On Wed, Jul 11 2018, David Miller wrote: > From: David Miller <da...@davemloft.net> > Date: Wed, 11 Jul 2018 22:46:58 -0700 (PDT) > >> From: NeilBrown <ne...@suse.com> >> Date: Fri, 06 Jul 2018 17:08:35 +1000 >> >>> >>> Some users of rhashtable might need to change the key >>> of an object and move it to a different location in the table. >>> Other users might want to allocate objects using >>> SLAB_TYPESAFE_BY_RCU which can result in the same memory allocation >>> being used for a different (type-compatible) purpose and similarly >>> end up in a different hash-chain. >>> >>> To support these, we store a unique NULLS_MARKER at the end of >>> each chain, and when a search fails to find a match, we check >>> if the NULLS marker found was the expected one. If not, >>> the search is repeated. >>> >>> The unique NULLS_MARKER is derived from the address of the >>> head of the chain. >>> >>> If an object is removed and re-added to the same hash chain, we won't >>> notice by looking that the NULLS marker. In this case we must be sure >>> that it was not re-added *after* its original location, or a lookup may >>> incorrectly fail. The easiest solution is to ensure it is inserted at >>> the start of the chain. insert_slow() already does that, >>> insert_fast() does not. So this patch changes insert_fast to always >>> insert at the head of the chain. >>> >>> Note that such a user must do their own double-checking of >>> the object found by rhashtable_lookup_fast() after ensuring >>> mutual exclusion which anything that might change the key, such as >>> successfully taking a new reference. >>> >>> Signed-off-by: NeilBrown <ne...@suse.com> >> >> Applied to net-next. > > Actually, reverted, it doesn't even compile. > > lib/rhashtable.c: In function ‘rht_bucket_nested’: > lib/rhashtable.c:1187:39: error: macro "INIT_RHT_NULLS_HEAD" passed 3 > arguments, but takes just 1 > INIT_RHT_NULLS_HEAD(rhnull, NULL, 0); > ^ > lib/rhashtable.c:1187:4: error: ‘INIT_RHT_NULLS_HEAD’ undeclared (first use > in this function); did you mean ‘INIT_LIST_HEAD’? > INIT_RHT_NULLS_HEAD(rhnull, NULL, 0); > ^~~~~~~~~~~~~~~~~~~ > INIT_LIST_HEAD > lib/rhashtable.c:1187:4: note: each undeclared identifier is reported only > once for each function it appears in
How embarrassing :-( I had tested a series, but not each individual patch. Sorry about that. I'll post the correct patch. Thanks, NeilBrown
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