Date: Tue, 26 Jan 2016 16:22:21 -0500
From: Bob Copeland <me@bobcopeland.com>
To: Johannes Berg <johannes@sipsolutions.net>
Cc: Henning Rogge <hrogge@gmail.com>, linux-wireless@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	Henning Rogge <henning.rogge@fkie.fraunhofer.de>
Subject: Re: [PATCH 1/2] mac80211: Remove connected MPP table entries with
 MPath
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On Tue, Jan 26, 2016 at 09:53:33PM +0100, Johannes Berg wrote:
> Oh. Interesting. Yeah, I guess that should be OK then.
> 
> It's not *nice*, since that's pretty much unexpected, and you then do
> need the rcu_read_lock() ... hmm.

Yeah, I puzzled over that a bit last week as well -- I rewrote it like
this in the series I haven't posted yet:

void mesh_path_flush_by_nexthop(struct sta_info *sta)
{
    [...]
	rhashtable_walk_start(&iter);
	while ((mpath = rhashtable_walk_next(&iter))) {
		if (IS_ERR(mpath) && PTR_ERR(mpath) == -EAGAIN)
			continue;
		if (IS_ERR(mpath))
			break;

		if (rcu_access_pointer(mpath->next_hop) == sta)
			__mesh_path_del(tbl, mpath);
	}
	rhashtable_walk_stop(&iter);
    [...]
}

...this still relies on the rcu read lock inside _walk_start and _walk_stop,
though.

-- 
Bob Copeland %% http://bobcopeland.com/