_exit(2) and execve(2) need to obey the locking protocol described in
proc.h when manipulating the per-process interval timer state.
While we're here we can also remove the now pointless splclock/splx
dance from execve(2).
The easiest way to obey the locking protocol is to reuse the interface
the syscalls are using: setitimer() in kern_time.c.
Given that we only want to cancel the timers I wrote a small helper
function, cancelitimer(). I think it's tidier than putting the
prototype for setitimer() into sys/time.h and requiring the caller to
prepare an itimerval struct before calling.
Compare:
struct itimerval itv;
timerclear(&itv.it_value);
timerclear(&itv.it_interval);
setitimer(ITIMER_REAL, &itv, NULL);
with:
cancelitimer(ITIMER_REAL);
... should I shove the for-loop into the helper function too? Maybe
call it "cancel_all_itimers()"? I have a vague feeling that showing
the reader that there are multiple timers is a good thing here, but
then again maybe I'm wrong and nobody cares.
Preferences? ok?
Index: kern/kern_exec.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_exec.c,v
retrieving revision 1.217
diff -u -p -r1.217 kern_exec.c
--- kern/kern_exec.c 11 Jul 2020 22:59:05 -0000 1.217
+++ kern/kern_exec.c 15 Oct 2020 01:02:45 -0000
@@ -656,14 +656,9 @@ sys_execve(struct proc *p, void *v, regi
}
if (pr->ps_flags & PS_SUGIDEXEC) {
- int i, s = splclock();
-
- timeout_del(&pr->ps_realit_to);
- for (i = 0; i < nitems(pr->ps_timer); i++) {
- timespecclear(&pr->ps_timer[i].it_interval);
- timespecclear(&pr->ps_timer[i].it_value);
- }
- splx(s);
+ int i;
+ for (i = 0; i < nitems(pr->ps_timer); i++)
+ cancelitimer(i);
}
/* reset CPU time usage for the thread, but not the process */
Index: kern/kern_exit.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_exit.c,v
retrieving revision 1.188
diff -u -p -r1.188 kern_exit.c
--- kern/kern_exit.c 18 Mar 2020 15:48:21 -0000 1.188
+++ kern/kern_exit.c 15 Oct 2020 01:02:45 -0000
@@ -194,7 +194,11 @@ exit1(struct proc *p, int xexit, int xsi
/* close open files and release open-file table */
fdfree(p);
- timeout_del(&pr->ps_realit_to);
+ /* cancel all interval timers */
+ int i;
+ for (i = 0; i < nitems(pr->ps_timer); i++)
+ cancelitimer(i);
+
timeout_del(&pr->ps_rucheck_to);
#ifdef SYSVSEM
semexit(pr);
Index: sys/time.h
===================================================================
RCS file: /cvs/src/sys/sys/time.h,v
retrieving revision 1.55
diff -u -p -r1.55 time.h
--- sys/time.h 6 Jul 2020 13:33:09 -0000 1.55
+++ sys/time.h 15 Oct 2020 01:02:45 -0000
@@ -307,6 +307,7 @@ time_t getuptime(void);
struct proc;
int clock_gettime(struct proc *, clockid_t, struct timespec *);
+void cancelitimer(int);
int itimerfix(struct timeval *);
int itimerdecr(struct itimerspec *, long);
int settime(const struct timespec *);
