linux-kernel - [PATCH v2] cpuidle: riscv-sbi: fix device node release in early exit of for_each_possible

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Message-Id: <20241031-cpuidle-riscv-sbi-cleanup-v2-1-aae62d383118@gmail.com>
Date: Thu, 31 Oct 2024 13:21:17 +0100
From: Javier Carrasco <javier.carrasco.cruz@...il.com>
To: Anup Patel <anup@...infault.org>, 
 "Rafael J. Wysocki" <rafael@...nel.org>, 
 Daniel Lezcano <daniel.lezcano@...aro.org>, 
 Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Atish Patra <atishp@...osinc.com>
Cc: Palmer Dabbelt <palmer@...osinc.com>, linux-pm@...r.kernel.org, 
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Javier Carrasco <javier.carrasco.cruz@...il.com>
Subject: [PATCH v2] 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: 6abf32f1d9c5 ("cpuidle: Add RISC-V SBI CPU idle driver")
Signed-off-by: Javier Carrasco <javier.carrasco.cruz@...il.com>
---
Changes in v2:
- Squash patches for mainline solution without intermediate steps.
- Link to v1: https://lore.kernel.org/r/20241030-cpuidle-riscv-sbi-cleanup-v1-0-5e08a22c9409@gmail.com
---
 drivers/cpuidle/cpuidle-riscv-sbi.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-riscv-sbi.c b/drivers/cpuidle/cpuidle-riscv-sbi.c
index 14462c092039..3a78d6b7598b 100644
--- a/drivers/cpuidle/cpuidle-riscv-sbi.c
+++ b/drivers/cpuidle/cpuidle-riscv-sbi.c
@@ -504,12 +504,13 @@ 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")) {

---
base-commit: 6fb2fa9805c501d9ade047fc511961f3273cdcb5
change-id: 20241029-cpuidle-riscv-sbi-cleanup-e9b3cb96e16d

Best regards,
-- 
Javier Carrasco <javier.carrasco.cruz@...il.com>