[src/netbsd-9]: src/sys/external/bsd/common/linux Pull up following revision(...

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

details:   https://anonhg.NetBSD.org/src/rev/4392bf588840
branches:  netbsd-9
changeset: 744787:4392bf588840
user:      martin <martin%NetBSD.org@localhost>
date:      Wed Feb 12 20:02:19 2020 +0000

description:
Pull up following revision(s) (requested by riastradh in ticket #703):

        sys/external/bsd/common/linux/linux_work.c: revision 1.45

Fix abuse of TAILQ_CONCAT.

Other parts of this expect that the entries will be on wq->wq_queue
or wq->wq_dqueue, so we can't just move a batch of entries onto a
temporary queue.  Instead, use a marker node to delimit when the
batch ends.

XXX pullup

diffstat:

 sys/external/bsd/common/linux/linux_work.c |  29 +++++++++++++++--------------
 1 files changed, 15 insertions(+), 14 deletions(-)

diffs (70 lines):

diff -r 439106497042 -r 4392bf588840 sys/external/bsd/common/linux/linux_work.c
--- a/sys/external/bsd/common/linux/linux_work.c        Wed Feb 12 19:59:22 2020 +0000
+++ b/sys/external/bsd/common/linux/linux_work.c        Wed Feb 12 20:02:19 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_work.c,v 1.44 2019/03/19 08:17:46 ryo Exp $      */
+/*     $NetBSD: linux_work.c,v 1.44.4.1 2020/02/12 20:02:19 martin Exp $       */
 
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.44 2019/03/19 08:17:46 ryo Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.44.4.1 2020/02/12 20:02:19 martin Exp $");
 
 #include <sys/types.h>
 #include <sys/atomic.h>
@@ -348,8 +348,8 @@
 linux_workqueue_thread(void *cookie)
 {
        struct workqueue_struct *const wq = cookie;
-       struct work_head queue, dqueue;
-       struct work_head *const q[2] = { &queue, &dqueue };
+       struct work_head *const q[2] = { &wq->wq_queue, &wq->wq_dqueue };
+       struct work_struct marker, *work;
        unsigned i;
 
        lwp_setspecific(workqueue_key, wq);
@@ -368,22 +368,22 @@
                        continue;
                }
 
-               /* Grab a batch of work off the queue.  */
+               /*
+                * Start a batch of work.  Use a marker to delimit when
+                * the batch ends so we can advance the generation
+                * after the batch.
+                */
                SDT_PROBE1(sdt, linux, work, batch__start,  wq);
-               TAILQ_INIT(&queue);
-               TAILQ_INIT(&dqueue);
-               TAILQ_CONCAT(&queue, &wq->wq_queue, work_entry);
-               TAILQ_CONCAT(&dqueue, &wq->wq_dqueue, work_entry);
-
-               /* Process each work item in the batch.  */
                for (i = 0; i < 2; i++) {
-                       while (!TAILQ_EMPTY(q[i])) {
-                               struct work_struct *work = TAILQ_FIRST(q[i]);
+                       if (TAILQ_EMPTY(q[i]))
+                               continue;
+                       TAILQ_INSERT_TAIL(q[i], &marker, work_entry);
+                       while ((work = TAILQ_FIRST(q[i])) != &marker) {
                                void (*func)(struct work_struct *);
 
                                KASSERT(work_queue(work) == wq);
                                KASSERT(work_claimed(work, wq));
-                               KASSERTMSG((q[i] != &dqueue ||
+                               KASSERTMSG((q[i] != &wq->wq_dqueue ||
                                        container_of(work, struct delayed_work,
                                            work)->dw_state ==
                                        DELAYED_WORK_IDLE),
@@ -407,6 +407,7 @@
                                wq->wq_current_work = NULL;
                                cv_broadcast(&wq->wq_cv);
                        }
+                       TAILQ_REMOVE(q[i], &marker, work_entry);
                }
 
                /* Notify flush that we've completed a batch of work.  */