IB/mlx4: Bug fixes in mlx4_ib_resize_cq

1. Before the entries alignment, we need to check that the entries
doesn't exceed the device's max cqe.

2. After the alignment, we need to make sure that the aligned number
doesn't exceed the max cqes+1. The additional cqe is used to denote
that the resizing operation has completed.

3. If the users asks to resize the CQ with entries less than the
oustanding cqes we should fail instead of returning 0.

Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/mlx4/cq.c

@@ -367,8 +367,7 @@ int mlx4_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 	int err;
 
 	mutex_lock(&cq->resize_mutex);
-
-	if (entries < 1) {
+	if (entries < 1 || entries > dev->dev->caps.max_cqes) {
 		err = -EINVAL;
 		goto out;
 	}
@@ -379,7 +378,7 @@ int mlx4_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 		goto out;
 	}
 
-	if (entries > dev->dev->caps.max_cqes) {
+	if (entries > dev->dev->caps.max_cqes + 1) {
 		err = -EINVAL;
 		goto out;
 	}
@@ -392,7 +391,7 @@ int mlx4_ib_resize_cq(struct ib_cq *ibcq, int entries, struct ib_udata *udata)
 		/* Can't be smaller than the number of outstanding CQEs */
 		outst_cqe = mlx4_ib_get_outstanding_cqes(cq);
 		if (entries < outst_cqe + 1) {
-			err = 0;
+			err = -EINVAL;
 			goto out;
 		}