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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-05-13 12:32:28 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-06-14 16:37:26 -0700
commita25909a4d4a29e272f953e12595bf2f04a292dbd (patch)
tree86b54bc29aa126eff797b98728133ea960f8bd01
parent71d1d5c722db9ae3b3f9c08ef7ddcd7759fbb1e0 (diff)
lockdep: Add an in_workqueue_context() lockdep-based test function
Some recent uses of RCU make use of workqueues. In these uses, execution within the context of a specific workqueue takes the place of the usual RCU read-side primitives such as rcu_read_lock(), and flushing of workqueues takes the place of the usual RCU grace-period primitives. Checking for correct use of rcu_dereference() in such cases requires a test of whether the code is executing in the context of a particular workqueue. This commit adds an in_workqueue_context() function that provides this test. This new function is only defined when lockdep is enabled, which allows it to be used as the second argument of rcu_dereference_check(). Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--include/linux/workqueue.h4
-rw-r--r--kernel/workqueue.c15
2 files changed, 19 insertions, 0 deletions
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 9466e860d8c..d0f7c817849 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -297,4 +297,8 @@ static inline long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg)
#else
long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg);
#endif /* CONFIG_SMP */
+
+#ifdef CONFIG_LOCKDEP
+int in_workqueue_context(struct workqueue_struct *wq);
+#endif
#endif
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 327d2deb445..59fef1531dd 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -68,6 +68,21 @@ struct workqueue_struct {
#endif
};
+#ifdef CONFIG_LOCKDEP
+/**
+ * in_workqueue_context() - in context of specified workqueue?
+ * @wq: the workqueue of interest
+ *
+ * Checks lockdep state to see if the current task is executing from
+ * within a workqueue item. This function exists only if lockdep is
+ * enabled.
+ */
+int in_workqueue_context(struct workqueue_struct *wq)
+{
+ return lock_is_held(&wq->lockdep_map);
+}
+#endif
+
#ifdef CONFIG_DEBUG_OBJECTS_WORK
static struct debug_obj_descr work_debug_descr;