[PATCH] iio: Simplify IIO provider access locking mechanism

Ivan T. Ivanov
2015-01-09T15:38:32Z

Instead of checking whether provider module is still
loaded on every access to device just lock module to
memory when client get reference to provider device.

Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
---
drivers/iio/industrialio-buffer.c | 18 +-------
drivers/iio/industrialio-core.c | 10 -----
drivers/iio/industrialio-event.c | 11 +----
drivers/iio/inkern.c | 93 +++++----------------------------------
include/linux/iio/iio.h | 15 +++++--
5 files changed, 23 insertions(+), 124 deletions(-)

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index 403b728..34e6c3d 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -55,9 +55,6 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
struct iio_buffer *rb = indio_dev->buffer;
int ret;

- if (!indio_dev->info)
- return -ENODEV;
-
if (!rb || !rb->access->read_first_n)
return -EINVAL;

@@ -67,12 +64,9 @@ ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
return -EAGAIN;

ret = wait_event_interruptible(rb->pollq,
- iio_buffer_data_available(rb) ||
- indio_dev->info == NULL);
+ iio_buffer_data_available(rb));
if (ret)
return ret;
- if (indio_dev->info == NULL)
- return -ENODEV;
}

ret = rb->access->read_first_n(rb, n, buf);
@@ -92,9 +86,6 @@ unsigned int iio_buffer_poll(struct file *filp,
struct iio_dev *indio_dev = filp->private_data;
struct iio_buffer *rb = indio_dev->buffer;

- if (!indio_dev->info)
- return -ENODEV;
-
poll_wait(filp, &rb->pollq, wait);
if (iio_buffer_data_available(rb))
return POLLIN | POLLRDNORM;
@@ -685,7 +676,6 @@ int iio_update_buffers(struct iio_dev *indio_dev,
if (insert_buffer == remove_buffer)
return 0;

- mutex_lock(&indio_dev->info_exist_lock);
mutex_lock(&indio_dev->mlock);

if (insert_buffer && iio_buffer_is_active(insert_buffer))
@@ -699,16 +689,10 @@ int iio_update_buffers(struct iio_dev *indio_dev,
goto out_unlock;
}

- if (indio_dev->info == NULL) {
- ret = -ENODEV;
- goto out_unlock;
- }
-
ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);

out_unlock:
mutex_unlock(&indio_dev->mlock);
- mutex_unlock(&indio_dev->info_exist_lock);

return ret;
}
diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
index 69feb91..b4105be 100644
--- a/drivers/iio/industrialio-core.c
+++ b/drivers/iio/industrialio-core.c
@@ -976,7 +976,6 @@ struct iio_dev *iio_device_alloc(int sizeof_priv)
device_initialize(&dev->dev);
dev_set_drvdata(&dev->dev, (void *)dev);
mutex_init(&dev->mlock);
- mutex_init(&dev->info_exist_lock);
INIT_LIST_HEAD(&dev->channel_attr_list);

dev->id = ida_simple_get(&iio_ida, 0, 0, GFP_KERNEL);
@@ -1111,9 +1110,6 @@ static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
int __user *ip = (int __user *)arg;
int fd;

- if (!indio_dev->info)
- return -ENODEV;
-
if (cmd == IIO_GET_EVENT_FD_IOCTL) {
fd = iio_event_getfd(indio_dev);
if (copy_to_user(ip, &fd, sizeof(fd)))
@@ -1243,8 +1239,6 @@ EXPORT_SYMBOL(iio_device_register);
**/
void iio_device_unregister(struct iio_dev *indio_dev)
{
- mutex_lock(&indio_dev->info_exist_lock);
-
device_del(&indio_dev->dev);

if (indio_dev->chrdev.dev)
@@ -1253,13 +1247,9 @@ 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);
-
iio_buffer_free_sysfs_and_mask(indio_dev);
}
EXPORT_SYMBOL(iio_device_unregister);
diff --git a/drivers/iio/industrialio-event.c b/drivers/iio/industrialio-event.c
index 3f5cee0..f20868e 100644
--- a/drivers/iio/industrialio-event.c
+++ b/drivers/iio/industrialio-event.c
@@ -83,9 +83,6 @@ static unsigned int iio_event_poll(struct file *filep,
struct iio_event_interface *ev_int = indio_dev->event_interface;
unsigned int events = 0;

- if (!indio_dev->info)
- return -ENODEV;
-
poll_wait(filep, &ev_int->wait, wait);

if (!kfifo_is_empty(&ev_int->det_events))
@@ -104,9 +101,6 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
unsigned int copied;
int ret;

- if (!indio_dev->info)
- return -ENODEV;
-
if (count < sizeof(struct iio_event_data))
return -EINVAL;

@@ -116,12 +110,9 @@ static ssize_t iio_event_chrdev_read(struct file *filep,
return -EAGAIN;

ret = wait_event_interruptible(ev_int->wait,
- !kfifo_is_empty(&ev_int->det_events) ||
- indio_dev->info == NULL);
+ !kfifo_is_empty(&ev_int->det_events));
if (ret)
return ret;
- if (indio_dev->info == NULL)
- return -ENODEV;
}

if (mutex_lock_interruptible(&ev_int->read_lock))
diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 2800b80..0c077b7 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -146,6 +146,9 @@ static int __of_iio_channel_get(struct iio_channel *channel,
return -EPROBE_DEFER;

indio_dev = dev_to_iio_dev(idev);
+ iio_device_get(indio_dev);
+ /* and put the reference of the find */
+ put_device(idev);
channel->indio_dev = indio_dev;
if (indio_dev->info->of_xlate)
index = indio_dev->info->of_xlate(indio_dev, &iiospec);
@@ -467,41 +470,17 @@ static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,

int iio_read_channel_raw(struct iio_channel *chan, int *val)
{
- int ret;
-
- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
- ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);
-
- return ret;
+ return iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_channel_raw);

int iio_read_channel_average_raw(struct iio_channel *chan, int *val)
{
- int ret;
-
- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
- ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_AVERAGE_RAW);
-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);
-
- return ret;
+ return iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_AVERAGE_RAW);
}
EXPORT_SYMBOL_GPL(iio_read_channel_average_raw);

-static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
+int iio_convert_raw_to_processed(struct iio_channel *chan,
int raw, int *processed, unsigned int scale)
{
int scale_type, scale_val, scale_val2, offset;
@@ -550,88 +529,36 @@ static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,

return 0;
}
-
-int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
- int *processed, unsigned int scale)
-{
- int ret;
-
- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
- ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
- scale);
-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);
-
- return ret;
-}
EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);

int iio_read_channel_processed(struct iio_channel *chan, int *val)
{
int ret;

- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
ret = iio_channel_read(chan, val, NULL,
IIO_CHAN_INFO_PROCESSED);
} else {
ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
- if (ret < 0)
- goto err_unlock;
- ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
+ if (ret >= 0)
+ ret = iio_convert_raw_to_processed(chan, *val, val, 1);
}

-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);
-
return ret;
}
EXPORT_SYMBOL_GPL(iio_read_channel_processed);

int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
{
- int ret;
-
- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
- ret = iio_channel_read(chan, val, val2, IIO_CHAN_INFO_SCALE);
-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);
-
- return ret;
+ return iio_channel_read(chan, val, val2, IIO_CHAN_INFO_SCALE);
}
EXPORT_SYMBOL_GPL(iio_read_channel_scale);

int iio_get_channel_type(struct iio_channel *chan, enum iio_chan_type *type)
{
- int ret = 0;
- /* Need to verify underlying driver has not gone away */
-
- mutex_lock(&chan->indio_dev->info_exist_lock);
- if (chan->indio_dev->info == NULL) {
- ret = -ENODEV;
- goto err_unlock;
- }
-
*type = chan->channel->type;
-err_unlock:
- mutex_unlock(&chan->indio_dev->info_exist_lock);

- return ret;
+ return 0;
}
EXPORT_SYMBOL_GPL(iio_get_channel_type);

diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 878d861..ab410c5 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -13,6 +13,7 @@
#include <linux/device.h>
#include <linux/cdev.h>
#include <linux/iio/types.h>
+#include <linux/module.h>
#include <linux/of.h>
/* IIO TODO LIST */
/*
@@ -444,7 +445,6 @@ struct iio_buffer_setup_ops {
* @chan_attr_group: [INTERN] group for all attrs in base directory
* @name: [DRIVER] name of the device.
* @info: [DRIVER] callbacks and constant info from driver
- * @info_exist_lock: [INTERN] lock to prevent use during removal
* @setup_ops: [DRIVER] callbacks to call before and after buffer
* enable/disable
* @chrdev: [INTERN] associated character device
@@ -483,7 +483,6 @@ struct iio_dev {
struct attribute_group chan_attr_group;
const char *name;
const struct iio_info *info;
- struct mutex info_exist_lock;
const struct iio_buffer_setup_ops *setup_ops;
struct cdev chrdev;
#define IIO_MAX_GROUPS 6
@@ -513,8 +512,10 @@ extern struct bus_type iio_bus_type;
**/
static inline void iio_device_put(struct iio_dev *indio_dev)
{
- if (indio_dev)
+ if (indio_dev) {
put_device(&indio_dev->dev);
+ module_put(indio_dev->info->driver_module);
+ }
}

/**
@@ -536,7 +537,13 @@ static inline struct iio_dev *dev_to_iio_dev(struct device *dev)
**/
static inline struct iio_dev *iio_device_get(struct iio_dev *indio_dev)
{
- return indio_dev ? dev_to_iio_dev(get_device(&indio_dev->dev)) : NULL;
+ if (!indio_dev)
+ return NULL;
+
+ if (!try_module_get(indio_dev->info->driver_module))
+ return ERR_PTR(-ENODEV);
+
+ return dev_to_iio_dev(get_device(&indio_dev->dev));
}

--
1.9.1