2013-03-07 23:41:08

by Frederic Weisbecker

[permalink] [raw]
Subject: Re: [PATCH 07/33] nohz: Basic full dynticks interface

2013/2/20 Borislav Petkov <[email protected]>:
> On Mon, Feb 11, 2013 at 03:35:29PM +0100, Borislav Petkov wrote:
>> > +/* Parse the boot-time nohz CPU list from the kernel parameters. */
>> > +static int __init tick_nohz_full_setup(char *str)
>> > +{
>> > + alloc_bootmem_cpumask_var(&full_nohz_mask);
>> > + have_full_nohz_mask = true;
>> > + cpulist_parse(str, full_nohz_mask);
>>
>> Don't you want to check retval of cpulist_parse first here before
>> assigning have_full_nohz_mask and allocating cpumask var?
>>
>> We don't trust userspace, you know.
>>
>> > + return 1;
>> > +}
>> > +__setup("full_nohz=", tick_nohz_full_setup);
>
> One more thing. AFAICT, full_nohz requires rcu_nocbs to pass in the same
> mask, right?

Right!

> Maybe tick_nohz_full_setup() could be made to call rcu_nocb_setup()
> without the need to pass "rcu_nocbs=" option on the cmd line; in the
> sense that if user supplies a full_nohz mask, she wants the same mask
> for rcu_nocbs...

Yeah that's probably something we want. (added to the TODO list)

Thanks.