kcore: use usual list for kclist

This patchset is for /proc/kcore.  With this,

 - many per-arch hooks are removed.

 - /proc/kcore will know really valid physical memory area.

 - /proc/kcore will be aware of memory hotplug.

 - /proc/kcore will be architecture independent i.e.
   if an arch supports CONFIG_MMU, it can use /proc/kcore.
   (if the arch uses usual memory layout.)

This patch:

/proc/kcore uses its own list handling codes. It's better to use
generic list codes.

No changes in logic. just clean up.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/proc/kcore.c

@@ -20,6 +20,7 @@
 #include <linux/init.h>
 #include <asm/uaccess.h>
 #include <asm/io.h>
+#include <linux/list.h>
 
 #define CORE_STR "CORE"
 
@@ -57,7 +58,7 @@ struct memelfnote
 	void *data;
 };
 
-static struct kcore_list *kclist;
+static LIST_HEAD(kclist_head);
 static DEFINE_RWLOCK(kclist_lock);
 
 void
@@ -67,8 +68,7 @@ kclist_add(struct kcore_list *new, void *addr, size_t size)
 	new->size = size;
 
 	write_lock(&kclist_lock);
-	new->next = kclist;
-	kclist = new;
+	list_add_tail(&new->list, &kclist_head);
 	write_unlock(&kclist_lock);
 }
 
@@ -80,7 +80,7 @@ static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
 	*nphdr = 1; /* PT_NOTE */
 	size = 0;
 
-	for (m=kclist; m; m=m->next) {
+	list_for_each_entry(m, &kclist_head, list) {
 		try = kc_vaddr_to_offset((size_t)m->addr + m->size);
 		if (try > size)
 			size = try;
@@ -192,7 +192,7 @@ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 	nhdr->p_align	= 0;
 
 	/* setup ELF PT_LOAD program header for every area */
-	for (m=kclist; m; m=m->next) {
+	list_for_each_entry(m, &kclist_head, list) {
 		phdr = (struct elf_phdr *) bufp;
 		bufp += sizeof(struct elf_phdr);
 		offset += sizeof(struct elf_phdr);
@@ -317,7 +317,7 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 		struct kcore_list *m;
 
 		read_lock(&kclist_lock);
-		for (m=kclist; m; m=m->next) {
+		list_for_each_entry(m, &kclist_head, list) {
 			if (start >= m->addr && start < (m->addr+m->size))
 				break;
 		}

include/linux/proc_fs.h

@@ -79,7 +79,7 @@ struct proc_dir_entry {
 };
 
 struct kcore_list {
-	struct kcore_list *next;
+	struct list_head list;
 	unsigned long addr;
 	size_t size;
 };