[src/netbsd-7]: src/sys/dev/sysmon Pull up following revision(s) (requested b...

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

details:   https://anonhg.NetBSD.org/src/rev/e79e7dbae196
branches:  netbsd-7
changeset: 799178:e79e7dbae196
user:      snj <snj%NetBSD.org@localhost>
date:      Mon Apr 06 18:45:30 2015 +0000

description:
Pull up following revision(s) (requested by hannken in ticket #666):
        sys/dev/sysmon/sysmon_envsys.c: revision 1.129
        sys/dev/sysmon/sysmon_envsys_events.c: revision 1.114
        sys/dev/sysmon/sysmonvar.h: revision 1.46
Add a counter of busy events and stop enqueueing more work if a device =
is busy.
Protect this counter with a new short time lock "sme_work_mtx" and
keep "sme_mtx" as long time lock.
Removes a deadlock where an active event holds "sme_mtx", the callout
"sme_events_check" blocks on "sme_mtx" and callout processing stops.

diffstat:

 sys/dev/sysmon/sysmon_envsys.c        |   6 ++++--
 sys/dev/sysmon/sysmon_envsys_events.c |  21 +++++++++++++++++++--
 sys/dev/sysmon/sysmonvar.h            |   6 +++++-
 3 files changed, 28 insertions(+), 5 deletions(-)

diffs (116 lines):

diff -r 0761fa8fff3d -r e79e7dbae196 sys/dev/sysmon/sysmon_envsys.c
--- a/sys/dev/sysmon/sysmon_envsys.c    Mon Apr 06 02:03:15 2015 +0000
+++ b/sys/dev/sysmon/sysmon_envsys.c    Mon Apr 06 18:45:30 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sysmon_envsys.c,v 1.127 2014/08/10 16:44:36 tls Exp $  */
+/*     $NetBSD: sysmon_envsys.c,v 1.127.2.1 2015/04/06 18:45:30 snj Exp $      */
 
 /*-
  * Copyright (c) 2007, 2008 Juan Romero Pardines.
@@ -64,7 +64,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sysmon_envsys.c,v 1.127 2014/08/10 16:44:36 tls Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sysmon_envsys.c,v 1.127.2.1 2015/04/06 18:45:30 snj Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -485,6 +485,7 @@
        TAILQ_INIT(&sme->sme_sensors_list);
        LIST_INIT(&sme->sme_events_list);
        mutex_init(&sme->sme_mtx, MUTEX_DEFAULT, IPL_NONE);
+       mutex_init(&sme->sme_work_mtx, MUTEX_DEFAULT, IPL_NONE);
        cv_init(&sme->sme_condvar, "sme_wait");
 
        return sme;
@@ -508,6 +509,7 @@
                TAILQ_REMOVE(&sme->sme_sensors_list, edata, sensors_head);
        }
        mutex_destroy(&sme->sme_mtx);
+       mutex_destroy(&sme->sme_work_mtx);
        cv_destroy(&sme->sme_condvar);
        kmem_free(sme, sizeof(*sme));
 }
diff -r 0761fa8fff3d -r e79e7dbae196 sys/dev/sysmon/sysmon_envsys_events.c
--- a/sys/dev/sysmon/sysmon_envsys_events.c     Mon Apr 06 02:03:15 2015 +0000
+++ b/sys/dev/sysmon/sysmon_envsys_events.c     Mon Apr 06 18:45:30 2015 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: sysmon_envsys_events.c,v 1.110.4.1 2014/12/01 11:38:42 martin Exp $ */
+/* $NetBSD: sysmon_envsys_events.c,v 1.110.4.2 2015/04/06 18:45:30 snj Exp $ */
 
 /*-
  * Copyright (c) 2007, 2008 Juan Romero Pardines.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sysmon_envsys_events.c,v 1.110.4.1 2014/12/01 11:38:42 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sysmon_envsys_events.c,v 1.110.4.2 2015/04/06 18:45:30 snj Exp $");
 
 #include <sys/param.h>
 #include <sys/types.h>
@@ -42,6 +42,7 @@
 #include <sys/mutex.h>
 #include <sys/kmem.h>
 #include <sys/callout.h>
+#include <sys/syslog.h>
 
 #include <dev/sysmon/sysmonvar.h>
 #include <dev/sysmon/sysmon_envsysvar.h>
@@ -712,11 +713,23 @@
 
        KASSERT(sme != NULL);
 
+       mutex_enter(&sme->sme_work_mtx);
+       if (sme->sme_busy > 0) {
+               log(LOG_WARNING, "%s: workqueue busy: updates stopped\n",
+                   sme->sme_name);
+               mutex_exit(&sme->sme_work_mtx);
+               return;
+       }
+       mutex_exit(&sme->sme_work_mtx);
+
        mutex_enter(&sme->sme_mtx);
+       mutex_enter(&sme->sme_work_mtx);
        LIST_FOREACH(see, &sme->sme_events_list, see_list) {
                workqueue_enqueue(sme->sme_wq, &see->see_wk, NULL);
                see->see_edata->flags |= ENVSYS_FNEED_REFRESH;
+               sme->sme_busy++;
        }
+       mutex_exit(&sme->sme_work_mtx);
        if (!sysmon_low_power)
                sme_schedule_callout(sme);
        mutex_exit(&sme->sme_mtx);
@@ -796,6 +809,10 @@
 out:
        see->see_flags &= ~SEE_EVENT_WORKING;
        cv_broadcast(&sme->sme_condvar);
+       mutex_enter(&sme->sme_work_mtx);
+       KASSERT(sme->sme_busy > 0);
+       sme->sme_busy--;
+       mutex_exit(&sme->sme_work_mtx);
        mutex_exit(&sme->sme_mtx);
 }
 
diff -r 0761fa8fff3d -r e79e7dbae196 sys/dev/sysmon/sysmonvar.h
--- a/sys/dev/sysmon/sysmonvar.h        Mon Apr 06 02:03:15 2015 +0000
+++ b/sys/dev/sysmon/sysmonvar.h        Mon Apr 06 18:45:30 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sysmonvar.h,v 1.44.12.1 2014/12/01 11:38:42 martin Exp $       */
+/*     $NetBSD: sysmonvar.h,v 1.44.12.2 2015/04/06 18:45:30 snj Exp $  */
 
 /*-
  * Copyright (c) 2000 Zembu Labs, Inc.
@@ -207,7 +207,11 @@
        /*
         * Locking/synchronization.
         */
+       int sme_busy;                   /* number of items on workqueue,
+                                          sme_mtx or sme_work_mtx to read,
+                                          both to write */
        kmutex_t sme_mtx;
+       kmutex_t sme_work_mtx;
        kcondvar_t sme_condvar;
 };