Skip tests if scsi_debug module is already loaded and in use

Several tests across block/, scsi/, dm/, md/, zbd/, nvme/ require
exclusive access to the scsi_debug module because they load, unload
or reconfigure it. When scsi_debug is loadable and already loaded
by the environment (e.g., by another driver or a previous setup),
these tests fail with:

    modprobe: FATAL: Module scsi_debug is in use.
    Unloading scsi_debug failed

    scsi_debug            327680  4

To prevent these failures, this patch introduces a new helper function
_have_loadable_scsi_debug(). It verifies if the module is already loaded
by checking the ${MODULES_TO_UNLOAD[*]} array. If the module exists but
is not in the array, it indicates the module was loaded before the test
started, and the test is skipped.

Additionally, for cases where scsi_debug is built-in, the environment may
have already created additional hosts. To prevent the tests from disrupting
these hosts, _have_scsi_debug() now checks the add_host attribute. If the
number of hosts is greater than 1, the test is skipped.

Signed-off-by: Disha Goel <[email protected]>

Author: disgoel

common/scsi_debug

@@ -4,12 +4,33 @@
 #
 # scsi_debug helper functions.
 
+SD_PARAM_PATH=/sys/module/scsi_debug/parameters
+SD_PSEUDO_PATH=/sys/bus/pseudo/drivers/scsi_debug
+
 _have_scsi_debug() {
 	_have_driver scsi_debug
+
+	if _module_file_exists scsi_debug; then
+		_have_loadable_scsi_debug
+		return $?
+	fi
+
+	if [[ -e "$SD_PSEUDO_PATH/add_host" ]] && \
+		[[ $(cat "$SD_PSEUDO_PATH/add_host") -gt 1 ]]; then
+			SKIP_REASONS+=("scsi_debug already has multiple hosts configured")
+			return 1
+	fi
 }
 
-SD_PARAM_PATH=/sys/module/scsi_debug/parameters
-SD_PSEUDO_PATH=/sys/bus/pseudo/drivers/scsi_debug
+_have_loadable_scsi_debug() {
+	_have_module scsi_debug || return 1
+
+	if [[ -d /sys/module/scsi_debug ]] && \
+		[[ ! ${MODULES_TO_UNLOAD[*]} =~ scsi_debug ]]; then
+			SKIP_REASONS+=("scsi_debug is already loaded before test")
+			return 1
+	fi
+}
 
 _scsi_debug_key_path() {
 	local key=${1}

tests/block/009

@@ -12,7 +12,7 @@
 DESCRIPTION="check page-cache coherency after BLKDISCARD"
 
 requires() {
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 	_have_program xfs_io
 }
 

tests/block/025

@@ -12,7 +12,7 @@
 DESCRIPTION="do a huge discard with 4k sector size"
 
 requires() {
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 }
 
 test() {

tests/block/028

@@ -12,7 +12,7 @@ DESCRIPTION="do I/O on scsi_debug with DIF/DIX enabled"
 DMESG_FILTER="sed -r 's/(guard tag error at sector|ref tag error at location)/blktests failure: \\1/'"
 
 requires() {
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 }
 
 test_pi() {

tests/block/032

@@ -14,7 +14,7 @@ QUICK=1
 
 requires() {
 	_have_xfs
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 }
 
 test() {

tests/loop/004

@@ -12,7 +12,7 @@ QUICK=1
 
 requires() {
 	_have_program xfs_io
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 	_have_src_program loblksize
 	_have_loop_set_block_size
 }

tests/md/002

@@ -12,7 +12,7 @@ DESCRIPTION="test md atomic writes"
 QUICK=1
 
 requires() {
-	_have_driver scsi_debug
+	_have_scsi_debug
 	_stacked_atomic_test_requires
 }
 

tests/scsi/007

@@ -12,7 +12,7 @@ DESCRIPTION="Trigger the SCSI error handler"
 QUICK=1
 
 requires() {
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 }
 
 start_tracing() {

tests/scsi/009

@@ -12,7 +12,7 @@ DESCRIPTION="test scsi atomic writes"
 QUICK=1
 
 requires() {
-	_have_driver scsi_debug
+	_have_scsi_debug
 	_have_xfs_io_atomic_write
 }
 

tests/srp/rc

@@ -58,7 +58,7 @@ group_requires() {
 		_have_kver 5 5
 		_have_iproute2 190404
 	fi
-	_have_module scsi_debug
+	_have_loadable_scsi_debug
 	_have_module target_core_iblock
 	_have_module target_core_mod
 	_module_not_in_use scsi_transport_srp