cpuidle: riscv-sbi: fix device node release in early exit of for_each…

…_possible_cpu

The 'np' device_node is initialized via of_cpu_device_node_get(), which
requires explicit calls to of_node_put() when it is no longer required
to avoid leaking the resource.

Instead of adding the missing calls to of_node_put() in all execution
paths, use the cleanup attribute for 'np' by means of the __free()
macro, which automatically calls of_node_put() when the variable goes
out of scope. Given that 'np' is only used within the
for_each_possible_cpu(), reduce its scope to release the nood after
every iteration of the loop.

Fixes: 6abf32f ("cpuidle: Add RISC-V SBI CPU idle driver")
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Link: https://lore.kernel.org/r/20241116-cpuidle-riscv-sbi-cleanup-v3-1-a3a46372ce08@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

drivers/cpuidle/cpuidle-riscv-sbi.c

@@ -504,12 +504,12 @@ static int sbi_cpuidle_probe(struct platform_device *pdev)
 	int cpu, ret;
 	struct cpuidle_driver *drv;
 	struct cpuidle_device *dev;
-	struct device_node *np, *pds_node;
+	struct device_node *pds_node;
 
 	/* Detect OSI support based on CPU DT nodes */
 	sbi_cpuidle_use_osi = true;
 	for_each_possible_cpu(cpu) {
-		np = of_cpu_device_node_get(cpu);
+		struct device_node *np __free(device_node) = of_cpu_device_node_get(cpu);
 		if (np &&
 		    of_property_present(np, "power-domains") &&
 		    of_property_present(np, "power-domain-names")) {