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authorTejun Heo <tj@kernel.org>2010-08-24 14:22:47 +0200
committerTejun Heo <tj@kernel.org>2010-08-24 18:01:32 +0200
commite41e704bc4f49057fc68b643108366e6e6781aa3 (patch)
tree8cc85208970ba0c9adf533903243e28c506f23ae /kernel/workqueue.c
parent972fa1c5316d18c8297123e08e9b6930ca34f888 (diff)
workqueue: improve destroy_workqueue() debuggability
Now that the worklist is global, having works pending after wq destruction can easily lead to oops and destroy_workqueue() have several BUG_ON()s to catch these cases. Unfortunately, BUG_ON() doesn't tell much about how the work became pending after the final flush_workqueue(). This patch adds WQ_DYING which is set before the final flush begins. If a work is requested to be queued on a dying workqueue, WARN_ON_ONCE() is triggered and the request is ignored. This clearly indicates which caller is trying to queue a work on a dying workqueue and keeps the system working in most cases. Locking rule comment is updated such that the 'I' rule includes modifying the field from destruction path. Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/workqueue.c')
-rw-r--r--kernel/workqueue.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index cc3456f96c5..362b50d092e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -87,7 +87,8 @@ enum {
/*
* Structure fields follow one of the following exclusion rules.
*
- * I: Set during initialization and read-only afterwards.
+ * I: Modifiable by initialization/destruction paths and read-only for
+ * everyone else.
*
* P: Preemption protected. Disabling preemption is enough and should
* only be modified and accessed from the local cpu.
@@ -944,6 +945,9 @@ static void __queue_work(unsigned int cpu, struct workqueue_struct *wq,
debug_work_activate(work);
+ if (WARN_ON_ONCE(wq->flags & WQ_DYING))
+ return;
+
/* determine gcwq to use */
if (!(wq->flags & WQ_UNBOUND)) {
struct global_cwq *last_gcwq;
@@ -2828,6 +2832,7 @@ void destroy_workqueue(struct workqueue_struct *wq)
{
unsigned int cpu;
+ wq->flags |= WQ_DYING;
flush_workqueue(wq);
/*