[PATCH v2 1/2] ARM: cpuidle: Don't register the driver when back-end init returns -ENXIO

[PATCH v2 1/2] ARM: cpuidle: Don't register the driver when back-end init returns -ENXIO

[Ulf Hansson]

There's no point to register the cpuidle driver for the current CPU, when
the initialization of the arch specific back-end data fails by returning
-ENXIO.

Instead, let's re-order the sequence to its original flow, by first trying
to initialize the back-end part and then act accordingly on the returned
error code. Additionally, let's print the error message, no matter of what
error code that was returned.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Fixes: a0d46a3dfdc3 ("ARM: cpuidle: Register per cpuidle device")
Cc: <stable@vger.kernel.org> # v4.19+
---

Changes in v2:
	- Added a fixes and a stable tag.

---
 drivers/cpuidle/cpuidle-arm.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
index 073557f433eb..df564d783216 100644
--- a/drivers/cpuidle/cpuidle-arm.c
+++ b/drivers/cpuidle/cpuidle-arm.c
@@ -103,13 +103,6 @@ static int __init arm_idle_init_cpu(int cpu)
 		goto out_kfree_drv;
 	}
 
-	ret = cpuidle_register_driver(drv);
-	if (ret) {
-		if (ret != -EBUSY)
-			pr_err("Failed to register cpuidle driver\n");
-		goto out_kfree_drv;
-	}
-
 	/*
 	 * Call arch CPU operations in order to initialize
 	 * idle states suspend back-end specific data
@@ -117,15 +110,20 @@ static int __init arm_idle_init_cpu(int cpu)
 	ret = arm_cpuidle_init(cpu);
 
 	/*
-	 * Skip the cpuidle device initialization if the reported
+	 * Allow the initialization to continue for other CPUs, if the reported
 	 * failure is a HW misconfiguration/breakage (-ENXIO).
 	 */
-	if (ret == -ENXIO)
-		return 0;
-
 	if (ret) {
 		pr_err("CPU %d failed to init idle CPU ops\n", cpu);
-		goto out_unregister_drv;
+		ret = ret == -ENXIO ? 0 : ret;
+		goto out_kfree_drv;
+	}
+
+	ret = cpuidle_register_driver(drv);
+	if (ret) {
+		if (ret != -EBUSY)
+			pr_err("Failed to register cpuidle driver\n");
+		goto out_kfree_drv;
 	}
 
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
-- 
2.17.1

Re: [PATCH v2 1/2] ARM: cpuidle: Don't register the driver when back-end init returns -ENXIO

[Daniel Lezcano]

On 01/11/2018 13:22, Ulf Hansson wrote:
> There's no point to register the cpuidle driver for the current CPU, when
> the initialization of the arch specific back-end data fails by returning
> -ENXIO.
> 
> Instead, let's re-order the sequence to its original flow, by first trying
> to initialize the back-end part and then act accordingly on the returned
> error code. Additionally, let's print the error message, no matter of what
> error code that was returned.
> 
> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
> Fixes: a0d46a3dfdc3 ("ARM: cpuidle: Register per cpuidle device")
> Cc: <stable@vger.kernel.org> # v4.19+

Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>

> ---
> 
> Changes in v2:
> 	- Added a fixes and a stable tag.
> 
> ---
>  drivers/cpuidle/cpuidle-arm.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/cpuidle/cpuidle-arm.c b/drivers/cpuidle/cpuidle-arm.c
> index 073557f433eb..df564d783216 100644
> --- a/drivers/cpuidle/cpuidle-arm.c
> +++ b/drivers/cpuidle/cpuidle-arm.c
> @@ -103,13 +103,6 @@ static int __init arm_idle_init_cpu(int cpu)
>  		goto out_kfree_drv;
>  	}
>  
> -	ret = cpuidle_register_driver(drv);
> -	if (ret) {
> -		if (ret != -EBUSY)
> -			pr_err("Failed to register cpuidle driver\n");
> -		goto out_kfree_drv;
> -	}
> -
>  	/*
>  	 * Call arch CPU operations in order to initialize
>  	 * idle states suspend back-end specific data
> @@ -117,15 +110,20 @@ static int __init arm_idle_init_cpu(int cpu)
>  	ret = arm_cpuidle_init(cpu);
>  
>  	/*
> -	 * Skip the cpuidle device initialization if the reported
> +	 * Allow the initialization to continue for other CPUs, if the reported
>  	 * failure is a HW misconfiguration/breakage (-ENXIO).
>  	 */
> -	if (ret == -ENXIO)
> -		return 0;
> -
>  	if (ret) {
>  		pr_err("CPU %d failed to init idle CPU ops\n", cpu);
> -		goto out_unregister_drv;
> +		ret = ret == -ENXIO ? 0 : ret;
> +		goto out_kfree_drv;
> +	}
> +
> +	ret = cpuidle_register_driver(drv);
> +	if (ret) {
> +		if (ret != -EBUSY)
> +			pr_err("Failed to register cpuidle driver\n");
> +		goto out_kfree_drv;
>  	}
>  
>  	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
> 


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