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authorLars-Peter Clausen <lars@metafoo.de>2011-12-19 15:23:45 +0100
committerGreg Kroah-Hartman <gregkh@suse.de>2011-12-22 13:38:08 -0800
commitbb01443e2cdad4ff5b98e00252e93110d00f4392 (patch)
treefb57bb214b5721edeb64f050bd4ceeb0892d1eef /drivers/staging
parente38c79e0825b673d97cecfb36bae9e859e724f1b (diff)
downloadlinux-bb01443e2cdad4ff5b98e00252e93110d00f4392.tar.bz2
staging:iio: Make sure a device is only opened once at a time
Our buffer implementation does not support multiple concurrent readers. So we have to ensure that a device is only opened once at a time. So do the same thing we do for the event fd and introduce a per device busy flag. The flag gets set when opening the device and gets cleared when closing the device. If a open is attempted while the busy flag is set we return -EBUSY. Acked-by: Jonathan Cameron <jic23@kernel.org> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/staging')
-rw-r--r--drivers/staging/iio/iio.h3
-rw-r--r--drivers/staging/iio/industrialio-core.c17
2 files changed, 17 insertions, 3 deletions
diff --git a/drivers/staging/iio/iio.h b/drivers/staging/iio/iio.h
index 45b6d759c2e7..be6ced31f65e 100644
--- a/drivers/staging/iio/iio.h
+++ b/drivers/staging/iio/iio.h
@@ -313,6 +313,7 @@ struct iio_buffer_setup_ops {
* @chrdev: [INTERN] associated character device
* @groups: [INTERN] attribute groups
* @groupcounter: [INTERN] index of next attribute group
+ * @flags: [INTERN] file ops related flags including busy flag.
**/
struct iio_dev {
int id;
@@ -344,6 +345,8 @@ struct iio_dev {
#define IIO_MAX_GROUPS 6
const struct attribute_group *groups[IIO_MAX_GROUPS + 1];
int groupcounter;
+
+ unsigned long flags;
};
/**
diff --git a/drivers/staging/iio/industrialio-core.c b/drivers/staging/iio/industrialio-core.c
index 2eef85fa38c7..12d1576a0766 100644
--- a/drivers/staging/iio/industrialio-core.c
+++ b/drivers/staging/iio/industrialio-core.c
@@ -1083,9 +1083,18 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
{
struct iio_dev *indio_dev = container_of(inode->i_cdev,
struct iio_dev, chrdev);
+ unsigned int ret;
+
+ if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
+ return -EBUSY;
+
filp->private_data = indio_dev;
- return iio_chrdev_buffer_open(indio_dev);
+ ret = iio_chrdev_buffer_open(indio_dev);
+ if (ret < 0)
+ clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
+
+ return ret;
}
/**
@@ -1093,8 +1102,10 @@ static int iio_chrdev_open(struct inode *inode, struct file *filp)
**/
static int iio_chrdev_release(struct inode *inode, struct file *filp)
{
- iio_chrdev_buffer_release(container_of(inode->i_cdev,
- struct iio_dev, chrdev));
+ struct iio_dev *indio_dev = container_of(inode->i_cdev,
+ struct iio_dev, chrdev);
+ iio_chrdev_buffer_release(indio_dev);
+ clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
return 0;
}