[PATCH] RISC-V: Fix /proc/cpuinfo cpumask warning

[PATCH] RISC-V: Fix /proc/cpuinfo cpumask warning

[Andrew Jones]

Upcoming cpumask changes will start issuing warnings[*] when cpu
indices equal to nr_cpu_ids are passed to cpumask_next* functions.
Ensure we don't generate a warning when reading /proc/cpuinfo by
validating the cpu index before calling cpumask_next().

[*] Warnings will only appear with DEBUG_PER_CPU_MAPS enabled.

Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Cc: Yury Norov <yury.norov@gmail.com>
---
 arch/riscv/kernel/cpu.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 4aa8cd749441..592ff065e09f 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -166,9 +166,12 @@ static void print_mmu(struct seq_file *f)
 
 static void *c_start(struct seq_file *m, loff_t *pos)
 {
-	*pos = cpumask_next(*pos - 1, cpu_online_mask);
-	if ((*pos) < nr_cpu_ids)
-		return (void *)(uintptr_t)(1 + *pos);
+	if (*pos < nr_cpu_ids) {
+		*pos = cpumask_next(*pos - 1, cpu_online_mask);
+		if (*pos < nr_cpu_ids)
+			return (void *)(uintptr_t)(1 + *pos);
+	}
+
 	return NULL;
 }
 
-- 
2.37.3

Re: [PATCH] RISC-V: Fix /proc/cpuinfo cpumask warning

[Andrew Jones]

Boris pointed out on my x86 version of this patch that I didn't
give nearly enough information on why I sent it. Sorry about that!
I've tried to fill in some of that information in my reply to him
[1]. Sorry for lazily just pointing to that link here, but I'll
send a v2 with the information properly added tomorrow.

[1] https://lore.kernel.org/all/20221011181715.dpayrpjueha7kxoj@kamzik/

Thanks,
drew

On Tue, Oct 11, 2022 at 07:50:40PM +0200, Andrew Jones wrote:
> Upcoming cpumask changes will start issuing warnings[*] when cpu
> indices equal to nr_cpu_ids are passed to cpumask_next* functions.
> Ensure we don't generate a warning when reading /proc/cpuinfo by
> validating the cpu index before calling cpumask_next().
> 
> [*] Warnings will only appear with DEBUG_PER_CPU_MAPS enabled.
> 
> Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> Cc: Yury Norov <yury.norov@gmail.com>
> ---
>  arch/riscv/kernel/cpu.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> index 4aa8cd749441..592ff065e09f 100644
> --- a/arch/riscv/kernel/cpu.c
> +++ b/arch/riscv/kernel/cpu.c
> @@ -166,9 +166,12 @@ static void print_mmu(struct seq_file *f)
>  
>  static void *c_start(struct seq_file *m, loff_t *pos)
>  {
> -	*pos = cpumask_next(*pos - 1, cpu_online_mask);
> -	if ((*pos) < nr_cpu_ids)
> -		return (void *)(uintptr_t)(1 + *pos);
> +	if (*pos < nr_cpu_ids) {
> +		*pos = cpumask_next(*pos - 1, cpu_online_mask);
> +		if (*pos < nr_cpu_ids)
> +			return (void *)(uintptr_t)(1 + *pos);
> +	}
> +
>  	return NULL;
>  }
>  
> -- 
> 2.37.3
>