> On Mon, Oct 23, 2017 at 5:50 PM, Ingo Molnar <mi...@kernel.org> wrote: > >> * Rakib Mullick <rakib.mull...@gmail.com> wrote: >> +/** >> + * cpumask_last - get the last cpu in a cpumask > > Please capitalize 'CPU' properly in documentation. > OK. >> + int ret, lastcpu; >> >> alloc_bootmem_cpumask_var(&cpu_isolated_map); >> ret = cpulist_parse(str, cpu_isolated_map); >> - if (ret) { >> - pr_err("sched: Error, all isolcpus= values must be between 0 >> and %u\n", nr_cpu_ids); >> + lastcpu = cpumask_last(cpu_isolated_map); >> + if (ret || lastcpu >= nr_cpu_ids) { > > Any reason why 'lastcpu' has to be introduced - why not just use > cpumask_last() > directly in the condition? It looks obvious enough of a pattern. Thought it reflects what we're doing here, but yes, actually it's redundant.
>> + pr_err("sched: Error, all isolcpus= values must be between 0 >> and %u\n", >> + nr_cpu_ids-1); > > Please don't break the line mindlessly just due to checkpatch complaining - it > makes the code less readable. > Yes, right, mindlessly followed what checkpatch was complaining. Please see the following patch, with changes made based on your review and patched up against -rc6. Thanks, Rakib --- [PATCH](v1) Fix isocpus's param handling when CPUMASK_OFFSTACK=n. cpulist_parse() uses nr_cpumask_bits as limit to parse the passed buffer from kernel commandline. What nr_cpumask_bits represents varies depends upon CONFIG_CPUMASK_OFFSTACK option. If CONFIG_CPUMASK_OFFSTACK=n, then nr_cpumask_bits is same as NR_CPUS, which might not represent the # of cpus really exist (default 64). So, there's a chance of gap between nr_cpu_ids and NR_CPUS, which ultimately lead towards invalid cpulist_parse() operation. For example, if isolcpus=9 is passed on a 8 cpu system (CONFIG_CPUMASK_OFFSTACK=n) it doesn't show the error that it suppose to. This patch fixes this issue by effectively find out the last cpu of the passed isolcpus list and checking it with nr_cpu_ids. Also, fixes the error message where the nr_cpu_ids should be nr_cpu_ids-1, since the cpu numbering starts from 0. Changes since v0 (Ingo): * use cpumask_last() directly into the condition. * use CPU rather cpu in documentation * undo line break Signed-off-by: Rakib Mullick <rakib.mull...@gmail.com> --- include/linux/cpumask.h | 16 ++++++++++++++++ kernel/sched/topology.c | 4 ++-- 2 files changed, 18 insertions(+), 2 deletions(-) diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h index cd415b7..63661de 100644 --- a/include/linux/cpumask.h +++ b/include/linux/cpumask.h @@ -130,6 +130,11 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp) return 0; } +static inline unsigned int cpumask_last(const struct cpumask *srcp) +{ + return 0; +} + /* Valid inputs for n are -1 and 0. */ static inline unsigned int cpumask_next(int n, const struct cpumask *srcp) { @@ -178,6 +183,17 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp) return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits); } +/** + * cpumask_last - get the last CPU in a cpumask + * @srcp: - the cpumask pointer + * + * Returns >= nr_cpumask_bits if no CPUs set. + */ +static inline unsigned int cpumask_last(const struct cpumask *srcp) +{ + return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits); +} + unsigned int cpumask_next(int n, const struct cpumask *srcp); /** diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index f1cf4f3..060cee5 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -470,8 +470,8 @@ static int __init isolated_cpu_setup(char *str) alloc_bootmem_cpumask_var(&cpu_isolated_map); ret = cpulist_parse(str, cpu_isolated_map); - if (ret) { - pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids); + if (ret || cpumask_last(cpu_isolated_map) >= nr_cpu_ids) { + pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids-1); return 0; } return 1; -- 2.9.3