On Mon, May 01, 2017 at 06:04:42PM +0200, David Härdeman wrote:
> Using the kernel ida facilities, we can avoid a lot of unnecessary code and at the same
> time get rid of lirc_dev_lock in favour of per-device locks (the irctls array was used
> throughout lirc_dev so this patch necessarily touches a lot of code).
>
> Signed-off-by: David Härdeman <david@xxxxxxxxxxx>
> ---
> drivers/media/rc/ir-lirc-codec.c | 9 -
> drivers/media/rc/lirc_dev.c | 258 ++++++++++++-------------------
> drivers/staging/media/lirc/lirc_zilog.c | 16 +-
> include/media/lirc_dev.h | 14 --
> 4 files changed, 115 insertions(+), 182 deletions(-)
>
> diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
> index a30af91710fe..2c1221a61ea1 100644
> --- a/drivers/media/rc/ir-lirc-codec.c
> +++ b/drivers/media/rc/ir-lirc-codec.c
> @@ -382,7 +382,6 @@ static int ir_lirc_register(struct rc_dev *dev)
>
> snprintf(drv->name, sizeof(drv->name), "ir-lirc-codec (%s)",
> dev->driver_name);
> - drv->minor = -1;
> drv->features = features;
> drv->data = &dev->raw->lirc;
> drv->rbuf = NULL;
> @@ -394,11 +393,9 @@ static int ir_lirc_register(struct rc_dev *dev)
> drv->rdev = dev;
> drv->owner = THIS_MODULE;
>
> - drv->minor = lirc_register_driver(drv);
> - if (drv->minor < 0) {
> - rc = -ENODEV;
> + rc = lirc_register_driver(drv);
> + if (rc < 0)
> goto out;
> - }
>
> dev->raw->lirc.drv = drv;
> dev->raw->lirc.dev = dev;
> @@ -413,7 +410,7 @@ static int ir_lirc_unregister(struct rc_dev *dev)
> {
> struct lirc_codec *lirc = &dev->raw->lirc;
>
> - lirc_unregister_driver(lirc->drv->minor);
> + lirc_unregister_driver(lirc->drv);
> kfree(lirc->drv);
> lirc->drv = NULL;
>
> diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
> index e44e0b23b883..7db7d4c57991 100644
> --- a/drivers/media/rc/lirc_dev.c
> +++ b/drivers/media/rc/lirc_dev.c
> @@ -31,23 +31,35 @@
> #include <linux/bitops.h>
> #include <linux/device.h>
> #include <linux/cdev.h>
> +#include <linux/idr.h>
>
> #include <media/rc-core.h>
> #include <media/lirc.h>
> #include <media/lirc_dev.h>
>
> #define IRCTL_DEV_NAME "BaseRemoteCtl"
> -#define NOPLUG -1
> #define LOGHEAD "lirc_dev (%s[%d]): "
>
> static dev_t lirc_base_dev;
>
> +/**
> + * struct irctl - lirc per-device structure
> + * @d: internal copy of the &struct lirc_driver for the device
> + * @dead: if the device has gone away
> + * @users: the number of users of the lirc chardev (currently limited to 1)
> + * @mutex: synchronizes open()/close()/ioctl()/etc calls
> + * @buf: used to store lirc RX data
> + * @buf_internal: whether @buf was allocated internally or not
> + * @chunk_size: @buf stores and read() returns data chunks of this size
> + * @dev: the &struct device for the lirc device
> + * @cdev: the &struct device for the lirc chardev
> + */
> struct irctl {
> struct lirc_driver d;
> - int attached;
> - int open;
> + bool dead;
> + unsigned users;
>
> - struct mutex irctl_lock;
> + struct mutex mutex;
> struct lirc_buffer *buf;
> bool buf_internal;
> unsigned int chunk_size;
> @@ -56,9 +68,9 @@ struct irctl {
> struct cdev cdev;
> };
>
> -static DEFINE_MUTEX(lirc_dev_lock);
> -
> -static struct irctl *irctls[MAX_IRCTL_DEVICES];
> +/* Used to keep track of allocated lirc devices */
> +#define LIRC_MAX_DEVICES 256
> +static DEFINE_IDA(lirc_ida);
>
> /* Only used for sysfs but defined to void otherwise */
> static struct class *lirc_class;
> @@ -72,9 +84,6 @@ static void lirc_release(struct device *ld)
> kfree(ir->buf);
> }
>
> - mutex_lock(&lirc_dev_lock);
> - irctls[ir->d.minor] = NULL;
> - mutex_unlock(&lirc_dev_lock);
> kfree(ir);
> }
>
> @@ -117,7 +126,18 @@ static int lirc_allocate_buffer(struct irctl *ir)
> return err;
> }
>
> -int lirc_register_driver(struct lirc_driver *d)
> +/**
> + * lirc_register_driver() - create a new lirc device by registering a driver
> + * @d: the &struct lirc_driver to register
> + *
> + * This function allocates and registers a lirc device for a given
> + * &lirc_driver. The &lirc_driver structure is updated to contain
> + * information about the allocated device (minor, buffer, etc).
> + *
> + * Return: zero on success or a negative error value.
> + */
> +int
> +lirc_register_driver(struct lirc_driver *d)
> {
> struct irctl *ir;
> int minor;
> @@ -138,12 +158,6 @@ int lirc_register_driver(struct lirc_driver *d)
> return -EINVAL;
> }
>
> - if (d->minor >= MAX_IRCTL_DEVICES) {
> - dev_err(d->dev, "minor must be between 0 and %d!\n",
> - MAX_IRCTL_DEVICES - 1);
> - return -EBADRQC;
> - }
> -
> if (d->code_length < 1 || d->code_length > (BUFLEN * 8)) {
> dev_err(d->dev, "code length must be less than %d bits\n",
> BUFLEN * 8);
> @@ -156,49 +170,30 @@ int lirc_register_driver(struct lirc_driver *d)
> return -EBADRQC;
> }
>
> - mutex_lock(&lirc_dev_lock);
> -
> - minor = d->minor;
> + d->name[sizeof(d->name)-1] = '\0';
> + if (d->features == 0)
> + d->features = LIRC_CAN_REC_LIRCCODE;
>
> - if (minor < 0) {
> - /* find first free slot for driver */
> - for (minor = 0; minor < MAX_IRCTL_DEVICES; minor++)
> - if (!irctls[minor])
> - break;
> - if (minor == MAX_IRCTL_DEVICES) {
> - dev_err(d->dev, "no free slots for drivers!\n");
> - err = -ENOMEM;
> - goto out_lock;
> - }
> - } else if (irctls[minor]) {
> - dev_err(d->dev, "minor (%d) just registered!\n", minor);
> - err = -EBUSY;
> - goto out_lock;
> - }
> + minor = ida_simple_get(&lirc_ida, 0, LIRC_MAX_DEVICES, GFP_KERNEL);
> + if (minor < 0)
> + return minor;
> + d->minor = minor;
>
> ir = kzalloc(sizeof(struct irctl), GFP_KERNEL);
> if (!ir) {
> err = -ENOMEM;
> - goto out_lock;
> + goto out_minor;
> }
>
> - mutex_init(&ir->irctl_lock);
> - irctls[minor] = ir;
> - d->minor = minor;
> -
> - /* some safety check 8-) */
> - d->name[sizeof(d->name)-1] = '\0';
> -
> - if (d->features == 0)
> - d->features = LIRC_CAN_REC_LIRCCODE;
> + mutex_init(&ir->mutex);
>
> ir->d = *d;
Here we copy lirc_driver.
>
> if (LIRC_CAN_REC(d->features)) {
> - err = lirc_allocate_buffer(irctls[minor]);
> + err = lirc_allocate_buffer(ir);
> if (err) {
> kfree(ir);
> - goto out_lock;
> + goto out_minor;
> }
> d->rbuf = ir->buf;
> }
> @@ -218,107 +213,82 @@ int lirc_register_driver(struct lirc_driver *d)
> if (err)
> goto out_free_dev;
>
> - ir->attached = 1;
> -
> err = device_add(&ir->dev);
> if (err)
> goto out_cdev;
>
> - mutex_unlock(&lirc_dev_lock);
> -
> dev_info(ir->d.dev, "lirc_dev: driver %s registered at minor = %d\n",
> ir->d.name, ir->d.minor);
>
> - return minor;
> + d->lirc_internal = ir;
And now a store a pointer to the copy in the original lirc_driver.
It would be much better to not copy lirc_driver and the lirc_internal
member would be unnecessary.
> + return 0;
>
> out_cdev:
> cdev_del(&ir->cdev);
> out_free_dev:
> put_device(&ir->dev);
> -out_lock:
> - mutex_unlock(&lirc_dev_lock);
> +out_minor:
> + ida_simple_remove(&lirc_ida, minor);
>
> return err;
> }
> EXPORT_SYMBOL(lirc_register_driver);
>
> -int lirc_unregister_driver(int minor)
> +/**
> + * lirc_unregister_driver() - remove the lirc device for a given driver
> + * @d: the &struct lirc_driver to unregister
> + *
> + * This function unregisters the lirc device for a given &lirc_driver.
> + */
> +void
> +lirc_unregister_driver(struct lirc_driver *d)
> {
> struct irctl *ir;
>
> - if (minor < 0 || minor >= MAX_IRCTL_DEVICES) {
> - pr_err("minor (%d) must be between 0 and %d!\n",
> - minor, MAX_IRCTL_DEVICES - 1);
> - return -EBADRQC;
> - }
> + if (!d->lirc_internal)
> + return;
>
> - ir = irctls[minor];
> - if (!ir) {
> - pr_err("failed to get irctl\n");
> - return -ENOENT;
> - }
> + ir = d->lirc_internal;
This is done to find a our copy again.
> - mutex_lock(&lirc_dev_lock);
> -
> - if (ir->d.minor != minor) {
> - dev_err(ir->d.dev, "lirc_dev: minor %d device not registered\n",
> - minor);
> - mutex_unlock(&lirc_dev_lock);
> - return -ENOENT;
> - }
> + mutex_lock(&ir->mutex);
>
> dev_dbg(ir->d.dev, "lirc_dev: driver %s unregistered from minor = %d\n",
> ir->d.name, ir->d.minor);
>
> - ir->attached = 0;
> - if (ir->open) {
> + ir->dead = true;
> + if (ir->users) {
> dev_dbg(ir->d.dev, LOGHEAD "releasing opened driver\n",
> ir->d.name, ir->d.minor);
> wake_up_interruptible(&ir->buf->wait_poll);
> }
>
> - mutex_unlock(&lirc_dev_lock);
> + mutex_unlock(&ir->mutex);
>
> device_del(&ir->dev);
> cdev_del(&ir->cdev);
> - put_device(&ir->dev);
> -
> - return 0;
> + ida_simple_remove(&lirc_ida, d->minor);
> + d->minor = -1;
> + d->lirc_internal = NULL;
> }
> EXPORT_SYMBOL(lirc_unregister_driver);
>
> int lirc_dev_fop_open(struct inode *inode, struct file *file)
> {
> - struct irctl *ir;
> + struct irctl *ir = container_of(inode->i_cdev, struct irctl, cdev);
> int retval;
>
> - if (iminor(inode) >= MAX_IRCTL_DEVICES) {
> - pr_err("open result for %d is -ENODEV\n", iminor(inode));
> - return -ENODEV;
> - }
> -
> - if (mutex_lock_interruptible(&lirc_dev_lock))
> - return -ERESTARTSYS;
> + mutex_lock(&ir->mutex);
>
> - ir = irctls[iminor(inode)];
> - mutex_unlock(&lirc_dev_lock);
> -
> - if (!ir) {
> - retval = -ENODEV;
> + if (ir->users) {
> + retval = -EBUSY;
> + mutex_unlock(&ir->mutex);
> goto error;
> }
> + ir->users++;
>
> - dev_dbg(ir->d.dev, LOGHEAD "open called\n", ir->d.name, ir->d.minor);
> -
> - if (ir->d.minor == NOPLUG) {
> - retval = -ENODEV;
> - goto error;
> - }
> + mutex_unlock(&ir->mutex);
>
> - if (ir->open) {
> - retval = -EBUSY;
> - goto error;
> - }
> + dev_dbg(ir->d.dev, LOGHEAD "open called\n", ir->d.name, ir->d.minor);
>
> if (ir->d.rdev) {
> retval = rc_open(ir->d.rdev);
> @@ -329,8 +299,7 @@ int lirc_dev_fop_open(struct inode *inode, struct file *file)
> if (ir->buf)
> lirc_buffer_clear(ir->buf);
>
> - ir->open++;
> -
> + file->private_data = ir;
> nonseekable_open(inode, file);
>
> return 0;
> @@ -342,22 +311,14 @@ EXPORT_SYMBOL(lirc_dev_fop_open);
>
> int lirc_dev_fop_close(struct inode *inode, struct file *file)
> {
> - struct irctl *ir = irctls[iminor(inode)];
> - int ret;
> -
> - if (!ir) {
> - pr_err("called with invalid irctl\n");
> - return -EINVAL;
> - }
> + struct irctl *ir = file->private_data;
>
> - ret = mutex_lock_killable(&lirc_dev_lock);
> - WARN_ON(ret);
> + mutex_lock(&ir->mutex);
>
> rc_close(ir->d.rdev);
> + ir->users--;
>
> - ir->open--;
> - if (!ret)
> - mutex_unlock(&lirc_dev_lock);
> + mutex_unlock(&ir->mutex);
>
> return 0;
> }
> @@ -365,26 +326,21 @@ EXPORT_SYMBOL(lirc_dev_fop_close);
>
> unsigned int lirc_dev_fop_poll(struct file *file, poll_table *wait)
> {
> - struct irctl *ir = irctls[iminor(file_inode(file))];
> + struct irctl *ir = file->private_data;
> unsigned int ret;
>
> - if (!ir) {
> - pr_err("called with invalid irctl\n");
> - return POLLERR;
> - }
> -
> - if (!ir->attached)
> + if (ir->dead)
> return POLLHUP | POLLERR;
>
> - if (ir->buf) {
> - poll_wait(file, &ir->buf->wait_poll, wait);
> + if (!ir->buf)
> + return POLLERR;
> +
> + poll_wait(file, &ir->buf->wait_poll, wait);
>
> - if (lirc_buffer_empty(ir->buf))
> - ret = 0;
> - else
> - ret = POLLIN | POLLRDNORM;
> - } else
> - ret = POLLERR;
> + if (lirc_buffer_empty(ir->buf))
> + ret = 0;
> + else
> + ret = POLLIN | POLLRDNORM;
>
> dev_dbg(ir->d.dev, LOGHEAD "poll result = %d\n",
> ir->d.name, ir->d.minor, ret);
> @@ -395,25 +351,20 @@ EXPORT_SYMBOL(lirc_dev_fop_poll);
>
> long lirc_dev_fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> {
> + struct irctl *ir = file->private_data;
> __u32 mode;
> int result = 0;
> - struct irctl *ir = irctls[iminor(file_inode(file))];
> -
> - if (!ir) {
> - pr_err("no irctl found!\n");
> - return -ENODEV;
> - }
>
> dev_dbg(ir->d.dev, LOGHEAD "ioctl called (0x%x)\n",
> ir->d.name, ir->d.minor, cmd);
>
> - if (ir->d.minor == NOPLUG || !ir->attached) {
> + if (ir->dead) {
> dev_err(ir->d.dev, LOGHEAD "ioctl result = -ENODEV\n",
> ir->d.name, ir->d.minor);
> return -ENODEV;
> }
>
> - mutex_lock(&ir->irctl_lock);
> + mutex_lock(&ir->mutex);
>
> switch (cmd) {
> case LIRC_GET_FEATURES:
> @@ -468,7 +419,7 @@ long lirc_dev_fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
> result = -ENOTTY;
> }
>
> - mutex_unlock(&ir->irctl_lock);
> + mutex_unlock(&ir->mutex);
>
> return result;
> }
> @@ -479,16 +430,11 @@ ssize_t lirc_dev_fop_read(struct file *file,
> size_t length,
> loff_t *ppos)
> {
> - struct irctl *ir = irctls[iminor(file_inode(file))];
> + struct irctl *ir = file->private_data;
> unsigned char *buf;
> int ret = 0, written = 0;
> DECLARE_WAITQUEUE(wait, current);
>
> - if (!ir) {
> - pr_err("called with invalid irctl\n");
> - return -ENODEV;
> - }
> -
> if (!LIRC_CAN_REC(ir->d.features))
> return -EINVAL;
>
> @@ -498,11 +444,12 @@ ssize_t lirc_dev_fop_read(struct file *file,
> if (!buf)
> return -ENOMEM;
>
> - if (mutex_lock_interruptible(&ir->irctl_lock)) {
> + if (mutex_lock_interruptible(&ir->mutex)) {
> ret = -ERESTARTSYS;
> goto out_unlocked;
> }
> - if (!ir->attached) {
> +
> + if (ir->dead) {
> ret = -ENODEV;
> goto out_locked;
> }
> @@ -541,18 +488,18 @@ ssize_t lirc_dev_fop_read(struct file *file,
> break;
> }
>
> - mutex_unlock(&ir->irctl_lock);
> + mutex_unlock(&ir->mutex);
> set_current_state(TASK_INTERRUPTIBLE);
> schedule();
> set_current_state(TASK_RUNNING);
>
> - if (mutex_lock_interruptible(&ir->irctl_lock)) {
> + if (mutex_lock_interruptible(&ir->mutex)) {
> ret = -ERESTARTSYS;
> remove_wait_queue(&ir->buf->wait_poll, &wait);
> goto out_unlocked;
> }
>
> - if (!ir->attached) {
> + if (ir->dead) {
> ret = -ENODEV;
> goto out_locked;
> }
> @@ -570,7 +517,7 @@ ssize_t lirc_dev_fop_read(struct file *file,
> remove_wait_queue(&ir->buf->wait_poll, &wait);
>
> out_locked:
> - mutex_unlock(&ir->irctl_lock);
> + mutex_unlock(&ir->mutex);
>
> out_unlocked:
> kfree(buf);
> @@ -581,7 +528,8 @@ EXPORT_SYMBOL(lirc_dev_fop_read);
>
> void *lirc_get_pdata(struct file *file)
> {
> - return irctls[iminor(file_inode(file))]->d.data;
> + struct irctl *ir = file->private_data;
> + return ir->d.data;
> }
> EXPORT_SYMBOL(lirc_get_pdata);
>
> @@ -596,7 +544,7 @@ static int __init lirc_dev_init(void)
> return PTR_ERR(lirc_class);
> }
>
> - retval = alloc_chrdev_region(&lirc_base_dev, 0, MAX_IRCTL_DEVICES,
> + retval = alloc_chrdev_region(&lirc_base_dev, 0, LIRC_MAX_DEVICES,
> IRCTL_DEV_NAME);
> if (retval) {
> class_destroy(lirc_class);
> @@ -613,7 +561,7 @@ static int __init lirc_dev_init(void)
> static void __exit lirc_dev_exit(void)
> {
> class_destroy(lirc_class);
> - unregister_chrdev_region(lirc_base_dev, MAX_IRCTL_DEVICES);
> + unregister_chrdev_region(lirc_base_dev, LIRC_MAX_DEVICES);
> pr_info("module unloaded\n");
> }
>
> diff --git a/drivers/staging/media/lirc/lirc_zilog.c b/drivers/staging/media/lirc/lirc_zilog.c
> index 59e05aa1bc55..ffb70dee4547 100644
> --- a/drivers/staging/media/lirc/lirc_zilog.c
> +++ b/drivers/staging/media/lirc/lirc_zilog.c
> @@ -183,11 +183,7 @@ static void release_ir_device(struct kref *ref)
> * ir->open_count == 0 - happens on final close()
> * ir_lock, tx_ref_lock, rx_ref_lock, all released
> */
> - if (ir->l.minor >= 0) {
> - lirc_unregister_driver(ir->l.minor);
> - ir->l.minor = -1;
> - }
> -
> + lirc_unregister_driver(&ir->l);
> if (kfifo_initialized(&ir->rbuf.fifo))
> lirc_buffer_free(&ir->rbuf);
> list_del(&ir->list);
> @@ -1382,7 +1378,6 @@ static const struct file_operations lirc_fops = {
>
> static struct lirc_driver lirc_template = {
> .name = "lirc_zilog",
> - .minor = -1,
> .code_length = 13,
> .buffer_size = BUFLEN / 2,
> .chunk_size = 2,
> @@ -1597,14 +1592,13 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
> }
>
> /* register with lirc */
> - ir->l.minor = lirc_register_driver(&ir->l);
> - if (ir->l.minor < 0) {
> + ret = lirc_register_driver(&ir->l);
> + if (ret < 0) {
> dev_err(tx->ir->l.dev,
> - "%s: lirc_register_driver() failed: %i\n",
> - __func__, ir->l.minor);
> - ret = -EBADRQC;
> + "%s: lirc_register_driver failed: %i\n", __func__, ret);
> goto out_put_xx;
> }
> +
> dev_info(ir->l.dev,
> "IR unit on %s (i2c-%d) registered as lirc%d and ready\n",
> adap->name, adap->nr, ir->l.minor);
> diff --git a/include/media/lirc_dev.h b/include/media/lirc_dev.h
> index 1f327e25a9be..f7629ff116a9 100644
> --- a/include/media/lirc_dev.h
> +++ b/include/media/lirc_dev.h
> @@ -9,7 +9,6 @@
> #ifndef _LINUX_LIRC_DEV_H
> #define _LINUX_LIRC_DEV_H
>
> -#define MAX_IRCTL_DEVICES 8
> #define BUFLEN 16
>
> #define mod(n, div) ((n) % (div))
> @@ -164,6 +163,8 @@ static inline unsigned int lirc_buffer_write(struct lirc_buffer *buf,
> * device.
> *
> * @owner: the module owning this struct
> + *
> + * @lirc_internal: lirc_dev bookkeeping data, don't touch.
It's not a great name or comment :)
Otherwise, it's a good idea.
Sean
> */
> struct lirc_driver {
> char name[40];
> @@ -182,19 +183,12 @@ struct lirc_driver {
> const struct file_operations *fops;
> struct device *dev;
> struct module *owner;
> + void *lirc_internal;
> };
>
> -/* following functions can be called ONLY from user context
> - *
> - * returns negative value on error or minor number
> - * of the registered device if success
> - * contents of the structure pointed by p is copied
> - */
> extern int lirc_register_driver(struct lirc_driver *d);
>
> -/* returns negative value on error or 0 if success
> -*/
> -extern int lirc_unregister_driver(int minor);
> +extern void lirc_unregister_driver(struct lirc_driver *d);
>
> /* Returns the private data stored in the lirc_driver
> * associated with the given device file pointer.
