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From: Herbert Xu <herbert@gondor.apana.org.au>
To: NeilBrown <neilb@suse.com>
Cc: Thomas Graf <tgraf@suug.ch>,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/8] rhashtable: remove nulls_base and related code.
Date: Sat, 5 May 2018 17:12:08 +0800	[thread overview]
Message-ID: <20180505091208.tnsxi6hdpjn456yz@gondor.apana.org.au> (raw)
In-Reply-To: <152540605427.18473.12277050439942480863.stgit@noble>

On Fri, May 04, 2018 at 01:54:14PM +1000, NeilBrown wrote:
> This "feature" is unused, undocumented, and untested and so
> doesn't really belong.  If a use for the nulls marker
> is found, all this code would need to be reviewed to
> ensure it works as required.  It would be just as easy to
> just add the code if/when it is needed instead.
> 
> This patch actually fixes a bug too.  The table resizing allows a
> table to grow to 2^31 buckets, but the hash is truncated to 27 bits -
> any growth beyond 2^27 is wasteful an ineffective.
> 
> This patch result in NULLS_MARKER(0) being used for all chains,
> and leave the use of rht_is_a_null() to test for it.
> 
> Signed-off-by: NeilBrown <neilb@suse.com>

I disagree.  This is a fundamental requirement for the use of
rhashtable in certain networking systems such as TCP/UDP.  So
we know that there will be a use for this.

As to the bug fix, please separate it out of the patch and resubmit.

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

  reply	other threads:[~2018-05-05  9:12 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-04  3:54 [PATCH 0/8] Assorted rhashtable fixes and cleanups NeilBrown
2018-05-04  3:54 ` [PATCH 8/8] rhashtable: don't hold lock on first table throughout insertion NeilBrown
2018-05-05  9:41   ` Herbert Xu
2018-05-05 22:00     ` NeilBrown
2018-05-06  5:20       ` Herbert Xu
2018-05-06 22:24         ` NeilBrown
2018-05-07  9:29           ` Herbert Xu
2018-05-08  0:23             ` NeilBrown
2018-05-04  3:54 ` [PATCH 6/8] rhashtable: further improve stability of rhashtable_walk NeilBrown
2018-05-05  9:42   ` Herbert Xu
2018-05-05 21:50     ` NeilBrown
2018-05-07  9:30       ` Herbert Xu
2018-05-08  0:54         ` NeilBrown
2018-05-04  3:54 ` [PATCH 1/8] rhashtable: silence RCU warning in rhashtable_test NeilBrown
2018-05-05  9:10   ` Herbert Xu
2018-05-05 21:49     ` NeilBrown
2018-05-04  3:54 ` [PATCH 2/8] rhashtable: remove nulls_base and related code NeilBrown
2018-05-05  9:12   ` Herbert Xu [this message]
2018-05-05 21:37     ` NeilBrown
2018-05-07  9:27       ` Herbert Xu
2018-05-08  1:14         ` NeilBrown
2018-05-04  3:54 ` [PATCH 5/8] rhashtable: remove rhashtable_walk_peek() NeilBrown
2018-05-05  9:30   ` Herbert Xu
2018-05-04  3:54 ` [PATCH 7/8] rhashtable: add rhashtable_walk_prev() NeilBrown
2018-05-05  9:43   ` Herbert Xu
2018-05-05 15:40     ` Tom Herbert
2018-05-06 22:16       ` NeilBrown
2018-05-04  3:54 ` [PATCH 4/8] rhashtable: fix race in nested_table_alloc() NeilBrown
2018-05-05  9:29   ` Herbert Xu
2018-05-05 21:48     ` NeilBrown
2018-05-06  5:18       ` Herbert Xu
2018-05-06 22:02         ` NeilBrown
2018-05-04  3:54 ` [PATCH 3/8] rhashtable: use cmpxchg() to protect ->future_tbl NeilBrown
2018-05-05  9:27   ` Herbert Xu
2018-05-05 21:45     ` NeilBrown
2018-05-04 17:07 ` [PATCH 0/8] Assorted rhashtable fixes and cleanups David Miller

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