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Date: Fri, 20 May 2016 09:59:18 -0700
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Manfred Schlaegl <manfred.schlaegl@....at>
Cc: Thierry Reding <thierry.reding@...il.com>,
Manfred Schlaegl <manfred.schlaegl@...zinger.com>,
Luis de Bethencourt <luis@...ethencourt.com>,
Olivier Sobrie <olivier@...rie.be>,
linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] Input: pwm-beeper - fix: scheduling while atomic
Hi Manfred,
On Wed, May 18, 2016 at 05:16:49PM +0200, Manfred Schlaegl wrote:
> @@ -133,6 +149,8 @@ static int pwm_beeper_remove(struct platform_device *pdev)
> {
> struct pwm_beeper *beeper = platform_get_drvdata(pdev);
>
> + cancel_work_sync(&beeper->work);
> +
> input_unregister_device(beeper->input);
This is racy, request to play may come in after cancel_work_sync()
returns but before we unregistered input device. I think you want the
version below.
--
Dmitry
Input: pwm-beeper - fix 'scheduling while atomic'
From: Manfred Schlaegl <manfred.schlaegl@....at>
Pwm config may sleep so defer it using a worker.
Trigger:
On a Freescale i.MX53 based board we ran into "BUG: scheduling while
atomic" because input_inject_event locks interrupts, but
imx_pwm_config_v2 sleeps.
Tested on Freescale i.MX53 SoC with 4.6.0 and 4.1.24.
Signed-off-by: Manfred Schlaegl <manfred.schlaegl@....at>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
drivers/input/misc/pwm-beeper.c | 70 +++++++++++++++++++++++++++------------
1 file changed, 49 insertions(+), 21 deletions(-)
diff --git a/drivers/input/misc/pwm-beeper.c b/drivers/input/misc/pwm-beeper.c
index f2261ab..27de150 100644
--- a/drivers/input/misc/pwm-beeper.c
+++ b/drivers/input/misc/pwm-beeper.c
@@ -20,21 +20,41 @@
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
+#include <linux/workqueue.h>
struct pwm_beeper {
struct input_dev *input;
struct pwm_device *pwm;
+ struct work_struct work;
unsigned long period;
};
#define HZ_TO_NANOSECONDS(x) (1000000000UL/(x))
+static void __pwm_beeper_set(struct pwm_beeper *beeper)
+{
+ unsigned long period = beeper->period;
+
+ pwm_config(beeper->pwm, period / 2, period);
+
+ if (period == 0)
+ pwm_disable(beeper->pwm);
+ else
+ pwm_enable(beeper->pwm);
+}
+
+static void pwm_beeper_work(struct work_struct *work)
+{
+ struct pwm_beeper *beeper =
+ container_of(work, struct pwm_beeper, work);
+
+ __pwm_beeper_set(beeper);
+}
+
static int pwm_beeper_event(struct input_dev *input,
unsigned int type, unsigned int code, int value)
{
- int ret = 0;
struct pwm_beeper *beeper = input_get_drvdata(input);
- unsigned long period;
if (type != EV_SND || value < 0)
return -EINVAL;
@@ -49,22 +69,31 @@ static int pwm_beeper_event(struct input_dev *input,
return -EINVAL;
}
- if (value == 0) {
- pwm_disable(beeper->pwm);
- } else {
- period = HZ_TO_NANOSECONDS(value);
- ret = pwm_config(beeper->pwm, period / 2, period);
- if (ret)
- return ret;
- ret = pwm_enable(beeper->pwm);
- if (ret)
- return ret;
- beeper->period = period;
- }
+ if (value == 0)
+ beeper->period = 0;
+ else
+ beeper->period = HZ_TO_NANOSECONDS(value);
+
+ schedule_work(&beeper->work);
return 0;
}
+static void pwm_beeper_stop(struct pwm_beeper *beeper)
+{
+ cancel_work_sync(&beeper->work);
+
+ if (beeper->period)
+ pwm_disable(beeper->pwm);
+}
+
+static void pwm_beeper_close(struct input_dev *input)
+{
+ struct pwm_beeper *beeper = input_get_drvdata(input);
+
+ pwm_beeper_stop(beeper);
+}
+
static int pwm_beeper_probe(struct platform_device *pdev)
{
unsigned long pwm_id = (unsigned long)dev_get_platdata(&pdev->dev);
@@ -87,6 +116,8 @@ static int pwm_beeper_probe(struct platform_device *pdev)
goto err_free;
}
+ INIT_WORK(&beeper->work, pwm_beeper_work);
+
beeper->input = input_allocate_device();
if (!beeper->input) {
dev_err(&pdev->dev, "Failed to allocate input device\n");
@@ -106,6 +137,7 @@ static int pwm_beeper_probe(struct platform_device *pdev)
beeper->input->sndbit[0] = BIT(SND_TONE) | BIT(SND_BELL);
beeper->input->event = pwm_beeper_event;
+ beeper->input->close = pwm_beeper_close;
input_set_drvdata(beeper->input, beeper);
@@ -135,7 +167,6 @@ static int pwm_beeper_remove(struct platform_device *pdev)
input_unregister_device(beeper->input);
- pwm_disable(beeper->pwm);
pwm_free(beeper->pwm);
kfree(beeper);
@@ -147,8 +178,7 @@ static int __maybe_unused pwm_beeper_suspend(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
- if (beeper->period)
- pwm_disable(beeper->pwm);
+ pwm_beeper_stop(beeper);
return 0;
}
@@ -157,10 +187,8 @@ static int __maybe_unused pwm_beeper_resume(struct device *dev)
{
struct pwm_beeper *beeper = dev_get_drvdata(dev);
- if (beeper->period) {
- pwm_config(beeper->pwm, beeper->period / 2, beeper->period);
- pwm_enable(beeper->pwm);
- }
+ if (beeper->period)
+ __pwm_beeper_set(beeper);
return 0;
}
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