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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 /include
parent972fa1c5316d18c8297123e08e9b6930ca34f888 (diff)
downloadlinux-e41e704bc4f49057fc68b643108366e6e6781aa3.tar.gz
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 'include')
-rw-r--r--include/linux/workqueue.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 4f9d277bcd9a..c959666eafca 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -241,6 +241,8 @@ enum {
 	WQ_HIGHPRI		= 1 << 4, /* high priority */
 	WQ_CPU_INTENSIVE	= 1 << 5, /* cpu instensive workqueue */
 
+	WQ_DYING		= 1 << 6, /* internal: workqueue is dying */
+
 	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
 	WQ_MAX_UNBOUND_PER_CPU	= 4,	  /* 4 * #cpus for unbound wq */
 	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,