From: NeilBrown <neilb@suse.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Thomas Graf <tgraf@suug.ch>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] rhashtable: use bit_spin_locks to protect hash bucket.
Date: Wed, 27 Mar 2019 09:40:14 +1100 [thread overview]
Message-ID: <871s2t45v5.fsf@notabene.neil.brown.name> (raw)
In-Reply-To: <20190326052714.rqxuiqumjnw2qtb6@gondor.apana.org.au>
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On Tue, Mar 26 2019, Herbert Xu wrote:
> On Mon, Mar 25, 2019 at 04:05:39PM +1100, NeilBrown wrote:
>>
>> +/*
>> + * If 'p' is a bucket head and might be locked:
>> + * rht_ptr() returns the address without the lock bit.
>> + * rht_ptr_locked() returns the address WITH the lock bit.
>> + * rht_is_locked() tests if the lock bit is set.
>> + */
>> +static inline struct rhash_head __rcu *rht_ptr(const struct rhash_head *p)
>> +{
>> + return (void *)(((unsigned long)p) & ~2UL);
>> +}
>
> My preference would be to turn rhash_head * into an opaque type
> that can only be dereferenced through rht_ptr.
I can try that.
Presumably the 'next' pointer in 'struct rhash_head' can still be a
normal pointer, but the buckets in the bucket_table would need to
opaque pointers.
Maybe pointers to some new undefined struct, which gets cast and masked
as appropriate?
I'll have a go and see how it looks.
Thanks,
NeilBrown
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next prev parent reply other threads:[~2019-03-27 1:10 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 5:05 [PATCH 0/4] Convert rhashtable to use bitlocks NeilBrown
2019-03-25 5:05 ` [PATCH 1/4] rhashtable: use cmpxchg() in nested_table_alloc() NeilBrown
2019-03-25 5:05 ` [PATCH 3/4] rhashtable: use bit_spin_locks to protect hash bucket NeilBrown
2019-03-26 5:03 ` Herbert Xu
2019-03-26 15:36 ` Paul E. McKenney
2019-03-27 3:45 ` Herbert Xu
2019-03-26 22:35 ` NeilBrown
2019-03-27 3:45 ` Herbert Xu
2019-03-27 15:04 ` Paul E. McKenney
2019-03-26 5:27 ` Herbert Xu
2019-03-26 22:40 ` NeilBrown [this message]
2019-03-25 5:05 ` [PATCH 4/4] rhashtable: add lockdep tracking to bucket bit-spin-locks NeilBrown
2019-03-25 5:05 ` [PATCH 2/4] rhashtable: allow rht_bucket_var to return NULL NeilBrown
-- strict thread matches above, loose matches on Subject: below --
2019-04-01 23:07 [PATCH 0/4 v2] Convert rhashtable to use bitlocks NeilBrown
2019-04-01 23:07 ` [PATCH 3/4] rhashtable: use bit_spin_locks to protect hash bucket NeilBrown
2019-04-02 10:11 ` David Laight
2019-04-02 21:10 ` NeilBrown
2019-04-03 9:26 ` David Laight
2019-04-04 0:13 ` NeilBrown
2019-04-08 2:34 ` Herbert Xu
2019-04-10 19:34 ` Guenter Roeck
2019-04-11 0:48 ` NeilBrown
2019-04-11 2:15 ` David Miller
2019-04-11 6:13 ` NeilBrown
2019-04-11 6:40 ` NeilBrown
2019-04-11 12:44 ` Guenter Roeck
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