[src/netbsd-6-0]: src/sys/arch/xen/xen Pull up following revision(s) (request...

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

details:   https://anonhg.NetBSD.org/src/rev/bbb825d778f1
branches:  netbsd-6-0
changeset: 774896:bbb825d778f1
user:      riz <riz%NetBSD.org@localhost>
date:      Tue Dec 17 22:39:49 2013 +0000

description:
Pull up following revision(s) (requested by bouyer in ticket #995):
        sys/arch/xen/xen/evtchn.c: revision 1.70
Remove the "evtchn_do_event: handler %p didn't lower ipl %d %d\n" printf.
With help from Robert Elz we've finally figured out what's going on, and
it actually isn't a bug in the handler, but related to spin mutexes.
When a spin mutex is released, the IPL isn't lowered back if the
curcpu is holding other spin mutexes. This is because mutexes may not
be released in order (and, in this case, the CPU in interrupted while
it holds a spin mutex at IPL < IPL_SCHED).
Also remove the test and resetting the IPL, it will be reset anyway
inside the loop, or at the end of the loop.

diffstat:

 sys/arch/xen/xen/evtchn.c |  11 ++---------
 1 files changed, 2 insertions(+), 9 deletions(-)

diffs (32 lines):

diff -r 19ef01f30ba1 -r bbb825d778f1 sys/arch/xen/xen/evtchn.c
--- a/sys/arch/xen/xen/evtchn.c Tue Dec 17 22:34:07 2013 +0000
+++ b/sys/arch/xen/xen/evtchn.c Tue Dec 17 22:39:49 2013 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: evtchn.c,v 1.62 2012/02/12 14:24:08 jym Exp $  */
+/*     $NetBSD: evtchn.c,v 1.62.8.1 2013/12/17 22:39:49 riz Exp $      */
 
 /*
  * Copyright (c) 2006 Manuel Bouyer.
@@ -54,7 +54,7 @@
 
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: evtchn.c,v 1.62 2012/02/12 14:24:08 jym Exp $");
+__KERNEL_RCSID(0, "$NetBSD: evtchn.c,v 1.62.8.1 2013/12/17 22:39:49 riz Exp $");
 
 #include "opt_xen.h"
 #include "isa.h"
@@ -347,13 +347,6 @@
                                        ih_fun = (void *)ih->ih_fun;
                                        ih_fun(ih->ih_arg, regs);
                                        cli();
-                                       if (ci->ci_ilevel != i) {
-                                               printf("evtchn_do_event: "
-                                                   "handler %p didn't lower "
-                                                   "ipl %d %d\n",
-                                                   ih_fun, ci->ci_ilevel, i);
-                                               ci->ci_ilevel = i;
-                                       }
                                }
                                hypervisor_enable_ipl(i);
                                /* more pending IPLs may have been registered */