Re: [PATCH] net: xen-netbank: hash.c: Use built-in RCU list checking

From: Wei Liu
Date: Wed Jan 15 2020 - 10:04:33 EST


On Wed, Jan 15, 2020 at 07:36:38PM +0530, Madhuparna Bhowmik wrote:
[...]
>
> > The surrounding code makes it pretty clear that the lock is already held
> > by the time list_for_each_entry_rcu is called, yet the checking involved
> > in lockdep_is_held is not trivial, so I'm afraid I don't consider this a
> > strict improvement over the existing code.
> >
> > Actually, we want to make CONFIG_PROVE_LIST_RCU enabled by default.

I think you meant CONFIG_PROVE_RCU_LIST.

> And if the cond argument is not passed when the usage of
> list_for_each_entry_rcu()
> is outside of rcu_read_lock(), it will lead to a false positive.
> Therefore, I think this patch is required.

Fair enough.

Wei.