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 4/8] rhashtable: fix race in nested_table_alloc()
Date: Sun, 6 May 2018 13:18:59 +0800 [thread overview]
Message-ID: <20180506051859.w7evarps5jdcplz6@gondor.apana.org.au> (raw)
In-Reply-To: <871sepepuj.fsf@notabene.neil.brown.name>
On Sun, May 06, 2018 at 07:48:20AM +1000, NeilBrown wrote:
>
> The spinlock protects 2 or more buckets. The nested table contains at
> least 512 buckets, maybe more.
> It is quite possible for two insertions into 2 different buckets to both
> get their spinlock and both try to instantiate the same nested table.
I think you missed the fact that when we use nested tables the spin
lock table is limited to just a single page and hence corresponds
to the first level in the nested table. Therefore it's always safe.
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 5:19 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
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 [this message]
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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