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iio: adc: ad_sigma_delta: Fix a race condition

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The ad_sigma_delta driver helper uses irq_disable_nosync(). With that
one it is possible that the irq handler still runs after the
irq_disable_nosync() function call returns. Also to properly synchronize
irq disabling in the different threads proper locking is needed and
because it's unclear if the irq handler's irq_disable_nosync() call
comes first or the one in the enabler's error path, all code locations
that disable the irq must check for .irq_dis first to ensure there is
exactly one disable call per enable call.

So add a spinlock to the struct ad_sigma_delta and use it to synchronize
irq enabling and disabling. Also only act in the irq handler if the irq
is still enabled.

Fixes: af3008485ea0 ("iio:adc: Add common code for ADI Sigma Delta devices")
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Link: https://patch.msgid.link/9e6def47e2e773e0e15b7a2c29d22629b53d91b1.1733504533.git.u.kleine-koenig@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
Uwe Kleine-König 2024-12-06 18:28:38 +01:00 committed by Jonathan Cameron
parent 90b8b2fe60
commit f522589c13
2 changed files with 36 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
drivers/iio/adc/ad_sigma_delta.c
View File

@ -202,6 +202,27 @@ int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
}
EXPORT_SYMBOL_NS_GPL(ad_sd_reset, "IIO_AD_SIGMA_DELTA");
static bool ad_sd_disable_irq(struct ad_sigma_delta *sigma_delta)
{
guard(spinlock_irqsave)(&sigma_delta->irq_lock);
/* It's already off, return false to indicate nothing was changed */
if (sigma_delta->irq_dis)
return false;
sigma_delta->irq_dis = true;
disable_irq_nosync(sigma_delta->irq_line);
return true;
}
static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
{
guard(spinlock_irqsave)(&sigma_delta->irq_lock);
sigma_delta->irq_dis = false;
enable_irq(sigma_delta->irq_line);
}
int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
unsigned int mode, unsigned int channel)
{
@ -221,12 +242,10 @@ int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
if (ret < 0)
goto out;
sigma_delta->irq_dis = false;
enable_irq(sigma_delta->irq_line);
ad_sd_enable_irq(sigma_delta);
time_left = wait_for_completion_timeout(&sigma_delta->completion, 2 * HZ);
if (time_left == 0) {
sigma_delta->irq_dis = true;
disable_irq_nosync(sigma_delta->irq_line);
ad_sd_disable_irq(sigma_delta);
ret = -EIO;
} else {
ret = 0;
@ -294,8 +313,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
sigma_delta->irq_dis = false;
enable_irq(sigma_delta->irq_line);
ad_sd_enable_irq(sigma_delta);
ret = wait_for_completion_interruptible_timeout(
&sigma_delta->completion, HZ);
@ -314,10 +332,7 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
&raw_sample);
out:
if (!sigma_delta->irq_dis) {
disable_irq_nosync(sigma_delta->irq_line);
sigma_delta->irq_dis = true;
}
ad_sd_disable_irq(sigma_delta);
sigma_delta->keep_cs_asserted = false;
ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@ -396,8 +411,7 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
if (ret)
goto err_unlock;
sigma_delta->irq_dis = false;
enable_irq(sigma_delta->irq_line);
ad_sd_enable_irq(sigma_delta);
return 0;
@ -414,10 +428,7 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
reinit_completion(&sigma_delta->completion);
wait_for_completion_timeout(&sigma_delta->completion, HZ);
if (!sigma_delta->irq_dis) {
disable_irq_nosync(sigma_delta->irq_line);
sigma_delta->irq_dis = true;
}
ad_sd_disable_irq(sigma_delta);
sigma_delta->keep_cs_asserted = false;
ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@ -516,8 +527,7 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
irq_handled:
iio_trigger_notify_done(indio_dev->trig);
sigma_delta->irq_dis = false;
enable_irq(sigma_delta->irq_line);
ad_sd_enable_irq(sigma_delta);
return IRQ_HANDLED;
}
@ -551,11 +561,13 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
* So read the MOSI line as GPIO (if available) and only trigger the irq
* if the line is active. Without such a GPIO assume this is a valid
* interrupt.
*
* Also as disable_irq_nosync() is used to disable the irq, only act if
* the irq wasn't disabled before.
*/
if (!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) {
if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
ad_sd_disable_irq(sigma_delta)) {
complete(&sigma_delta->completion);
disable_irq_nosync(irq);
sigma_delta->irq_dis = true;
iio_trigger_poll(sigma_delta->trig);
return IRQ_HANDLED;
@ -691,6 +703,8 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
}
}
spin_lock_init(&sigma_delta->irq_lock);
if (info->irq_line)
sigma_delta->irq_line = info->irq_line;
else

1
include/linux/iio/adc/ad_sigma_delta.h
View File

@ -86,6 +86,7 @@ struct ad_sigma_delta {
/* private: */
struct completion completion;
spinlock_t irq_lock; /* protects .irq_dis and irq en/disable state */
bool irq_dis;
bool bus_locked;