[dpdk-stable] patch 'hash: fix eviction counter' has been queued to stable release 17.08.1

[Yuanhan Liu]

Hi,

FYI, your patch has been queued to stable release 17.08.1

Note it hasn't been pushed to http://dpdk.org/browse/dpdk-stable yet.
It will be pushed if I get no objections before 11/24/17. So please
shout if anyone has objections.

Thanks.

	--yliu

---
>From b0c63e4bd8d20f48891a29770a0b0955b5fc3d19 Mon Sep 17 00:00:00 2001
From: Pablo de Lara <pablo.de.lara.guarch at intel.com>
Date: Fri, 22 Sep 2017 05:25:43 +0100
Subject: [PATCH] hash: fix eviction counter

[ upstream commit 98b8ec70604065f511aea0a567b039421bc524cc ]

When adding a new entry in a hash table, there is
a maximum number of evictions that can be
performed. When the counter of these evictions reaches
this maximum, the entry cannot be added, as it is considered
that the algorithm has encountered an infinite loop.

The problem with the current implementation, is that this
counter was declared as a static variable.
If there are multiple threads adding entries in the same table
or in different tables, they should access different counters,
one per core and per table.

Therefore, the variable has been modified to be non-static.

Fixes: 243e93a5046f ("hash: fix unlimited cuckoo path")

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch at intel.com>
Acked-by: Bruce Richardson <bruce.richardson at intel.com>
---
 lib/librte_hash/rte_cuckoo_hash.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/lib/librte_hash/rte_cuckoo_hash.c b/lib/librte_hash/rte_cuckoo_hash.c
index 87b25c0..e69b911 100644
--- a/lib/librte_hash/rte_cuckoo_hash.c
+++ b/lib/librte_hash/rte_cuckoo_hash.c
@@ -417,9 +417,9 @@ rte_hash_reset(struct rte_hash *h)
 
 /* Search for an entry that can be pushed to its alternative location */
 static inline int
-make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
+make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt,
+		unsigned int *nr_pushes)
 {
-	static unsigned int nr_pushes;
 	unsigned i, j;
 	int ret;
 	uint32_t next_bucket_idx;
@@ -456,15 +456,14 @@ make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
 			break;
 
 	/* All entries have been pushed, so entry cannot be added */
-	if (i == RTE_HASH_BUCKET_ENTRIES || nr_pushes > RTE_HASH_MAX_PUSHES)
+	if (i == RTE_HASH_BUCKET_ENTRIES || ++(*nr_pushes) > RTE_HASH_MAX_PUSHES)
 		return -ENOSPC;
 
 	/* Set flag to indicate that this entry is going to be pushed */
 	bkt->flag[i] = 1;
 
-	nr_pushes++;
 	/* Need room in alternative bucket to insert the pushed entry */
-	ret = make_space_bucket(h, next_bkt[i]);
+	ret = make_space_bucket(h, next_bkt[i], nr_pushes);
 	/*
 	 * After recursive function.
 	 * Clear flags and insert the pushed entry
@@ -472,7 +471,6 @@ make_space_bucket(const struct rte_hash *h, struct rte_hash_bucket *bkt)
 	 * or return error
 	 */
 	bkt->flag[i] = 0;
-	nr_pushes = 0;
 	if (ret >= 0) {
 		next_bkt[i]->sig_alt[ret] = bkt->sig_current[i];
 		next_bkt[i]->sig_current[ret] = bkt->sig_alt[i];
@@ -515,6 +513,7 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 	unsigned n_slots;
 	unsigned lcore_id;
 	struct lcore_cache *cached_free_slots = NULL;
+	unsigned int nr_pushes = 0;
 
 	if (h->add_key == ADD_KEY_MULTIWRITER)
 		rte_spinlock_lock(h->multiwriter_lock);
@@ -648,7 +647,7 @@ __rte_hash_add_key_with_hash(const struct rte_hash *h, const void *key,
 		 * if successful or return error and
 		 * store the new slot back in the ring
 		 */
-		ret = make_space_bucket(h, prim_bkt);
+		ret = make_space_bucket(h, prim_bkt, &nr_pushes);
 		if (ret >= 0) {
 			prim_bkt->sig_current[ret] = sig;
 			prim_bkt->sig_alt[ret] = alt_hash;
-- 
2.7.4