This patch adds the missing bits to allow multiple rehashes.  The
read-side as well as remove already handle this correctly.  So it's
only the rehasher and insertion that need modification to handle
this.

Note that this patch doesn't actually enable it so for now rehashing
is still only performed by the worker thread.

This patch also disables the explicit expand/shrink interface because
the table is meant to expand and shrink automatically, and continuing
to export these interfaces unnecessarily complicates the life of the
rehasher since the rehash process is now composed of two parts.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch converts test_rhashtable to the inlined rhashtable
interface.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch converts test_rhashtable to use rhashtable max_size
instead of the obsolete max_shift.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch adds a rehash counter to bucket_table to indicate
the last bucket that has been rehashed.  This serves two purposes:

1. Any bucket that has been rehashed can never gain a new object.
2. If the rehash counter reaches the size of the table, the table
will forever remain empty.

This patch also downsizes bucket_table->size to an unsigned int
since we do not support sizes greater than 32 bits yet.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Currently, all real users of rhashtable default their grow and shrink
decision functions to rht_grow_above_75() and rht_shrink_below_30(),
so that there's currently no need to have this explicitly selectable.

It can/should be generic and private inside rhashtable until a real
use case pops up. Since we can make this private, we'll save us this
additional indirection layer and can improve insertion/deletion time
as well.

Reference: http://patchwork.ozlabs.org/patch/443040/Suggested-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While commit c0c09bfd ("rhashtable: avoid unnecessary wakeup for
worker queue") rightfully moved part of the decision making of
whether we should expand or shrink from the expand/shrink functions
themselves into insert/delete functions in order to avoid unnecessary
worker wake-ups, it however introduced a regression by doing so.

Before that change, if no max_shift was specified (= 0) on rhashtable
initialization, rhashtable_expand() would just grow unconditionally
and lets the available memory be the limiting factor. After that
change, if no max_shift was specified, there would be _no_ expansion
step at all.

Given that netlink and tipc have a max_shift specified, it was not
visible there, but Josh Hunt reported that if nft that starts out
with a default element hint of 3 if not otherwise provided, would
slow i.e. inserts down trememdously as it cannot grow larger to
relax table occupancy.

Given that the test case verifies shrinks/expands manually, we also
must remove pointer to the helper functions to explicitly avoid
parallel resizing on insertions/deletions. test_bucket_stats() and
test_rht_lookup() could also be wrapped around rhashtable mutex to
explicitly synchronize a walk from resizing, but I think that defeats
the actual test case which intended to have explicit test steps,
i.e. 1) inserts, 2) expands, 3) shrinks, 4) deletions, with object
verification after each stage.
Reported-by: NJosh Hunt <johunt@akamai.com>
Fixes: c0c09bfd ("rhashtable: avoid unnecessary wakeup for worker queue")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: Josh Hunt <johunt@akamai.com>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

There's no good reason why to disallow unloading of the rhashtable
test case module.

Commit 9d6dbe1b moved the code from a boot test into a stand-alone
module, but only converted the subsys_initcall() handler into a
module_init() function without a related exit handler, and thus
preventing the test module from unloading.

Fixes: 9d6dbe1b ("rhashtable: Make selftest modular")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

With object runtime debugging enabled, the rhashtable test suite
will rightfully throw a warning "ODEBUG: object is on stack, but
not annotated" from rhashtable_init().

This is because run_work is (correctly) being initialized via
INIT_WORK(), and not annotated by INIT_WORK_ONSTACK(). Meaning,
rhashtable_init() is okay as is, we just need to move ht e.g.,
into global scope.

It never triggered anything, since test_rhashtable is rather a
controlled environment and effectively runs to completion, so
that stack memory is not vanishing underneath us, we shouldn't
confuse any testers with it though.

Fixes: 7e1e7763 ("lib: Resizable, Scalable, Concurrent Hash Table")
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Allow the selftest on the resizable hash table to be built modular, just
like all other tests that do not depend on DEBUG_KERNEL.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Acked-by: NThomas Graf <tgraf@suug.ch>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>