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* [PATCH] regulator: core: Add devres versions of regulator_enable/disable
@ 2019-08-09  3:03 Chuhong Yuan
  2019-08-09 15:11 ` Mark Brown
  0 siblings, 1 reply; 6+ messages in thread
From: Chuhong Yuan @ 2019-08-09  3:03 UTC (permalink / raw)
  Cc: Liam Girdwood, Mark Brown, linux-kernel, Chuhong Yuan

I wrote a coccinelle script to detect possible chances
of utilizing devm_() APIs to simplify the driver.
The script found 147 drivers in total and 22 of them
have be patched.

Within the 125 left ones, at least 31 of them (24.8%)
are hindered from benefiting from devm_() APIs because
of lack of a devres version of regulator_enable().

Therefore I implemented devm_regulator_enable/disable()
to make more drivers possible to use devm_() APIs.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
---
 drivers/regulator/devres.c | 55 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/regulator/devres.c b/drivers/regulator/devres.c
index 3ea1c170f840..507151a71fd3 100644
--- a/drivers/regulator/devres.c
+++ b/drivers/regulator/devres.c
@@ -115,6 +115,61 @@ void devm_regulator_put(struct regulator *regulator)
 }
 EXPORT_SYMBOL_GPL(devm_regulator_put);
 
+static void devm_regulator_off(struct device *dev, void *res)
+{
+	regulator_disable(*(struct regulator **)res);
+}
+
+/**
+ * devm_regulator_enable - Resource managed regulator_enable()
+ * @regulator: regulator to enable
+ *
+ * Managed regulator_enable(). Regulator enabled is automatically
+ * disabled on driver detach. See regulator_enable() for more
+ * information.
+ */
+int devm_regulator_enable(struct device *dev, struct regulator *regulator)
+{
+	struct regulator **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_regulator_off, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = regulator_enable(regulator);
+	if (!ret) {
+		*ptr = regulator;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_regulator_enable);
+
+/**
+ * devm_regulator_disable - Resource managed regulator_disable()
+ * @regulator: regulator to disable
+ *
+ * Disable a regulator enabled by devm_regulator_enable().
+ * Normally this function will not need to be called and the
+ * resource management code will ensure that the regulator is
+ * disabled.
+ */
+void devm_regulator_disable(struct regulator *regulator)
+{
+	int rc;
+
+	rc = devres_release(regulator->dev, devm_regulator_off,
+			    devm_regulator_match, regulator);
+
+	if (rc != 0)
+		WARN_ON(rc);
+}
+EXPORT_SYMBOL_GPL(devm_regulator_disable);
+
 struct regulator_bulk_devres {
 	struct regulator_bulk_data *consumers;
 	int num_consumers;
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 6+ messages in thread

* Re: [PATCH] regulator: core: Add devres versions of regulator_enable/disable
  2019-08-09  3:03 [PATCH] regulator: core: Add devres versions of regulator_enable/disable Chuhong Yuan
@ 2019-08-09 15:11 ` Mark Brown
  2019-08-10  1:44   ` Chuhong Yuan
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Brown @ 2019-08-09 15:11 UTC (permalink / raw)
  To: Chuhong Yuan; +Cc: Liam Girdwood, linux-kernel

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On Fri, Aug 09, 2019 at 11:03:52AM +0800, Chuhong Yuan wrote:
> I wrote a coccinelle script to detect possible chances
> of utilizing devm_() APIs to simplify the driver.
> The script found 147 drivers in total and 22 of them
> have be patched.

> Within the 125 left ones, at least 31 of them (24.8%)
> are hindered from benefiting from devm_() APIs because
> of lack of a devres version of regulator_enable().

I'm not super keen on managed versions of these functions since they're
very likely to cause reference counting issues between the probe/remove
path and the suspend/resume path which aren't obvious from the code, I'm
especially worried about double frees on release.

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^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] regulator: core: Add devres versions of regulator_enable/disable
  2019-08-09 15:11 ` Mark Brown
@ 2019-08-10  1:44   ` Chuhong Yuan
  2019-08-12 11:07     ` Mark Brown
  0 siblings, 1 reply; 6+ messages in thread
From: Chuhong Yuan @ 2019-08-10  1:44 UTC (permalink / raw)
  To: Mark Brown; +Cc: Liam Girdwood, LKML

On Fri, Aug 9, 2019 at 11:11 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Fri, Aug 09, 2019 at 11:03:52AM +0800, Chuhong Yuan wrote:
> > I wrote a coccinelle script to detect possible chances
> > of utilizing devm_() APIs to simplify the driver.
> > The script found 147 drivers in total and 22 of them
> > have be patched.
>
> > Within the 125 left ones, at least 31 of them (24.8%)
> > are hindered from benefiting from devm_() APIs because
> > of lack of a devres version of regulator_enable().
>
> I'm not super keen on managed versions of these functions since they're
> very likely to cause reference counting issues between the probe/remove
> path and the suspend/resume path which aren't obvious from the code, I'm
> especially worried about double frees on release.

I find that 29 of 31 cases I found call regulator_disable() only when encounter
probe failure or in .remove.
So I think the devm versions of regulator_enable/disable() will not cause big
problems.

I even found a driver to forget to disable regulator when encounter
probe failure,
which is drivers/iio/adc/ti-adc128s052.c.
And a devm version of regulator_enable() can prevent such mistakes.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] regulator: core: Add devres versions of regulator_enable/disable
  2019-08-10  1:44   ` Chuhong Yuan
@ 2019-08-12 11:07     ` Mark Brown
  2019-08-12 12:51       ` Chuhong Yuan
  0 siblings, 1 reply; 6+ messages in thread
From: Mark Brown @ 2019-08-12 11:07 UTC (permalink / raw)
  To: Chuhong Yuan; +Cc: Liam Girdwood, LKML

[-- Attachment #1: Type: text/plain, Size: 911 bytes --]

On Sat, Aug 10, 2019 at 09:44:45AM +0800, Chuhong Yuan wrote:
> On Fri, Aug 9, 2019 at 11:11 PM Mark Brown <broonie@kernel.org> wrote:

> > I'm not super keen on managed versions of these functions since they're
> > very likely to cause reference counting issues between the probe/remove
> > path and the suspend/resume path which aren't obvious from the code, I'm
> > especially worried about double frees on release.

> I find that 29 of 31 cases I found call regulator_disable() only when encounter
> probe failure or in .remove.
> So I think the devm versions of regulator_enable/disable() will not cause big
> problems.

There's way more drivers using regulators than that...

> I even found a driver to forget to disable regulator when encounter
> probe failure,
> which is drivers/iio/adc/ti-adc128s052.c.
> And a devm version of regulator_enable() can prevent such mistakes.

Yes, it's useful for that.

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^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] regulator: core: Add devres versions of regulator_enable/disable
  2019-08-12 11:07     ` Mark Brown
@ 2019-08-12 12:51       ` Chuhong Yuan
  2019-08-12 14:19         ` Chuhong Yuan
  0 siblings, 1 reply; 6+ messages in thread
From: Chuhong Yuan @ 2019-08-12 12:51 UTC (permalink / raw)
  To: Mark Brown; +Cc: Liam Girdwood, LKML

On Mon, Aug 12, 2019 at 7:07 PM Mark Brown <broonie@kernel.org> wrote:
>
> On Sat, Aug 10, 2019 at 09:44:45AM +0800, Chuhong Yuan wrote:
> > On Fri, Aug 9, 2019 at 11:11 PM Mark Brown <broonie@kernel.org> wrote:
>
> > > I'm not super keen on managed versions of these functions since they're
> > > very likely to cause reference counting issues between the probe/remove
> > > path and the suspend/resume path which aren't obvious from the code, I'm
> > > especially worried about double frees on release.
>
> > I find that 29 of 31 cases I found call regulator_disable() only when encounter
> > probe failure or in .remove.
> > So I think the devm versions of regulator_enable/disable() will not cause big
> > problems.
>
> There's way more drivers using regulators than that...
>

I wrote a new coccinelle script to detect all regulator_disable() in .remove,
101 drivers are found in total.
Within them, 25 drivers cannot benefit from devres version of regulator_enable()
since they have additional non-devm operations after
regulator_disable() in .remove.
Within the left 76 cases, 60 drivers (79%) only use
regulator_disable() when encounter
probe failure or in .remove.
The left 16 cases mostly use regulator_disable() in _suspend().
Furthermore, 3 cases of 76 are found to forget to disable regulator
when fail in probe.
So I think a devres version of regulator_enable/disable() has more
benefits than potential
risk.

> > I even found a driver to forget to disable regulator when encounter
> > probe failure,
> > which is drivers/iio/adc/ti-adc128s052.c.
> > And a devm version of regulator_enable() can prevent such mistakes.
>
> Yes, it's useful for that.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [PATCH] regulator: core: Add devres versions of regulator_enable/disable
  2019-08-12 12:51       ` Chuhong Yuan
@ 2019-08-12 14:19         ` Chuhong Yuan
  0 siblings, 0 replies; 6+ messages in thread
From: Chuhong Yuan @ 2019-08-12 14:19 UTC (permalink / raw)
  To: Mark Brown; +Cc: Liam Girdwood, LKML

On Mon, Aug 12, 2019 at 8:51 PM Chuhong Yuan <hslester96@gmail.com> wrote:
>
> On Mon, Aug 12, 2019 at 7:07 PM Mark Brown <broonie@kernel.org> wrote:
> >
> > On Sat, Aug 10, 2019 at 09:44:45AM +0800, Chuhong Yuan wrote:
> > > On Fri, Aug 9, 2019 at 11:11 PM Mark Brown <broonie@kernel.org> wrote:
> >
> > > > I'm not super keen on managed versions of these functions since they're
> > > > very likely to cause reference counting issues between the probe/remove
> > > > path and the suspend/resume path which aren't obvious from the code, I'm
> > > > especially worried about double frees on release.
> >
> > > I find that 29 of 31 cases I found call regulator_disable() only when encounter
> > > probe failure or in .remove.
> > > So I think the devm versions of regulator_enable/disable() will not cause big
> > > problems.
> >
> > There's way more drivers using regulators than that...
> >
>
> I wrote a new coccinelle script to detect all regulator_disable() in .remove,
> 101 drivers are found in total.
> Within them, 25 drivers cannot benefit from devres version of regulator_enable()
> since they have additional non-devm operations after
> regulator_disable() in .remove.

I find 6 of 25 can benefit from devm_regulator_enable().
They are included in my previously found 147 cases so I incorrectly skipped them
while checking.
Therefore, there are 82 cases that can benefit from devm_regulator_enable() and
66 of them(80.5%) only call regulator_disable() when fail in probe or
in .remove.

> Within the left 76 cases, 60 drivers (79%) only use
> regulator_disable() when encounter
> probe failure or in .remove.
> The left 16 cases mostly use regulator_disable() in _suspend().
> Furthermore, 3 cases of 76 are found to forget to disable regulator
> when fail in probe.
> So I think a devres version of regulator_enable/disable() has more
> benefits than potential
> risk.
>
> > > I even found a driver to forget to disable regulator when encounter
> > > probe failure,
> > > which is drivers/iio/adc/ti-adc128s052.c.
> > > And a devm version of regulator_enable() can prevent such mistakes.
> >
> > Yes, it's useful for that.

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2019-08-12 14:19 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-08-09  3:03 [PATCH] regulator: core: Add devres versions of regulator_enable/disable Chuhong Yuan
2019-08-09 15:11 ` Mark Brown
2019-08-10  1:44   ` Chuhong Yuan
2019-08-12 11:07     ` Mark Brown
2019-08-12 12:51       ` Chuhong Yuan
2019-08-12 14:19         ` Chuhong Yuan

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