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>
diff --git a/drivers/input/input.c b/drivers/input/input.c
index ace3f7c..53a0dde 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -14,6 +14,7 @@
#include <linux/init.h>
#include <linux/types.h>
+#include <linux/idr.h>
#include <linux/input/mt.h>
#include <linux/module.h>
#include <linux/slab.h>
@@ -32,7 +33,9 @@
MODULE_DESCRIPTION("Input core");
MODULE_LICENSE("GPL");
-#define INPUT_DEVICES 256
+#define INPUT_MAX_CHAR_DEVICES 1024
+#define INPUT_FIRST_DYNAMIC_DEV 256
+static DEFINE_IDA(input_ida);
static LIST_HEAD(input_dev_list);
static LIST_HEAD(input_handler_list);
@@ -45,8 +48,6 @@
*/
static DEFINE_MUTEX(input_mutex);
-static struct input_handler *input_table[8];
-
static const struct input_value input_value_sync = { EV_SYN, SYN_REPORT, 1 };
static inline int is_event_supported(unsigned int code,
@@ -1218,7 +1219,7 @@
seq_printf(seq, "N: Number=%u Name=%s", state->pos, handler->name);
if (handler->filter)
seq_puts(seq, " (filter)");
- if (handler->fops)
+ if (handler->legacy_minors)
seq_printf(seq, " Minor=%d", handler->minor);
seq_putc(seq, '\n');
@@ -2016,22 +2017,14 @@
int input_register_handler(struct input_handler *handler)
{
struct input_dev *dev;
- int retval;
+ int error;
- retval = mutex_lock_interruptible(&input_mutex);
- if (retval)
- return retval;
+ error = mutex_lock_interruptible(&input_mutex);
+ if (error)
+ return error;
INIT_LIST_HEAD(&handler->h_list);
- if (handler->fops != NULL) {
- if (input_table[handler->minor >> 5]) {
- retval = -EBUSY;
- goto out;
- }
- input_table[handler->minor >> 5] = handler;
- }
-
list_add_tail(&handler->node, &input_handler_list);
list_for_each_entry(dev, &input_dev_list, node)
@@ -2039,9 +2032,8 @@
input_wakeup_procfs_readers();
- out:
mutex_unlock(&input_mutex);
- return retval;
+ return 0;
}
EXPORT_SYMBOL(input_register_handler);
@@ -2064,9 +2056,6 @@
list_del_init(&handler->node);
- if (handler->fops != NULL)
- input_table[handler->minor >> 5] = NULL;
-
input_wakeup_procfs_readers();
mutex_unlock(&input_mutex);
@@ -2183,51 +2172,52 @@
}
EXPORT_SYMBOL(input_unregister_handle);
-static int input_open_file(struct inode *inode, struct file *file)
+/**
+ * input_get_new_minor - allocates a new input minor number
+ * @legacy_base: beginning or the legacy range to be searched
+ * @legacy_num: size of legacy range
+ * @allow_dynamic: whether we can also take ID from the dynamic range
+ *
+ * This function allocates a new device minor for from input major namespace.
+ * Caller can request legacy minor by specifying @legacy_base and @legacy_num
+ * parameters and whether ID can be allocated from dynamic range if there are
+ * no free IDs in legacy range.
+ */
+int input_get_new_minor(int legacy_base, unsigned int legacy_num,
+ bool allow_dynamic)
{
- struct input_handler *handler;
- const struct file_operations *old_fops, *new_fops = NULL;
- int err;
-
- err = mutex_lock_interruptible(&input_mutex);
- if (err)
- return err;
-
- /* No load-on-demand here? */
- handler = input_table[iminor(inode) >> 5];
- if (handler)
- new_fops = fops_get(handler->fops);
-
- mutex_unlock(&input_mutex);
-
/*
- * That's _really_ odd. Usually NULL ->open means "nothing special",
- * not "no device". Oh, well...
+ * This function should be called from input handler's ->connect()
+ * methods, which are serialized with input_mutex, so no additional
+ * locking is needed here.
*/
- if (!new_fops || !new_fops->open) {
- fops_put(new_fops);
- err = -ENODEV;
- goto out;
+ if (legacy_base >= 0) {
+ int minor = ida_simple_get(&input_ida,
+ legacy_base,
+ legacy_base + legacy_num,
+ GFP_KERNEL);
+ if (minor >= 0 || !allow_dynamic)
+ return minor;
}
- old_fops = file->f_op;
- file->f_op = new_fops;
-
- err = new_fops->open(inode, file);
- if (err) {
- fops_put(file->f_op);
- file->f_op = fops_get(old_fops);
- }
- fops_put(old_fops);
-out:
- return err;
+ return ida_simple_get(&input_ida,
+ INPUT_FIRST_DYNAMIC_DEV, INPUT_MAX_CHAR_DEVICES,
+ GFP_KERNEL);
}
+EXPORT_SYMBOL(input_get_new_minor);
-static const struct file_operations input_fops = {
- .owner = THIS_MODULE,
- .open = input_open_file,
- .llseek = noop_llseek,
-};
+/**
+ * input_free_minor - release previously allocated minor
+ * @minor: minor to be released
+ *
+ * This function releases previously allocated input minor so that it can be
+ * reused later.
+ */
+void input_free_minor(unsigned int minor)
+{
+ ida_simple_remove(&input_ida, minor);
+}
+EXPORT_SYMBOL(input_free_minor);
static int __init input_init(void)
{
@@ -2243,7 +2233,8 @@
if (err)
goto fail1;
- err = register_chrdev(INPUT_MAJOR, "input", &input_fops);
+ err = register_chrdev_region(MKDEV(INPUT_MAJOR, 0),
+ INPUT_MAX_CHAR_DEVICES, "input");
if (err) {
pr_err("unable to register char major %d", INPUT_MAJOR);
goto fail2;
@@ -2259,7 +2250,8 @@
static void __exit input_exit(void)
{
input_proc_exit();
- unregister_chrdev(INPUT_MAJOR, "input");
+ unregister_chrdev_region(MKDEV(INPUT_MAJOR, 0),
+ INPUT_MAX_CHAR_DEVICES);
class_unregister(&input_class);
}