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 v2] iio: trigger: Avoid data race
Date: Wed, 28 May 2025 17:01:19 +0900 [thread overview]
Message-ID: <20250528080119.9380-1-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` was 0.
Now it returns early when `use_count` was not 0.
Signed-off-by: Gyeyoung Baek <gye976@gmail.com>
---
Changelog:
v2:
- Edit commit message.
- Separate variable declaration from logic. (Andy)
---
drivers/iio/industrialio-trigger.c | 32 +++++++++++++++---------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..fc799910c74d 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -196,15 +196,15 @@ 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);
+ 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)
- generic_handle_irq(trig->subirq_base + i);
- else
- iio_trigger_notify_done_atomic(trig);
- }
+ 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);
}
}
EXPORT_SYMBOL(iio_trigger_poll);
@@ -227,15 +227,15 @@ 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 (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
WARNING: multiple messages have this Message-ID (diff)
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 v3] iio: trigger: Avoid data race
Date: Wed, 28 May 2025 23:56:48 +0900 [thread overview]
Message-ID: <20250528080119.9380-1-gye976@gmail.com> (raw)
Message-ID: <20250528145648.puTzwVz0ui-4FeoUrMKBPfq9aNfc8m7ZQ8-jOSPrSbo@z> (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` was 0.
Now it returns early when `use_count` was not 0.
Fixes: a1a8e1dc111d ("iio:trigger: Fix use_count race condition")
Reviewed-by: Andy Shevchenko <andy@kernel.org>
Signed-off-by: Gyeyoung Baek <gye976@gmail.com>
---
Changelog:
v3:
- Add Fixes tag.
v2:
- Edit commit message.
- Separate variable declaration from logic.
---
drivers/iio/industrialio-trigger.c | 32 +++++++++++++++---------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/drivers/iio/industrialio-trigger.c b/drivers/iio/industrialio-trigger.c
index 54416a384232..fc799910c74d 100644
--- a/drivers/iio/industrialio-trigger.c
+++ b/drivers/iio/industrialio-trigger.c
@@ -196,15 +196,15 @@ 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);
+ 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)
- generic_handle_irq(trig->subirq_base + i);
- else
- iio_trigger_notify_done_atomic(trig);
- }
+ 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);
}
}
EXPORT_SYMBOL(iio_trigger_poll);
@@ -227,15 +227,15 @@ 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 (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:[~2025-05-28 8:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-28 8:01 Gyeyoung Baek [this message]
2025-05-28 9:22 ` [PATCH v2] iio: trigger: Avoid data race Andy Shevchenko
2025-05-28 13:27 ` Gyeyoung Baek
2025-05-28 17:03 ` Jonathan Cameron
2025-05-29 17:01 ` Gyeyoung Baek
2025-05-28 14:56 ` [PATCH v3] " Gyeyoung Baek
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