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authorStephen Boyd <sboyd@codeaurora.org>2013-08-13 14:12:40 -0700
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2013-08-14 00:42:05 +0200
commit40fea92ffb5fa0ef26d10ae0fe5688bc8e61c791 (patch)
treedc3d38be74a14dc868a6ee9d420451afd435f6f1
parentd4e4ab86bcba5a72779c43dc1459f71fea3d89c8 (diff)
downloadlinux-40fea92ffb5fa0ef26d10ae0fe5688bc8e61c791.tar.gz
PM / QoS: Fix workqueue deadlock when using pm_qos_update_request_timeout()
pm_qos_update_request_timeout() updates a qos and then schedules a delayed work item to bring the qos back down to the default after the timeout. When the work item runs, pm_qos_work_fn() will call pm_qos_update_request() and deadlock because it tries to cancel itself via cancel_delayed_work_sync(). Future callers of that qos will also hang waiting to cancel the work that is canceling itself. Let's extract the little bit of code that does the real work of pm_qos_update_request() and call it from the work function so that we don't deadlock. Before ed1ac6e (PM: don't use [delayed_]work_pending()) this didn't happen because the work function wouldn't try to cancel itself. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Reviewed-by: Tejun Heo <tj@kernel.org> Cc: 3.9+ <stable@vger.kernel.org> # 3.9+ Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-rw-r--r--kernel/power/qos.c20
1 files changed, 13 insertions, 7 deletions
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 06fe28589e9c..a394297f8b2f 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -296,6 +296,17 @@ int pm_qos_request_active(struct pm_qos_request *req)
}
EXPORT_SYMBOL_GPL(pm_qos_request_active);
+static void __pm_qos_update_request(struct pm_qos_request *req,
+ s32 new_value)
+{
+ trace_pm_qos_update_request(req->pm_qos_class, new_value);
+
+ if (new_value != req->node.prio)
+ pm_qos_update_target(
+ pm_qos_array[req->pm_qos_class]->constraints,
+ &req->node, PM_QOS_UPDATE_REQ, new_value);
+}
+
/**
* pm_qos_work_fn - the timeout handler of pm_qos_update_request_timeout
* @work: work struct for the delayed work (timeout)
@@ -308,7 +319,7 @@ static void pm_qos_work_fn(struct work_struct *work)
struct pm_qos_request,
work);
- pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
+ __pm_qos_update_request(req, PM_QOS_DEFAULT_VALUE);
}
/**
@@ -364,12 +375,7 @@ void pm_qos_update_request(struct pm_qos_request *req,
}
cancel_delayed_work_sync(&req->work);
-
- trace_pm_qos_update_request(req->pm_qos_class, new_value);
- if (new_value != req->node.prio)
- pm_qos_update_target(
- pm_qos_array[req->pm_qos_class]->constraints,
- &req->node, PM_QOS_UPDATE_REQ, new_value);
+ __pm_qos_update_request(req, new_value);
}
EXPORT_SYMBOL_GPL(pm_qos_update_request);