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| author | Tejun Heo <tj@kernel.org> | 2010-08-24 14:22:47 +0200 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2010-08-24 18:01:32 +0200 |
| commit | e41e704bc4f49057fc68b643108366e6e6781aa3 (patch) | |
| tree | 8cc85208970ba0c9adf533903243e28c506f23ae | |
| parent | 972fa1c5316d18c8297123e08e9b6930ca34f888 (diff) | |
| download | talos-obmc-linux-e41e704bc4f49057fc68b643108366e6e6781aa3.tar.gz talos-obmc-linux-e41e704bc4f49057fc68b643108366e6e6781aa3.zip | |
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>
| -rw-r--r-- | include/linux/workqueue.h | 2 | ||||
| -rw-r--r-- | kernel/workqueue.c | 7 |
2 files changed, 8 insertions, 1 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, diff --git a/kernel/workqueue.c b/kernel/workqueue.c index cc3456f96c56..362b50d092e2 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); /* |
