- Close races with signals and other AST's being triggered while we are in

  the process of exiting the kernel.  The ast() function now loops as long
  as the PS_ASTPENDING or PS_NEEDRESCHED flags are set.  It returns with
  preemption disabled so that any further AST's that arrive via an
  interrupt will be delayed until the low-level MD code returns to user
  mode.
- Use u_int's to store the tick counts for profiling purposes so that we
  do not need sched_lock just to read p_sticks.  This also closes a
  problem where the call to addupc_task() could screw up the arithmetic
  due to non-atomic reads of p_sticks.
- Axe need_proftick(), aston(), astoff(), astpending(), need_resched(),
  clear_resched(), and resched_wanted() in favor of direct bit operations
  on p_sflag.
- Fix up locking with sched_lock some.  In addupc_intr(), use sched_lock
  to ensure pr_addr and pr_ticks are updated atomically with setting
  PS_OWEUPC.  In ast() we clear pr_ticks atomically with clearing
  PS_OWEUPC.  We also do not grab the lock just to test a flag.
- Simplify the handling of Giant in ast() slightly.

Reviewed by:	bde (mostly)

1 files changed, 4 insertions, 8 deletions

diff --git a/sys/kern/kern_clock.c b/sys/kern/kern_clock.c
index 87f9515..f48b212 100644
--- a/sys/kern/kern_clock.c
+++ b/sys/kern/kern_clock.c
@@ -172,15 +172,11 @@ hardclock_process(p, user)
 	pstats = p->p_stats;
 	if (user &&
 	    timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
-	    itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
-		p->p_sflag |= PS_ALRMPEND;
-		aston(p);
-	}
+	    itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
+		p->p_sflag |= PS_ALRMPEND | PS_ASTPENDING;
 	if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
-	    itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
-		p->p_sflag |= PS_PROFPEND;
-		aston(p);
-	}
+	    itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
+		p->p_sflag |= PS_PROFPEND | PS_ASTPENDING;
 }
 
 /*