Re: [PATCH 1/3] mfd: syscon: Fix race in device_node_get_regmap()

Krzysztof Kozlowski
2024-12-12T09:31:14Z

On 11/12/2024 21:57, Rob Herring (Arm) wrote:
> It is possible for multiple, simultaneous callers calling
> device_node_get_regmap() with the same node to fail to find an entry in
> the syscon_list. There is a period of time while the first caller is
> calling of_syscon_register() that subsequent callers also fail to find
> an entry in the syscon_list and then call of_syscon_register() a second
> time.
>
> Fix this by keeping the lock held until after of_syscon_register()
> completes and adds the node to syscon_list. Convert the spinlock to a
> mutex as many of the functions called in of_syscon_register() may sleep.

Maybe mention the reason for conversion to mutex: lock will be now
containing non-atomic kzalloc and regmap_init_mmio, where the latter
calls clk_get and clk_prepare, which both are sleeping, I believe.

Otherwise it feels you are converting to mutex just to make code better,
which would be then a separate commit.

Everything else looks good.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Best regards,
Krzysztof