net/mlx5: fix indexed pool local cache crash

[ upstream commit 7869d60 ]

Local cache for an indexed pool is not initialized in the situation when
all the indices are allocated on one CPU core and freed on another one.
That leads to a crash once we try to check its reference counter.
Check that the local cache is initialized before accessing this counter.

Fixes: d15c094 ("net/mlx5: add indexed pool local cache")

Signed-off-by: Alexander Kozyrev <akozyrev@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

drivers/net/mlx5/mlx5_utils.c

@@ -479,7 +479,7 @@ _mlx5_ipool_free_cache(struct mlx5_indexed_pool *pool, int cidx, uint32_t idx)
 	mlx5_ipool_lock(pool);
 	gc = pool->gc;
 	if (ilc->lc != gc) {
-		if (!(--ilc->lc->ref_cnt))
+		if (ilc->lc && !(--ilc->lc->ref_cnt))
 			olc = ilc->lc;
 		gc->ref_cnt++;
 		ilc->lc = gc;