aboutsummaryrefslogtreecommitdiff
path: root/drivers/iio/industrialio-trigger.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/iio/industrialio-trigger.c')
-rw-r--r--drivers/iio/industrialio-trigger.c36
1 files changed, 35 insertions, 1 deletions
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 93990ff1dfe3..f504ed351b3e 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -162,6 +162,39 @@ static struct iio_trigger *iio_trigger_acquire_by_name(const char *name)
return trig;
}
+static void iio_reenable_work_fn(struct work_struct *work)
+{
+ struct iio_trigger *trig = container_of(work, struct iio_trigger,
+ reenable_work);
+
+ /*
+ * This 'might' occur after the trigger state is set to disabled -
+ * in that case the driver should skip reenabling.
+ */
+ trig->ops->reenable(trig);
+}
+
+/*
+ * In general, reenable callbacks may need to sleep and this path is
+ * not performance sensitive, so just queue up a work item
+ * to reneable the trigger for us.
+ *
+ * Races that can cause this.
+ * 1) A handler occurs entirely in interrupt context so the counter
+ * the final decrement is still in this interrupt.
+ * 2) The trigger has been removed, but one last interrupt gets through.
+ *
+ * For (1) we must call reenable, but not in atomic context.
+ * For (2) it should be safe to call reenanble, if drivers never blindly
+ * reenable after state is off.
+ */
+static void iio_trigger_notify_done_atomic(struct iio_trigger *trig)
+{
+ if (atomic_dec_and_test(&trig->use_count) && trig->ops &&
+ trig->ops->reenable)
+ schedule_work(&trig->reenable_work);
+}
+
void iio_trigger_poll(struct iio_trigger *trig)
{
int i;
@@ -173,7 +206,7 @@ void iio_trigger_poll(struct iio_trigger *trig)
if (trig->subirqs[i].enabled)
generic_handle_irq(trig->subirq_base + i);
else
- iio_trigger_notify_done(trig);
+ iio_trigger_notify_done_atomic(trig);
}
}
}
@@ -535,6 +568,7 @@ struct iio_trigger *viio_trigger_alloc(struct device *parent,
trig->dev.type = &iio_trig_type;
trig->dev.bus = &iio_bus_type;
device_initialize(&trig->dev);
+ INIT_WORK(&trig->reenable_work, iio_reenable_work_fn);
mutex_init(&trig->pool_lock);
trig->subirq_base = irq_alloc_descs(-1, 0,