Now that the return value semantics of cv's for multithreaded processes

have been unified with that of msleep(9), further refine the sleepq
interface and consolidate some duplicated code:
- Move the pre-sleep checks for theaded processes into a
  thread_sleep_check() function in kern_thread.c.
- Move all handling of TDF_SINTR to be internal to subr_sleepqueue.c.
  Specifically, if a thread is awakened by something other than a signal
  while checking for signals before going to sleep, clear TDF_SINTR in
  sleepq_catch_signals().  This removes a sched_lock lock/unlock combo in
  that edge case during an interruptible sleep.  Also, fix
  sleepq_check_signals() to properly handle the condition if TDF_SINTR is
  clear rather than requiring the callers of the sleepq API to notice
  this edge case and call a non-_sig variant of sleepq_wait().
- Clarify the flags arguments to sleepq_add(), sleepq_signal() and
  sleepq_broadcast() by creating an explicit submask for sleepq types.
  Also, add an explicit SLEEPQ_MSLEEP type rather than a magic number of
  0.  Also, add a SLEEPQ_INTERRUPTIBLE flag for use with sleepq_add() and
  move the setting of TDF_SINTR to sleepq_add() if this flag is set rather
  than sleepq_catch_signals().  Note that it is the caller's responsibility
  to ensure that sleepq_catch_signals() is called if and only if this flag
  is passed to the preceeding sleepq_add().  Note that this also removes a
  sched_lock lock/unlock pair from sleepq_catch_signals().  It also ensures
  that for an interruptible sleep, TDF_SINTR is always set when
  TD_ON_SLEEPQ() is true.

1 files changed, 16 insertions, 39 deletions

diff --git a/sys/kern/kern_condvar.c b/sys/kern/kern_condvar.c
index ff619ec..fc0f799 100644
--- a/sys/kern/kern_condvar.c
+++ b/sys/kern/kern_condvar.c
@@ -153,7 +153,6 @@ cv_wait_sig(struct cv *cvp, struct mtx *mp)
 
 	td = curthread;
 	p = td->td_proc;
-	rval = 0;
 #ifdef KTRACE
 	if (KTRPOINT(td, KTR_CSW))
 		ktrcsw(1, 0);
@@ -180,32 +179,21 @@ cv_wait_sig(struct cv *cvp, struct mtx *mp)
 	 * thread or if our thread is marked as interrupted.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (p->p_flag & P_SA || p->p_numthreads > 1) {
-		if ((p->p_flag & P_SINGLE_EXIT) && p->p_singlethread != td)
-			rval = EINTR;
-		else if (td->td_flags & TDF_INTERRUPT)
-			rval = td->td_intrval;
-		if (rval != 0) {
-			mtx_unlock_spin(&sched_lock);
-			sleepq_release(cvp);
-			return (rval);
-		}
-	}
+	rval = thread_sleep_check(td);
 	mtx_unlock_spin(&sched_lock);
+	if (rval != 0) {
+		sleepq_release(cvp);
+		return (rval);
+	}
 
 	cvp->cv_waiters++;
 	DROP_GIANT();
 	mtx_unlock(mp);
 
-	sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
+	sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR |
+	    SLEEPQ_INTERRUPTIBLE);
 	sig = sleepq_catch_signals(cvp);
-	if (sig == 0 && !TD_ON_SLEEPQ(td)) {
-		mtx_lock_spin(&sched_lock);
-		td->td_flags &= ~TDF_SINTR;
-		mtx_unlock_spin(&sched_lock);
-		sleepq_wait(cvp);
-	} else       
-		rval = sleepq_wait_sig(cvp);
+	rval = sleepq_wait_sig(cvp);
 	if (rval == 0)
 		rval = sleepq_calc_signal_retval(sig);
 
@@ -320,33 +308,22 @@ cv_timedwait_sig(struct cv *cvp, struct mtx *mp, int timo)
 	 * thread or if our thread is marked as interrupted.
 	 */
 	mtx_lock_spin(&sched_lock);
-	if (p->p_flag & P_SA || p->p_numthreads > 1) {
-		if ((p->p_flag & P_SINGLE_EXIT) && p->p_singlethread != td)
-			rval = EINTR;
-		else if (td->td_flags & TDF_INTERRUPT)
-			rval = td->td_intrval;
-		if (rval != 0) {
-			mtx_unlock_spin(&sched_lock);
-			sleepq_release(cvp);
-			return (rval);
-		}
-	}
+	rval = thread_sleep_check(td);
 	mtx_unlock_spin(&sched_lock);
+	if (rval != 0) {
+		sleepq_release(cvp);
+		return (rval);
+	}
 
 	cvp->cv_waiters++;
 	DROP_GIANT();
 	mtx_unlock(mp);
 
-	sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR);
+	sleepq_add(sq, cvp, mp, cvp->cv_description, SLEEPQ_CONDVAR |
+	    SLEEPQ_INTERRUPTIBLE);
 	sleepq_set_timeout(cvp, timo);
 	sig = sleepq_catch_signals(cvp);
-	if (sig == 0 && !TD_ON_SLEEPQ(td)) {
-		mtx_lock_spin(&sched_lock);
-		td->td_flags &= ~TDF_SINTR;
-		mtx_unlock_spin(&sched_lock);
-		rval = sleepq_timedwait(cvp);
-	} else       
-		rval = sleepq_timedwait_sig(cvp, sig != 0);
+	rval = sleepq_timedwait_sig(cvp, sig != 0);
 	if (rval == 0)
 		rval = sleepq_calc_signal_retval(sig);