Input: ensure device is ready before delivering events

When a device is opened via input_open_device(), the driver's open()
callback is invoked. Some drivers, like cm109, submit URBs or perform
other hardware initialization in their open() callbacks.

However, the input core does not prevent dev->event() from being called
concurrently during the driver's open() execution. For instance, if a
console beep occurs, the kbd handler might inject an EV_SND event. This
can lead to double list_add BUGs if the driver submits the same URB in
both open() and event() paths without adequate synchronization.

To fix this, introduce a ready flag in the input_dev structure.
For complex devices (where dev->open is defined), this flag is set to true
only after the driver's open() method successfully completes. The core now
checks ready in input_event_dispose() and input_dev_toggle()
to prevent events from reaching the hardware before it is fully prepared.
For simple devices (no open callback), events are delivered immediately.

We also replay the logical state in input_open_device() by calling
input_dev_toggle() right after marking the device ready, ensuring no
events are permanently lost.

In the inhibit path, we ensure that physical feedback (LEDs/sounds) is
turned off before the device is closed, and we synchronize the inhibited
state transition under the event lock to prevent races with incoming events.

Assisted-by: Antigravity:gemini-3.5-flash
Link: https://patch.msgid.link/20260803005210.1251102-1-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

0 files changed, 0 insertions, 0 deletions