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Date: Fri, 28 Oct 2022 09:48:28 +0200 From: Andrew Jones <ajones@...tanamicro.com> To: x86@...nel.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, Yury Norov <yury.norov@...il.com>, Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Albert Ou <aou@...s.berkeley.edu>, Jonas Bonn <jonas@...thpole.se>, Stefan Kristiansson <stefan.kristiansson@...nalahti.fi>, Stafford Horne <shorne@...il.com>, openrisc@...ts.librecores.org, Michael Ellerman <mpe@...erman.id.au>, linuxppc-dev@...ts.ozlabs.org, Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>, Alexander Gordeev <agordeev@...ux.ibm.com>, linux-s390@...r.kernel.org Subject: Re: [PATCH v3 2/2] x86: Fix /proc/cpuinfo cpumask warning On Fri, Oct 14, 2022 at 05:58:45PM +0200, Andrew Jones wrote: > 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@...tanamicro.com> > Cc: Yury Norov <yury.norov@...il.com> > --- > arch/x86/kernel/cpu/proc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c > index 099b6f0d96bd..de3f93ac6e49 100644 > --- a/arch/x86/kernel/cpu/proc.c > +++ b/arch/x86/kernel/cpu/proc.c > @@ -153,6 +153,9 @@ static int show_cpuinfo(struct seq_file *m, void *v) > > 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 &cpu_data(*pos); > -- > 2.37.3 > Hi x86 maintainers, I realize 78e5a3399421 has now been reverted, so this fix is no longer urgent. I don't believe it's wrong, though, so if it's still of interest, then please consider this a friendly ping. Thanks, drew
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