Re: [PATCH v3 2/7] mac80211: Remove mesh paths when an interface is removed

[Johannes Berg <johannes@sipsolutions.net>]

On Tue, 2011-08-30 at 05:19 +0200, Johannes Berg wrote:
> On Mon, 2011-08-29 at 13:23 -0700, Javier Cardona wrote:
> 
> > +static void mpp_path_flush(struct ieee80211_sub_if_data *sdata)
> > +{
> > +	struct mesh_table *tbl;
> > +	struct mesh_path *mpath;
> > +	struct mpath_node *node;
> > +	struct hlist_node *p;
> > +	int i;
> > +
> > +	read_lock_bh(&pathtbl_resize_lock);
> > +	tbl = rcu_dereference_protected(mpp_paths,
> > +					lockdep_is_held(pathtbl_resize_lock));
> > +	for_each_mesh_entry(tbl, p, node, i) {
> > +		mpath = node->mpath;
> > +		if (mpath->sdata != sdata)
> > +			continue;
> > +		spin_lock_bh(&tbl->hashwlock[i]);
> > +		spin_lock_bh(&mpath->state_lock);
> > +		call_rcu(&node->rcu, mesh_path_node_reclaim);
> 
> Why is read_lock sufficient? Why is this even a r/w lock?

n/m, I thought about this again and also saw the explanation in patch 9,
definitely seems fine. It's just a little unusual to me to have
per-bucket locks as well :)

johannes