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Subject[PATCH v1] iio: trigger: warn about non-registered iio trigger getting attempt
Date
As a part of patch series about wrong trigger register() and get()
calls order in the some IIO drivers trigger initialization path:

https://lore.kernel.org/all/20220524181150.9240-1-ddrokosov@sberdevices.ru/

runtime WARN() is added to alarm IIO driver authors who make such
a mistake.

When IIO driver allocates a new IIO trigger, it should register it before
calling get() operation. Otherwise, the next iio_trigger_put() will upset
refcnt balance.

Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
---
include/linux/iio/trigger.h | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h
index 4c69b144677b..4a008b952710 100644
--- a/include/linux/iio/trigger.h
+++ b/include/linux/iio/trigger.h
@@ -93,6 +93,15 @@ static inline void iio_trigger_put(struct iio_trigger *trig)
static inline struct iio_trigger *iio_trigger_get(struct iio_trigger *trig)
{
get_device(&trig->dev);
+
+ /*
+ * If driver hasn't called iio_trigger_register() before and trig->owner
+ * wasn't initialized properly, trigger will have wrong number of users
+ */
+ WARN(!trig->owner,
+ "Ignore module getting for non-registered iio trigger %s\n",
+ trig->name);
+
__module_get(trig->owner);

return trig;
--
2.36.0
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