From d14e99bf95510fa2d6affc371ad68161afc1dc8e Mon Sep 17 00:00:00 2001
From: Andrew Jones <ajones@ventanamicro.com>
Date: Fri, 14 Oct 2022 17:58:44 +0200
Subject: [PATCH] RISC-V: Fix /proc/cpuinfo cpumask warning
Commit 78e5a3399421 ("cpumask: fix checking valid cpu range") has
started issuing warnings[*] when cpu indices equal to nr_cpu_ids - 1
are passed to cpumask_next* functions. seq_read_iter() and cpuinfo's
start and next seq operations implement a pattern like
n = cpumask_next(n - 1, mask);
show(n);
while (1) {
++n;
n = cpumask_next(n - 1, mask);
if (n >= nr_cpu_ids)
break;
show(n);
}
which will issue the warning when reading /proc/cpuinfo. Ensure no
warning is generated 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>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
Acked-by: Yury Norov <yury.norov@gmail.com>
Link: https://lore.kernel.org/r/20221014155845.1986223-2-ajones@ventanamicro.com/
Fixes: 78e5a3399421 ("cpumask: fix checking valid cpu range")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---
arch/riscv/kernel/cpu.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index fa427bdcf773d..852ecccd8920f 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -213,6 +213,9 @@ static void print_mmu(struct seq_file *f)
static void *c_start(struct seq_file *m, loff_t *pos)
{
+ if (*pos == nr_cpu_ids)
+ return NULL;
+
*pos = cpumask_next(*pos - 1, cpu_online_mask);
if ((*pos) < nr_cpu_ids)
return (void *)(uintptr_t)(1 + *pos);
--
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