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authorJohannes Berg <johannes.berg@intel.com>2015-04-23 17:38:43 +0300
committerDavid S. Miller <davem@davemloft.net>2015-04-24 18:38:12 +0300
commit1d8dc3d3c8f1d8ee1da9d54c5d7c8694419ade42 (patch)
tree8fee42496cb0eccbd5f48d406fa219aa017229b0 /include/linux/rhashtable.h
parente580267df97eda407c525dbaee5430e0d51a0edb (diff)
downloadlinux-1d8dc3d3c8f1d8ee1da9d54c5d7c8694419ade42.tar.xz
rhashtable: don't attempt to grow when at max_size
The conversion of mac80211's station table to rhashtable had a bug that I found by accident in code review, that hadn't been found as rhashtable apparently managed to have a maximum hash chain length of one (!) in all our testing. In order to test the bug and verify the fix I set my rhashtable's max_size very low (4) in order to force getting hash collisions. At that point, rhashtable WARNed in rhashtable_insert_rehash() but didn't actually reject the hash table insertion. This caused it to lose insertions - my master list of stations would have 9 entries, but the rhashtable only had 5. This may warrant a deeper look, but that WARN_ON() just shouldn't happen. Fix this by not returning true from rht_grow_above_100() when the rhashtable's max_size has been reached - in this case the user is explicitly configuring it to be at most that big, so even if it's now above 100% it shouldn't attempt to resize. This fixes the "lost insertion" issue and consequently allows my code to display its error (and verify my fix for it.) Signed-off-by: Johannes Berg <johannes.berg@intel.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/linux/rhashtable.h')
-rw-r--r--include/linux/rhashtable.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index e23d242d1230..dbcbcc59aa92 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -282,7 +282,8 @@ static inline bool rht_shrink_below_30(const struct rhashtable *ht,
static inline bool rht_grow_above_100(const struct rhashtable *ht,
const struct bucket_table *tbl)
{
- return atomic_read(&ht->nelems) > tbl->size;
+ return atomic_read(&ht->nelems) > tbl->size &&
+ (!ht->p.max_size || tbl->size < ht->p.max_size);
}
/* The bucket lock is selected based on the hash and protects mutations