Commit Graph

177 Commits

Author SHA1 Message Date
Herbert Xu 2d2ab658d2 rhashtable: Do not lower max_elems when max_size is zero
The commit 6d684e5469 ("rhashtable: Cap total number of entries
to 2^31") breaks rhashtable users that do not set max_size.  This
is because when max_size is zero max_elems is also incorrectly set
to zero instead of 2^31.

This patch fixes it by only lowering max_elems when max_size is not
zero.

Fixes: 6d684e5469 ("rhashtable: Cap total number of entries to 2^31")
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Reported-by: kernel test robot <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-28 10:14:09 -04:00
Herbert Xu 6d684e5469 rhashtable: Cap total number of entries to 2^31
When max_size is not set or if it set to a sufficiently large
value, the nelems counter can overflow.  This would cause havoc
with the automatic shrinking as it would then attempt to fit a
huge number of entries into a tiny hash table.

This patch fixes this by adding max_elems to struct rhashtable
to cap the number of elements.  This is set to 2^31 as nelems is
not a precise count.  This is sufficiently smaller than UINT_MAX
that it should be safe.

When max_size is set max_elems will be lowered to at most twice
max_size as is the status quo.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-27 11:48:24 -04:00
Florian Westphal 038a3e858d rhashtable: remove insecure_max_entries param
no users in the tree, insecure_max_entries is always set to
ht->p.max_size * 2 in rhtashtable_init().

Replace only spot that uses it with a ht->p.max_size check.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-26 14:39:24 -04:00
Florian Westphal 5f8ddeab10 rhashtable: remove insecure_elasticity
commit 83e7e4ce9e ("mac80211: Use rhltable instead of rhashtable")
removed the last user that made use of 'insecure_elasticity' parameter,
i.e. the default of 16 is used everywhere.

Replace it with a constant.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-04-18 13:49:14 -04:00
Ingo Molnar b2d0910310 sched/headers: Prepare to use <linux/rcuupdate.h> instead of <linux/rculist.h> in <linux/sched.h>
We don't actually need the full rculist.h header in sched.h anymore,
we will be able to include the smaller rcupdate.h header instead.

But first update code that relied on the implicit header inclusion.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-03-02 08:42:38 +01:00
Herbert Xu c4d2603dac rhashtable: Fix RCU dereference annotation in rht_bucket_nested
The current annotation is wrong as it says that we're only called
under spinlock.  In fact it should be marked as under either
spinlock or RCU read lock.

Fixes: da20420f83 ("rhashtable: Add nested tables")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-26 21:33:43 -05:00
Herbert Xu ca435407ba rhashtable: Fix use before NULL check in bucket_table_free
Dan Carpenter reported a use before NULL check bug in the function
bucket_table_free.  In fact we don't need the NULL check at all as
no caller can provide a NULL argument.  So this patch fixes this by
simply removing it.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-26 21:32:57 -05:00
Herbert Xu da20420f83 rhashtable: Add nested tables
This patch adds code that handles GFP_ATOMIC kmalloc failure on
insertion.  As we cannot use vmalloc, we solve it by making our
hash table nested.  That is, we allocate single pages at each level
and reach our desired table size by nesting them.

When a nested table is created, only a single page is allocated
at the top-level.  Lower levels are allocated on demand during
insertion.  Therefore for each insertion to succeed, only two
(non-consecutive) pages are needed.

After a nested table is created, a rehash will be scheduled in
order to switch to a vmalloced table as soon as possible.  Also,
the rehash code will never rehash into a nested table.  If we
detect a nested table during a rehash, the rehash will be aborted
and a new rehash will be scheduled.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2017-02-17 12:28:35 -05:00
Herbert Xu ca26893f05 rhashtable: Add rhlist interface
The insecure_elasticity setting is an ugly wart brought out by
users who need to insert duplicate objects (that is, distinct
objects with identical keys) into the same table.

In fact, those users have a much bigger problem.  Once those
duplicate objects are inserted, they don't have an interface to
find them (unless you count the walker interface which walks
over the entire table).

Some users have resorted to doing a manual walk over the hash
table which is of course broken because they don't handle the
potential existence of multiple hash tables.  The result is that
they will break sporadically when they encounter a hash table
resize/rehash.

This patch provides a way out for those users, at the expense
of an extra pointer per object.  Essentially each object is now
a list of objects carrying the same key.  The hash table will
only see the lists so nothing changes as far as rhashtable is
concerned.

To use this new interface, you need to insert a struct rhlist_head
into your objects instead of struct rhash_head.  While the hash
table is unchanged, for type-safety you'll need to use struct
rhltable instead of struct rhashtable.  All the existing interfaces
have been duplicated for rhlist, including the hash table walker.

One missing feature is nulls marking because AFAIK the only potential
user of it does not need duplicate objects.  Should anyone need
this it shouldn't be too hard to add.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-20 04:43:36 -04:00
David S. Miller 60175ccdf4 Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf-next
Pablo Neira Ayuso says:

====================
Netfilter updates for net-next

The following patchset contains Netfilter updates for your net-next
tree.  Most relevant updates are the removal of per-conntrack timers to
use a workqueue/garbage collection approach instead from Florian
Westphal, the hash and numgen expression for nf_tables from Laura
Garcia, updates on nf_tables hash set to honor the NLM_F_EXCL flag,
removal of ip_conntrack sysctl and many other incremental updates on our
Netfilter codebase.

More specifically, they are:

1) Retrieve only 4 bytes to fetch ports in case of non-linear skb
   transport area in dccp, sctp, tcp, udp and udplite protocol
   conntrackers, from Gao Feng.

2) Missing whitespace on error message in physdev match, from Hangbin Liu.

3) Skip redundant IPv4 checksum calculation in nf_dup_ipv4, from Liping Zhang.

4) Add nf_ct_expires() helper function and use it, from Florian Westphal.

5) Replace opencoded nf_ct_kill() call in IPVS conntrack support, also
   from Florian.

6) Rename nf_tables set implementation to nft_set_{name}.c

7) Introduce the hash expression to allow arbitrary hashing of selector
   concatenations, from Laura Garcia Liebana.

8) Remove ip_conntrack sysctl backward compatibility code, this code has
   been around for long time already, and we have two interfaces to do
   this already: nf_conntrack sysctl and ctnetlink.

9) Use nf_conntrack_get_ht() helper function whenever possible, instead
   of opencoding fetch of hashtable pointer and size, patch from Liping Zhang.

10) Add quota expression for nf_tables.

11) Add number generator expression for nf_tables, this supports
    incremental and random generators that can be combined with maps,
    very useful for load balancing purpose, again from Laura Garcia Liebana.

12) Fix a typo in a debug message in FTP conntrack helper, from Colin Ian King.

13) Introduce a nft_chain_parse_hook() helper function to parse chain hook
    configuration, this is used by a follow up patch to perform better chain
    update validation.

14) Add rhashtable_lookup_get_insert_key() to rhashtable and use it from the
    nft_set_hash implementation to honor the NLM_F_EXCL flag.

15) Missing nulls check in nf_conntrack from nf_conntrack_tuple_taken(),
    patch from Florian Westphal.

16) Don't use the DYING bit to know if the conntrack event has been already
    delivered, instead a state variable to track event re-delivery
    states, also from Florian.

17) Remove the per-conntrack timer, use the workqueue approach that was
    discussed during the NFWS, from Florian Westphal.

18) Use the netlink conntrack table dump path to kill stale entries,
    again from Florian.

19) Add a garbage collector to get rid of stale conntracks, from
    Florian.

20) Reschedule garbage collector if eviction rate is high.

21) Get rid of the __nf_ct_kill_acct() helper.

22) Use ARPHRD_ETHER instead of hardcoded 1 from ARP logger.

23) Make nf_log_set() interface assertive on unsupported families.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
2016-09-06 12:45:26 -07:00
David S. Miller 6abdd5f593 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
All three conflicts were cases of simple overlapping
changes.

Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-30 00:54:02 -04:00
Eric Dumazet 9dbeea7f08 rhashtable: fix a memory leak in alloc_bucket_locks()
If vmalloc() was successful, do not attempt a kmalloc_array()

Fixes: 4cf0b354d9 ("rhashtable: avoid large lock-array allocations")
Reported-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Florian Westphal <fw@strlen.de>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: CAI Qian <caiqian@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-26 21:59:53 -07:00
Pablo Neira Ayuso 5ca8cc5bf1 rhashtable: add rhashtable_lookup_get_insert_key()
This patch modifies __rhashtable_insert_fast() so it returns the
existing object that clashes with the one that you want to insert.
In case the object is successfully inserted, NULL is returned.
Otherwise, you get an error via ERR_PTR().

This patch adapts the existing callers of __rhashtable_insert_fast()
so they handle this new logic, and it adds a new
rhashtable_lookup_get_insert_key() interface to fetch this existing
object.

nf_tables needs this change to improve handling of EEXIST cases via
honoring the NLM_F_EXCL flag and by checking if the data part of the
mapping matches what we have.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
2016-08-26 17:29:41 +02:00
Herbert Xu 246779dd09 rhashtable: Remove GFP flag from rhashtable_walk_init
The commit 8f6fd83c6c ("rhashtable:
accept GFP flags in rhashtable_walk_init") added a GFP flag argument
to rhashtable_walk_init because some users wish to use the walker
in an unsleepable context.

In fact we don't need to allocate memory in rhashtable_walk_init
at all.  The walker is always paired with an iterator so we could
just stash ourselves there.

This patch does that by introducing a new enter function to replace
the existing init function.  This way we don't have to churn all
the existing users again.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-19 14:40:24 -07:00
Vegard Nossum 12311959ec rhashtable: fix shift by 64 when shrinking
I got this:

    ================================================================================
    UBSAN: Undefined behaviour in ./include/linux/log2.h:63:13
    shift exponent 64 is too large for 64-bit type 'long unsigned int'
    CPU: 1 PID: 721 Comm: kworker/1:1 Not tainted 4.8.0-rc1+ #87
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
    Workqueue: events rht_deferred_worker
     0000000000000000 ffff88011661f8d8 ffffffff82344f50 0000000041b58ab3
     ffffffff84f98000 ffffffff82344ea4 ffff88011661f900 ffff88011661f8b0
     0000000000000001 ffff88011661f6b8 dffffc0000000000 ffffffff867f7640
    Call Trace:
     [<ffffffff82344f50>] dump_stack+0xac/0xfc
     [<ffffffff82344ea4>] ? _atomic_dec_and_lock+0xc4/0xc4
     [<ffffffff8242f5b8>] ubsan_epilogue+0xd/0x8a
     [<ffffffff82430c41>] __ubsan_handle_shift_out_of_bounds+0x255/0x29a
     [<ffffffff824309ec>] ? __ubsan_handle_out_of_bounds+0x180/0x180
     [<ffffffff84003436>] ? nl80211_req_set_reg+0x256/0x2f0
     [<ffffffff812112ba>] ? print_context_stack+0x8a/0x160
     [<ffffffff81200031>] ? amd_pmu_reset+0x341/0x380
     [<ffffffff823af808>] rht_deferred_worker+0x1618/0x1790
     [<ffffffff823af808>] ? rht_deferred_worker+0x1618/0x1790
     [<ffffffff823ae1f0>] ? rhashtable_jhash2+0x370/0x370
     [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970
     [<ffffffff8134c1cf>] process_one_work+0x79f/0x1970
     [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970
     [<ffffffff8134ba30>] ? try_to_grab_pending+0x4c0/0x4c0
     [<ffffffff8134d564>] ? worker_thread+0x1c4/0x1340
     [<ffffffff8134d8ff>] worker_thread+0x55f/0x1340
     [<ffffffff845e904f>] ? __schedule+0x4df/0x1d40
     [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970
     [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970
     [<ffffffff813642f7>] kthread+0x237/0x390
     [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280
     [<ffffffff845f8c93>] ? _raw_spin_unlock_irq+0x33/0x50
     [<ffffffff845f95df>] ret_from_fork+0x1f/0x40
     [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280
    ================================================================================

roundup_pow_of_two() is undefined when called with an argument of 0, so
let's avoid the call and just fall back to ht->p.min_size (which should
never be smaller than HASH_MIN_SIZE).

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-15 11:10:09 -07:00
Florian Westphal 4cf0b354d9 rhashtable: avoid large lock-array allocations
Sander reports following splat after netfilter nat bysrc table got
converted to rhashtable:

swapper/0: page allocation failure: order:3, mode:0x2084020(GFP_ATOMIC|__GFP_COMP)
 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-rc1 [..]
 [<ffffffff811633ed>] warn_alloc_failed+0xdd/0x140
 [<ffffffff811638b1>] __alloc_pages_nodemask+0x3e1/0xcf0
 [<ffffffff811a72ed>] alloc_pages_current+0x8d/0x110
 [<ffffffff8117cb7f>] kmalloc_order+0x1f/0x70
 [<ffffffff811aec19>] __kmalloc+0x129/0x140
 [<ffffffff8146d561>] bucket_table_alloc+0xc1/0x1d0
 [<ffffffff8146da1d>] rhashtable_insert_rehash+0x5d/0xe0
 [<ffffffff819fcfff>] nf_nat_setup_info+0x2ef/0x400

The failure happens when allocating the spinlock array.
Even with GFP_KERNEL its unlikely for such a large allocation
to succeed.

Thomas Graf pointed me at inet_ehash_locks_alloc(), so in addition
to adding NOWARN for atomic allocations this also makes the bucket-array
sizing more conservative.

In commit 095dc8e0c3 ("tcp: fix/cleanup inet_ehash_locks_alloc()"),
Eric Dumazet says: "Budget 2 cache lines per cpu worth of 'spinlocks'".
IOW, consider size needed by a single spinlock when determining
number of locks per cpu.  So with 64 byte per cacheline and 4 byte per
spinlock this gives 32 locks per cpu.

Resulting size of the lock-array (sizeof(spinlock) == 4):

cpus:    1   2   4   8   16   32   64
old:    1k  1k  4k  8k  16k  16k  16k
new:   128 256 512  1k   2k   4k   8k

8k allocation should have decent chance of success even
with GFP_ATOMIC, and should not fail with GFP_KERNEL.

With 72-byte spinlock (LOCKDEP):
cpus :   1   2
old:    9k 18k
new:   ~2k ~4k

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Suggested-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-14 21:12:57 -07:00
Bob Copeland 8f6fd83c6c rhashtable: accept GFP flags in rhashtable_walk_init
In certain cases, the 802.11 mesh pathtable code wants to
iterate over all of the entries in the forwarding table from
the receive path, which is inside an RCU read-side critical
section.  Enable walks inside atomic sections by allowing
GFP_ATOMIC allocations for the walker state.

Change all existing callsites to pass in GFP_KERNEL.

Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Bob Copeland <me@bobcopeland.com>
[also adjust gfs2/glock.c and rhashtable tests]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-04-05 10:56:32 +02:00
David S. Miller c07f30ad68 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-12-31 18:20:10 -05:00
Herbert Xu 179ccc0a73 rhashtable: Kill harmless RCU warning in rhashtable_walk_init
The commit c6ff526829 ("rhashtable:
Fix walker list corruption") causes a suspicious RCU usage warning
because we no longer hold ht->mutex when we dereference ht->tbl.

However, this is a false positive because we now hold ht->lock
which also guarantees that ht->tbl won't disppear from under us.

This patch kills the warning by using rcu_dereference_protected.

Reported-by: kernel test robot <ying.huang@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-18 23:44:18 -05:00
David S. Miller b3e0d3d7ba Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
	drivers/net/geneve.c

Here we had an overlapping change, where in 'net' the extraneous stats
bump was being removed whilst in 'net-next' the final argument to
udp_tunnel6_xmit_skb() was being changed.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-17 22:08:28 -05:00
Herbert Xu c6ff526829 rhashtable: Fix walker list corruption
The commit ba7c95ea38 ("rhashtable:
Fix sleeping inside RCU critical section in walk_stop") introduced
a new spinlock for the walker list.  However, it did not convert
all existing users of the list over to the new spin lock.  Some
continued to use the old mutext for this purpose.  This obviously
led to corruption of the list.

The fix is to use the spin lock everywhere where we touch the list.

This also allows us to do rcu_rad_lock before we take the lock in
rhashtable_walk_start.  With the old mutex this would've deadlocked
but it's safe with the new spin lock.

Fixes: ba7c95ea38 ("rhashtable: Fix sleeping inside RCU...")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 11:13:14 -05:00
Herbert Xu 3a324606bb rhashtable: Enforce minimum size on initial hash table
William Hua <william.hua@canonical.com> wrote:
>
> I wasn't aware there was an enforced minimum size. I simply set the
> nelem_hint in the rhastable_params struct to 1, expecting it to grow as
> needed. This caused a segfault afterwards when trying to insert an
> element.

OK we're doing the size computation before we enforce the limit
on min_size.

---8<---
We need to do the initial hash table size computation after we
have obtained the correct min_size/max_size parameters.  Otherwise
we may end up with a hash table whose size is outside the allowed
envelope.

Fixes: a998f712f7 ("rhashtable: Round up/down min/max_size to...")
Reported-by: William Hua <william.hua@canonical.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 10:44:08 -05:00
Herbert Xu 46c749eac9 rhashtable: Remove unnecessary wmb for future_tbl
The patch 9497df88ab ("rhashtable:
Fix reader/rehash race") added a pair of barriers.  In fact the
wmb is superfluous because every subsequent write to the old or
new hash table uses rcu_assign_pointer, which itself carriers a
full barrier prior to the assignment.

Therefore we may remove the explicit wmb.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-08 22:46:32 -05:00
David S. Miller a90099d9fa Revert "rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation"
This reverts commit d3716f18a7.

vmalloc cannot be used in BH disabled contexts, even
with GFP_ATOMIC.  And we certainly want to support
rhashtable users inserting entries with software
interrupts disabled.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-05 22:47:11 -05:00
Herbert Xu d3716f18a7 rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation
When an rhashtable user pounds rhashtable hard with back-to-back
insertions we may end up growing the table in GFP_ATOMIC context.
Unfortunately when the table reaches a certain size this often
fails because we don't have enough physically contiguous pages
to hold the new table.

Eric Dumazet suggested (and in fact wrote this patch) using
__vmalloc instead which can be used in GFP_ATOMIC context.

Reported-by: Phil Sutter <phil@nwl.cc>
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-04 16:53:05 -05:00
Herbert Xu 3cf92222a3 rhashtable: Prevent spurious EBUSY errors on insertion
Thomas and Phil observed that under stress rhashtable insertion
sometimes failed with EBUSY, even though this error should only
ever been seen when we're under attack and our hash chain length
has grown to an unacceptable level, even after a rehash.

It turns out that the logic for detecting whether there is an
existing rehash is faulty.  In particular, when two threads both
try to grow the same table at the same time, one of them may see
the newly grown table and thus erroneously conclude that it had
been rehashed.  This is what leads to the EBUSY error.

This patch fixes this by remembering the current last table we
used during insertion so that rhashtable_insert_rehash can detect
when another thread has also done a resize/rehash.  When this is
detected we will give up our resize/rehash and simply retry the
insertion with the new table.

Reported-by: Thomas Graf <tgraf@suug.ch>
Reported-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Tested-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-04 14:38:26 -05:00
Dmitriy Vyukov 7def0f952e lib: fix data race in rhashtable_rehash_one
rhashtable_rehash_one() uses complex logic to update entry->next field,
after INIT_RHT_NULLS_HEAD and NULLS_MARKER expansion:

entry->next = 1 | ((base + off) << 1)

This can be compiled along the lines of:

entry->next = base + off
entry->next <<= 1
entry->next |= 1

Which will break concurrent readers.

NULLS value recomputation is not needed here, so just remove
the complex logic.

The data race was found with KernelThreadSanitizer (KTSAN).

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-22 17:36:07 -07:00
Phil Sutter 142b942a75 rhashtable: fix for resize events during table walk
If rhashtable_walk_next detects a resize operation in progress, it jumps
to the new table and continues walking that one. But it misses to drop
the reference to it's current item, leading it to continue traversing
the new table's bucket in which the current item is sorted into, and
after reaching that bucket's end continues traversing the new table's
second bucket instead of the first one, thereby potentially missing
items.

This fixes the rhashtable runtime test for me. Bug probably introduced
by Herbert Xu's patch eddee5ba ("rhashtable: Fix walker behaviour during
rehash") although not explicitly tested.

Fixes: eddee5ba ("rhashtable: Fix walker behaviour during rehash")
Signed-off-by: Phil Sutter <phil@nwl.cc>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-07-08 14:53:49 -07:00
David S. Miller 941742f497 Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2015-06-08 20:06:56 -07:00
Hauke Mehrtens 6d7954130c rhashtable: add missing import <linux/export.h>
rhashtable uses EXPORT_SYMBOL_GPL() without importing linux/export.h
directly it is only imported indirectly through some other includes.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-06-07 00:10:15 -07:00
David S. Miller 36583eb54d Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
Conflicts:
	drivers/net/ethernet/cadence/macb.c
	drivers/net/phy/phy.c
	include/linux/skbuff.h
	net/ipv4/tcp.c
	net/switchdev/switchdev.c

Switchdev was a case of RTNH_H_{EXTERNAL --> OFFLOAD}
renaming overlapping with net-next changes of various
sorts.

phy.c was a case of two changes, one adding a local
variable to a function whilst the second was removing
one.

tcp.c overlapped a deadlock fix with the addition of new tcp_info
statistic values.

macb.c involved the addition of two zyncq device entries.

skbuff.h involved adding back ipv4_daddr to nf_bridge_info
whilst net-next changes put two other existing members of
that struct into a union.

Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-23 01:22:35 -04:00
Herbert Xu 07ee0722bf rhashtable: Add cap on number of elements in hash table
We currently have no limit on the number of elements in a hash table.
This is a problem because some users (tipc) set a ceiling on the
maximum table size and when that is reached the hash table may
degenerate.  Others may encounter OOM when growing and if we allow
insertions when that happens the hash table perofrmance may also
suffer.

This patch adds a new paramater insecure_max_entries which becomes
the cap on the table.  If unset it defaults to max_size * 2.  If
it is also zero it means that there is no cap on the number of
elements in the table.  However, the table will grow whenever the
utilisation hits 100% and if that growth fails, you will get ENOMEM
on insertion.

As allowing oversubscription is potentially dangerous, the name
contains the word insecure.

Note that the cap is not a hard limit.  This is done for performance
reasons as enforcing a hard limit will result in use of atomic ops
that are heavier than the ones we currently use.

The reasoning is that we're only guarding against a gross over-
subscription of the table, rather than a small breach of the limit.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-16 18:08:26 -04:00
Thomas Graf c936a79fc0 rhashtable: Simplify iterator code
Remove useless obj variable and goto logic.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-05 19:30:47 -04:00
Thomas Graf a87b9ebf17 rhashtable: Do not schedule more than one rehash if we can't grow further
The current code currently only stops inserting rehashes into the
chain when no resizes are currently scheduled. As long as resizes
are scheduled and while inserting above the utilization watermark,
more and more rehashes will be scheduled.

This lead to a perfect DoS storm with thousands of rehashes
scheduled which lead to thousands of spinlocks to be taken
sequentially.

Instead, only allow either a series of resizes or a single rehash.
Drop any further rehashes and return -EBUSY.

Fixes: ccd57b1bd3 ("rhashtable: Add immediate rehash during insertion")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-22 14:17:22 -04:00
Thomas Graf e2307ed6cb rhashtable: Schedule async resize when sync realloc fails
When rhashtable_insert_rehash() fails with ENOMEM, this indicates that
we can't allocate the necessary memory in the current context but the
limits as set by the user would still allow to grow.

Thus attempt an async resize in the background where we can allocate
using GFP_KERNEL which is more likely to succeed. The insertion itself
will still fail to indicate pressure.

This fixes a bug where the table would never continue growing once the
utilization is above 100%.

Fixes: ccd57b1bd3 ("rhashtable: Add immediate rehash during insertion")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-22 14:17:22 -04:00
Patrick McHardy 49f7b33e63 rhashtable: provide len to obj_hashfn
nftables sets will be converted to use so called setextensions, moving
the key to a non-fixed position. To hash it, the obj_hashfn must be used,
however it so far doesn't receive the length parameter.

Pass the key length to obj_hashfn() and convert existing users.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2015-03-25 17:18:33 +01:00
Thomas Graf 6b6f302ced rhashtable: Add rhashtable_free_and_destroy()
rhashtable_destroy() variant which stops rehashes, iterates over
the table and calls a callback to release resources.

Avoids need for nft_hash to embed rhashtable internals and allows to
get rid of the being_destroyed flag. It also saves a 2nd mutex
lock upon destruction.

Also fixes an RCU lockdep splash on nft set destruction due to
calling rht_for_each_entry_safe() without holding bucket locks.
Open code this loop as we need know that no mutations may occur in
parallel.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 17:48:40 -04:00
Thomas Graf b5e2c150ac rhashtable: Disable automatic shrinking by default
Introduce a new bool automatic_shrinking to require the
user to explicitly opt-in to automatic shrinking of tables.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 17:48:40 -04:00
Thomas Graf 299e5c32a3 rhashtable: Use 'unsigned int' consistently
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 17:48:39 -04:00
Herbert Xu 27ed44a5d6 rhashtable: Add comment on choice of elasticity value
This patch adds a comment on the choice of the value 16 as the
maximum chain length before we force a rehash.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:57:04 -04:00
Herbert Xu ba7c95ea38 rhashtable: Fix sleeping inside RCU critical section in walk_stop
The commit 963ecbd41a ("rhashtable:
Fix use-after-free in rhashtable_walk_stop") fixed a real bug
but created another one because we may end up sleeping inside an
RCU critical section.

This patch fixes it properly by replacing the mutex with a spin
lock that specifically protects the walker lists.

Reported-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:16:07 -04:00
Herbert Xu ccd57b1bd3 rhashtable: Add immediate rehash during insertion
This patch reintroduces immediate rehash during insertion.  If
we find during insertion that the table is full or the chain
length exceeds a set limit (currently 16 but may be disabled
with insecure_elasticity) then we will force an immediate rehash.
The rehash will contain an expansion if the table utilisation
exceeds 75%.

If this rehash fails then the insertion will fail.  Otherwise the
insertion will be reattempted in the new hash table.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:52 -04:00
Herbert Xu b9ecfdaa10 rhashtable: Allow GFP_ATOMIC bucket table allocation
This patch adds the ability to allocate bucket table with GFP_ATOMIC
instead of GFP_KERNEL.  This is needed when we perform an immediate
rehash during insertion.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:52 -04:00
Herbert Xu b824478b21 rhashtable: Add multiple rehash support
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: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:52 -04:00
Herbert Xu 18093d1c0d rhashtable: Shrink to fit
This patch changes rhashtable_shrink to shrink to the smallest
size possible rather than halving the table.  This is needed
because with multiple rehashing we will defer shrinking until
all other rehashing is done, meaning that when we do shrink
we may be able to shrink a lot.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:52 -04:00
Herbert Xu 31ccde2dac rhashtable: Allow hashfn to be unset
Since every current rhashtable user uses jhash as their hash
function, the fact that jhash is an inline function causes each
user to generate a copy of its code.

This function provides a solution to this problem by allowing
hashfn to be unset.  In which case rhashtable will automatically
set it to jhash.  Furthermore, if the key length is a multiple
of 4, we will switch over to jhash2.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:51 -04:00
Herbert Xu d88252f9bb rhashtable: Add barrier to ensure we see new tables in walker
The walker is a lockless reader so it too needs an smp_rmb before
reading the future_tbl field in order to see any new tables that
may contain elements that we should have walked over.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-23 22:07:51 -04:00
Herbert Xu dc0ee268d8 rhashtable: Rip out obsolete out-of-line interface
Now that all rhashtable users have been converted over to the
inline interface, this patch removes the unused out-of-line
interface.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 16:16:24 -04:00
Herbert Xu 02fd97c3d4 rhashtable: Allow hash/comparison functions to be inlined
This patch deals with the complaint that we make indirect function
calls on the fast paths unnecessarily in rhashtable.  We resolve
it by moving the fast paths into inline functions that take struct
rhashtable_param (which obviously must be the same set of parameters
supplied to rhashtable_init) as an argument.

The only remaining indirect call is to obj_hashfn (or key_hashfn it
obj_hashfn is unset) on the rehash as well as the insert-during-
rehash slow path.

This patch also extends the support of vairable-length keys to
include those where the key is fixed but scattered in the object.
For example, in netlink we want to key off the namespace and the
portid but they're not next to each other.

This patch does this by directly using the object hash function
as the indicator of whether the key is accessible or not.  It
also adds a new function obj_cmpfn to compare a key against an
object.  This means that the caller no longer needs to supply
explicit compare functions.

All this is done in a backwards compatible manner so no existing
users are affected until they convert to the new interface.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 16:16:24 -04:00
Herbert Xu 488fb86ee9 rhashtable: Make rhashtable_init params argument const
This patch marks the rhashtable_init params argument const as
there is no reason to modify it since we will always make a copy
of it in the rhashtable.

This patch also fixes a bug where we don't actually round up the
value of min_size unless it is less than HASH_MIN_SIZE.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 16:16:24 -04:00
Thomas Graf a998f712f7 rhashtable: Round up/down min/max_size to ensure we respect limit
Round up min_size respectively round down max_size to the next power
of two to make sure we always respect the limit specified by the
user. This is required because we compare the table size against the
limit before we expand or shrink.

Also fixes a minor bug where we modified min_size in the params
provided instead of the copy stored in struct rhashtable.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-19 21:02:23 -04:00
Herbert Xu e2e21c1c58 rhashtable: Remove max_shift and min_shift
Now that nobody uses max_shift and min_shift, we can safely remove
them.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-18 12:46:41 -04:00
Herbert Xu c2e213cff7 rhashtable: Introduce max_size/min_size
This patch adds the parameters max_size and min_size which are
meant to replace max_shift and min_shift.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-18 12:46:40 -04:00
Herbert Xu 6aebd94084 rhashtable: Remove shift from bucket_table
Keeping both size and shift is silly.  We only need one.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-18 12:46:40 -04:00
Thomas Graf 617011e7d5 rhashtable: Avoid calculating hash again to unlock
Caching the lock pointer avoids having to hash on the object
again to unlock the bucket locks.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-16 17:14:34 -04:00
Thomas Graf db4374f48a rhashtable: Annotate RCU locking of walkers
Fixes the following sparse warnings:

lib/rhashtable.c:767:5: warning: context imbalance in 'rhashtable_walk_start' - wrong count at exit
lib/rhashtable.c:849:6: warning: context imbalance in 'rhashtable_walk_stop' - unexpected unlock

Fixes: f2dba9c6ff ("rhashtable: Introduce rhashtable_walk_*")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-16 16:24:13 -04:00
Herbert Xu 565e86404e rhashtable: Fix rhashtable_remove failures
The commit 9d901bc051 ("rhashtable:
Free bucket tables asynchronously after rehash") causes gratuitous
failures in rhashtable_remove.

The reason is that it inadvertently introduced multiple rehashing
from the perspective of readers.  IOW it is now possible to see
more than two tables during a single RCU critical section.

Fortunately the other reader rhashtable_lookup already deals with
this correctly thanks to c4db8848af
("rhashtable: rhashtable: Move future_tbl into struct bucket_table")
so only rhashtable_remove is broken by this change.

This patch fixes this by looping over every table from the first
one to the last or until we find the element that we were trying
to delete.

Incidentally the simple test for detecting rehashing to prevent
starting another shrinking no longer works.  Since it isn't needed
anyway (the work queue and the mutex serves as a natural barrier
to unnecessary rehashes) I've simply killed the test.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 22:22:08 -04:00
Herbert Xu 963ecbd41a rhashtable: Fix use-after-free in rhashtable_walk_stop
The commit c4db8848af ("rhashtable:
Move future_tbl into struct bucket_table") introduced a use-after-
free bug in rhashtable_walk_stop because it dereferences tbl after
droping the RCU read lock.

This patch fixes it by moving the RCU read unlock down to the bottom
of rhashtable_walk_stop.  In fact this was how I had it originally
but it got dropped while rearranging patches because this one
depended on the async freeing of bucket_table.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 22:22:08 -04:00
Herbert Xu c4db8848af rhashtable: Move future_tbl into struct bucket_table
This patch moves future_tbl to open up the possibility of having
multiple rehashes on the same table.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu 63d512d0cf rhashtable: Add rehash counter to bucket_table
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: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu 9d901bc051 rhashtable: Free bucket tables asynchronously after rehash
There is in fact no need to wait for an RCU grace period in the
rehash function, since all insertions are guaranteed to go into
the new table through spin locks.

This patch uses call_rcu to free the old/rehashed table at our
leisure.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu 5269b53da4 rhashtable: Move seed init into bucket_table_alloc
It seems that I have already made every rehash redo the random
seed even though my commit message indicated otherwise :)

Since we have already taken that step, this patch goes one step
further and moves the seed initialisation into bucket_table_alloc.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu 8f2484bdb5 rhashtable: Use SINGLE_DEPTH_NESTING
We only nest one level deep there is no need to roll our own
subclasses.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu eddee5ba34 rhashtable: Fix walker behaviour during rehash
Previously whenever the walker encountered a resize it simply
snaps back to the beginning and starts again.  However, this only
works if the rehash started and completed while the walker was
idle.

If the walker attempts to restart while the rehash is still ongoing,
we may miss objects that we shouldn't have.

This patch fixes this by making the walker walk the old table
followed by the new table just like all other readers.  If a
rehash is detected we will still signal our caller of the fact
so they can prepare for duplicates but we will simply continue
the walk onto the new table after the old one is finished either
by us or by the rehasher.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 01:35:34 -04:00
Herbert Xu 393619474e rhashtable: Fix read-side crash during rehash
This patch fixes a typo rhashtable_lookup_compare where we fail
to recompute the hash when looking up the new table.  This causes
elements to be missed and potentially a crash during a resize.

Reported-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 23:02:30 -04:00
Daniel Borkmann a5b6846f9e rhashtable: kill ht->shift atomic operations
Commit c0c09bfdc4 ("rhashtable: avoid unnecessary wakeup for worker
queue") changed ht->shift to be atomic, which is actually unnecessary.

Instead of leaving the current shift in the core rhashtable structure,
it can be cached inside the individual bucket tables.

There, it will only be initialized once during a new table allocation
in the shrink/expansion slow path, and from then onward it stays immutable
for the rest of the bucket table liftime.

That allows shift to be non-atomic. The patch also moves hash_rnd
management into the table setup. The rhashtable structure now consumes
3 instead of 4 cachelines.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ying Xue <ying.xue@windriver.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 23:02:30 -04:00
Herbert Xu 9497df88ab rhashtable: Fix reader/rehash race
There is a potential race condition between readers and the rehasher.
In particular, the rehasher could have started a rehash while the
reader finishes a scan of the old table but fails to see the new
table pointer.

This patch closes this window by adding smp_wmb/smp_rmb.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 23:02:30 -04:00
Herbert Xu ec9f71c59e rhashtable: Remove obj_raw_hashfn
Now that the only caller of obj_raw_hashfn is head_hashfn, we can
simply kill it and fold it into the latter.

This patch also moves the common shift from head_hashfn/key_hashfn
into rht_bucket_index.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 14:35:30 -04:00
Herbert Xu cffaa9cb92 rhashtable: Remove key length argument to key_hashfn
key_hashfn has only one caller and it doesn't really need to supply
the key length as an extra parameter.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 14:35:30 -04:00
Herbert Xu eca8493330 rhashtable: Use head_hashfn instead of obj_raw_hashfn
Now that we don't have cross-table hashes, we no longer need to
keep the entire hash value so all users of obj_raw_hashfn can
use head_hashfn instead.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 14:35:30 -04:00
Herbert Xu 8d2b18793d rhashtable: Move masking back into key_hashfn
This patch reverts commit c88455ce50
("rhashtable: key_hashfn() must return full hash value") because
the only user of it always masks the hash value.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 14:35:30 -04:00
Herbert Xu 84ed82b74d rhashtable: Add annotation to nested lock
Commit aa34a6cb04 ("rhashtable:
Add arbitrary rehash function") killed the annotation on the
nested lock which leads to bitching from lockdep.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 23:53:40 -04:00
Herbert Xu aa34a6cb04 rhashtable: Add arbitrary rehash function
This patch adds a rehash function that supports the use of any
hash function for the new table.  This is needed to support changing
the random seed value during the lifetime of the hash table.

However for now the random seed value is still constant and the
rehash function is simply used to replace the existing expand/shrink
functions.

[ ASSERT_BUCKET_LOCK() and thus debug_dump_table() +
  debug_dump_buckets() are not longer used, so delete them
  entirely. -DaveM ]

Signed-off-by: Herbert Xu <herbert.xu@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 16:36:21 -04:00
Herbert Xu 988dfbd795 rhashtable: Move hash_rnd into bucket_table
Currently hash_rnd is a parameter that users can set.  However,
no existing users set this parameter.  It is also something that
people are unlikely to want to set directly since it's just a
random number.

In preparation for allowing the reseeding/rehashing of rhashtable,
this patch moves hash_rnd into bucket_table so that it's now an
internal state rather than a parameter.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 16:28:25 -04:00
Eric Dumazet 5beb5c90c1 rhashtable: use cond_resched()
If a hash table has 128 slots and 16384 elems, expand to 256 slots
takes more than one second. For larger sets, a soft lockup is detected.

Holding cpu for that long, even in a work queue is a show stopper
for non preemptable kernels.

cond_resched() at strategic points to allow process scheduler
to reschedule us.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-27 17:55:14 -05:00
Daniel Borkmann 4c4b52d9b2 rhashtable: remove indirection for grow/shrink decision functions
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: David S. Miller <davem@davemloft.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-27 16:06:02 -05:00
Daniel Borkmann 8331de75cb rhashtable: unconditionally grow when max_shift is not specified
While commit c0c09bfdc4 ("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: Josh Hunt <johunt@akamai.com>
Fixes: c0c09bfdc4 ("rhashtable: avoid unnecessary wakeup for worker queue")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: Josh Hunt <johunt@akamai.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-27 16:06:02 -05:00
Sasha Levin 71bb0012c3 rhashtable: initialize all rhashtable walker members
Commit f2dba9c6ff ("rhashtable: Introduce rhashtable_walk_*") forgot to
initialize the members of struct rhashtable_walker after allocating it, which
caused an undefined value for 'resize' which is used later on.

Fixes: f2dba9c6ff ("rhashtable: Introduce rhashtable_walk_*")
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-23 15:23:19 -05:00
Daniel Borkmann eb6d1abf1b rhashtable: better high order allocation attempts
When trying to allocate future tables via bucket_table_alloc(), it seems
overkill on large table shifts that we probe for kzalloc() unconditionally
first, as it's likely to fail.

Only probe with kzalloc() for more reasonable table sizes and use vzalloc()
either as a fallback on failure or directly in case of large table sizes.

Fixes: 7e1e77636e ("lib: Resizable, Scalable, Concurrent Hash Table")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-20 17:38:09 -05:00
Daniel Borkmann 342100d937 rhashtable: don't test for shrink on insert, expansion on delete
Restore pre 54c5b7d311 behaviour and only probe for expansions on inserts
and shrinks on deletes. Currently, it will happen that on initial inserts
into a sparse hash table, we may i.e. shrink it first simply because it's
not fully populated yet, only to later realize that we need to grow again.

This however is counter intuitive, e.g. an initial default size of 64
elements is already small enough, and in case an elements size hint is given
to the hash table by a user, we should avoid unnecessary expansion steps,
so a shrink is clearly unintended here.

Fixes: 54c5b7d311 ("rhashtable: introduce rhashtable_wakeup_worker helper function")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Ying Xue <ying.xue@windriver.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-20 17:38:09 -05:00
Stephen Rothwell 61d7b09773 rhashtable: using ERR_PTR requires linux/err.h
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-08 21:52:24 -08:00
Thomas Graf 020219a69d rhashtable: Fix remove logic to avoid cross references between buckets
The remove logic properly searched the remaining chain for a matching
entry with an identical hash but it did this while searching from both
the old and new table. Instead in order to not leave stale references
behind we need to:

 1. When growing and searching from the new table:
    Search remaining chain for entry with same hash to avoid having
    the new table directly point to a entry with a different hash.

 2. When shrinking and searching from the old table:
    Check if the element after the removed would create a cross
    reference and avoid it if so.

These bugs were present from the beginning in nft_hash.

Also, both insert functions calculated the hash based on the mask of
the new table. This worked while growing. Wwhile shrinking, the mask
of the inew table is smaller than the mask of the old table. This lead
to a bit not being taken into account when selecting the bucket lock
and thus caused the wrong bucket to be locked eventually.

Fixes: 7e1e77636e ("lib: Resizable, Scalable, Concurrent Hash Table")
Fixes: 97defe1ecf ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Reported-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:19:17 -08:00
Thomas Graf cf52d52f9c rhashtable: Avoid bucket cross reference after removal
During a resize, when two buckets in the larger table map to
a single bucket in the smaller table and the new table has already
been (partially) linked to the old table. Removal of an element
may result the bucket in the larger table to point to entries
which all hash to a different value than the bucket index. Thus
causing two buckets to point to the same sub chain after unzipping.
This is not illegal *during* the resize phase but after it has
completed.

Keep the old table around until all of the unzipping is done to
allow the removal code to only search for matching hashed entries
during this special period.

Reported-by: Ying Xue <ying.xue@windriver.com>
Fixes: 97defe1ecf ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:35 -08:00
Thomas Graf 7cd10db8de rhashtable: Add more lock verification
Catch hash miscalculations which result in hard to track down race
conditions.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:34 -08:00
Thomas Graf a03eaec0df rhashtable: Dump bucket tables on locking violation under PROVE_LOCKING
This simplifies debugging of locking violations if compiled with
CONFIG_PROVE_LOCKING.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:34 -08:00
Thomas Graf 2af4b52988 rhashtable: Wait for RCU readers after final unzip work
We need to wait for all RCU readers to complete after the last bit of
unzipping has been completed. Otherwise the old table is freed up
prematurely.

Fixes: 7e1e77636e ("lib: Resizable, Scalable, Concurrent Hash Table")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:34 -08:00
Thomas Graf a5ec68e3b8 rhashtable: Use a single bucket lock for sibling buckets
rhashtable currently allows to use a bucket lock per bucket. This
requires multiple levels of complicated nested locking because when
resizing, a single bucket of the smaller table will map to two
buckets in the larger table. So far rhashtable has explicitly locked
both buckets in the larger table.

By excluding the highest bit of the hash from the bucket lock map and
thus only allowing locks to buckets in a ratio of 1:2, the locking
can be simplified a lot without losing the benefits of multiple locks.
Larger tables which benefit from multiple locks will not have a single
lock per bucket anyway.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:34 -08:00
Thomas Graf c88455ce50 rhashtable: key_hashfn() must return full hash value
The value computed by key_hashfn() is used by rhashtable_lookup_compare()
to traverse both tables during a resize. key_hashfn() must therefore
return the hash value without the buckets mask applied so it can be
masked to the size of each individual table.

Fixes: 97defe1ecf ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-06 15:18:34 -08:00
Herbert Xu f2dba9c6ff rhashtable: Introduce rhashtable_walk_*
Some existing rhashtable users get too intimate with it by walking
the buckets directly.  This prevents us from easily changing the
internals of rhashtable.

This patch adds the helpers rhashtable_walk_init/exit/start/next/stop
which will replace these custom walkers.

They are meant to be usable for both procfs seq_file walks as well
as walking by a netlink dump.  The iterator structure should fit
inside a netlink dump cb structure, with at least one element to
spare.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 20:34:52 -08:00
Herbert Xu 28134a53d6 rhashtable: Fix potential crash on destroy in rhashtable_shrink
The current being_destroyed check in rhashtable_expand is not
enough since if we start a shrinking process after freeing all
elements in the table that's also going to crash.

This patch adds a being_destroyed check to the deferred worker
thread so that we bail out as soon as we take the lock.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 20:34:52 -08:00
Geert Uytterhoeven 9d6dbe1bba rhashtable: Make selftest modular
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: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-30 18:06:33 -08:00
Thomas Graf fe6a043c53 rhashtable: rhashtable_remove() must unlink in both tbl and future_tbl
As removals can occur during resizes, entries may be referred to from
both tbl and future_tbl when the removal is requested. Therefore
rhashtable_remove() must unlink the entry in both tables if this is
the case. The existing code did search both tables but stopped when it
hit the first match.

Failing to unlink in both tables resulted in use after free.

Fixes: 97defe1ecf ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Reported-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-26 11:56:34 -08:00
Ying Xue 57699a40b4 rhashtable: Fix race in rhashtable_destroy() and use regular work_struct
When we put our declared work task in the global workqueue with
schedule_delayed_work(), its delay parameter is always zero.
Therefore, we should define a regular work in rhashtable structure
instead of a delayed work.

By the way, we add a condition to check whether resizing functions
are NULL before cancelling the work, avoiding to cancel an
uninitialized work.

Lastly, while we wait for all work items we submitted before to run
to completion with cancel_delayed_work(), ht->mutex has been taken in
rhashtable_destroy(). Moreover, cancel_delayed_work() doesn't return
until all work items are accomplished, and when work items are
scheduled, the work's function - rht_deferred_worker() will be called.
However, as rht_deferred_worker() also needs to acquire the lock,
deadlock might happen at the moment as the lock is already held before.
So if the cancel work function is moved out of the lock covered scope,
this will avoid the deadlock.

Fixes: 97defe1 ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-16 01:18:51 -05:00
Thomas Graf 80ca8c3a84 rhashtable: Lower/upper bucket may map to same lock while shrinking
Each per bucket lock covers a configurable number of buckets. While
shrinking, two buckets in the old table contain entries for a single
bucket in the new table. We need to lock down both while linking.
Check if they are protected by different locks to avoid a recursive
lock.

Fixes: 97defe1e ("rhashtable: Per bucket locks & deferred expansion/shrinking")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-14 00:21:44 -05:00
Ying Xue 7a868d1e9a rhashtable: involve rhashtable_lookup_compare_insert routine
Introduce a new function called rhashtable_lookup_compare_insert()
which is very similar to rhashtable_lookup_insert(). But the former
makes use of users' given compare function to look for an object,
and then inserts it into hash table if found. As the entire process
of search and insertion is under protection of per bucket lock, this
can help users to avoid the involvement of extra lock.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-13 14:01:00 -05:00
Ying Xue 545a148e43 rhashtable: initialize atomic nelems variable
Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-08 19:47:13 -08:00
Ying Xue c0c09bfdc4 rhashtable: avoid unnecessary wakeup for worker queue
Move condition statements of verifying whether hash table size exceeds
its maximum threshold or reaches its minimum threshold from resizing
functions to resizing decision functions, avoiding unnecessary wakeup
for worker queue thread.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-08 19:47:11 -08:00
Ying Xue bd6d4db552 rhashtable: future table needs to be traversed when remove an object
When remove an object from hash table, we currently only traverse old
bucket table to check whether the object exists. If the object is not
found in it, we will try again. But in the second search loop, we still
search the object from the old table instead of future table. As a
result, the object may be not removed from hash table especially when
resizing is currently in progress and the object is just saved in the
future table.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-08 19:47:11 -08:00
Ying Xue db30485408 rhashtable: involve rhashtable_lookup_insert routine
Involve a new function called rhashtable_lookup_insert() which makes
lookup and insertion atomic under bucket lock protection, helping us
avoid to introduce an extra lock when we search and insert an object
into hash table.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-08 19:47:11 -08:00
Ying Xue 54c5b7d311 rhashtable: introduce rhashtable_wakeup_worker helper function
Introduce rhashtable_wakeup_worker() helper function to reduce
duplicated code where to wake up worker.

By the way, as long as the both "future_tbl" and "tbl" bucket table
pointers point to the same bucket array, we should try to wake up
the resizing worker thread, otherwise, it indicates the work of
resizing hash table is not finished yet. However, currently we will
wake up the worker thread only when the two pointers point to
different bucket array. Obviously this is wrong. So, the issue is
also fixed as well in the patch.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Cc: Thomas Graf <tgraf@suug.ch>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-08 19:47:10 -08:00