From: Gyeyoung Baek <gye976@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: "David Lechner" <dlechner@baylibre.com>,
"Nuno Sá" <nuno.sa@analog.com>,
"Andy Shevchenko" <andy@kernel.org>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org,
"Gyeyoung Baek" <gye976@gmail.com>
Subject: [PATCH] iio: trigger: Avoid data race
Date: Wed, 28 May 2025 05:05:34 +0900 [thread overview]
Message-ID: <20250527200534.98689-1-gye976@gmail.com> (raw)
A data race could occur between `atomic_read()` and `atomic_set()`
Use `atomic_cmpxchg_relaxed()` to group them atomically.
Previously the main logic was executed when `use_count` is 0.
Now it returns early when `use_count` is not 0.
Signed-off-by: Gyeyoung Baek <gye976@gmail.com>
---
drivers/iio/industrialio-trigger.c | 38 +++++++++++++-----------------
1 file changed, 17 insertions(+), 21 deletions(-)
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..33a565037e0d 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -194,17 +194,15 @@ static void iio_trigger_notify_done_atomic(struct iio_trigger *trig)
*/
void iio_trigger_poll(struct iio_trigger *trig)
{
- int i;
-
- if (!atomic_read(&trig->use_count)) {
- atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
-
- for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
- if (trig->subirqs[i].enabled)
- generic_handle_irq(trig->subirq_base + i);
- else
- iio_trigger_notify_done_atomic(trig);
- }
+ if (atomic_cmpxchg_relaxed(&trig->use_count, 0,
+ CONFIG_IIO_CONSUMERS_PER_TRIGGER))
+ return;
+
+ for (int i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
+ if (trig->subirqs[i].enabled)
+ generic_handle_irq(trig->subirq_base + i);
+ else
+ iio_trigger_notify_done_atomic(trig);
}
}
EXPORT_SYMBOL(iio_trigger_poll);
@@ -225,17 +223,15 @@ EXPORT_SYMBOL(iio_trigger_generic_data_rdy_poll);
*/
void iio_trigger_poll_nested(struct iio_trigger *trig)
{
- int i;
-
- if (!atomic_read(&trig->use_count)) {
- atomic_set(&trig->use_count, CONFIG_IIO_CONSUMERS_PER_TRIGGER);
+ if (atomic_cmpxchg_relaxed(&trig->use_count, 0,
+ CONFIG_IIO_CONSUMERS_PER_TRIGGER))
+ return;
- for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
- if (trig->subirqs[i].enabled)
- handle_nested_irq(trig->subirq_base + i);
- else
- iio_trigger_notify_done(trig);
- }
+ for (int i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
+ if (trig->subirqs[i].enabled)
+ handle_nested_irq(trig->subirq_base + i);
+ else
+ iio_trigger_notify_done(trig);
}
}
EXPORT_SYMBOL(iio_trigger_poll_nested);
--
2.43.0
next reply other threads:[~2025-05-27 20:05 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-27 20:05 Gyeyoung Baek [this message]
2025-05-27 20:24 ` [PATCH] iio: trigger: Avoid data race Andy Shevchenko
2025-05-27 21:10 ` Gyeyoung Baek
2025-05-27 21:18 ` Andy Shevchenko
2025-05-28 7:17 ` Gyeyoung Baek
2025-05-28 17:02 ` Jonathan Cameron
2025-05-29 5:42 ` Andy Shevchenko
2025-05-29 9:32 ` Jonathan Cameron
2025-05-29 13:34 ` Gyeyoung Baek
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