Userland test programs

kernel_module/Makefile

@@ -1,10 +1,13 @@
 obj-m += $(addsuffix .o, $(notdir $(basename $(wildcard $(BR2_EXTERNAL_KERNEL_MODULE_PATH)/*.c))))
 ccflags-y := -Wno-declaration-after-statement -std=gnu99
 
-.PHONY: all clean
+.PHONY: all clean test
 
-all:
+all: test
 	$(MAKE) -C '$(LINUX_DIR)' M='$(PWD)' modules
 
 clean:
 	$(MAKE) -C '$(LINUX_DIR)' M='$(PWD)' clean
+
+test:
+	$(MAKE) -C '$(PWD)/test'

kernel_module/delay.c

@@ -43,7 +43,9 @@ void cleanup_module(void)
 {
 	/* This waits for the work to finish. From docstring: */
 	/* > Cancel @work and wait for its execution to finish. */
-	cancel_work_sync(&work);
+	cancel_work(&work);
+
+	/*cancel_work(&work);*/
 
 	destroy_workqueue(queue);
 }

kernel_module/external.mk

@@ -13,7 +13,8 @@ define KERNEL_MODULE_BUILD_CMDS
 endef
 
 define KERNEL_MODULE_INSTALL_TARGET_CMDS
-	$(INSTALL) -D -m 0755 $(@D)/*.ko '$(TARGET_DIR)'
+	$(INSTALL) -D -m 0655 $(@D)/*.ko '$(TARGET_DIR)'
+	$(INSTALL) -D -m 0755 $(@D)/test/ins_rm_mod '$(TARGET_DIR)'
 endef
 
 $(eval $(kernel-module))

kernel_module/test/Makefile

@@ -0,0 +1,9 @@
+CC = gcc
+
+.PHONY: clean
+
+ins_rm_mod: ins_rm_mod.c
+	$(CC) -o '$@' '$<'
+
+clean:
+	rm ins_rm_mod

kernel_module/test/README.md

@@ -0,0 +1,9 @@
+# Test
+
+Userland C programs used to test our kernel module.
+
+`sh` programs are simpler, and installed copied directly with an overlay.
+
+C programs require cross compiling, but give us more control over system calls.
+
+These programs can also be compiled and used on host.

kernel_module/test/ins_rm_mod.c

@@ -0,0 +1,36 @@
+/*
+http://stackoverflow.com/questions/5947286/how-can-linux-kernel-modules-be-loaded-from-c-code/38606527#38606527
+*/
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <sys/stat.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
+#define delete_module(name, flags) syscall(__NR_delete_module, name, flags)
+
+int main(void) {
+    int fd = open("hello.ko", O_RDONLY);
+    struct stat st;
+    fstat(fd, &st);
+    size_t image_size = st.st_size;
+    void *image = malloc(image_size);
+    read(fd, image, image_size);
+    close(fd);
+    if (init_module(image, image_size, "") != 0) {
+        perror("init_module");
+        return EXIT_FAILURE;
+    }
+    free(image);
+    if (delete_module("hello", O_NONBLOCK) != 0) {
+        perror("delete_modul");
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}