[Linux-kernel-mentees] [PATCH] net: batman-adv: Use built-in RCU list checking

Madhuparna Bhowmik madhuparnabhowmik10 at gmail.com
Sun Feb 16 15:52:44 UTC 2020

On Sun, Feb 16, 2020 at 04:35:54PM +0100, Sven Eckelmann wrote:
> On Sunday, 16 February 2020 16:33:24 CET Madhuparna Bhowmik wrote:
> [...]
> > > Can you tell us how you've identified these four hlist_for_each_entry_rcu?
> >
> > The other hlist_for_each_entry_rcu() are used under the protection of
> > rcu_read_lock(). We only need to pass the cond when
> > hlist_for_each_entry_rcu() is used under a
> > different lock (not under rcu_red_lock()) because according to the current scheme a lockdep splat
> > is generated when hlist_for_each_entry_rcu() is used outside of
> > rcu_read_lock() or the lockdep condition (the cond argument) evaluates
> > to false. So, we need to pass this cond when it is used under the
> > protection of spinlock or mutex etc. and not required if rcu_read_lock()
> > is used.
> I understand this part. I was asking how you've identified them. Did you use 
> any tool for that? coccinelle, sparse, ...

Not really, I did it manually by inspecting each occurence.
Thank you,

> Kind regards,
> 	Sven

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