- 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, 3 insertions, 3 deletions

diff --git a/sys/kern/kern_intr.c b/sys/kern/kern_intr.c
index 07ee598..84dbc6b 100644
--- a/sys/kern/kern_intr.c
+++ b/sys/kern/kern_intr.c
@@ -371,8 +371,8 @@ ithread_schedule(struct ithd *ithread, int do_switch)
 	 * Set it_need to tell the thread to keep running if it is already
 	 * running.  Then, grab sched_lock and see if we actually need to
 	 * put this thread on the runqueue.  If so and the do_switch flag is
-	 * true, then switch to the ithread immediately.  Otherwise, use
-	 * need_resched() to guarantee that this ithread will run before any
+	 * true, then switch to the ithread immediately.  Otherwise, set the
+	 * needresched flag to guarantee that this ithread will run before any
 	 * userland processes.
 	 */
 	ithread->it_need = 1;
@@ -387,7 +387,7 @@ ithread_schedule(struct ithd *ithread, int do_switch)
 			curproc->p_stats->p_ru.ru_nivcsw++;
 			mi_switch();
 		} else
-			need_resched(curproc);
+			curproc->p_sflag |= PS_NEEDRESCHED;
 	} else {
 		CTR3(KTR_INTR, __func__ ": pid %d: it_need %d, state %d",
 		    p->p_pid, ithread->it_need, p->p_stat);