diff options
| author | Thomas Graf <tgraf@suug.ch> | 2015-01-12 23:58:21 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2015-01-14 00:21:44 -0500 |
| commit | 80ca8c3a84c74a87977558861bb8eef650732912 (patch) | |
| tree | e275dc10e62e28ea8b7f4c25e6a30664974e233f /lib | |
| parent | df8a39defad46b83694ea6dd868d332976d62cc0 (diff) | |
| download | lwn-80ca8c3a84c74a87977558861bb8eef650732912.tar.gz lwn-80ca8c3a84c74a87977558861bb8eef650732912.zip | |
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>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/rhashtable.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/lib/rhashtable.c b/lib/rhashtable.c index ed6ae1ad304c..aca699813ba9 100644 --- a/lib/rhashtable.c +++ b/lib/rhashtable.c @@ -443,8 +443,16 @@ int rhashtable_shrink(struct rhashtable *ht) new_bucket_lock = bucket_lock(new_tbl, new_hash); spin_lock_bh(old_bucket_lock1); - spin_lock_bh_nested(old_bucket_lock2, RHT_LOCK_NESTED); - spin_lock_bh_nested(new_bucket_lock, RHT_LOCK_NESTED2); + + /* Depending on the lock per buckets mapping, the bucket in + * the lower and upper region may map to the same lock. + */ + if (old_bucket_lock1 != old_bucket_lock2) { + spin_lock_bh_nested(old_bucket_lock2, RHT_LOCK_NESTED); + spin_lock_bh_nested(new_bucket_lock, RHT_LOCK_NESTED2); + } else { + spin_lock_bh_nested(new_bucket_lock, RHT_LOCK_NESTED); + } rcu_assign_pointer(*bucket_tail(new_tbl, new_hash), tbl->buckets[new_hash]); @@ -452,7 +460,8 @@ int rhashtable_shrink(struct rhashtable *ht) tbl->buckets[new_hash + new_tbl->size]); spin_unlock_bh(new_bucket_lock); - spin_unlock_bh(old_bucket_lock2); + if (old_bucket_lock1 != old_bucket_lock2) + spin_unlock_bh(old_bucket_lock2); spin_unlock_bh(old_bucket_lock1); } |