim->rlim_max) {
                                sig = SIGKILL;
-                       else {
+                               log(LOG_ERR, "pid %d is killed: %s\n", 
p->p_pid, "exceeded RLIMIT_CPU");
+                               uprintf("sorry, pid %d, command %s, is killed: 
%s\n", p->p_pid, p->p_comm, "exceeded RLIMIT_CPU");
+                       } else {
                                sig = SIGXCPU;
                                if (rlim->rlim_cur < rlim->rlim_max)
                                        rlim->rlim_cur += 5;
@@ -1262,7 +1264,7 @@
                if (__predict_false(runtm < 0)) {
                        if (!backwards) {
                                backwards = true;
-                               printf("WARNING: negative runtime; "
+                               log(LOG_WARNING, "WARNING: negative runtime; "
                                    "monotonic clock has gone backwards\n");
                        }
                } else if (__predict_false(sig)) {