diff options
Diffstat (limited to 'drivers/iio/industrialio-trigger.c')
| -rw-r--r-- | drivers/iio/industrialio-trigger.c | 36 |
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, |