netdev - Re: [PATCH 6/6] rhashtable: add rhashtable_walk

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Message-ID: <20180418143501.kzvknyvgnjo7v75k@gondor.apana.org.au>
Date:   Wed, 18 Apr 2018 22:35:02 +0800
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     NeilBrown <neilb@...e.com>
Cc:     Thomas Graf <tgraf@...g.ch>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 6/6] rhashtable: add rhashtable_walk_prev()

On Wed, Apr 18, 2018 at 04:47:02PM +1000, NeilBrown wrote:
> rhashtable_walk_prev() returns the object returned by
> the previous rhashtable_walk_next(), providing it is still in the
> table (or was during this grace period).
> This works even if rhashtable_walk_stop() and rhashtable_talk_start()
> have been called since the last rhashtable_walk_next().
> 
> If there have been no calls to rhashtable_walk_next(), or if the
> object is gone from the table, then NULL is returned.
> 
> This can usefully be used in a seq_file ->start() function.
> If the pos is the same as was returned by the last ->next() call,
> then rhashtable_walk_prev() can be used to re-establish the
> current location in the table.  If it returns NULL, then
> rhashtable_walk_next() should be used.
> 
> Signed-off-by: NeilBrown <neilb@...e.com>

Can you explain the need for this function and its difference
from the existing rhashtable_walk_peek?

Thanks,
-- 
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