Commit-ID: a25909a4d4a29e272f953e12595bf2f04a292dbd
Gitweb: http://git.kernel.org/tip/a25909a4d4a29e272f953e12595bf2f04a292dbd
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Thu, 13 May 2010 12:32:28 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon, 14 Jun 2010 16:37:26 -0700
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@xxxxxxxxxxxxxxxxxx>
---
include/linux/workqueue.h | 4 ++++
kernel/workqueue.c | 15 +++++++++++++++
2 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 9466e86..d0f7c81 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 327d2de..59fef15 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;
--
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