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 8/8] rhashtable: don't hold lock on first table throughout insertion.
Date: Sun, 6 May 2018 13:20:00 +0800 [thread overview]
Message-ID: <20180506052000.7yehd5lke3smccoj@gondor.apana.org.au> (raw)
In-Reply-To: <87sh75dapa.fsf@notabene.neil.brown.name>
On Sun, May 06, 2018 at 08:00:49AM +1000, NeilBrown wrote:
>
> The insert function must (and does) take the lock on the bucket before
> testing if there is a "next" table.
> If one inserter finds that it has locked the "last" table (because there
> is no next) and successfully inserts, then the other inserter cannot
> have locked that table yet, else it would have inserted. When it does,
> it will find what the first inserter inserted.
If you release the lock to the first table then it may be deleted
by the resize thread. Hence the other inserter may not have even
started from the same place.
Cheers,
--
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
next prev parent reply other threads:[~2018-05-06 5:20 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 [this message]
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
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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