netdev - Re: [PATCH 1/2] mac80211: Use linked list instead of rhashtable walk for mesh tables

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Message-ID: <20190213134727.iyrxk7utxmihj7ac@gondor.apana.org.au>
Date:   Wed, 13 Feb 2019 21:47:27 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     David Miller <davem@...emloft.net>, johannes@...solutions.net,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org, j@...fi,
        tgraf@...g.ch, johannes.berg@...el.com
Subject: Re: [PATCH 1/2] mac80211: Use linked list instead of rhashtable walk
 for mesh tables

On Wed, Feb 13, 2019 at 01:16:13PM +0800, Herbert Xu wrote:
> The mesh table code walks over hash tables for two purposes.  First of
> all it's used as part of a netlink dump process, but it is also used
> for looking up entries to delete using criteria other than the hash
> key.
> 
> The second purpose is directly contrary to the design specification
> of rhashtable walks.  It is only meant for use by netlink dumps.
> 
> This is because rhashtable is resizable and you cannot obtain a
> stable walk over it during a resize process.
> 
> In fact mesh's use of rhashtable for dumping is bogus too.  Rather
> than using rhashtable walk's iterator to keep track of the current
> position, it always converts the current position to an integer
> which defeats the purpose of the iterator.
> 
> Therefore this patch converts all uses of rhashtable walk into a
> simple linked list.
> 
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

OK this patch is broken because there is no locking on the linked
list.  I'll repost the series.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt