Re: [PATCH 2/4] cpuidle: riscv-sbi: Use scoped device node handling to simplify error paths

Jonathan Cameron
2024-08-19T16:13:18Z

On Fri, 16 Aug 2024 17:09:29 +0200
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org> wrote:

> Obtain the device node reference with scoped/cleanup.h to reduce error
> handling and make the code a bit simpler.
>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
The original code looks suspect. See below.

> ---
> drivers/cpuidle/cpuidle-riscv-sbi.c | 21 +++++++--------------
> 1 file changed, 7 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
> index a6e123dfe394..5bb3401220d2 100644
> --- a/drivers/cpuidle/cpuidle-riscv-sbi.c
> +++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
> @@ -8,6 +8,7 @@
>
> #define pr_fmt(fmt) "cpuidle-riscv-sbi: " fmt
>
> +#include <linux/cleanup.h>
> #include <linux/cpuhotplug.h>
> #include <linux/cpuidle.h>
> #include <linux/cpumask.h>
> @@ -236,19 +237,16 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
> {
> struct sbi_cpuidle_data *data = per_cpu_ptr(&sbi_cpuidle_data, cpu);
> struct device_node *state_node;
> - struct device_node *cpu_node;
> u32 *states;
> int i, ret;
>
> - cpu_node = of_cpu_device_node_get(cpu);
> + struct device_node *cpu_node __free(device_node) = of_cpu_device_node_get(cpu);
> if (!cpu_node)
> return -ENODEV;
>
> states = devm_kcalloc(dev, state_count, sizeof(*states), GFP_KERNEL);
> - if (!states) {
> - ret = -ENOMEM;
> - goto fail;
> - }
> + if (!states)
> + return -ENOMEM;
>
> /* Parse SBI specific details from state DT nodes */
> for (i = 1; i < state_count; i++) {
> @@ -264,10 +262,8 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
>
> pr_debug("sbi-state %#x index %d\n", states[i], i);
> }
> - if (i != state_count) {
> - ret = -ENODEV;
> - goto fail;
> - }
> + if (i != state_count)
> + return -ENODEV;
>
> /* Initialize optional data, used for the hierarchical topology. */
> ret = sbi_dt_cpu_init_topology(drv, data, state_count, cpu);
The handling of error ret from here doesn't free the node.

Bug or something subtle I'm missing?

If it's a bug, then fixes tag.

> @@ -277,10 +273,7 @@ static int sbi_cpuidle_dt_init_states(struct device *dev,
> /* Store states in the per-cpu struct. */
> data->states = states;
>
> -fail:
> - of_node_put(cpu_node);
> -
> - return ret;
> + return 0;
> }
>
> static void sbi_cpuidle_deinit_cpu(int cpu)