Re: [PATCH v2 0/3] input: Dynamic Minor Numbers

diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c
index f0909ed..c82f76f 100644
--- a/drivers/input/joydev.c
+++ b/drivers/input/joydev.c

@@ -27,6 +27,7 @@
 #include <linux/poll.h>
 #include <linux/init.h>
 #include <linux/device.h>
+#include <linux/cdev.h>

 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 MODULE_DESCRIPTION("Joystick device interfaces");

@@ -39,13 +40,13 @@ MODULE_LICENSE("GPL");

 struct joydev {
        int open;
-       int minor;
        struct input_handle handle;
        wait_queue_head_t wait;
        struct list_head client_list;
        spinlock_t client_lock; /* protects client_list */
        struct mutex mutex;
        struct device dev;
+       struct cdev cdev;
        bool exist;

        struct js_corr corr[ABS_CNT];

@@ -70,9 +71,6 @@ struct joydev_client {
        struct list_head node;
 };

-static struct joydev *joydev_table[JOYDEV_MINORS];
-static DEFINE_MUTEX(joydev_table_mutex);
-
 static int joydev_correct(int value, struct js_corr *corr)
 {
        switch (corr->type) {

@@ -252,30 +250,14 @@ static int joydev_release(struct inode *inode, struct file *file)

 static int joydev_open(struct inode *inode, struct file *file)
 {
+       struct joydev *joydev =
+                       container_of(inode->i_cdev, struct joydev, cdev);
        struct joydev_client *client;
-       struct joydev *joydev;
-       int i = iminor(inode) - JOYDEV_MINOR_BASE;
        int error;

-       if (i >= JOYDEV_MINORS)
-               return -ENODEV;
-
-       error = mutex_lock_interruptible(&joydev_table_mutex);
-       if (error)
-               return error;
-       joydev = joydev_table[i];
-       if (joydev)
-               get_device(&joydev->dev);
-       mutex_unlock(&joydev_table_mutex);
-
-       if (!joydev)
-               return -ENODEV;
-
        client = kzalloc(sizeof(struct joydev_client), GFP_KERNEL);
-       if (!client) {
-               error = -ENOMEM;
-               goto err_put_joydev;
-       }
+       if (!client)
+               return -ENOMEM;

        spin_lock_init(&client->buffer_lock);
        client->joydev = joydev;

@@ -288,13 +270,12 @@ static int joydev_open(struct inode *inode, struct file *file)
        file->private_data = client;
        nonseekable_open(inode, file);

+       get_device(&joydev->dev);
        return 0;

  err_free_client:
        joydev_detach_client(joydev, client);
        kfree(client);
- err_put_joydev:
-       put_device(&joydev->dev);
        return error;
 }

@@ -747,19 +728,6 @@ static const struct file_operations joydev_fops = {
        .llseek         = no_llseek,
 };

-static int joydev_install_chrdev(struct joydev *joydev)
-{
-       joydev_table[joydev->minor] = joydev;
-       return 0;
-}
-
-static void joydev_remove_chrdev(struct joydev *joydev)
-{
-       mutex_lock(&joydev_table_mutex);
-       joydev_table[joydev->minor] = NULL;
-       mutex_unlock(&joydev_table_mutex);
-}
-
 /*
  * Mark device non-existent. This disables writes, ioctls and
  * prevents new users from opening the device. Already posted

@@ -778,7 +746,8 @@ static void joydev_cleanup(struct joydev *joydev)

        joydev_mark_dead(joydev);
        joydev_hangup(joydev);
-       joydev_remove_chrdev(joydev);
+
+       cdev_del(&joydev->cdev);

        /* joydev is marked dead so no one else accesses joydev->open */
        if (joydev->open)

@@ -803,30 +772,33 @@ static int joydev_connect(struct input_handler *handler, struct input_dev *dev,
                          const struct input_device_id *id)
 {
        struct joydev *joydev;
-       int i, j, t, minor;
+       int i, j, t, minor, dev_no;
        int error;

-       for (minor = 0; minor < JOYDEV_MINORS; minor++)
-               if (!joydev_table[minor])
-                       break;
-
-       if (minor == JOYDEV_MINORS) {
-               pr_err("no more free joydev devices\n");
-               return -ENFILE;
+       minor = input_get_new_minor(JOYDEV_MINOR_BASE, JOYDEV_MINORS, true);
+       if (minor < 0) {
+               error = minor;
+               pr_err("failed to reserve new minor: %d\n", error);
+               return error;

        }

        joydev = kzalloc(sizeof(struct joydev), GFP_KERNEL);
-       if (!joydev)
-               return -ENOMEM;
+       if (!joydev) {
+               error = -ENOMEM;
+               goto err_free_minor;
+       }

        INIT_LIST_HEAD(&joydev->client_list);
        spin_lock_init(&joydev->client_lock);
        mutex_init(&joydev->mutex);
        init_waitqueue_head(&joydev->wait);
-
-       dev_set_name(&joydev->dev, "js%d", minor);
        joydev->exist = true;
-       joydev->minor = minor;
+
+       dev_no = minor;
+       /* Normalize device number if it falls into legacy range */
+       if (dev_no < JOYDEV_MINOR_BASE + JOYDEV_MINORS)
+               dev_no -= JOYDEV_MINOR_BASE;
+       dev_set_name(&joydev->dev, "js%d", dev_no);

        joydev->handle.dev = input_get_device(dev);
        joydev->handle.name = dev_name(&joydev->dev);

@@ -880,7 +852,7 @@ static int joydev_connect(struct input_handler *handler, struct input_dev *dev,
                }
        }

-       joydev->dev.devt = MKDEV(INPUT_MAJOR, JOYDEV_MINOR_BASE + minor);
+       joydev->dev.devt = MKDEV(INPUT_MAJOR, minor);
        joydev->dev.class = &input_class;
        joydev->dev.parent = &dev->dev;
        joydev->dev.release = joydev_free;

@@ -890,7 +862,8 @@ static int joydev_connect(struct input_handler *handler, struct input_dev *dev,
        if (error)
                goto err_free_joydev;

-       error = joydev_install_chrdev(joydev);
+       cdev_init(&joydev->cdev, &joydev_fops);
+       error = cdev_add(&joydev->cdev, joydev->dev.devt, 1);
        if (error)
                goto err_unregister_handle;

@@ -906,6 +879,8 @@ static int joydev_connect(struct input_handler *handler, struct input_dev *dev,
        input_unregister_handle(&joydev->handle);
  err_free_joydev:
        put_device(&joydev->dev);
+ err_free_minor:
+       input_free_minor(minor);
        return error;
 }

@@ -915,6 +890,7 @@ static void joydev_disconnect(struct input_handle *handle)

        device_del(&joydev->dev);
        joydev_cleanup(joydev);
+       input_free_minor(MINOR(joydev->dev.devt));
        input_unregister_handle(handle);
        put_device(&joydev->dev);
 }

@@ -966,8 +942,6 @@ static struct input_handler joydev_handler = {
        .match          = joydev_match,
        .connect        = joydev_connect,
        .disconnect     = joydev_disconnect,
-       .fops           = &joydev_fops,
-       .minor          = JOYDEV_MINOR_BASE,
        .name           = "joydev",
        .id_table       = joydev_ids,
 };

diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 964e43d..7fd9d91 100644
--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c

@@ -24,10 +24,8 @@
 #include <linux/random.h>
 #include <linux/major.h>
 #include <linux/device.h>
+#include <linux/cdev.h>
 #include <linux/kernel.h>
-#ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
-#include <linux/miscdevice.h>
-#endif

 MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
 MODULE_DESCRIPTION("Mouse (ExplorerPS/2) device interfaces");

@@ -61,17 +59,18 @@ struct mousedev_hw_data {

 struct mousedev {
        int open;
-       int minor;
        struct input_handle handle;
        wait_queue_head_t wait;
        struct list_head client_list;
        spinlock_t client_lock; /* protects client_list */
        struct mutex mutex;
        struct device dev;
+       struct cdev cdev;
        bool exist;
+       bool is_mixdev;

        struct list_head mixdev_node;
-       int mixdev_open;
+       bool mixdev_open;

        struct mousedev_hw_data packet;
        unsigned int pkt_count;

@@ -114,10 +113,6 @@ struct mousedev_client {
 static unsigned char mousedev_imps_seq[] = { 0xf3, 200, 0xf3, 100, 0xf3, 80 };
 static unsigned char mousedev_imex_seq[] = { 0xf3, 200, 0xf3, 200, 0xf3, 80 };

-static struct input_handler mousedev_handler;
-
-static struct mousedev *mousedev_table[MOUSEDEV_MINORS];
-static DEFINE_MUTEX(mousedev_table_mutex);
 static struct mousedev *mousedev_mix;
 static LIST_HEAD(mousedev_mix_list);

@@ -433,7 +428,7 @@ static int mousedev_open_device(struct mousedev *mousedev)
        if (retval)
                return retval;

-       if (mousedev->minor == MOUSEDEV_MIX)
+       if (mousedev->is_mixdev)
                mixdev_open_devices();
        else if (!mousedev->exist)
                retval = -ENODEV;

@@ -451,7 +446,7 @@ static void mousedev_close_device(struct mousedev *mousedev)
 {
        mutex_lock(&mousedev->mutex);

-       if (mousedev->minor == MOUSEDEV_MIX)
+       if (mousedev->is_mixdev)
                mixdev_close_devices();
        else if (mousedev->exist && !--mousedev->open)
                input_close_device(&mousedev->handle);

@@ -476,7 +471,7 @@ static void mixdev_open_devices(void)
                        if (mousedev_open_device(mousedev))
                                continue;

-                       mousedev->mixdev_open = 1;
+                       mousedev->mixdev_open = true;
                }
        }
 }

@@ -495,7 +490,7 @@ static void mixdev_close_devices(void)

        list_for_each_entry(mousedev, &mousedev_mix_list, mixdev_node) {
                if (mousedev->mixdev_open) {
-                       mousedev->mixdev_open = 0;
+                       mousedev->mixdev_open = false;
                        mousedev_close_device(mousedev);
                }
        }

@@ -538,35 +533,17 @@ static int mousedev_open(struct inode *inode, struct file *file)
        struct mousedev_client *client;
        struct mousedev *mousedev;
        int error;
-       int i;

 #ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
        if (imajor(inode) == MISC_MAJOR)
-               i = MOUSEDEV_MIX;
+               mousedev = mousedev_mix;
        else
 #endif
-               i = iminor(inode) - MOUSEDEV_MINOR_BASE;
-
-       if (i >= MOUSEDEV_MINORS)
-               return -ENODEV;
-
-       error = mutex_lock_interruptible(&mousedev_table_mutex);
-       if (error)
-               return error;
-
-       mousedev = mousedev_table[i];
-       if (mousedev)
-               get_device(&mousedev->dev);
-       mutex_unlock(&mousedev_table_mutex);
-
-       if (!mousedev)
-               return -ENODEV;
+               mousedev = container_of(inode->i_cdev, struct mousedev, cdev);

        client = kzalloc(sizeof(struct mousedev_client), GFP_KERNEL);
-       if (!client) {
-               error = -ENOMEM;
-               goto err_put_mousedev;
-       }
+       if (!client)
+               return -ENOMEM;

        spin_lock_init(&client->packet_lock);
        client->pos_x = xres / 2;

@@ -579,13 +556,14 @@ static int mousedev_open(struct inode *inode, struct file *file)
                goto err_free_client;

        file->private_data = client;
+       nonseekable_open(inode, file);
+
+       get_device(&mousedev->dev);
        return 0;

  err_free_client:
        mousedev_detach_client(mousedev, client);
        kfree(client);
- err_put_mousedev:
-       put_device(&mousedev->dev);
        return error;
 }

@@ -785,29 +763,16 @@ static unsigned int mousedev_poll(struct file *file, poll_table *wait)
 }

 static const struct file_operations mousedev_fops = {
-       .owner =        THIS_MODULE,
-       .read =         mousedev_read,
-       .write =        mousedev_write,
-       .poll =         mousedev_poll,
-       .open =         mousedev_open,
-       .release =      mousedev_release,
-       .fasync =       mousedev_fasync,
-       .llseek = noop_llseek,
+       .owner          = THIS_MODULE,
+       .read           = mousedev_read,
+       .write          = mousedev_write,
+       .poll           = mousedev_poll,
+       .open           = mousedev_open,
+       .release        = mousedev_release,
+       .fasync         = mousedev_fasync,
+       .llseek         = noop_llseek,
 };

-static int mousedev_install_chrdev(struct mousedev *mousedev)
-{
-       mousedev_table[mousedev->minor] = mousedev;
-       return 0;
-}
-
-static void mousedev_remove_chrdev(struct mousedev *mousedev)
-{
-       mutex_lock(&mousedev_table_mutex);
-       mousedev_table[mousedev->minor] = NULL;
-       mutex_unlock(&mousedev_table_mutex);
-}
-
 /*
  * Mark device non-existent. This disables writes, ioctls and
  * prevents new users from opening the device. Already posted

@@ -842,24 +807,50 @@ static void mousedev_cleanup(struct mousedev *mousedev)

        mousedev_mark_dead(mousedev);
        mousedev_hangup(mousedev);
-       mousedev_remove_chrdev(mousedev);
+
+       cdev_del(&mousedev->cdev);

        /* mousedev is marked dead so no one else accesses mousedev->open */
        if (mousedev->open)
                input_close_device(handle);
 }

+static int mousedev_reserve_minor(bool mixdev)
+{
+       int minor;
+
+       if (mixdev) {
+               minor = input_get_new_minor(MOUSEDEV_MIX, 1, false);
+               if (minor < 0)
+                       pr_err("failed to reserve mixdev minor: %d\n", minor);
+       } else {
+               minor = input_get_new_minor(MOUSEDEV_MINOR_BASE,
+                                           MOUSEDEV_MINORS, true);
+               if (minor < 0)
+                       pr_err("failed to reserve new minor: %d\n", minor);
+       }
+
+       return minor;
+}
+
 static struct mousedev *mousedev_create(struct input_dev *dev,
                                        struct input_handler *handler,
-                                       int minor)
+                                       bool mixdev)
 {
        struct mousedev *mousedev;
+       int minor;
        int error;

+       minor = mousedev_reserve_minor(mixdev);
+       if (minor < 0) {
+               error = minor;
+               goto err_out;
+       }
+
        mousedev = kzalloc(sizeof(struct mousedev), GFP_KERNEL);
        if (!mousedev) {
                error = -ENOMEM;
-               goto err_out;
+               goto err_free_minor;
        }

        INIT_LIST_HEAD(&mousedev->client_list);

@@ -867,16 +858,21 @@ static struct mousedev *mousedev_create(struct input_dev *dev,
        spin_lock_init(&mousedev->client_lock);
        mutex_init(&mousedev->mutex);
        lockdep_set_subclass(&mousedev->mutex,
-                            minor == MOUSEDEV_MIX ? SINGLE_DEPTH_NESTING : 0);
+                            mixdev ? SINGLE_DEPTH_NESTING : 0);
        init_waitqueue_head(&mousedev->wait);

-       if (minor == MOUSEDEV_MIX)
+       if (mixdev) {
                dev_set_name(&mousedev->dev, "mice");
-       else
-               dev_set_name(&mousedev->dev, "mouse%d", minor);
+       } else {
+               int dev_no = minor;
+               /* Normalize device number if it falls into legacy range */
+               if (dev_no < MOUSEDEV_MINOR_BASE + MOUSEDEV_MINORS)
+                       dev_no -= MOUSEDEV_MINOR_BASE;
+               dev_set_name(&mousedev->dev, "mouse%d", dev_no);
+       }

-       mousedev->minor = minor;
        mousedev->exist = true;
+       mousedev->is_mixdev = mixdev;
        mousedev->handle.dev = input_get_device(dev);
        mousedev->handle.name = dev_name(&mousedev->dev);
        mousedev->handle.handler = handler;

@@ -885,17 +881,18 @@ static struct mousedev *mousedev_create(struct input_dev *dev,
        mousedev->dev.class = &input_class;
        if (dev)
                mousedev->dev.parent = &dev->dev;
-       mousedev->dev.devt = MKDEV(INPUT_MAJOR, MOUSEDEV_MINOR_BASE + minor);
+       mousedev->dev.devt = MKDEV(INPUT_MAJOR, minor);
        mousedev->dev.release = mousedev_free;
        device_initialize(&mousedev->dev);

-       if (minor != MOUSEDEV_MIX) {
+       if (!mixdev) {
                error = input_register_handle(&mousedev->handle);
                if (error)
                        goto err_free_mousedev;
        }

-       error = mousedev_install_chrdev(mousedev);
+       cdev_init(&mousedev->cdev, &mousedev_fops);
+       error = cdev_add(&mousedev->cdev, mousedev->dev.devt, 1);
        if (error)
                goto err_unregister_handle;

@@ -908,10 +905,12 @@ static struct mousedev *mousedev_create(struct input_dev *dev,
  err_cleanup_mousedev:
        mousedev_cleanup(mousedev);
  err_unregister_handle:
-       if (minor != MOUSEDEV_MIX)
+       if (!mixdev)
                input_unregister_handle(&mousedev->handle);
  err_free_mousedev:
        put_device(&mousedev->dev);
+ err_free_minor:
+       input_free_minor(minor);
  err_out:
        return ERR_PTR(error);
 }

@@ -920,7 +919,8 @@ static void mousedev_destroy(struct mousedev *mousedev)
 {
        device_del(&mousedev->dev);
        mousedev_cleanup(mousedev);
-       if (mousedev->minor != MOUSEDEV_MIX)
+       input_free_minor(MINOR(mousedev->dev.devt));
+       if (!mousedev->is_mixdev)
                input_unregister_handle(&mousedev->handle);
        put_device(&mousedev->dev);
 }

@@ -938,7 +938,7 @@ static int mixdev_add_device(struct mousedev *mousedev)
                if (retval)
                        goto out;

-               mousedev->mixdev_open = 1;
+               mousedev->mixdev_open = true;
        }

        get_device(&mousedev->dev);

@@ -954,7 +954,7 @@ static void mixdev_remove_device(struct mousedev *mousedev)
        mutex_lock(&mousedev_mix->mutex);

        if (mousedev->mixdev_open) {
-               mousedev->mixdev_open = 0;
+               mousedev->mixdev_open = false;
                mousedev_close_device(mousedev);
        }

@@ -969,19 +969,9 @@ static int mousedev_connect(struct input_handler *handler,
                            const struct input_device_id *id)
 {
        struct mousedev *mousedev;
-       int minor;
        int error;

-       for (minor = 0; minor < MOUSEDEV_MINORS; minor++)
-               if (!mousedev_table[minor])
-                       break;
-
-       if (minor == MOUSEDEV_MINORS) {
-               pr_err("no more free mousedev devices\n");
-               return -ENFILE;
-       }
-
-       mousedev = mousedev_create(dev, handler, minor);
+       mousedev = mousedev_create(dev, handler, false);
        if (IS_ERR(mousedev))
                return PTR_ERR(mousedev);

@@ -1054,27 +1044,59 @@ static const struct input_device_id mousedev_ids[] = {
 MODULE_DEVICE_TABLE(input, mousedev_ids);

 static struct input_handler mousedev_handler = {
-       .event =        mousedev_event,
-       .connect =      mousedev_connect,
-       .disconnect =   mousedev_disconnect,
-       .fops =         &mousedev_fops,
-       .minor =        MOUSEDEV_MINOR_BASE,
-       .name =         "mousedev",
-       .id_table =     mousedev_ids,
+       .event          = mousedev_event,
+       .connect        = mousedev_connect,
+       .disconnect     = mousedev_disconnect,
+       .name           = "mousedev",
+       .id_table       = mousedev_ids,
 };

 #ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
+#include <linux/miscdevice.h>
+
 static struct miscdevice psaux_mouse = {
-       PSMOUSE_MINOR, "psaux", &mousedev_fops
+       .minor  = PSMOUSE_MINOR,
+       .name   = "psaux",
+       .fops   = &mousedev_fops,
 };
-static int psaux_registered;
+static bool psaux_registered;
+
+static void __init mousedev_psaux_register(void)
+{
+       int error;
+
+       error = misc_register(&psaux_mouse);
+       if (error)
+               pr_warn("could not register psaux device, error: %d\n",
+                          error);
+       else
+               psaux_registered = true;
+

+}
+
+static void __exit mousedev_psaux_unregister(void)
+{
+       if (psaux_registered)
+               misc_deregister(&psaux_mouse);
+}
+
+#else
+
+static inline void mousedev_psaux_register(void)
+{
+}
+
+static inline void mousedev_psaux_unregister(void)
+{
+}
+
 #endif

 static int __init mousedev_init(void)
 {
        int error;

-       mousedev_mix = mousedev_create(NULL, &mousedev_handler, MOUSEDEV_MIX);
+       mousedev_mix = mousedev_create(NULL, &mousedev_handler, true);
        if (IS_ERR(mousedev_mix))
                return PTR_ERR(mousedev_mix);

@@ -1084,14 +1106,7 @@ static int __init mousedev_init(void)
                return error;
        }

-#ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
-       error = misc_register(&psaux_mouse);
-       if (error)
-               pr_warn("could not register psaux device, error: %d\n",
-                          error);
-       else
-               psaux_registered = 1;
-#endif
+       mousedev_psaux_register();

        pr_info("PS/2 mouse device common for all mice\n");

@@ -1100,10 +1115,7 @@ static int __init mousedev_init(void)

 static void __exit mousedev_exit(void)
 {
-#ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
-       if (psaux_registered)
-               misc_deregister(&psaux_mouse);
-#endif
+       mousedev_psaux_unregister();
        input_unregister_handler(&mousedev_handler);
        mousedev_destroy(mousedev_mix);
 }

diff --git a/include/linux/input.h b/include/linux/input.h
index 725dcd0..c698e7e 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h

@@ -1387,9 +1387,6 @@ struct input_handle;
  * @start: starts handler for given handle. This function is called by
  *     input core right after connect() method and also when a process
  *     that "grabbed" a device releases it
- * @fops: file operations this driver implements
- * @minor: beginning of range of 32 minors for devices this driver
- *     can provide
  * @name: name of the handler, to be shown in /proc/bus/input/handlers
  * @id_table: pointer to a table of input_device_ids this driver can
  *     handle

@@ -1420,8 +1417,6 @@ struct input_handler {
        void (*disconnect)(struct input_handle *handle);
        void (*start)(struct input_handle *handle);

-       const struct file_operations *fops;
-       int minor;
        const char *name;

        const struct input_device_id *id_table;

@@ -1488,6 +1483,10 @@ void input_reset_device(struct input_dev *);
 int __must_check input_register_handler(struct input_handler *);
 void input_unregister_handler(struct input_handler *);

+int __must_check input_get_new_minor(int legacy_base, unsigned int legacy_num,
+                                    bool allow_dynamic);
+void input_free_minor(unsigned int minor);
+
 int input_handler_for_each_handle(struct input_handler *, void *data,
                                  int (*fn)(struct input_handle *, void *));