Re: [PATCH] powerpc/rng: wire up during setup_arch

[Christophe Leroy]

Le 11/06/2022 à 10:11, Jason A. Donenfeld a écrit :
> The platform's RNG must be available before random_init() in order to be
> useful for initial seeding, which in turn means that it needs to be
> called from setup_arch(), rather than from an init call. Fortunately,
> each platform already has a setup_arch function pointer, which means
> it's easy to wire this up for each of the three platforms that have an
> RNG. This commit also removes some noisy log messages that don't add
> much.

Can't we use one of the machine initcalls for that ?
Like machine_early_initcall() or machine_arch_initcall() ?

Today it is using  machine_subsys_initcall() and you didn't remove it. 
It means rng_init() will be called twice. Is that ok ?



> 
> Cc: stable@xxxxxxxxxxxxxxx
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> ---
>   arch/powerpc/platforms/microwatt/rng.c   |  9 ++-------
>   arch/powerpc/platforms/microwatt/setup.c |  8 ++++++++
>   arch/powerpc/platforms/powernv/rng.c     | 17 ++++-------------
>   arch/powerpc/platforms/powernv/setup.c   |  4 ++++
>   arch/powerpc/platforms/pseries/rng.c     | 11 ++---------
>   arch/powerpc/platforms/pseries/setup.c   |  3 +++
>   6 files changed, 23 insertions(+), 29 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/microwatt/rng.c b/arch/powerpc/platforms/microwatt/rng.c
> index 7bc4d1cbfaf0..d13f656910ad 100644
> --- a/arch/powerpc/platforms/microwatt/rng.c
> +++ b/arch/powerpc/platforms/microwatt/rng.c
> @@ -29,7 +29,7 @@ static int microwatt_get_random_darn(unsigned long *v)
>   	return 1;
>   }
>   
> -static __init int rng_init(void)
> +__init void microwatt_rng_init(void)
>   {
>   	unsigned long val;
>   	int i;
> @@ -37,12 +37,7 @@ static __init int rng_init(void)
>   	for (i = 0; i < 10; i++) {
>   		if (microwatt_get_random_darn(&val)) {
>   			ppc_md.get_random_seed = microwatt_get_random_darn;
> -			return 0;
> +			return;
>   		}
>   	}
> -
> -	pr_warn("Unable to use DARN for get_random_seed()\n");
> -
> -	return -EIO;
>   }
> -machine_subsys_initcall(, rng_init);
> diff --git a/arch/powerpc/platforms/microwatt/setup.c b/arch/powerpc/platforms/microwatt/setup.c
> index 0b02603bdb74..23c996dcc870 100644
> --- a/arch/powerpc/platforms/microwatt/setup.c
> +++ b/arch/powerpc/platforms/microwatt/setup.c
> @@ -32,10 +32,18 @@ static int __init microwatt_populate(void)
>   }
>   machine_arch_initcall(microwatt, microwatt_populate);
>   
> +__init void microwatt_rng_init(void);
> +
> +static void __init microwatt_setup_arch(void)
> +{
> +	microwatt_rng_init();
> +}
> +
>   define_machine(microwatt) {
>   	.name			= "microwatt",
>   	.probe			= microwatt_probe,
>   	.init_IRQ		= microwatt_init_IRQ,
> +	.setup_arch		= microwatt_setup_arch,
>   	.progress		= udbg_progress,
>   	.calibrate_decr		= generic_calibrate_decr,
>   };
> diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
> index e3d44b36ae98..ef24e72a1b69 100644
> --- a/arch/powerpc/platforms/powernv/rng.c
> +++ b/arch/powerpc/platforms/powernv/rng.c
> @@ -84,24 +84,20 @@ static int powernv_get_random_darn(unsigned long *v)
>   	return 1;
>   }
>   
> -static int __init initialise_darn(void)
> +static void __init initialise_darn(void)
>   {
>   	unsigned long val;
>   	int i;
>   
>   	if (!cpu_has_feature(CPU_FTR_ARCH_300))
> -		return -ENODEV;
> +		return;
>   
>   	for (i = 0; i < 10; i++) {
>   		if (powernv_get_random_darn(&val)) {
>   			ppc_md.get_random_seed = powernv_get_random_darn;
> -			return 0;
> +			return;
>   		}
>   	}
> -
> -	pr_warn("Unable to use DARN for get_random_seed()\n");
> -
> -	return -EIO;
>   }
>   
>   int powernv_get_random_long(unsigned long *v)
> @@ -163,14 +159,12 @@ static __init int rng_create(struct device_node *dn)
>   
>   	rng_init_per_cpu(rng, dn);
>   
> -	pr_info_once("Registering arch random hook.\n");
> -
>   	ppc_md.get_random_seed = powernv_get_random_long;
>   
>   	return 0;
>   }
>   
> -static __init int rng_init(void)
> +__init void powernv_rng_init(void)
>   {
>   	struct device_node *dn;
>   	int rc;
> @@ -188,7 +182,4 @@ static __init int rng_init(void)
>   	}
>   
>   	initialise_darn();
> -
> -	return 0;
>   }
> -machine_subsys_initcall(powernv, rng_init);
> diff --git a/arch/powerpc/platforms/powernv/setup.c b/arch/powerpc/platforms/powernv/setup.c
> index 824c3ad7a0fa..a0c5217bc5c0 100644
> --- a/arch/powerpc/platforms/powernv/setup.c
> +++ b/arch/powerpc/platforms/powernv/setup.c
> @@ -184,6 +184,8 @@ static void __init pnv_check_guarded_cores(void)
>   	}
>   }
>   
> +__init void powernv_rng_init(void);
> +
>   static void __init pnv_setup_arch(void)
>   {
>   	set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT);
> @@ -203,6 +205,8 @@ static void __init pnv_setup_arch(void)
>   	pnv_check_guarded_cores();
>   
>   	/* XXX PMCS */
> +
> +	powernv_rng_init();
>   }
>   
>   static void __init pnv_init(void)
> diff --git a/arch/powerpc/platforms/pseries/rng.c b/arch/powerpc/platforms/pseries/rng.c
> index 6268545947b8..d39bfce39aa1 100644
> --- a/arch/powerpc/platforms/pseries/rng.c
> +++ b/arch/powerpc/platforms/pseries/rng.c
> @@ -24,19 +24,12 @@ static int pseries_get_random_long(unsigned long *v)
>   	return 0;
>   }
>   
> -static __init int rng_init(void)
> +__init void pseries_rng_init(void)
>   {
>   	struct device_node *dn;
> -
>   	dn = of_find_compatible_node(NULL, NULL, "ibm,random");
>   	if (!dn)
> -		return -ENODEV;
> -
> -	pr_info("Registering arch random hook.\n");
> -
> +		return;
>   	ppc_md.get_random_seed = pseries_get_random_long;
> -
>   	of_node_put(dn);
> -	return 0;
>   }
> -machine_subsys_initcall(pseries, rng_init);
> diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
> index afb074269b42..7f3ee2658163 100644
> --- a/arch/powerpc/platforms/pseries/setup.c
> +++ b/arch/powerpc/platforms/pseries/setup.c
> @@ -779,6 +779,8 @@ static resource_size_t pseries_pci_iov_resource_alignment(struct pci_dev *pdev,
>   }
>   #endif
>   
> +__init void pseries_rng_init(void);
> +
>   static void __init pSeries_setup_arch(void)
>   {
>   	set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT);
> @@ -839,6 +841,7 @@ static void __init pSeries_setup_arch(void)
>   	}
>   
>   	ppc_md.pcibios_root_bridge_prepare = pseries_root_bridge_prepare;
> +	pseries_rng_init();
>   }
>   
>   static void pseries_panic(char *str)