svn commit: r244717 - projects/calloutng/sys/kern

[Alexander Motin]

Author: mav
Date: Wed Dec 26 21:44:50 2012
New Revision: 244717
URL: http://svnweb.freebsd.org/changeset/base/244717

Log:
  Revert poll() and select() implementations back to absolute time.  Closer
  look on the code shown that thread can be woken up by events not requested
  by caller.  In such case sleep should be restarted for the remaining time.

Modified:
  projects/calloutng/sys/kern/sys_generic.c

Modified: projects/calloutng/sys/kern/sys_generic.c
==============================================================================
--- projects/calloutng/sys/kern/sys_generic.c	Wed Dec 26 20:07:47 2012	(r244716)
+++ projects/calloutng/sys/kern/sys_generic.c	Wed Dec 26 21:44:50 2012	(r244717)
@@ -102,7 +102,7 @@ static int	dofilewrite(struct thread *, 
 		    off_t, int);
 static void	doselwakeup(struct selinfo *, int);
 static void	seltdinit(struct thread *);
-static int	seltdwait(struct thread *, struct bintime);
+static int	seltdwait(struct thread *, struct bintime, struct bintime);
 static void	seltdclear(struct thread *);
 
 /*
@@ -903,7 +903,7 @@ kern_select(struct thread *td, int nd, f
 	 */
 	fd_mask s_selbits[howmany(2048, NFDBITS)];
 	fd_mask *ibits[3], *obits[3], *selbits, *sbp;
-	struct bintime rbt;
+	struct bintime abt, precision, rbt;
 	struct timeval rtv;
 	int error, lf, ndu;
 	u_int nbufbytes, ncpbytes, ncpubytes, nfdbits;
@@ -1004,19 +1004,28 @@ kern_select(struct thread *td, int nd, f
 			goto done;
 		}
 		timeval2bintime(&rtv, &rbt);
+		precision = rbt;
+		bintime_shift(&precision, -tc_timeexp);
+		if (TIMESEL(&abt, &rbt))
+			bintime_add(&abt, &tc_tick_bt);
+		bintime_add(&abt, &rbt);
 	} else {
-		rbt.sec = -1;
-		rbt.frac = 0;
+		abt.sec = (time_t)-1;
+		abt.frac = 0;
 	}
 	seltdinit(td);
-	error = selscan(td, ibits, obits, nd);
-	if (error || td->td_retval[0] != 0)
-		goto done1;
-	error = seltdwait(td, rbt);
-	if (error)
-		goto done1;
-	error = selrescan(td, ibits, obits);
-done1:
+	/* Iterate until the timeout expires or descriptors become ready. */
+	for (;;) {
+		error = selscan(td, ibits, obits, nd);
+		if (error || td->td_retval[0] != 0)
+			break;
+		error = seltdwait(td, abt, precision);
+		if (error)
+			break;
+		error = selrescan(td, ibits, obits);
+		if (error || td->td_retval[0] != 0)
+			break;
+	}
 	seltdclear(td);
 
 done:
@@ -1242,7 +1251,7 @@ sys_poll(td, uap)
 {
 	struct pollfd *bits;
 	struct pollfd smallbits[32];
-	struct bintime rbt;
+	struct bintime abt, precision, rbt;
 	int error;
 	u_int nfds;
 	size_t ni;
@@ -1265,19 +1274,28 @@ sys_poll(td, uap)
 		}
 		rbt.sec = uap->timeout / 1000;
 		rbt.frac = (uap->timeout % 1000) * (((uint64_t)1 << 63) / 500);
+		precision = rbt;
+		bintime_shift(&precision, -tc_timeexp);
+		if (TIMESEL(&abt, &rbt))
+			bintime_add(&abt, &tc_tick_bt);
+		bintime_add(&abt, &rbt);
 	} else {
-		rbt.sec = -1;
-		rbt.frac = 0;
+		abt.sec = (time_t)-1;
+		abt.frac = 0;
 	}
 	seltdinit(td);
-	error = pollscan(td, bits, nfds);
-	if (error || td->td_retval[0] != 0)
-		goto done1;
-	error = seltdwait(td, rbt);
-	if (error)
-		goto done1;
-	error = pollrescan(td);
-done1:
+	/* Iterate until the timeout expires or descriptors become ready. */
+	for (;;) {
+		error = pollscan(td, bits, nfds);
+		if (error || td->td_retval[0] != 0)
+			break;
+		error = seltdwait(td, abt, precision);
+		if (error)
+			break;
+		error = pollrescan(td);
+		if (error || td->td_retval[0] != 0)
+			break;
+	}
 	seltdclear(td);
 
 done:
@@ -1613,7 +1631,7 @@ out:
 }
 
 static int
-seltdwait(struct thread *td, struct bintime bt)
+seltdwait(struct thread *td, struct bintime bt, struct bintime precision)
 {
 	struct seltd *stp;
 	int error;
@@ -1634,9 +1652,9 @@ seltdwait(struct thread *td, struct bint
 	}
 	if (!bintime_isset(&bt))
 		error = EWOULDBLOCK;
-	else if (bt.sec >= 0)
+	else if (bt.sec != (time_t)-1)
 		error = cv_timedwait_sig_bt(&stp->st_wait, &stp->st_mtx,
-		    bt, zero_bt, 0);
+		    bt, precision, C_ABSOLUTE);
 	else
 		error = cv_wait_sig(&stp->st_wait, &stp->st_mtx);
 	mtx_unlock(&stp->st_mtx);