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Input: sparse-keymap - implement safer freeing of the keymap

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Allow calling sparse_keymap_free() before unregistering input device
whithout risk of racing with EVIOCGETKEYCODE and EVIOCSETKEYCODE.
This makes life of drivers writers easier.

Acked-by: Yong Wang <yong.y.wang@intel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
This commit is contained in:
Dmitry Torokhov
2010-03-21 22:56:15 -07:00
parent 13bad37b04
commit 2e2e3b96d9
2 changed files with 40 additions and 19 deletions
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9
drivers/input/input.c
View File

@@ -659,7 +659,14 @@ static int input_default_setkeycode(struct input_dev *dev,
int input_get_keycode(struct input_dev *dev, int input_get_keycode(struct input_dev *dev,
unsigned int scancode, unsigned int *keycode) unsigned int scancode, unsigned int *keycode)
{ {
return dev->getkeycode(dev, scancode, keycode); unsigned long flags;
int retval;
spin_lock_irqsave(&dev->event_lock, flags);
retval = dev->getkeycode(dev, scancode, keycode);
spin_unlock_irqrestore(&dev->event_lock, flags);
return retval;
} }
EXPORT_SYMBOL(input_get_keycode); EXPORT_SYMBOL(input_get_keycode);

28
drivers/input/sparse-keymap.c
View File

@@ -67,13 +67,15 @@ static int sparse_keymap_getkeycode(struct input_dev *dev,
unsigned int scancode, unsigned int scancode,
unsigned int *keycode) unsigned int *keycode)
{ {
const struct key_entry *key = const struct key_entry *key;
sparse_keymap_entry_from_scancode(dev, scancode);
if (dev->keycode) {
key = sparse_keymap_entry_from_scancode(dev, scancode);
if (key && key->type == KE_KEY) { if (key && key->type == KE_KEY) {
*keycode = key->keycode; *keycode = key->keycode;
return 0; return 0;
} }
}
return -EINVAL; return -EINVAL;
} }
@@ -85,9 +87,7 @@ static int sparse_keymap_setkeycode(struct input_dev *dev,
struct key_entry *key; struct key_entry *key;
int old_keycode; int old_keycode;
if (keycode < 0 || keycode > KEY_MAX) if (dev->keycode) {
return -EINVAL;
key = sparse_keymap_entry_from_scancode(dev, scancode); key = sparse_keymap_entry_from_scancode(dev, scancode);
if (key && key->type == KE_KEY) { if (key && key->type == KE_KEY) {
old_keycode = key->keycode; old_keycode = key->keycode;
@@ -97,6 +97,7 @@ static int sparse_keymap_setkeycode(struct input_dev *dev,
clear_bit(old_keycode, dev->keybit); clear_bit(old_keycode, dev->keybit);
return 0; return 0;
} }
}
return -EINVAL; return -EINVAL;
} }
@@ -175,14 +176,27 @@ EXPORT_SYMBOL(sparse_keymap_setup);
* *
* This function is used to free memory allocated by sparse keymap * This function is used to free memory allocated by sparse keymap
* in an input device that was set up by sparse_keymap_setup(). * in an input device that was set up by sparse_keymap_setup().
* NOTE: It is safe to cal this function while input device is
* still registered (however the drivers should care not to try to
* use freed keymap and thus have to shut off interrups/polling
* before freeing the keymap).
*/ */
void sparse_keymap_free(struct input_dev *dev) void sparse_keymap_free(struct input_dev *dev)
{ {
unsigned long flags;
/*
* Take event lock to prevent racing with input_get_keycode()
* and input_set_keycode() if we are called while input device
* is still registered.
*/
spin_lock_irqsave(&dev->event_lock, flags);
kfree(dev->keycode); kfree(dev->keycode);
dev->keycode = NULL; dev->keycode = NULL;
dev->keycodemax = 0; dev->keycodemax = 0;
dev->getkeycode = NULL;
dev->setkeycode = NULL; spin_unlock_irqrestore(&dev->event_lock, flags);
} }
EXPORT_SYMBOL(sparse_keymap_free); EXPORT_SYMBOL(sparse_keymap_free);