Re: [PATCH v4 0/4] HID: wiimote: new LED behavior on connect + scoped_guards

["Rafael Passos" <rafael@rcpassos.me>]

Hi!

[Sorry for the dupplicated email, I sent this in the V3 by mistake ;( ]

I'm looking for feedback in this patchset.
I believe this is a good time,
since the merge window was just closed.
Maybe this could be ready for 7.4 ?

Thanks,
Rafael Passos

On Mon Aug 17, 2026 at 6:38 PM -03, Rafael Passos wrote:
> Hi,
> This patchset contains one feature change, and 3 patches appying 
> scoped cleanup to locking and to the initialization functions for
> the led probing and the main wiimote probe call.
>
> The feature is turning different LEDs for each of the first 4 wiimotes connected.
> From id 5 forward, the LED will cycle back to 1, and so on.
> This uses the ida struct, so its quite simple and lightweight.
> The hid_info log message prints out the controller id.
>
> While implementing this feature, I decided to cleanup the code using
> scoped_guard for the many spinlocks in the driver. There are two places
> where the original lock/unlock version fits best, and I left them
> untouched.
> I also used the __free scope cleanup in the wiimote_probe and LED probe.
> This was trivial for the LED probe.
> The wiimote_probe required a new state tracker bitmask, now the wiimote_destroy
> is used both on disconnect (hid_remove) and in the probe cleanup.
>
> It was really fun working with this driver.
> I tested it with 4 Wii Motion Plus remotes (gen2).
> Video recording of my tests (48s video).
> https://rcpassos.me/video/wiimote-led-linux-driver
>
> Thanks,
> Rafael Passos
>
> ---
> V1: https://lore.kernel.org/linux-input/20260710153456.2093889-1-rafael@rcpassos.me/
> Changes from v1:
>     (1/3):
>     - fix ida_alloc_min error handling to consider negative values
>     - remove fallback to 1 on ida_alloc_min failure
>     - move player_leds static array to hid-wiimote-core.c
>     - s/instance_id/player_id/g
>     - store player_id on an u8
>     (2/3):
>     - add header include for cleanup.h
>     - add identation to one-liner scoped_guards
>     (3/3):
>     - add scoped cleanup function to wiimote_probe, with a bitmask to track state
>       Patch used for testing this:
>       https://lore.kernel.org/linux-input/20260715213513.3929001-1-rafael@rcpassos.me/
>     (4/4) *new patch* :
>     - sashiko found a pre-existing uaf. Unlikely, but correct.
>       implemented using the playstation driver as an inspiration
>
> V2: https://lore.kernel.org/linux-input/20260710153456.2093889-1-rafael@rcpassos.me/
> Changes from v2:
>     (2/4):
>     - join the last two locks into a single scoped_guard lock in wiimote_modules_load
>
> V3: https://lore.rcpassos.me/wiimote/20260729164928.1138468-1-rafael@rcpassos.me/
> Changes from v3:
>     - dropped false uaf patch (previous 4/4). It was a false alarm.
>       Discussion in:
>       https://lore.kernel.org/linux-input/20260729164928.1138468-1-rafael@rcpassos.me/T/#t
>
>     (1/4):
>     - I tested how the changes looked if using ida from 0 instead of 1,
>       and I believe it ended up less clean. I decided to keep them as is,
>       with a few additional comments.
>     - explicit initialization of player_id to 0 before allocating an id
>     - avoid using a new int during ida_alloc (use ret instead)
>     - use u8 instead of __u8
>     - move ida_remove from wiimote_hid_remove to wiimote_destroy
>     - add debugfs entry for the player_id entry
>     (3/4):
>     - move changes to wiimote_probe from this patch to the next
>     - update patch title
>     (4/4): *new patch*
>     - scoped cleanup in the wiimote_probe call, using a bitmask to keep
>       track of state during initialization
>     - update wiimote_destroy so it can be the cleanup function
>     - add a debugfs entry for this new entry
>
> As we discussed in the v3, tell me if you like the changes in patch 4/4.
> If you prefer not to apply it, I can send a new patchset revision, or
> just drop it from the set if nothing else needs changes.
>
> Thanks!
>
>
> Rafael Passos (4):
>   HID: wiimote: turn on the LEDs indicating the controller id
>   HID: wiimote: replace spinlock pairs with scoped_guard
>   HID: wiimote: led_probe with scoped cleanup
>   HID: wiimote: wiimote_probe with scoped cleanup
>
>  drivers/hid/hid-wiimote-core.c    | 346 ++++++++++++++++--------------
>  drivers/hid/hid-wiimote-debug.c   |  71 +++---
>  drivers/hid/hid-wiimote-modules.c |  24 +--
>  drivers/hid/hid-wiimote.h         |  10 +
>  4 files changed, 240 insertions(+), 211 deletions(-)