lkml.org 
[lkml]   [2013]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC: PATCH 2/2] iio: adc: exynos_adc: Handle timeout and race conditions
Date
This patch does the following
1. Handle the return values of wait_for_completion_interruptible_timeout
2. Add spin locks to avoid race conditions during ISR.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Lars-Peter Clausen <lars@metafoo.de>
---
Discussion thread for this patch can be found at
http://www.gossamer-threads.com/lists/linux/kernel/1693284?page=last

I've not seen any reference to spin lock usage in IIO.
Kindly, suggest me if there is a better way to avoid the race.

Thanks,
Naveen
drivers/iio/adc/exynos_adc.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/exynos_adc.c b/drivers/iio/adc/exynos_adc.c
index ed6fdd7..4de28ae 100644
--- a/drivers/iio/adc/exynos_adc.c
+++ b/drivers/iio/adc/exynos_adc.c
@@ -91,6 +91,7 @@ struct exynos_adc {

struct completion completion;

+ spinlock_t reg_lock;
u32 value;
unsigned int version;
};
@@ -117,7 +118,7 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
long mask)
{
struct exynos_adc *info = iio_priv(indio_dev);
- unsigned long timeout;
+ long timeout;
u32 con1, con2;

if (mask != IIO_CHAN_INFO_RAW)
@@ -143,15 +144,19 @@ static int exynos_read_raw(struct iio_dev *indio_dev,
ADC_V1_CON(info->regs));
}

+ INIT_COMPLETION(info->completion);
+
timeout = wait_for_completion_interruptible_timeout
(&info->completion, EXYNOS_ADC_TIMEOUT);
+
*val = info->value;

mutex_unlock(&indio_dev->mlock);

if (timeout == 0)
return -ETIMEDOUT;
-
+ else if (timeout < 0)
+ return timeout;
return IIO_VAL_INT;
}

@@ -159,6 +164,8 @@ static irqreturn_t exynos_adc_isr(int irq, void *dev_id)
{
struct exynos_adc *info = (struct exynos_adc *)dev_id;

+ spin_lock(&info->reg_lock);
+
/* Read value */
info->value = readl(ADC_V1_DATX(info->regs)) &
ADC_DATX_MASK;
@@ -170,6 +177,8 @@ static irqreturn_t exynos_adc_isr(int irq, void *dev_id)

complete(&info->completion);

+ spin_unlock(&info->reg_lock);
+
return IRQ_HANDLED;
}

@@ -327,6 +336,7 @@ static int exynos_adc_probe(struct platform_device *pdev)
else
indio_dev->num_channels = MAX_ADC_V2_CHANNELS;

+ spin_lock_init(&info->reg_lock);
ret = iio_device_register(indio_dev);
if (ret)
goto err_irq;
--
1.7.9.5


\
 
 \ /
  Last update: 2013-03-15 18:21    [W:0.063 / U:0.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site