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lockdep: Add an in_workqueue_context() lockdep-based test function

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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>
This commit is contained in:
Paul E. McKenney 2010-05-13 12:32:28 -07:00
commit a25909a4d4
2 changed files with 19 additions and 0 deletions
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4
include/linux/workqueue.h
View file

@ -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

15
kernel/workqueue.c
View file

@ -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;