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Input: do not pass injected events back to the originating handler
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Sometimes input handlers (as opposed to input devices) have a need to
inject (or re-inject) events back into input core. For example sysrq
filter may want to inject previously suppressed Alt-SysRq so that user
can take a screen print. In this case we do not want to pass such events
back to the same same handler that injected them to avoid loops.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Dmitry Torokhov committed Nov 11, 2010
1 parent 17d01f2 commit 5fdbe44
Showing 1 changed file with 26 additions and 11 deletions.
37 changes: 26 additions & 11 deletions drivers/input/input.c
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Original file line number Diff line number Diff line change
Expand Up @@ -74,6 +74,7 @@ static int input_defuzz_abs_event(int value, int old_val, int fuzz)
* dev->event_lock held and interrupts disabled.
*/
static void input_pass_event(struct input_dev *dev,
struct input_handler *src_handler,
unsigned int type, unsigned int code, int value)
{
struct input_handler *handler;
Expand All @@ -92,6 +93,15 @@ static void input_pass_event(struct input_dev *dev,
continue;

handler = handle->handler;

/*
* If this is the handler that injected this
* particular event we want to skip it to avoid
* filters firing again and again.
*/
if (handler == src_handler)
continue;

if (!handler->filter) {
if (filtered)
break;
Expand Down Expand Up @@ -121,7 +131,7 @@ static void input_repeat_key(unsigned long data)
if (test_bit(dev->repeat_key, dev->key) &&
is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) {

input_pass_event(dev, EV_KEY, dev->repeat_key, 2);
input_pass_event(dev, NULL, EV_KEY, dev->repeat_key, 2);

if (dev->sync) {
/*
Expand All @@ -130,7 +140,7 @@ static void input_repeat_key(unsigned long data)
* Otherwise assume that the driver will send
* SYN_REPORT once it's done.
*/
input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
}

if (dev->rep[REP_PERIOD])
Expand Down Expand Up @@ -163,6 +173,7 @@ static void input_stop_autorepeat(struct input_dev *dev)
#define INPUT_PASS_TO_ALL (INPUT_PASS_TO_HANDLERS | INPUT_PASS_TO_DEVICE)

static int input_handle_abs_event(struct input_dev *dev,
struct input_handler *src_handler,
unsigned int code, int *pval)
{
bool is_mt_event;
Expand Down Expand Up @@ -206,13 +217,15 @@ static int input_handle_abs_event(struct input_dev *dev,
/* Flush pending "slot" event */
if (is_mt_event && dev->slot != input_abs_get_val(dev, ABS_MT_SLOT)) {
input_abs_set_val(dev, ABS_MT_SLOT, dev->slot);
input_pass_event(dev, EV_ABS, ABS_MT_SLOT, dev->slot);
input_pass_event(dev, src_handler,
EV_ABS, ABS_MT_SLOT, dev->slot);
}

return INPUT_PASS_TO_HANDLERS;
}

static void input_handle_event(struct input_dev *dev,
struct input_handler *src_handler,
unsigned int type, unsigned int code, int value)
{
int disposition = INPUT_IGNORE_EVENT;
Expand Down Expand Up @@ -265,7 +278,8 @@ static void input_handle_event(struct input_dev *dev,

case EV_ABS:
if (is_event_supported(code, dev->absbit, ABS_MAX))
disposition = input_handle_abs_event(dev, code, &value);
disposition = input_handle_abs_event(dev, src_handler,
code, &value);

break;

Expand Down Expand Up @@ -323,7 +337,7 @@ static void input_handle_event(struct input_dev *dev,
dev->event(dev, type, code, value);

if (disposition & INPUT_PASS_TO_HANDLERS)
input_pass_event(dev, type, code, value);
input_pass_event(dev, src_handler, type, code, value);
}

/**
Expand Down Expand Up @@ -352,7 +366,7 @@ void input_event(struct input_dev *dev,

spin_lock_irqsave(&dev->event_lock, flags);
add_input_randomness(type, code, value);
input_handle_event(dev, type, code, value);
input_handle_event(dev, NULL, type, code, value);
spin_unlock_irqrestore(&dev->event_lock, flags);
}
}
Expand Down Expand Up @@ -382,7 +396,8 @@ void input_inject_event(struct input_handle *handle,
rcu_read_lock();
grab = rcu_dereference(dev->grab);
if (!grab || grab == handle)
input_handle_event(dev, type, code, value);
input_handle_event(dev, handle->handler,
type, code, value);
rcu_read_unlock();

spin_unlock_irqrestore(&dev->event_lock, flags);
Expand Down Expand Up @@ -595,10 +610,10 @@ static void input_dev_release_keys(struct input_dev *dev)
for (code = 0; code <= KEY_MAX; code++) {
if (is_event_supported(code, dev->keybit, KEY_MAX) &&
__test_and_clear_bit(code, dev->key)) {
input_pass_event(dev, EV_KEY, code, 0);
input_pass_event(dev, NULL, EV_KEY, code, 0);
}
}
input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
}
}

Expand Down Expand Up @@ -873,9 +888,9 @@ int input_set_keycode(struct input_dev *dev,
!is_event_supported(old_keycode, dev->keybit, KEY_MAX) &&
__test_and_clear_bit(old_keycode, dev->key)) {

input_pass_event(dev, EV_KEY, old_keycode, 0);
input_pass_event(dev, NULL, EV_KEY, old_keycode, 0);
if (dev->sync)
input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
input_pass_event(dev, NULL, EV_SYN, SYN_REPORT, 1);
}

out:
Expand Down

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