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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Leon Romanovsky <leon@kernel.org>,
        Doug Ledford <dledford@redhat.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 058/143] IB/rxe: put the pool on allocation failure
Date:   Fri,  2 Nov 2018 19:34:03 +0100
Message-Id: <20181102182901.715058348@linuxfoundation.org>
In-Reply-To: <20181102182857.064326086@linuxfoundation.org>
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4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 6b9f8970cd30929cb6b372fa44fa66da9e59c650 ]

If the allocation of elem fails, it is not sufficient to simply check
for NULL and return.  We need to also put our reference on the pool or
else we will leave the pool with a permanent ref count and we will never
be able to free it.

Fixes: 4831ca9e4a8e ("IB/rxe: check for allocation failure on elem")
Suggested-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: Doug Ledford <dledford@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/infiniband/sw/rxe/rxe_pool.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_pool.c b/drivers/infiniband/sw/rxe/rxe_pool.c
index 3b4916680018..b4a8acc7bb7d 100644
--- a/drivers/infiniband/sw/rxe/rxe_pool.c
+++ b/drivers/infiniband/sw/rxe/rxe_pool.c
@@ -394,23 +394,25 @@ void *rxe_alloc(struct rxe_pool *pool)
 
 	kref_get(&pool->rxe->ref_cnt);
 
-	if (atomic_inc_return(&pool->num_elem) > pool->max_elem) {
-		atomic_dec(&pool->num_elem);
-		rxe_dev_put(pool->rxe);
-		rxe_pool_put(pool);
-		return NULL;
-	}
+	if (atomic_inc_return(&pool->num_elem) > pool->max_elem)
+		goto out_put_pool;
 
 	elem = kmem_cache_zalloc(pool_cache(pool),
 				 (pool->flags & RXE_POOL_ATOMIC) ?
 				 GFP_ATOMIC : GFP_KERNEL);
 	if (!elem)
-		return NULL;
+		goto out_put_pool;
 
 	elem->pool = pool;
 	kref_init(&elem->ref_cnt);
 
 	return elem;
+
+out_put_pool:
+	atomic_dec(&pool->num_elem);
+	rxe_dev_put(pool->rxe);
+	rxe_pool_put(pool);
+	return NULL;
 }
 
 void rxe_elem_release(struct kref *kref)
-- 
2.17.1