[RFC] rcu: Check the range of jiffies_till_xxx_fqs on setting them

[Byungchul Park]

Hello Paul and folks,

I've thought the code should've been like the below since the range
checking of jiffies_till_first_fqs and jiffies_till_next_fqs everytime
in the loop of rcu_gp_kthread are unnecessary at all. However, it's ok
even if you don't think it's worth doing it.

Secondly, I also think jiffies_till_first_fqs = 0 is meaningless so
added checking and adjusting it as what's done on jiffies_till_next_fqs.
Thought?

Thank you in advance.
Byungchul

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