* [PATCH] iio: events: Make iio_push_event() IRQ context save
@ 2013-03-07 19:53 Lars-Peter Clausen
2013-03-17 19:47 ` Jonathan Cameron
0 siblings, 1 reply; 2+ messages in thread
From: Lars-Peter Clausen @ 2013-03-07 19:53 UTC (permalink / raw)
To: Jonathan Cameron; +Cc: linux-iio, Lars-Peter Clausen
Currently it is not save to call iio_push_event() from hard IRQ context since
the IIO event code uses spin_lock()/spin_unlock() and it is not save to mix
calls to spin_lock()/spin_unlock() from different contexts on the same lock.
E.g. if the lock is being held in iio_event_chrdev_read() and an interrupts
kicks in and the interrupt handler calls iio_push_event() we end uo with a
deadlock.
This patch updates iio_push_event() to use spin_lock_irqsave()/
spin_unlock_irqstrestore(), since it can be called from both IRQ and non-IRQ
context. All other other users of the lock, which are always run in non-IRQ
context, are updated to spin_lock_irq()/spin_unlock_irq().
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
As far as I can see all current callers of iio_push_event() run in non-IRQ
context, so this doesn't need to applied to the fixes branch.
---
drivers/iio/industrialio-event.c | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)
diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index 261cae0..10aa9ef8 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -46,10 +46,11 @@ int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
{
struct iio_event_interface *ev_int = indio_dev->event_interface;
struct iio_event_data ev;
+ unsigned long flags;
int copied;
/* Does anyone care? */
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irqsave(&ev_int->wait.lock, flags);
if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
ev.id = ev_code;
@@ -59,7 +60,7 @@ int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
if (copied != 0)
wake_up_locked_poll(&ev_int->wait, POLLIN);
}
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irqrestore(&ev_int->wait.lock, flags);
return 0;
}
@@ -76,10 +77,10 @@ static unsigned int iio_event_poll(struct file *filep,
poll_wait(filep, &ev_int->wait, wait);
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irq(&ev_int->wait.lock);
if (!kfifo_is_empty(&ev_int->det_events))
events = POLLIN | POLLRDNORM;
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
return events;
}
@@ -96,14 +97,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
if (count < sizeof(struct iio_event_data))
return -EINVAL;
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irq(&ev_int->wait.lock);
if (kfifo_is_empty(&ev_int->det_events)) {
if (filep->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
goto error_unlock;
}
/* Blocking on device; waiting for something to be there */
- ret = wait_event_interruptible_locked(ev_int->wait,
+ ret = wait_event_interruptible_locked_irq(ev_int->wait,
!kfifo_is_empty(&ev_int->det_events));
if (ret)
goto error_unlock;
@@ -113,7 +114,7 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
error_unlock:
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
return ret ? ret : copied;
}
@@ -122,7 +123,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{
struct iio_event_interface *ev_int = filep->private_data;
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irq(&ev_int->wait.lock);
__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
/*
* In order to maintain a clean state for reopening,
@@ -130,7 +131,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
* any new __iio_push_event calls running.
*/
kfifo_reset_out(&ev_int->det_events);
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
return 0;
}
@@ -151,18 +152,18 @@ int iio_event_getfd(struct iio_dev *indio_dev)
if (ev_int == NULL)
return -ENODEV;
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irq(&ev_int->wait.lock);
if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
return -EBUSY;
}
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
fd = anon_inode_getfd("iio:event",
&iio_event_chrdev_fileops, ev_int, O_RDONLY);
if (fd < 0) {
- spin_lock(&ev_int->wait.lock);
+ spin_lock_irq(&ev_int->wait.lock);
__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
- spin_unlock(&ev_int->wait.lock);
+ spin_unlock_irq(&ev_int->wait.lock);
}
return fd;
}
--
1.8.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] iio: events: Make iio_push_event() IRQ context save
2013-03-07 19:53 [PATCH] iio: events: Make iio_push_event() IRQ context save Lars-Peter Clausen
@ 2013-03-17 19:47 ` Jonathan Cameron
0 siblings, 0 replies; 2+ messages in thread
From: Jonathan Cameron @ 2013-03-17 19:47 UTC (permalink / raw)
To: Lars-Peter Clausen; +Cc: linux-iio
On 03/07/2013 07:53 PM, Lars-Peter Clausen wrote:
> Currently it is not save to call iio_push_event() from hard IRQ context since
> the IIO event code uses spin_lock()/spin_unlock() and it is not save to mix
> calls to spin_lock()/spin_unlock() from different contexts on the same lock.
> E.g. if the lock is being held in iio_event_chrdev_read() and an interrupts
> kicks in and the interrupt handler calls iio_push_event() we end uo with a
> deadlock.
>
> This patch updates iio_push_event() to use spin_lock_irqsave()/
> spin_unlock_irqstrestore(), since it can be called from both IRQ and non-IRQ
> context. All other other users of the lock, which are always run in non-IRQ
> context, are updated to spin_lock_irq()/spin_unlock_irq().
>
> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
I'm assuming a driver using this is coming right up?
Anyhow applied to togreg branch of iio.git
>
> ---
> As far as I can see all current callers of iio_push_event() run in non-IRQ
> context, so this doesn't need to applied to the fixes branch.
> ---
> drivers/iio/industrialio-event.c | 29 +++++++++++++++--------------
> 1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
> index 261cae0..10aa9ef8 100644
> --- a/drivers/iio/industrialio-event.c
> +++ b/drivers/iio/industrialio-event.c
> @@ -46,10 +46,11 @@ int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
> {
> struct iio_event_interface *ev_int = indio_dev->event_interface;
> struct iio_event_data ev;
> + unsigned long flags;
> int copied;
>
> /* Does anyone care? */
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irqsave(&ev_int->wait.lock, flags);
> if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
>
> ev.id = ev_code;
> @@ -59,7 +60,7 @@ int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
> if (copied != 0)
> wake_up_locked_poll(&ev_int->wait, POLLIN);
> }
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irqrestore(&ev_int->wait.lock, flags);
>
> return 0;
> }
> @@ -76,10 +77,10 @@ static unsigned int iio_event_poll(struct file *filep,
>
> poll_wait(filep, &ev_int->wait, wait);
>
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irq(&ev_int->wait.lock);
> if (!kfifo_is_empty(&ev_int->det_events))
> events = POLLIN | POLLRDNORM;
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
>
> return events;
> }
> @@ -96,14 +97,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
> if (count < sizeof(struct iio_event_data))
> return -EINVAL;
>
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irq(&ev_int->wait.lock);
> if (kfifo_is_empty(&ev_int->det_events)) {
> if (filep->f_flags & O_NONBLOCK) {
> ret = -EAGAIN;
> goto error_unlock;
> }
> /* Blocking on device; waiting for something to be there */
> - ret = wait_event_interruptible_locked(ev_int->wait,
> + ret = wait_event_interruptible_locked_irq(ev_int->wait,
> !kfifo_is_empty(&ev_int->det_events));
> if (ret)
> goto error_unlock;
> @@ -113,7 +114,7 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
> ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
>
> error_unlock:
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
>
> return ret ? ret : copied;
> }
> @@ -122,7 +123,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
> {
> struct iio_event_interface *ev_int = filep->private_data;
>
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irq(&ev_int->wait.lock);
> __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
> /*
> * In order to maintain a clean state for reopening,
> @@ -130,7 +131,7 @@ static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
> * any new __iio_push_event calls running.
> */
> kfifo_reset_out(&ev_int->det_events);
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
>
> return 0;
> }
> @@ -151,18 +152,18 @@ int iio_event_getfd(struct iio_dev *indio_dev)
> if (ev_int == NULL)
> return -ENODEV;
>
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irq(&ev_int->wait.lock);
> if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
> return -EBUSY;
> }
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
> fd = anon_inode_getfd("iio:event",
> &iio_event_chrdev_fileops, ev_int, O_RDONLY);
> if (fd < 0) {
> - spin_lock(&ev_int->wait.lock);
> + spin_lock_irq(&ev_int->wait.lock);
> __clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
> - spin_unlock(&ev_int->wait.lock);
> + spin_unlock_irq(&ev_int->wait.lock);
> }
> return fd;
> }
>
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2013-03-17 22:42 UTC | newest]
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2013-03-07 19:53 [PATCH] iio: events: Make iio_push_event() IRQ context save Lars-Peter Clausen
2013-03-17 19:47 ` Jonathan Cameron
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