[RFC] iio: Release irq if set_trigger_state fails

[Crestez Dan Leonard]

When attaching a pollfunc iio_trigger_attach_poll_func will allocate a
virtual irq and call the driver's set_trigger_state function. Fix error
handling to release the irq if set_trigger_state fails.

Otherwise when using triggered buffers and the driver's
set_trigger_state fails once then the buffer becomes unusable.

It is not possible to handle this sort of error by calling
iio_trigger_detach_poll_func externally somehow. That function should
only be called if attach is successful.

Signed-off-by: Crestez Dan Leonard <leonard.cres...@intel.com>
---

I ran into this while adding some validation in driver's set_trigger_state
function. It's much better to use buffer_ops->predisable for that kind of stuff
but the iio core should still handle set_trigger_state errors correctly.

 drivers/iio/industrialio-trigger.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/iio/industrialio-trigger.c 
b/drivers/iio/industrialio-trigger.c
index ae2806a..cf2be3e 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -214,18 +214,23 @@ static int iio_trigger_attach_poll_func(struct 
iio_trigger *trig,
        ret = request_threaded_irq(pf->irq, pf->h, pf->thread,
                                   pf->type, pf->name,
                                   pf);
-       if (ret < 0) {
-               module_put(pf->indio_dev->info->driver_module);
-               return ret;
-       }
+       if (ret < 0)
+               goto out_put_module;
 
        if (trig->ops && trig->ops->set_trigger_state && notinuse) {
                ret = trig->ops->set_trigger_state(trig, true);
                if (ret < 0)
-                       module_put(pf->indio_dev->info->driver_module);
+                       goto out_put_irq;
        }
 
        return ret;
+
+out_put_irq:
+       iio_trigger_put_irq(trig, pf->irq);
+       free_irq(pf->irq, pf);
+out_put_module:
+       module_put(pf->indio_dev->info->driver_module);
+       return ret;
 }
 
 static int iio_trigger_detach_poll_func(struct iio_trigger *trig,
-- 
2.5.5