Keyboard handler should not attempt to traverse handler->h_list on
its own, without any locking, otherwise it races with registering
and unregistering of input handles which leads to crashes.
Introduce input_handler_for_each_handle() helper that allows safely
iterate over all handles attached to a particular handler and switch
keyboard handler to use it.
Reported-by: Jim Paradis <jparadis@xxxxxxxxxx>
Signed-off-by: Dmitry Torokhov <dtor@xxxxxxx>
---
drivers/char/keyboard.c | 189 ++++++++++++++++++++++++-----------------------
drivers/input/input.c | 37 +++++++++
include/linux/input.h | 10 ++
3 files changed, 140 insertions(+), 96 deletions(-)
diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 737be95..8847ea6 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -46,8 +46,6 @@
extern void ctrl_alt_del(void);
-#define to_handle_h(n) container_of(n, struct input_handle, h_node)
-
/*
* Exported functions/variables
*/
@@ -190,78 +188,85 @@ EXPORT_SYMBOL_GPL(unregister_keyboard_notifier);
* etc.). So this means that scancodes for the extra function keys won't
* be valid for the first event device, but will be for the second.
*/
+
+struct getset_keycode_data {
+ unsigned int scancode;
+ unsigned int keycode;
+ int error;
+};
+
+static int getkeycode_helper(struct input_handle *handle, void *data)
+{
+ struct getset_keycode_data *d = data;
+
+ d->error = input_get_keycode(handle->dev, d->scancode, &d->keycode);
+
+ return d->error == 0; /* stop as soon as we successfully get one */
+}
+
int getkeycode(unsigned int scancode)
{
- struct input_handle *handle;
- int keycode;
- int error = -ENODEV;
+ struct getset_keycode_data d = { scancode, 0, -ENODEV };
- list_for_each_entry(handle, &kbd_handler.h_list, h_node) {
- error = input_get_keycode(handle->dev, scancode, &keycode);
- if (!error)
- return keycode;
- }
+ input_handler_for_each_handle(&kbd_handler, &d, getkeycode_helper);
- return error;
+ return d.error;
+}
+
+static int setkeycode_helper(struct input_handle *handle, void *data)
+{
+ struct getset_keycode_data *d = data;
+
+ d->error = input_set_keycode(handle->dev, d->scancode, d->keycode);
+
+ return d->error == 0; /* stop as soon as we successfully set one */
}
int setkeycode(unsigned int scancode, unsigned int keycode)
{
- struct input_handle *handle;
- int error = -ENODEV;
+ struct getset_keycode_data d = { scancode, keycode, -ENODEV };
- list_for_each_entry(handle, &kbd_handler.h_list, h_node) {
- error = input_set_keycode(handle->dev, scancode, keycode);
- if (!error)
- break;
- }
+ input_handler_for_each_handle(&kbd_handler, &d, setkeycode_helper);
- return error;
+ return d.error;
}
/*
* Making beeps and bells.
*/
-static void kd_nosound(unsigned long ignored)
+
+static int kd_sound_helper(struct input_handle *handle, void *data)
{
- struct input_handle *handle;
+ unsigned int *hz = data;
+ struct input_dev *dev = handle->dev;
- list_for_each_entry(handle, &kbd_handler.h_list, h_node) {
- if (test_bit(EV_SND, handle->dev->evbit)) {
- if (test_bit(SND_TONE, handle->dev->sndbit))
- input_inject_event(handle, EV_SND, SND_TONE, 0);
- if (test_bit(SND_BELL, handle->dev->sndbit))
- input_inject_event(handle, EV_SND, SND_BELL, 0);
- }
+ if (test_bit(EV_SND, dev->evbit)) {
+ if (test_bit(SND_TONE, dev->sndbit))
+ input_inject_event(handle, EV_SND, SND_TONE, *hz);
+ if (test_bit(SND_BELL, handle->dev->sndbit))
+ input_inject_event(handle, EV_SND, SND_BELL, *hz ? 1 : 0);
}
+
+ return 0;
+}
+
+static void kd_nosound(unsigned long ignored)
+{
+ static unsigned int zero;
+
+ input_handler_for_each_handle(&kbd_handler, &zero, kd_sound_helper);
}
static DEFINE_TIMER(kd_mksound_timer, kd_nosound, 0, 0);
void kd_mksound(unsigned int hz, unsigned int ticks)
{
- struct list_head *node;
+ del_timer_sync(&kd_mksound_timer);
- del_timer(&kd_mksound_timer);
+ input_handler_for_each_handle(&kbd_handler, &hz, kd_sound_helper);
- if (hz) {
- list_for_each_prev(node, &kbd_handler.h_list) {
- struct input_handle *handle = to_handle_h(node);
- if (test_bit(EV_SND, handle->dev->evbit)) {
- if (test_bit(SND_TONE, handle->dev->sndbit)) {
- input_inject_event(handle, EV_SND, SND_TONE, hz);
- break;
- }
- if (test_bit(SND_BELL, handle->dev->sndbit)) {
- input_inject_event(handle, EV_SND, SND_BELL, 1);
- break;
- }
- }
- }
- if (ticks)
- mod_timer(&kd_mksound_timer, jiffies + ticks);
- } else
- kd_nosound(0);
+ if (hz && ticks)
+ mod_timer(&kd_mksound_timer, jiffies + ticks);
}
EXPORT_SYMBOL(kd_mksound);
@@ -269,30 +274,33 @@ EXPORT_SYMBOL(kd_mksound);
* Setting the keyboard rate.
*/
-int kbd_rate(struct kbd_repeat *rep)
+static int kbd_rate_helper(struct input_handle *handle, void *data)
{
- struct list_head *node;
+ struct input_dev *dev = handle->dev;
+ struct kbd_repeat *rep = data;
unsigned int d = 0;
unsigned int p = 0;
- list_for_each(node, &kbd_handler.h_list) {
- struct input_handle *handle = to_handle_h(node);
- struct input_dev *dev = handle->dev;
-
- if (test_bit(EV_REP, dev->evbit)) {
- if (rep->delay > 0)
- input_inject_event(handle, EV_REP, REP_DELAY, rep->delay);
- if (rep->period > 0)
- input_inject_event(handle, EV_REP, REP_PERIOD, rep->period);
- d = dev->rep[REP_DELAY];
- p = dev->rep[REP_PERIOD];
- }
+ if (test_bit(EV_REP, dev->evbit)) {
+ if (rep->delay > 0)
+ input_inject_event(handle, EV_REP, REP_DELAY, rep->delay);
+ if (rep->period > 0)
+ input_inject_event(handle, EV_REP, REP_PERIOD, rep->period);
+ d = dev->rep[REP_DELAY];
+ p = dev->rep[REP_PERIOD];
}
+
rep->delay = d;
rep->period = p;
+
return 0;
}
+int kbd_rate(struct kbd_repeat *rep)
+{
+ return input_handler_for_each_handle(&kbd_handler, rep, kbd_rate_helper);
+}
+
/*
* Helper Functions.
*/
@@ -997,36 +1005,36 @@ static inline unsigned char getleds(void)
return leds;
}
+static int kbd_update_leds_helper(struct input_handle *handle, void *data)
+{
+ unsigned char leds = *(unsigned char *)data;
+
+ if (test_bit(EV_LED, handle->dev->evbit)) {
+ input_inject_event(handle, EV_LED, LED_SCROLLL, !!(leds & 0x01));
+ input_inject_event(handle, EV_LED, LED_NUML, !!(leds & 0x02));
+ input_inject_event(handle, EV_LED, LED_CAPSL, !!(leds & 0x04));
+ input_inject_event(handle, EV_SYN, SYN_REPORT, 0);
+ }
+
+ return 0;
+}
+
/*
- * This routine is the bottom half of the keyboard interrupt
- * routine, and runs with all interrupts enabled. It does
- * console changing, led setting and copy_to_cooked, which can
- * take a reasonably long time.
- *
- * Aside from timing (which isn't really that important for
- * keyboard interrupts as they happen often), using the software
- * interrupt routines for this thing allows us to easily mask
- * this when we don't want any of the above to happen.
- * This allows for easy and efficient race-condition prevention
- * for kbd_start => input_inject_event(dev, EV_LED, ...) => ...
+ * This is the tasklet that updates LED state on all keyboards
+ * attached to the box. he reason we use tasklet is that we
+ * need to handle the scenario when keyboard handler is not
+ * registered yet but we already getting updates form VT to
+ * update led state.
*/
-
static void kbd_bh(unsigned long dummy)
{
- struct list_head *node;
unsigned char leds = getleds();
if (leds != ledstate) {
- list_for_each(node, &kbd_handler.h_list) {
- struct input_handle *handle = to_handle_h(node);
- input_inject_event(handle, EV_LED, LED_SCROLLL, !!(leds & 0x01));
- input_inject_event(handle, EV_LED, LED_NUML, !!(leds & 0x02));
- input_inject_event(handle, EV_LED, LED_CAPSL, !!(leds & 0x04));
- input_inject_event(handle, EV_SYN, SYN_REPORT, 0);
- }
+ input_handler_for_each_handle(&kbd_handler, &leds,
+ kbd_update_leds_helper);
+ ledstate = leds;
}
-
- ledstate = leds;
}
DECLARE_TASKLET_DISABLED(keyboard_tasklet, kbd_bh, 0);
@@ -1300,6 +1308,7 @@ static void kbd_event(struct input_handle *handle, unsigned int event_type,
kbd_rawcode(value);
if (event_type == EV_KEY)
kbd_keycode(event_code, value, HW_RAW(handle->dev));
+
tasklet_schedule(&keyboard_tasklet);
do_poke_blanked_console = 1;
schedule_console_callback();
@@ -1363,15 +1372,11 @@ static void kbd_disconnect(struct input_handle *handle)
*/
static void kbd_start(struct input_handle *handle)
{
- unsigned char leds = ledstate;
-
tasklet_disable(&keyboard_tasklet);
- if (leds != 0xff) {
- input_inject_event(handle, EV_LED, LED_SCROLLL, !!(leds & 0x01));
- input_inject_event(handle, EV_LED, LED_NUML, !!(leds & 0x02));
- input_inject_event(handle, EV_LED, LED_CAPSL, !!(leds & 0x04));
- input_inject_event(handle, EV_SYN, SYN_REPORT, 0);
- }
+
+ if (ledstate != 0xff)
+ kbd_update_leds_helper(handle, &ledstate);
+
tasklet_enable(&keyboard_tasklet);
}
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 77b6efe..b991e64 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -1664,6 +1664,38 @@ void input_unregister_handler(struct input_handler *handler)
EXPORT_SYMBOL(input_unregister_handler);
/**
+ * input_handler_for_each_handle - handle iterator
+ * @handler: input handler to iterate
+ * @data: data for the callback
+ * @fn: function to be called for each handle
+ *
+ * Iterate over @bus's list of devices, and call @fn for each, passing
+ * it @data and stop when @fn returns a non-zero value. The function is
+ * using RCU to traverse the list and therefore may be usind in atonic
+ * contexts. The @fn callback is invoked from RCU critical section and
+ * thus must not sleep.
+ */
+int input_handler_for_each_handle(struct input_handler *handler, void *data,
+ int (*fn)(struct input_handle *, void *))
+{
+ struct input_handle *handle;
+ int retval = 0;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(handle, &handler->h_list, h_node) {
+ retval = fn(handle, data);
+ if (retval)
+ break;
+ }
+
+ rcu_read_unlock();
+
+ return retval;
+}
+EXPORT_SYMBOL(input_handler_for_each_handle);
+
+/**
* input_register_handle - register a new input handle
* @handle: handle to register
*
@@ -1696,7 +1728,7 @@ int input_register_handle(struct input_handle *handle)
* we can't be racing with input_unregister_handle()
* and so separate lock is not needed here.
*/
- list_add_tail(&handle->h_node, &handler->h_list);
+ list_add_tail_rcu(&handle->h_node, &handler->h_list);
if (handler->start)
handler->start(handle);
@@ -1719,7 +1751,7 @@ void input_unregister_handle(struct input_handle *handle)
{
struct input_dev *dev = handle->dev;
- list_del_init(&handle->h_node);
+ list_del_rcu(&handle->h_node);
/*
* Take dev->mutex to prevent race with input_release_device().
@@ -1727,6 +1759,7 @@ void input_unregister_handle(struct input_handle *handle)
mutex_lock(&dev->mutex);
list_del_rcu(&handle->d_node);
mutex_unlock(&dev->mutex);
+
synchronize_rcu();
}
EXPORT_SYMBOL(input_unregister_handle);
diff --git a/include/linux/input.h b/include/linux/input.h
index 4637f90..8693bc6 100644
--- a/include/linux/input.h
+++ b/include/linux/input.h
@@ -1021,9 +1021,12 @@ struct ff_effect {
* @keycodesize: size of elements in keycode table
* @keycode: map of scancodes to keycodes for this device
* @setkeycode: optional method to alter current keymap, used to implement
- * sparse keymaps. If not supplied default mechanism will be used
+ * sparse keymaps. If not supplied default mechanism will be used.
+ * The methid is being called while holding event_lock and thus must
+ * not sleep.
* @getkeycode: optional method to retrieve current keymap. If not supplied
- * default mechanism will be used
+ * default mechanism will be used. The method is being called while
+ * holding event_lock and thus must not sleep.
* @ff: force feedback structure associated with the device if device
* supports force feedback effects
* @repeat_key: stores key code of the last key pressed; used to implement
@@ -1295,6 +1298,9 @@ void input_unregister_device(struct input_dev *);
int __must_check input_register_handler(struct input_handler *);
void input_unregister_handler(struct input_handler *);
+int input_handler_for_each_handle(struct input_handler *, void *data,
+ int (*fn)(struct input_handle *, void *));
+
int input_register_handle(struct input_handle *);
void input_unregister_handle(struct input_handle *);
--
Dmitry
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