iio: Wakeup poll and blocking reads when the device is unregistered

Once the device has been unregistered there won't be any new data no matter how
long a userspace application waits, so we might as well wake them up and let
them know.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index 9209f47..7512cf7 100644 (file)
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -50,6 +50,7 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
 #define iio_buffer_read_first_n_outer_addr (&iio_buffer_read_first_n_outer)
 
 void iio_disable_all_buffers(struct iio_dev *indio_dev);
+void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
 
 #else
 
@@ -57,11 +58,13 @@ void iio_disable_all_buffers(struct iio_dev *indio_dev);
 #define iio_buffer_read_first_n_outer_addr NULL
 
 static inline void iio_disable_all_buffers(struct iio_dev *indio_dev) {}
+static inline void iio_buffer_wakeup_poll(struct iio_dev *indio_dev) {}
 
 #endif
 
 int iio_device_register_eventset(struct iio_dev *indio_dev);
 void iio_device_unregister_eventset(struct iio_dev *indio_dev);
+void iio_device_wakeup_eventset(struct iio_dev *indio_dev);
 int iio_event_getfd(struct iio_dev *indio_dev);
 
 #endif

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 6c7a9c5..5a46c57 100644 (file)
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -20,6 +20,7 @@
 #include <linux/cdev.h>
 #include <linux/slab.h>
 #include <linux/poll.h>
+#include <linux/sched.h>
 
 #include <linux/iio/iio.h>
 #include "iio_core.h"
@@ -75,6 +76,21 @@ unsigned int iio_buffer_poll(struct file *filp,
        return 0;
 }
 
+/**
+ * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
+ * @indio_dev: The IIO device
+ *
+ * Wakes up the event waitqueue used for poll(). Should usually
+ * be called when the device is unregistered.
+ */
+void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
+{
+       if (!indio_dev->buffer)
+               return;
+
+       wake_up(&indio_dev->buffer->pollq);
+}
+
 void iio_buffer_init(struct iio_buffer *buffer)
 {
        INIT_LIST_HEAD(&buffer->demux_list);

diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index a019a7b..dc24a9b 100644 (file)
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -1139,6 +1139,10 @@ void iio_device_unregister(struct iio_dev *indio_dev)
        iio_disable_all_buffers(indio_dev);
 
        indio_dev->info = NULL;
+
+       iio_device_wakeup_eventset(indio_dev);
+       iio_buffer_wakeup_poll(indio_dev);
+
        mutex_unlock(&indio_dev->info_exist_lock);
 }
 EXPORT_SYMBOL(iio_device_unregister);

diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index 837d450..d251f30 100644 (file)
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -113,9 +113,14 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
                }
                /* Blocking on device; waiting for something to be there */
                ret = wait_event_interruptible_locked_irq(ev_int->wait,
-                                       !kfifo_is_empty(&ev_int->det_events));
+                                       !kfifo_is_empty(&ev_int->det_events) ||
+                                       indio_dev->info == NULL);
                if (ret)
                        goto error_unlock;
+               if (indio_dev->info == NULL) {
+                       ret = -ENODEV;
+                       goto error_unlock;
+               }
                /* Single access device so no one else can get the data */
        }
 
@@ -454,6 +459,20 @@ error_ret:
        return ret;
 }
 
+/**
+ * iio_device_wakeup_eventset - Wakes up the event waitqueue
+ * @indio_dev: The IIO device
+ *
+ * Wakes up the event waitqueue used for poll() and blocking read().
+ * Should usually be called when the device is unregistered.
+ */
+void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
+{
+       if (indio_dev->event_interface == NULL)
+               return;
+       wake_up(&indio_dev->event_interface->wait);
+}
+
 void iio_device_unregister_eventset(struct iio_dev *indio_dev)
 {
        if (indio_dev->event_interface == NULL)