Change the default RDMA driver from rdma_rxe to siw

Since the siw driver is more stable than the rdma_rxe driver, change the
default into siw. See e.g.
https://lore.kernel.org/all/c3d1a966-b9b0-d015-38ec-86270b5045fc@acm.org/.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>

Documentation/running-tests.md

@@ -110,17 +110,19 @@ The NVMe tests can be additionally parameterized via environment variables.
 - nvme_num_iter: 1000 (default)
   The number of iterations a test should do.
 
-### Running nvme-rdma srp tests
+### Running nvme-rdma and SRP tests
+
+These tests will use the siw (soft-iWARP) driver by default. The rdma_rxe
+(soft-RoCE) driver is also supported.
 
-Most of these tests will use the rdma_rxe (soft-RoCE) driver by default. The siw (soft-iWARP) driver is also supported.
 ```sh
-To use the rdma_rxe driver:
+To use the siw driver:
 nvme_trtype=rdma ./check nvme/
 ./check srp/
 
-To use the siw driver:
-use_siw=1 nvme_trtype=rdma ./check nvme/
-use_siw=1 ./check srp/
+To use the rdma_rxe driver:
+use_rxe=1 nvme_trtype=rdma ./check nvme/
+use_rxe=1 ./check srp/
 ```
 
 ### Normal user

common/multipath-over-rdma

@@ -12,7 +12,7 @@ filesystem_type=ext4
 fio_aux_path=/tmp/fio-state-files
 memtotal=$(sed -n 's/^MemTotal:[[:blank:]]*\([0-9]*\)[[:blank:]]*kB$/\1/p' /proc/meminfo)
 max_ramdisk_size=$((1<<25))
-use_siw=${use_siw:-""}
+use_rxe=${use_rxe:-""}
 ramdisk_size=$((memtotal*(1024/16)))  # in bytes
 if [ $ramdisk_size -gt $max_ramdisk_size ]; then
 	ramdisk_size=$max_ramdisk_size
@@ -396,7 +396,7 @@ start_soft_rdma() {
 	local type
 
 	{
-	if [ -n "$use_siw" ]; then
+	if [ -z "$use_rxe" ]; then
 		modprobe siw || return $?
 		type=siw
 	else

tests/srp/rc

@@ -51,7 +51,13 @@ group_requires() {
 	_have_module ib_uverbs
 	_have_module null_blk
 	_have_module rdma_cm
-	_have_module rdma_rxe
+	if [ -n "$use_rxe" ]; then
+		_have_module rdma_rxe
+	else
+		_have_module siw
+		_have_kver 5 5
+		_have_iproute2 190404
+	fi
 	_have_module scsi_debug
 	_have_module target_core_iblock
 	_have_module target_core_mod