[src/trunk]: src/sys/kern No need to lock the selcluster in selscan() if either

[hannken <hannken%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/bafbe8edb549
branches:  trunk
changeset: 768112:bafbe8edb549
user:      hannken <hannken%NetBSD.org@localhost>
date:      Tue Aug 09 06:36:51 2011 +0000

description:
No need to lock the selcluster in selscan() if either
NO_DIRECT_SELECT is defined or all polls return an event.

diffstat:

 sys/kern/sys_select.c |  17 ++++++++++++-----
 1 files changed, 12 insertions(+), 5 deletions(-)

diffs (47 lines):

diff -r 5e3d6ba9f489 -r bafbe8edb549 sys/kern/sys_select.c
--- a/sys/kern/sys_select.c     Tue Aug 09 04:19:17 2011 +0000
+++ b/sys/kern/sys_select.c     Tue Aug 09 06:36:51 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_select.c,v 1.34 2011/08/06 11:04:25 hannken Exp $  */
+/*     $NetBSD: sys_select.c,v 1.35 2011/08/09 06:36:51 hannken Exp $  */
 
 /*-
  * Copyright (c) 2007, 2008, 2009, 2010 The NetBSD Foundation, Inc.
@@ -84,7 +84,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sys_select.c,v 1.34 2011/08/06 11:04:25 hannken Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sys_select.c,v 1.35 2011/08/09 06:36:51 hannken Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -390,7 +390,7 @@
                for (i = 0; i < nfd; i += NFDBITS) {
                        fd_mask ibits, obits;
 
-                       ibits = *ibitp++;
+                       ibits = *ibitp;
                        obits = 0;
                        while ((j = ffs(ibits)) && (fd = i + --j) < nfd) {
                                ibits &= ~(1 << j);
@@ -408,10 +408,17 @@
                                fd_putfile(fd);
                        }
                        if (obits != 0) {
-                               mutex_spin_enter(lock);
+#ifndef NO_DIRECT_SELECT
+                               if (obits != *ibitp)
+                                       mutex_spin_enter(lock);
                                *obitp |= obits;
-                               mutex_spin_exit(lock);
+                               if (obits != *ibitp)
+                                       mutex_spin_exit(lock);
+#else
+                               *obitp |= obits;
+#endif
                        }
+                       ibitp++;
                        obitp++;
                }
        }