Adding Makefile tests for lkm_debugfs and little renaming

Makefile

@@ -45,6 +45,7 @@ test:
 	@$(MAKE) test-module name=lkm_process
 	@$(MAKE) test-module name=lkm_sandbox
 	@$(MAKE) test-module name=lkm_skeleton
+	@$(MAKE) test-debugfs
 	@$(MAKE) test-device
 	@$(MAKE) test-memory
 	@$(MAKE) test-parameters
@@ -57,7 +58,7 @@ test:
 #
 
 test-module:
-	$(info Testing module '$(name)' by loading and displaying Kernel Message Ring Buffer...)
+	$(info Testing module '$(name)' by loading and displaying Kernel Message Ring Buffer)
 	$(info Root permissions are needed for clearing buffer with dmesg and loading/unloading with insmod/rmmod)
 	$(call test_module_exists,$(name))
 	$(call test_module,$(name))
@@ -66,6 +67,29 @@ test-module:
 # Targets for additional concept-based module tests
 #
 
+test-debugfs:
+	$(info Running additional tests for module 'lkm_debugfs' by loading, and testing both files in debugfs)
+	$(info Root permissions are needed for loading/unloading module with insmod/rmmod and accessing /sys/kernel/debug)
+
+	$(eval module = lkm_debugfs)
+	$(eval number_file = /sys/kernel/debug/lkm/number)
+	$(eval message_file = /sys/kernel/debug/lkm/message)
+	$(eval message = Hello, debugfs!)
+	$(eval number = 42)
+
+	$(call test_module_exists,$(module))
+	$(call load_module,$(module))
+
+	$(call test_file_exists,$(number_file),"-r", "sudo")
+	$(eval number_file_content = `sudo cat $(number_file)`)
+	$(call test_compare_values,$(number_file_content),"-eq",$(number))
+
+	$(eval message_file_content = `sudo cat $(message_file) | tr -d '\0'`)
+	$(call test_file_exists,$(message_file),"-r", "sudo")
+	$(call test_compare_values,"\"$(message_file_content)\"","=","\"$(message)\"")
+
+	@sudo rmmod $(module_filename)
+
 test-device:
 	$(info Running additional tests for module 'lkm_device' by loading, accessing major device number in /proc and creating device)
 	$(info Root permissions are needed for loading/unloading module with insmod/rmmod and creating device with mknod)
@@ -117,7 +141,7 @@ test-parameters:
 	@sudo rmmod $(module)
 
 test-proc:
-	$(info Running additional tests for 'lkm_proc' to access /proc filesystem by loading and cating '$(proc_file)'...)
+	$(info Running additional tests for 'lkm_proc' to access /proc filesystem by loading and cating '$(proc_file)')
 	$(info Root permissions are needed for loading/unloading with insmod/rmmod)
 
 	$(eval module = lkm_proc)

lkm_debugfs.c

@@ -1,5 +1,5 @@
 /*
- * LKM Sandbox::DebugFS
+ * LKM Sandbox::Debug Filesystem
  * <https://github.com/tpiekarski/lkm-sandbox>
  * ---
  * Copyright 2020 Thomas Piekarski <[email protected]>
@@ -45,7 +45,7 @@ static ssize_t debug_write(struct file *fp, const char *buffer, size_t count,
 char content[LKM_DEBUGFS_CONTENT_LEN];
 static struct dentry *debug_root;
 static struct dentry *debug_file_entry;
-static u64 value;
+static u64 number;
 static int file_value;
 
 static const struct file_operations fops = { .owner = THIS_MODULE,
@@ -91,8 +91,9 @@ static int __init lkm_debugfs_init(void)
 		return -ENODEV;
 	}
 
-	value = 42;
-	debugfs_create_u64("value", LKM_DEBUGFS_PERMISSION, debug_root, &value);
+	number = 42;
+	debugfs_create_u64("number", LKM_DEBUGFS_PERMISSION, debug_root,
+			   &number);
 
 	debug_file_entry =
 		debugfs_create_file("message", LKM_DEBUGFS_PERMISSION,

tests.mk

@@ -33,7 +33,7 @@ endef
 
 define test_file_exists
 	@echo "Testing if file $(1) exists."
-	@test $(2) $(1) \
+	@$(3) test $(2) $(1) \
 		|| (echo "  !! The file $(1) could not be found."; exit $(BUILD_ERROR))
 endef