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[v3,1/2] RISC-V: Fix /proc/cpuinfo cpumask warning

Message ID 20221014155845.1986223-2-ajones@ventanamicro.com (mailing list archive)
State Superseded
Commit d14e99bf95510fa2d6affc371ad68161afc1dc8e
Delegated to: Palmer Dabbelt
Headers show
Series Fix /proc/cpuinfo cpumask warning | expand

Commit Message

Andrew Jones Oct. 14, 2022, 3:58 p.m. UTC 
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>
Cc: Yury Norov <yury.norov@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Tested-by: Conor Dooley <conor.dooley@microchip.com>
---
 arch/riscv/kernel/cpu.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 4d0dece5996c..5aa0ae8dd115 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -166,6 +166,9 @@  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);