Input: extend the number of event (and other) devices

Extend the amount of character devices, such as eventX, mouseX and jsX,
from a hard limit of 32 per input handler to about 1024 shared across
all handlers.

To be compatible with legacy installations input handlers will start
creating char devices with minors in their legacy range, however once
legacy range is exhausted they will start allocating minors from the
dynamic range 256-1024.

Reviewed-by: David Herrmann <dh.herrmann@googlemail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 32 insertions, 56 deletions

diff --git a/drivers/input/joydev.c b/drivers/input/joydev.c
index 78f323ea1e4b..b62b5891f399 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;
 }
 
@@ -742,19 +723,6 @@ 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
@@ -773,7 +741,8 @@ 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)
@@ -798,30 +767,33 @@ 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);
@@ -875,7 +847,7 @@ 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;
@@ -885,7 +857,8 @@ 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;
 
@@ -901,6 +874,8 @@ 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;
 }
 
@@ -910,6 +885,7 @@ 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);
 }
@@ -961,7 +937,7 @@ static struct input_handler joydev_handler = {
         .match          = joydev_match,
         .connect        = joydev_connect,
         .disconnect     = joydev_disconnect,
-        .fops           = &joydev_fops,
+        .legacy_minors  = true,
         .minor          = JOYDEV_MINOR_BASE,
         .name           = "joydev",
         .id_table       = joydev_ids,