* [PATCH v2] iio: trigger: Avoid data race
@ 2025-05-28 8:01 Gyeyoung Baek
2025-05-28 9:22 ` Andy Shevchenko
2025-05-28 14:56 ` [PATCH v3] " Gyeyoung Baek
0 siblings, 2 replies; 6+ messages in thread
From: Gyeyoung Baek @ 2025-05-28 8:01 UTC (permalink / raw)
To: Jonathan Cameron
Cc: David Lechner, Nuno Sá, Andy Shevchenko, linux-iio,
linux-kernel, Gyeyoung Baek
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
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH v2] iio: trigger: Avoid data race
2025-05-28 8:01 [PATCH v2] iio: trigger: Avoid data race Gyeyoung Baek
@ 2025-05-28 9:22 ` Andy Shevchenko
2025-05-28 13:27 ` Gyeyoung Baek
2025-05-28 14:56 ` [PATCH v3] " Gyeyoung Baek
1 sibling, 1 reply; 6+ messages in thread
From: Andy Shevchenko @ 2025-05-28 9:22 UTC (permalink / raw)
To: Gyeyoung Baek
Cc: Jonathan Cameron, David Lechner, Nuno Sá, Andy Shevchenko,
linux-iio, linux-kernel
On Wed, May 28, 2025 at 10:01 AM Gyeyoung Baek <gye976@gmail.com> wrote:
>
> 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.
This needs Fixes tag, otherwise LGTM,
Reviewed-by: Andy Shevchenko <andy@kernel.org>
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] iio: trigger: Avoid data race
2025-05-28 9:22 ` Andy Shevchenko
@ 2025-05-28 13:27 ` Gyeyoung Baek
2025-05-28 17:03 ` Jonathan Cameron
0 siblings, 1 reply; 6+ messages in thread
From: Gyeyoung Baek @ 2025-05-28 13:27 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Jonathan Cameron, David Lechner, Nuno Sá, Andy Shevchenko,
linux-iio, linux-kernel
On Wed, May 28, 2025 at 6:22 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Wed, May 28, 2025 at 10:01 AM Gyeyoung Baek <gye976@gmail.com> wrote:
> >
> > 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.
>
> This needs Fixes tag, otherwise LGTM,
> Reviewed-by: Andy Shevchenko <andy@kernel.org>
Yes, then I'll send v3, thanks!
> --
> With Best Regards,
> Andy Shevchenko
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] iio: trigger: Avoid data race
2025-05-28 13:27 ` Gyeyoung Baek
@ 2025-05-28 17:03 ` Jonathan Cameron
2025-05-29 17:01 ` Gyeyoung Baek
0 siblings, 1 reply; 6+ messages in thread
From: Jonathan Cameron @ 2025-05-28 17:03 UTC (permalink / raw)
To: Gyeyoung Baek
Cc: Andy Shevchenko, Jonathan Cameron, David Lechner, Nuno Sá,
Andy Shevchenko, linux-iio, linux-kernel
On Wed, 28 May 2025 22:27:25 +0900
Gyeyoung Baek <gye976@gmail.com> wrote:
> On Wed, May 28, 2025 at 6:22 PM Andy Shevchenko
> <andy.shevchenko@gmail.com> wrote:
> >
> > On Wed, May 28, 2025 at 10:01 AM Gyeyoung Baek <gye976@gmail.com> wrote:
> > >
> > > 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.
> >
> > This needs Fixes tag, otherwise LGTM,
> > Reviewed-by: Andy Shevchenko <andy@kernel.org>
>
> Yes, then I'll send v3, thanks!
Slow down :)
Reply to v1. In general don't rush new versions out so quickly.
>
> > --
> > With Best Regards,
> > Andy Shevchenko
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v2] iio: trigger: Avoid data race
2025-05-28 17:03 ` Jonathan Cameron
@ 2025-05-29 17:01 ` Gyeyoung Baek
0 siblings, 0 replies; 6+ messages in thread
From: Gyeyoung Baek @ 2025-05-29 17:01 UTC (permalink / raw)
To: Jonathan Cameron
Cc: Andy Shevchenko, Jonathan Cameron, David Lechner, Nuno Sá,
Andy Shevchenko, linux-iio, linux-kernel
On Thu, May 29, 2025 at 2:03 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Wed, 28 May 2025 22:27:25 +0900
> Gyeyoung Baek <gye976@gmail.com> wrote:
>
> > On Wed, May 28, 2025 at 6:22 PM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:
> > >
> > > On Wed, May 28, 2025 at 10:01 AM Gyeyoung Baek <gye976@gmail.com> wrote:
> >
> > Yes, then I'll send v3, thanks!
> Slow down :)
>
> Reply to v1. In general don't rush new versions out so quickly.
Yes, I should have waited for your review...
I thought the situation was pretty simple,
but there were many details as you pointed out.
I'll be more careful going forward, thanks.
--
Best regards,
Gyeyoung
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH v3] iio: trigger: Avoid data race
2025-05-28 8:01 [PATCH v2] iio: trigger: Avoid data race Gyeyoung Baek
2025-05-28 9:22 ` Andy Shevchenko
@ 2025-05-28 14:56 ` Gyeyoung Baek
1 sibling, 0 replies; 6+ messages in thread
From: Gyeyoung Baek @ 2025-05-28 14:56 UTC (permalink / raw)
To: Jonathan Cameron
Cc: David Lechner, Nuno Sá, Andy Shevchenko, linux-iio,
linux-kernel, Gyeyoung Baek
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
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2025-05-29 17:01 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2025-05-28 8:01 [PATCH v2] iio: trigger: Avoid data race Gyeyoung Baek
2025-05-28 9:22 ` 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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