common/scsi_debug: use _patient_rmmod() to unload scsi_debug

The helper _have_scsi_debug_group_number_stats() loads and unloads
scsi_debug to check parameters of scsi_debug. However, the unload is too
soon after the load, then it often fails. To avoid such unload failures,
use _patient_rmmod() to unload scsi_debug.

Reported-by: Yi Zhang <[email protected]>
Closes: #241
[Shin'ichro: removed /dev/null redirect per suggestion by Bart]
Signed-off-by: Shin'ichiro Kawasaki <[email protected]>

Author: kawasaki

common/scsi_debug

@@ -57,7 +57,7 @@ _have_scsi_debug_group_number_stats() {
 		SKIP_REASONS+=("scsi_debug does not support group number statistics")
 		ret=1
 	fi
-	modprobe -qr scsi_debug >&/dev/null
+	_patient_rmmod scsi_debug
 	return ${ret}
 }