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>
---
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
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