Re: [PATCH] pinctrl: pinctrl-generic-mux: Fix provider resource leak on re-parse

[Linus Walleij]

On Wed, Sep 16, 2026 at 5:04 AM Chancel Liu <chancel.liu@xxxxxxxxxxx> wrote:

> From: Chancel Liu <chancel.liu@xxxxxxx>
>
> The pinctrl core re-parses a consumer's pinctrl on every probe attempt
> (pinctrl_bind_pins() runs before the driver's probe(), and again on each
> deferred-probe retry or re-bind), so .dt_node_to_map() must be side-effect
> free and safe to call repeatedly.
>
> mux_pinmux_dt_node_to_map() instead allocated provider-side resources on
> every call - the mux_pin_function, the group name table and a mux_state
> reference, plus a group name and a pinctrl_generic_add_group()
> registration via pinctrl_generic_to_map(). All of these are allocated
> with devm_*() against the provider device, so they live for the provider's
> lifetime and are only released when the provider itself is unbound. The
> .dt_free_map() path never touches them; it frees the per-consumer
> pinctrl_map only. Every re-parse therefore adds another set of
> provider-side allocations that are never reclaimed, so a consumer that
> repeatedly defers probe or is re-bound leaks memory and mux_state
> references on the provider without bound.
>
> The groups and functions of a board-level mux are static and fully
> described by the device tree, so build them once at probe time in the new
> mux_pinctrl_probe_dt(). mux_pinmux_dt_node_to_map() then only looks up the
> already registered group and builds the per-consumer mux map, which the
> core frees via .dt_free_map. As the mux has no pin electrical
> configuration, no config map is emitted.
>
> Reported-by: Sashiko <sashiko-bot@xxxxxxxxxx>
> Closes: https://sashiko.dev/#/patchset/20260824022020.2812810-1-chancel.liu%40oss.nxp.com
> Fixes: 34acc5a8adfb ("pinctrl: add generic board-level pinctrl driver using mux framework")
> Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx>
> Assisted-by: VeroCoder:claude-opus-4-8

Patch applied, we can think about other solutions, but that
can be handled by new patches, this works.

Yours,
Linus Walleij