netdev - Re: [PATCH net-next 1/5] rhashtable: Don't reset walker table in rhashtable_walk

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Date:   Sat, 2 Dec 2017 09:18:09 +1100
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Tom Herbert <tom@...ntonium.net>
Cc:     davem@...emloft.net, netdev@...r.kernel.org, rohit@...ntonium.net
Subject: Re: [PATCH net-next 1/5] rhashtable: Don't reset walker table in
 rhashtable_walk_start

On Thu, Nov 30, 2017 at 04:03:01PM -0800, Tom Herbert wrote:
> Remove the code that resets the walker table. The walker table should
> only be initialized in the walk init function or when a future table is
> encountered. If the walker table is NULL this is the indication that
> the walk has completed and this information can be used to break a
> multi-call walk in the table (e.g. successive calls to nelink_dump
> that are dumping elements of an rhashtable).
> 
> This also allows us to change rhashtable_walk_start to return void
> since the only error it was returning was -EAGAIN for a table change.
> This patch changes all the callers of rhashtable_walk_start to expect
> void which eliminates logic needed to check the return value for a
> rare condition. Note that -EAGAIN will be returned in a call
> to rhashtable_walk_next which seems to always follow the start
> of the walk so there should be no behavioral change in doing this.
> 
> Signed-off-by: Tom Herbert <tom@...ntonium.net>

Doesn't this mean that if a walk encounters a rehash you may end up
missing half or more of the hash table?

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