Index: sys_generic.c
===================================================================
--- sys_generic.c	(revision 187579)
+++ sys_generic.c	(working copy)
@@ -947,38 +947,44 @@
 	fd_mask **ibits, **obits;
 	int nfd;
 {
-	int msk, i, fd;
-	fd_mask bits;
+	int msk, n, i, j, flags, end, fd;
 	struct file *fp;
-	int n = 0;
 	/* Note: backend also returns POLLHUP/POLLERR if appropriate. */
 	static int flag[3] = { POLLRDNORM, POLLWRNORM, POLLRDBAND };
 	struct filedesc *fdp = td->td_proc->p_fd;
 
+	n = 0;
 	FILEDESC_SLOCK(fdp);
-	for (msk = 0; msk < 3; msk++) {
-		if (ibits[msk] == NULL)
-			continue;
-		for (i = 0; i < nfd; i += NFDBITS) {
-			bits = ibits[msk][i/NFDBITS];
-			/* ffs(int mask) not portable, fd_mask is long */
-			for (fd = i; bits && fd < nfd; fd++, bits >>= 1) {
-				if (!(bits & 1))
+	for (i = 0, fd = 0; i < nfd; i++) {
+		end = imin(fd + NFDBITS, nfd);
+		for (j = 0; fd < end; j++, fd++) {
+			flags = 0;
+			for (msk = 0; msk < 3; msk++) {
+				if (ibits[msk] == NULL)
 					continue;
-				if ((fp = fget_locked(fdp, fd)) == NULL) {
-					FILEDESC_SUNLOCK(fdp);
-					return (EBADF);
-				}
-				selfdalloc(td, (void *)(uintptr_t)fd);
-				if (fo_poll(fp, flag[msk], td->td_ucred,
-				    td)) {
+				if ((ibits[msk][i] & (1 << j)) == 0)
+					continue;
+				flags |= flag[msk];
+			}
+			if (flags == 0)
+				continue;
+			if ((fp = fget_locked(fdp, fd)) == NULL) {
+				FILEDESC_SUNLOCK(fdp);
+				return (EBADF);
+			}
+			selfdalloc(td, (void *)(uintptr_t)fd);
+			if (fo_poll(fp, flags, td->td_ucred, td)) {
+				for (msk = 0; msk < 3; msk++) {
+					if ((flags & flag[msk]) == 0)
+						continue;
 					obits[msk][(fd)/NFDBITS] |=
 					    ((fd_mask)1 << ((fd) % NFDBITS));
-					n++;
 				}
+				n++;
 			}
 		}
 	}
+
 	FILEDESC_SUNLOCK(fdp);
 	td->td_retval[0] = n;
 	return (0);