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From:   Dmitry Rokosov <DDRokosov@sberdevices.ru>
To:     "robh+dt@kernel.org" <robh+dt@kernel.org>,
        "jic23@kernel.org" <jic23@kernel.org>,
        "lars@metafoo.de" <lars@metafoo.de>,
        "andy.shevchenko@gmail.com" <andy.shevchenko@gmail.com>,
        "noname.nuno@gmail.com" <noname.nuno@gmail.com>
CC:     "linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>,
        kernel <kernel@sberdevices.ru>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "rockosov@gmail.com" <rockosov@gmail.com>,
        Dmitry Rokosov <DDRokosov@sberdevices.ru>
Subject: [PATCH v3] iio: trigger: warn about non-registered iio trigger
 getting attempt
Thread-Topic: [PATCH v3] iio: trigger: warn about non-registered iio trigger
 getting attempt
Thread-Index: AQHYep3lZdCBX5wfLkWR1miHp7T4Og==
Date:   Tue, 7 Jun 2022 18:39:18 +0000
Message-ID: <20220607183907.20017-1-ddrokosov@sberdevices.ru>
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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_ONCE() is added to alarm IIO driver authors who make such
a mistake.

When an IIO driver allocates a new IIO trigger, it should register it
before calling the get() operation. In other words, each IIO driver
must abide by IIO trigger alloc()/register()/get() calls order.

Signed-off-by: Dmitry Rokosov <ddrokosov@sberdevices.ru>
---
Changes:
v1 -> v2: totally reworked the patch, used trig->list entry instead of
          trig->owner as driver registration indicator.
          It works perfectly for both builtin and built as a module
          drivers.

v2 -> v3: changed WARN() call to WARN_ONCE() to avoid warn spamming
          during deferred probe() as Andy suggested.
---
 drivers/iio/industrialio-trigger.c | 2 ++
 include/linux/iio/trigger.h        | 5 +++++
 2 files changed, 7 insertions(+)

diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-=
trigger.c
index f504ed351b3e..d6277e72d515 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -581,6 +581,8 @@ struct iio_trigger *viio_trigger_alloc(struct device *p=
arent,
 	if (trig->name =3D=3D NULL)
 		goto free_descs;
=20
+	INIT_LIST_HEAD(&trig->list);
+
 	trig->subirq_chip.name =3D trig->name;
 	trig->subirq_chip.irq_mask =3D &iio_trig_subirqmask;
 	trig->subirq_chip.irq_unmask =3D &iio_trig_subirqunmask;
diff --git a/include/linux/iio/trigger.h b/include/linux/iio/trigger.h
index 4c69b144677b..03b1d6863436 100644
--- a/include/linux/iio/trigger.h
+++ b/include/linux/iio/trigger.h
@@ -93,6 +93,11 @@ static inline void iio_trigger_put(struct iio_trigger *t=
rig)
 static inline struct iio_trigger *iio_trigger_get(struct iio_trigger *trig=
)
 {
 	get_device(&trig->dev);
+
+	WARN_ONCE(list_empty(&trig->list),
+		  "Getting non-registered iio trigger %s is prohibited\n",
+		  trig->name);
+
 	__module_get(trig->owner);
=20
 	return trig;
--=20
2.36.0