lockdep: Add an in_workqueue_context() lockdep-based test function (a25909a4) · Commits · 戴 / test

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>

include/linux/workqueue.h

+4 −0

Original line number	Diff line number	Diff line
		@@ -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

kernel/workqueue.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -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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