#define pr_fmt(fmt)		"allocMemoryTest:"fmt

#include <linux/module.h>
#include <linux/list.h>
#include <linux/slab.h>
#include <uapi/asm-generic/errno-base.h>
#include <asm/page-def.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
/*
board:/ # insmod  /data/alloc_memory_test.ko
[11829.469158] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005eb58]flagstaff_obj_0
[11829.469172] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e2c0]flagstaff_obj_1
[11829.469180] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005eec8]flagstaff_obj_2
[11829.469185] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e210]flagstaff_obj_3
[11829.469190] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005eb00]flagstaff_obj_4
[11829.469195] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e160]flagstaff_obj_5
[11829.469201] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005edc0]flagstaff_obj_6
[11829.469207] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ed10]flagstaff_obj_7
[11829.469213] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ef78]flagstaff_obj_8
[11829.469219] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e790]flagstaff_obj_9
[11829.469224] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e528]flagstaff_obj_10
[11829.469231] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ef20]flagstaff_obj_11
[11829.469238] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ed68]flagstaff_obj_12
[11829.469244] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e7e8]flagstaff_obj_13
[11829.469250] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e948]flagstaff_obj_14
[11829.469255] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e108]flagstaff_obj_15
[11829.469261] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e0b0]flagstaff_obj_16
[11829.469266] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e840]flagstaff_obj_17
[11829.469271] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e478]flagstaff_obj_18
[11829.469277] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e1b8]flagstaff_obj_19
[11829.469282] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e000]flagstaff_obj_20
[11829.469288] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ecb8]flagstaff_obj_21
[11829.469293] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e898]flagstaff_obj_22
[11829.469298] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ee18]flagstaff_obj_23
[11829.469304] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ec08]flagstaff_obj_24
[11829.469310] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e580]flagstaff_obj_25
[11829.469315] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e318]flagstaff_obj_26
[11829.469321] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e3c8]flagstaff_obj_27
[11829.469326] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e688]flagstaff_obj_28
[11829.469331] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ebb0]flagstaff_obj_29
[11829.469336] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e9f8]flagstaff_obj_30
[11829.469342] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ee70]flagstaff_obj_31
[11829.469350] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e9a0]flagstaff_obj_32
[11829.469358] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e6e0]flagstaff_obj_33
[11829.469365] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e5d8]flagstaff_obj_34
[11829.469369] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e268]flagstaff_obj_35
[11829.469375] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e630]flagstaff_obj_36
[11829.469381] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e058]flagstaff_obj_37
[11829.469386] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e420]flagstaff_obj_38
[11829.469391] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005eaa8]flagstaff_obj_39
[11829.469397] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e370]flagstaff_obj_40
[11829.469403] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e8f0]flagstaff_obj_41
[11829.469408] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e4d0]flagstaff_obj_42
[11829.469414] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ec60]flagstaff_obj_43
[11829.469419] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005ea50]flagstaff_obj_44
[11829.469424] allocMemoryTest:flagstaff_kmem_alloc,100:The new flagstaff_mem is [0xffffff890005e738]flagstaff_obj_45
[11829.469431] allocMemoryTest:alloc_memory_test_drv_init,145:show_list:[0xffffff882dc48a80]flagstaffmem create by kmalloc
[11829.469436] allocMemoryTest:alloc_memory_test_drv_init,145:show_list:[0xffffff890005eb58]flagstaff_obj_0
[11829.469443] allocMemoryTest:alloc_memory_test_drv_init,163:This is a free mem from page which size is 4092, [PAGE_SIZE]4096.
[11829.469480] allocMemoryTest:alloc_memory_test_drv_init,173:[vfm->desc]This memory is from vmalloc.
board:/ # rmmod alloc_memory_test
[11832.689375] allocMemoryTest:alloc_memory_test_drv_exit,206:free:flagstaff_obj_0


*/
#define ALLOC_MEMORY_TEST_INFO_SHOW
#ifdef ALLOC_MEMORY_TEST_INFO_SHOW
#define ALLOC_MEMORY_TEST_INFO(fmt,...) \
do{\
    pr_info( "%s,%d:"fmt"\n",__func__,__LINE__,##__VA_ARGS__);\
}while(0)
#else
#define ALLOC_MEMORY_TEST_INFO(fmt,...)
#endif

struct flagstaff_mem {
	char desc[60];
	struct list_head list;
};

static struct kmem_cache *kc;
static LIST_HEAD(flagstaff_mem_head);

struct my_page {
	u8 mem[PAGE_SIZE - sizeof(int)];
	int size;
};
static struct my_page *mp;

static struct flagstaff_mem *vfm = NULL;

static void flagstaff_kmem_alloc(void *data) {
	static int alloc_count = 0;
	struct flagstaff_mem *fmem = data;
	if(IS_ERR_OR_NULL(fmem)) {
		pr_err("flagstaff_kmem_alloc alloc new flagstaff_mem in failed.\n");
		return;
	}

	sprintf(fmem->desc, "flagstaff_obj_%d", alloc_count++);
	ALLOC_MEMORY_TEST_INFO("The new flagstaff_mem is [0x%llx]%s", (u64)fmem, fmem->desc);
}

static int __init alloc_memory_test_drv_init()
{
	int count = 0;
	struct page *tmp_page = NULL;

	/*
		1.kmalloc family
	*/
	struct flagstaff_mem *my_mem = kmalloc(sizeof(struct flagstaff_mem), GFP_KERNEL);
	if(IS_ERR_OR_NULL(my_mem)) {
		pr_err("alloc my_mem in failed.\n");
		return -ENOMEM;
	}
	sprintf(my_mem->desc, "flagstaffmem create by kmalloc");
	list_add_tail(&my_mem->list, &flagstaff_mem_head);

	/*
		2.kmem_cache_xxx
		Note:
			Slab will allocate the number of your struct more than your need.Like the following.
			You only call kmem_cache_alloc once but constructor is called more than once to allocate 
			more your struct.This feature is why we name it to cache.
	*/
	kc = kmem_cache_create("flagstaff_mem",
		sizeof(struct flagstaff_mem),
		0,
		SLAB_PANIC,
		flagstaff_kmem_alloc);

	if(IS_ERR_OR_NULL(kc)) {
		pr_err("create cache infailed.\n");
		return -ENOMEM;
	}
#define FLAGSTAFF_MEM_COUNT_MAX		1
	for(count = 0 ; count < FLAGSTAFF_MEM_COUNT_MAX; ++count) {
		my_mem = kmem_cache_alloc(kc, GFP_KERNEL);
		if(!IS_ERR_OR_NULL(my_mem)) {
			list_add_tail(&my_mem->list, &flagstaff_mem_head);
		}
	}

	list_for_each_entry(my_mem, &flagstaff_mem_head, list)
		ALLOC_MEMORY_TEST_INFO("show_list:[0x%llx]%s", my_mem, my_mem->desc);

	/*
		3. gain memory by page
	*/
	tmp_page = alloc_page(GFP_KERNEL);
	if(IS_ERR_OR_NULL(tmp_page)) {
		pr_err("get one page failed.\n");
		return -ENOMEM;
	}
	mp = page_address(tmp_page);
	if(IS_ERR_OR_NULL(mp)) {
		pr_err("get page address in failed.\n");
		return -ENOMEM;
	}

	mp->size = PAGE_SIZE - sizeof(int);
	sprintf(mp->mem, "This is a free mem from page which size is %d, [PAGE_SIZE]%d.", mp->size, PAGE_SIZE);
	ALLOC_MEMORY_TEST_INFO("%s", mp->mem);
	/*
		4.get memory from vmalloc
	*/
	vfm = vmalloc(sizeof(struct flagstaff_mem));
	if(IS_ERR_OR_NULL(vfm)) {
		pr_err("get memory from vmalloc infailed.\n");
		return -ENOMEM;
	}
	sprintf(vfm->desc, "This memory is from vmalloc.", vfm);
	ALLOC_MEMORY_TEST_INFO("[vfm->desc]%s", vfm->desc);
	return 0;

}

static void __exit alloc_memory_test_drv_exit()
{
	struct flagstaff_mem *my_mem = NULL;
	struct flagstaff_mem *my_mem_tmp = NULL;
	/*
		1.free the memory allocated by kmalloc
	*/

	my_mem = list_first_entry(&flagstaff_mem_head, struct flagstaff_mem, list);
	if(IS_ERR_OR_NULL(my_mem)){
		pr_err("my_mem is null\n");
	}
	list_del(&my_mem->list);
	kfree(my_mem);

	/*
		2.free the memory allocated by kmem_cache_xx
	*/
	if(IS_ERR_OR_NULL(kc)){
		pr_err("my_mem is null\n");
		return;
	}

	list_for_each_entry_safe(my_mem, my_mem_tmp, &flagstaff_mem_head, list) {
		if(IS_ERR_OR_NULL(my_mem)) {
			pr_err("my_mem is null\n");
			continue;
		}
		ALLOC_MEMORY_TEST_INFO("free:%s", my_mem->desc);
		list_del(&my_mem->list);
		kmem_cache_free(kc, my_mem);
	}

	kmem_cache_destroy(kc);
	kc = NULL;
	/*
		3.free the memory from alloc_page
	*/
	if(!IS_ERR_OR_NULL(mp)){
		free_page((unsigned long)mp);
		mp = NULL;
	}
	/*
		4.free the memory from vmalloc
	*/
	if(!IS_ERR_OR_NULL(vfm)){
		vfree(vfm);
	}
}

module_init(alloc_memory_test_drv_init);
module_exit(alloc_memory_test_drv_exit);
MODULE_AUTHOR("flagstaff Chen<flagstaff.chen@fake.com>");
MODULE_DESCRIPTION("test the API of allocting memory from kernel.");
MODULE_LICENSE("GPL v2");