On Tue, Feb 12, 2019 at 08:03:17PM +0100, Johannes Berg wrote: > commit 60854fd94573f0d3b80b55b40cf0140a0430f3ab > Author: Bob Copeland <me@xxxxxxxxxxxxxxx> > Date: Wed Mar 2 10:09:20 2016 -0500 > > mac80211: mesh: convert path table to rhashtable > > which is kinda old. Not sure why this didn't surface before, because the > spinlock was introduced *before*, otherwise certainly the mutex would've > caused us to not be able to do this code to start with (commit > c6ff5268293 - rhashtable: Fix walker list corruption). > > That commit also just converted an existing hashtable walk to > rhashtable, so not sure that counts as having introduced the problem :-) Yeah, I didn't change any of the contexts in which the iterations were called, except making it possible to replace the previous mesh-specific RCU hashtable with rhashtable by introducing this. That said, it would certainly be nice to not have to walk the table to find paths that use a specific station as nexthop. > But I guess we should also ask Bob first: > 1) do you think it'd be easy to maintain a separate list or avoid the > iteration in some otherway, and make that a small enough patch to be > applicable for stable? I'm not sure, it's been a while. I guess most of the difficulties would be around station removal? > 2) or do you think maybe the mesh_plink_broken() call could just be > lifted into a workqueue instead? As far as I know, no reason this can't wait until later; we might send a few frames to the wrong destination but that can happen anyway. But there are a couple more walks in there like mesh_path_flush_by_nexthop(). -- Bob Copeland %% https://bobcopeland.com/
