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* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2016-01-011-1/+2
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| * rhashtable: Kill harmless RCU warning in rhashtable_walk_initHerbert Xu2015-12-191-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit c6ff5268293ef98e48a99597e765ffc417e39fa5 ("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>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2015-12-181-27/+40
|\| | | | | | | | | | | | | | | | | | | | | 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>
| * rhashtable: Fix walker list corruptionHerbert Xu2015-12-161-9/+7Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("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: ba7c95ea3870 ("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>
| * rhashtable: Enforce minimum size on initial hash tableHerbert Xu2015-12-161-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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: a998f712f77e ("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>
| * Revert "rhashtable: Use __vmalloc with GFP_ATOMIC for table allocation"David S. Miller2015-12-061-3/+2Star
| | | | | | | | | | | | | | | | | | | | | | This reverts commit d3716f18a7d841565c930efde30737a3557eee69. 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>
| * rhashtable: Use __vmalloc with GFP_ATOMIC for table allocationHerbert Xu2015-12-041-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * rhashtable: Prevent spurious EBUSY errors on insertionHerbert Xu2015-12-041-15/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | rhashtable: Remove unnecessary wmb for future_tblHerbert Xu2015-12-091-3/+0Star
|/ | | | | | | | | | | | | | The patch 9497df88ab5567daa001829051c5f87161a81ff0 ("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>
* lib: fix data race in rhashtable_rehash_oneDmitriy Vyukov2015-09-231-4/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* rhashtable: fix for resize events during table walkPhil Sutter2015-07-081-2/+2
| | | | | | | | | | | | | | | | | | | 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>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2015-06-091-0/+1
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| * rhashtable: add missing import <linux/export.h>Hauke Mehrtens2015-06-071-0/+1
| | | | | | | | | | | | | | | | 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>
* | Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netDavid S. Miller2015-05-231-0/+11
|\| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
| * rhashtable: Add cap on number of elements in hash tableHerbert Xu2015-05-171-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* | rhashtable: Simplify iterator codeThomas Graf2015-05-061-6/+2Star
|/ | | | | | | | 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>
* rhashtable: Do not schedule more than one rehash if we can't grow furtherThomas Graf2015-04-221-2/+2
| | | | | | | | | | | | | | | | | | | 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: ccd57b1bd324 ("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>
* rhashtable: Schedule async resize when sync realloc failsThomas Graf2015-04-221-1/+6
| | | | | | | | | | | | | | | | | | 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: ccd57b1bd324 ("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>
* rhashtable: provide len to obj_hashfnPatrick McHardy2015-03-251-1/+1
| | | | | | | | | | | 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>
* rhashtable: Add rhashtable_free_and_destroy()Thomas Graf2015-03-241-10/+39
| | | | | | | | | | | | | | | | | 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>
* rhashtable: Disable automatic shrinking by defaultThomas Graf2015-03-241-1/+1
| | | | | | | | 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>
* rhashtable: Use 'unsigned int' consistentlyThomas Graf2015-03-241-8/+10
| | | | | Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
* rhashtable: Add comment on choice of elasticity valueHerbert Xu2015-03-241-0/+12
| | | | | | | | 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>
* rhashtable: Fix sleeping inside RCU critical section in walk_stopHerbert Xu2015-03-241-2/+5
| | | | | | | | | | | | | | The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("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>
* rhashtable: Add immediate rehash during insertionHerbert Xu2015-03-241-1/+59
| | | | | | | | | | | | | | | | 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>
* rhashtable: Allow GFP_ATOMIC bucket table allocationHerbert Xu2015-03-241-11/+15
| | | | | | | | | | 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>
* rhashtable: Add multiple rehash supportHerbert Xu2015-03-241-15/+72
| | | | | | | | | | | | | | | | | | | 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>
* rhashtable: Shrink to fitHerbert Xu2015-03-241-3/+10
| | | | | | | | | | | | 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>
* rhashtable: Allow hashfn to be unsetHerbert Xu2015-03-241-1/+16
| | | | | | | | | | | | | | | 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>
* rhashtable: Add barrier to ensure we see new tables in walkerHerbert Xu2015-03-241-0/+3
| | | | | | | | | | 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>
* rhashtable: Rip out obsolete out-of-line interfaceHerbert Xu2015-03-201-284/+0Star
| | | | | | | | | 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>
* rhashtable: Allow hash/comparison functions to be inlinedHerbert Xu2015-03-201-113/+50Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* rhashtable: Make rhashtable_init params argument constHerbert Xu2015-03-201-3/+4
| | | | | | | | | | | | | 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>
* rhashtable: Round up/down min/max_size to ensure we respect limitThomas Graf2015-03-201-2/+8
| | | | | | | | | | | | | | 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>
* rhashtable: Remove max_shift and min_shiftHerbert Xu2015-03-181-6/+1Star
| | | | | | | | 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>
* rhashtable: Introduce max_size/min_sizeHerbert Xu2015-03-181-4/+8
| | | | | | | | 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>
* rhashtable: Remove shift from bucket_tableHerbert Xu2015-03-181-3/+2Star
| | | | | | | 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>
* rhashtable: Avoid calculating hash again to unlockThomas Graf2015-03-161-6/+5Star
| | | | | | | | 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>
* rhashtable: Annotate RCU locking of walkersThomas Graf2015-03-161-0/+2
| | | | | | | | | | | 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: f2dba9c6ff0d ("rhashtable: Introduce rhashtable_walk_*") Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
* rhashtable: Fix rhashtable_remove failuresHerbert Xu2015-03-161-10/+7Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | The commit 9d901bc05153bbf33b5da2cd6266865e531f0545 ("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 c4db8848af6af92f90462258603be844baeab44d ("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>
* rhashtable: Fix use-after-free in rhashtable_walk_stopHerbert Xu2015-03-161-3/+4
| | | | | | | | | | | | | | | The commit c4db8848af6af92f90462258603be844baeab44d ("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>
* rhashtable: Move future_tbl into struct bucket_tableHerbert Xu2015-03-151-16/+11Star
| | | | | | | | 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>
* rhashtable: Add rehash counter to bucket_tableHerbert Xu2015-03-151-0/+1
| | | | | | | | | | | | | | | 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>
* rhashtable: Free bucket tables asynchronously after rehashHerbert Xu2015-03-151-3/+6
| | | | | | | | | | | | 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>
* rhashtable: Move seed init into bucket_table_allocHerbert Xu2015-03-151-10/+6Star
| | | | | | | | | | | 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>
* rhashtable: Use SINGLE_DEPTH_NESTINGHerbert Xu2015-03-151-7/+2Star
| | | | | | | | 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>
* rhashtable: Fix walker behaviour during rehashHerbert Xu2015-03-151-23/+46
| | | | | | | | | | | | | | | | | | | | 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>
* rhashtable: Fix read-side crash during rehashHerbert Xu2015-03-131-1/+1
| | | | | | | | | | 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>
* rhashtable: kill ht->shift atomic operationsDaniel Borkmann2015-03-131-30/+25Star
| | | | | | | | | | | | | | | | | | | | | Commit c0c09bfdc415 ("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>
* rhashtable: Fix reader/rehash raceHerbert Xu2015-03-131-0/+6
| | | | | | | | | | | | 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>
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