From: NeilBrown <neilb@suse.com>
To: paulmck@linux.vnet.ibm.com
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
Thomas Graf <tgraf@suug.ch>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] rhashtable: don't hold lock on first table throughout insertion.
Date: Mon, 23 Jul 2018 09:13:43 +1000 [thread overview]
Message-ID: <87h8kqrhi0.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20180722215446.GH12945@linux.vnet.ibm.com>
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On Sun, Jul 22 2018, Paul E. McKenney wrote:
>
> One issue is that the ->func pointer can legitimately be NULL while on
> RCU's callback lists. This happens when someone invokes kfree_rcu()
> with the rcu_head structure at the beginning of the enclosing structure.
> I could add an offset to avoid this, or perhaps the kmalloc() folks
> could be persuaded Rao Shoaib's patch moving kfree_rcu() handling to
> the slab allocators, so that RCU only ever sees function pointers in
> the ->func field.
>
> Either way, this should be hidden behind an API to allow adjustments
> to be made if needed. Maybe something like is_after_call_rcu()?
> This would (for example) allow debug-object checks to be used to catch
> check-after-free bugs.
>
> Would something of that sort work for you?
Yes, if you could provide an is_after_call_rcu() API, that would
perfectly suit my use-case.
Thanks,
NeilBrown
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next prev parent reply other threads:[~2018-07-22 23:14 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 7:22 [PATCH 0/5] Rhashtable: convert to bit-spin locks NeilBrown
2018-07-06 7:22 ` [PATCH 2/5] rhashtable: don't hold lock on first table throughout insertion NeilBrown
2018-07-20 7:54 ` Herbert Xu
2018-07-20 14:41 ` Paul E. McKenney
2018-07-21 2:25 ` NeilBrown
2018-07-22 21:54 ` Paul E. McKenney
2018-07-22 23:13 ` NeilBrown [this message]
2018-07-23 20:56 ` Paul E. McKenney
2018-07-23 21:52 ` NeilBrown
2018-07-24 22:58 ` Paul E. McKenney
2018-07-25 4:53 ` NeilBrown
2018-07-25 15:22 ` Paul E. McKenney
2018-07-27 1:04 ` NeilBrown
2018-07-27 3:18 ` Paul E. McKenney
2018-07-27 14:57 ` Paul E. McKenney
2018-07-31 0:45 ` NeilBrown
2018-07-31 4:14 ` Paul E. McKenney
2018-07-31 5:04 ` NeilBrown
2018-07-31 14:44 ` Paul E. McKenney
2019-03-11 15:27 ` Paul E. McKenney
2019-03-11 21:50 ` NeilBrown
2019-03-11 22:10 ` Paul E. McKenney
2018-07-06 7:22 ` [PATCH 5/5] rhashtable: add lockdep tracking to bucket bit-spin-locks NeilBrown
2018-07-06 7:22 ` [PATCH 1/5] rhashtable: use cmpxchg() in nested_table_alloc() NeilBrown
2018-07-06 7:22 ` [PATCH 4/5] rhashtable: use bit_spin_locks to protect hash bucket NeilBrown
2018-07-06 7:22 ` [PATCH 3/5] rhashtable: allow rht_bucket_var to return NULL NeilBrown
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