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@xxxxxxxxxx>
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;
> }
>
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
