[src/trunk]: src/sys/external/bsd/common/linux Don't let more than one thread...

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

details:   https://anonhg.NetBSD.org/src/rev/033eba59df6c
branches:  trunk
changeset: 364832:033eba59df6c
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Aug 27 15:04:45 2018 +0000

description:
Don't let more than one thread claim credit for cancellation.

diffstat:

 sys/external/bsd/common/linux/linux_work.c |  47 +++++++++++++++++++++++++----
 1 files changed, 40 insertions(+), 7 deletions(-)

diffs (91 lines):

diff -r 3acdd6a71cb0 -r 033eba59df6c sys/external/bsd/common/linux/linux_work.c
--- a/sys/external/bsd/common/linux/linux_work.c        Mon Aug 27 15:04:32 2018 +0000
+++ b/sys/external/bsd/common/linux/linux_work.c        Mon Aug 27 15:04:45 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_work.c,v 1.33 2018/08/27 15:04:32 riastradh Exp $        */
+/*     $NetBSD: linux_work.c,v 1.34 2018/08/27 15:04:45 riastradh Exp $        */
 
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.33 2018/08/27 15:04:32 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.34 2018/08/27 15:04:45 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/atomic.h>
@@ -964,8 +964,6 @@
                        }
                        break;
                case DELAYED_WORK_SCHEDULED:
-               case DELAYED_WORK_RESCHEDULED:
-               case DELAYED_WORK_CANCELLED:
                        /*
                         * If it is scheduled, mark it cancelled and
                         * try to stop the callout before it starts.
@@ -982,6 +980,23 @@
                        if (!callout_stop(&dw->dw_callout))
                                cancel_delayed_work_done(wq, dw);
                        break;
+               case DELAYED_WORK_RESCHEDULED:
+                       /*
+                        * If it is being rescheduled, the callout has
+                        * already fired.  We must ask it to cancel.
+                        */
+                       dw->dw_state = DELAYED_WORK_CANCELLED;
+                       cancelled_p = true;
+                       break;
+               case DELAYED_WORK_CANCELLED:
+                       /*
+                        * If it is being cancelled, the callout has
+                        * already fired.  There is nothing more for us
+                        * to do.  Someone else claims credit for
+                        * cancelling it.
+                        */
+                       cancelled_p = false;
+                       break;
                default:
                        panic("invalid delayed work state: %d",
                            dw->dw_state);
@@ -1029,8 +1044,6 @@
                        }
                        break;
                case DELAYED_WORK_SCHEDULED:
-               case DELAYED_WORK_RESCHEDULED:
-               case DELAYED_WORK_CANCELLED:
                        /*
                         * If it is scheduled, mark it cancelled and
                         * try to stop the callout before it starts.
@@ -1046,9 +1059,29 @@
                         * dissociate it from the workqueue ourselves.
                         */
                        dw->dw_state = DELAYED_WORK_CANCELLED;
-                       cancelled_p = true;
                        if (!callout_halt(&dw->dw_callout, &wq->wq_lock))
                                cancel_delayed_work_done(wq, dw);
+                       cancelled_p = true;
+                       break;
+               case DELAYED_WORK_RESCHEDULED:
+                       /*
+                        * If it is being rescheduled, the callout has
+                        * already fired.  We must ask it to cancel and
+                        * wait for it to complete.
+                        */
+                       dw->dw_state = DELAYED_WORK_CANCELLED;
+                       (void)callout_halt(&dw->dw_callout, &wq->wq_lock);
+                       cancelled_p = true;
+                       break;
+               case DELAYED_WORK_CANCELLED:
+                       /*
+                        * If it is being cancelled, the callout has
+                        * already fired.  We need only wait for it to
+                        * complete.  Someone else, however, claims
+                        * credit for cancelling it.
+                        */
+                       (void)callout_halt(&dw->dw_callout, &wq->wq_lock);
+                       cancelled_p = false;
                        break;
                default:
                        panic("invalid delayed work state: %d",