[src/trunk]: src/sys/external/bsd/common/linux Non-waiting cancellation may n...

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

details:   https://anonhg.NetBSD.org/src/rev/b33c18c891a9
branches:  trunk
changeset: 835432:b33c18c891a9
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Mon Aug 27 15:01:13 2018 +0000

description:
Non-waiting cancellation may need to release work too.

diffstat:

 sys/external/bsd/common/linux/linux_work.c |  40 ++++++++++++++++++-----------
 1 files changed, 25 insertions(+), 15 deletions(-)

diffs (62 lines):

diff -r 4a6ba3bc5fb8 -r b33c18c891a9 sys/external/bsd/common/linux/linux_work.c
--- a/sys/external/bsd/common/linux/linux_work.c        Mon Aug 27 15:00:57 2018 +0000
+++ b/sys/external/bsd/common/linux/linux_work.c        Mon Aug 27 15:01:13 2018 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_work.c,v 1.20 2018/08/27 15:00:57 riastradh Exp $        */
+/*     $NetBSD: linux_work.c,v 1.21 2018/08/27 15:01:13 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 1.20 2018/08/27 15:00:57 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.21 2018/08/27 15:01:13 riastradh Exp $");
 
 #include <sys/types.h>
 #include <sys/atomic.h>
@@ -611,20 +611,30 @@
                case DELAYED_WORK_SCHEDULED:
                case DELAYED_WORK_RESCHEDULED:
                case DELAYED_WORK_CANCELLED:
-                       if (callout_stop(&dw->dw_callout)) {
-                               /*
-                                * Too late to stop, but we got in
-                                * before the callout acquired the
-                                * lock.  Tell it to give up.
-                                */
-                               dw->dw_state = DELAYED_WORK_CANCELLED;
-                       } else {
-                               /* Stopped it.  Kill it.  */
-                               callout_destroy(&dw->dw_callout);
-                               TAILQ_REMOVE(&wq->wq_delayed, dw, dw_entry);
-                               dw->dw_state = DELAYED_WORK_IDLE;
-                       }
+                       /*
+                        * If it is scheduled, mark it cancelled and
+                        * try to stop the callout before it starts.
+                        *
+                        * If it's too late and the callout has already
+                        * begun to execute, tough.
+                        *
+                        * If we stopped the callout before it started,
+                        * however, then destroy the callout and
+                        * dissociate it from the workqueue ourselves.
+                        *
+                        * XXX This logic is duplicated in the
+                        * DELAYED_WORK_CANCELLED case of
+                        * linux_workqueue_timeout.
+                        */
+                       dw->dw_state = DELAYED_WORK_CANCELLED;
                        cancelled_p = true;
+                       if (callout_stop(&dw->dw_callout))
+                               break;
+                       KASSERT(dw->dw_state == DELAYED_WORK_CANCELLED);
+                       dw->dw_state = DELAYED_WORK_IDLE;
+                       callout_destroy(&dw->dw_callout);
+                       TAILQ_REMOVE(&wq->wq_delayed, dw, dw_entry);
+                       release_work(&dw->work, wq);
                        break;
                default:
                        panic("invalid delayed work state: %d",