RDMA/srp: Fix a recently introduced memory leak

Only allocate a memory registration list if it will be used and if it will
be freed.

Link: https://lore.kernel.org/r/20210524041211.9480-5-bvanassche@acm.org
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Fixes: f273ad4f8d ("RDMA/srp: Remove support for FMR memory registration")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -998,7 +998,6 @@ static int srp_alloc_req_data(struct srp_rdma_ch *ch)
 	struct srp_device *srp_dev = target->srp_host->srp_dev;
 	struct ib_device *ibdev = srp_dev->dev;
 	struct srp_request *req;
-	void *mr_list;
 	dma_addr_t dma_addr;
 	int i, ret = -ENOMEM;
 
@@ -1009,12 +1008,12 @@ static int srp_alloc_req_data(struct srp_rdma_ch *ch)
 
 	for (i = 0; i < target->req_ring_size; ++i) {
 		req = &ch->req_ring[i];
-		mr_list = kmalloc_array(target->mr_per_cmd, sizeof(void *),
-					GFP_KERNEL);
-		if (!mr_list)
-			goto out;
-		if (srp_dev->use_fast_reg)
-			req->fr_list = mr_list;
+		if (srp_dev->use_fast_reg) {
+			req->fr_list = kmalloc_array(target->mr_per_cmd,
+						sizeof(void *), GFP_KERNEL);
+			if (!req->fr_list)
+				goto out;
+		}
 		req->indirect_desc = kmalloc(target->indirect_size, GFP_KERNEL);
 		if (!req->indirect_desc)
 			goto out;