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

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Message-Id: <20221011175040.1782772-1-ajones@ventanamicro.com>
Date:   Tue, 11 Oct 2022 19:50:40 +0200
From:   Andrew Jones <ajones@...tanamicro.com>
To:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Yury Norov <yury.norov@...il.com>
Subject: [PATCH] RISC-V: Fix /proc/cpuinfo cpumask warning

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@...tanamicro.com>
Cc: Yury Norov <yury.norov@...il.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