linux/lib/rhashtable.c, branch v4.3

lib: fix data race in rhashtable_rehash_one

2015-09-23T00:36:07Z

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 Acked-by: Eric Dumazet Acked-by: Thomas Graf Acked-by: Herbert Xu Signed-off-by: David S. Miller

rhashtable: fix for resize events during table walk

2015-07-08T21:53:49Z

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 Acked-by: Herbert Xu Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-06-09T03:06:56Z

rhashtable: add missing import

2015-06-07T07:10:15Z

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 Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net

2015-05-23T05:22:35Z

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

rhashtable: Add cap on number of elements in hash table

2015-05-16T22:08:26Z

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 Signed-off-by: David S. Miller

rhashtable: Simplify iterator code

2015-05-05T23:30:47Z

Remove useless obj variable and goto logic. Signed-off-by: Thomas Graf Acked-by: Herbert Xu Signed-off-by: David S. Miller

rhashtable: Do not schedule more than one rehash if we can't grow further

2015-04-22T18:17:22Z

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 Acked-by: Herbert Xu Signed-off-by: David S. Miller

rhashtable: Schedule async resize when sync realloc fails

2015-04-22T18:17:22Z

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 Acked-by: Herbert Xu Signed-off-by: David S. Miller

rhashtable: provide len to obj_hashfn

2015-03-25T16:18:33Z

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 Signed-off-by: Pablo Neira Ayuso