lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 02 Aug 2012 18:48:07 +0200 From: Sasha Levin <levinsasha928@...il.com> To: Josh Triplett <josh@...htriplett.org> CC: Tejun Heo <tj@...nel.org>, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, paul.gortmaker@...driver.com Subject: Re: [RFC 1/4] hashtable: introduce a small and naive hashtable On 08/02/2012 06:15 PM, Josh Triplett wrote: > On Thu, Aug 02, 2012 at 03:04:19PM +0200, Sasha Levin wrote: >> On 08/02/2012 01:23 PM, Sasha Levin wrote: >>>> #define DEFINE_HASH_TABLE(name, length) struct hash_table name = { .count = length, .buckets = { [0 ... (length - 1)] = HLIST_HEAD_INIT } } >>> The limitation of this approach is that the struct hash_table variable must be 'static', which is a bit limiting - see for example the use of hashtable in 'struct user_namespace'. >>> >> >> What if we just use two possible decelerations? One of static structs and one for regular ones. >> >> struct hash_table { >> size_t bits; >> struct hlist_head buckets[]; >> }; >> >> #define DEFINE_HASHTABLE(name, bits) \ >> union { \ >> struct hash_table name; \ >> struct { \ >> size_t bits; \ > > This shouldn't use "bits", since it'll get expanded to the macro > argument. > >> struct hlist_head buckets[1 << bits]; \ >> } __name; \ > > __##name > >> } >> >> #define DEFINE_STATIC_HASHTABLE(name, bit) \ >> static struct hash_table name = { .bits = bit, \ >> .buckets = { [0 ... (bit - 1)] = HLIST_HEAD_INIT } } > > You probably wanted to change that to [0 ... ((1 << bit) - 1)] , to > match DEFINE_HASHTABLE. I wrote it by hand and didn't compile test, will fix all of those. > Since your definition of DEFINE_HASHTABLE would also work fine when used > statically, why not just always use that? > > #define DEFINE_STATIC_HASHTABLE(name, bits) static DEFINE_HASHTABLE(name, bits) = { .name.bits = bits } It will get defined fine, but it will be awkward to use. We'd need to pass anonymous union to all the functions that handle this hashtable, which isn't pretty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists