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RISC-V: Fix /proc/cpuinfo cpumask warning

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Commit 78e5a33994 ("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: 78e5a33994 ("cpumask: fix checking valid cpu range")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Andrew Jones 2022-10-14 17:58:44 +02:00 committed by Palmer Dabbelt
parent 952b64d666
commit d14e99bf95
No known key found for this signature in database
GPG key ID: 2E1319F35FBB1889
1 changed files with 3 additions and 0 deletions
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3
arch/riscv/kernel/cpu.c
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@ -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);