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Commit a11edb59 authored by Zhang Yanfei's avatar Zhang Yanfei Committed by Linus Torvalds
Browse files

/dev/oldmem: Remove the interface 

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel.  Unfortunately, no one actually uses this
interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed.  See the discussion from the
link: https://lkml.org/lkml/2013/4/12/386

.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

[akpm@linux-foundation.org: mention /dev/oldmem obsolescence in devices.txt]
Suggested-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarZhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 266b7a02

Documentation/devices.txt

+1 −2
Original line number Diff line number Diff line
@@ -100,8 +100,7 @@ Your cooperation is appreciated. 
		 10 = /dev/aio		Asynchronous I/O notification interface

		 11 = /dev/kmsg		Writes to this come out as printk's, reads

					export the buffered printk records.

		 12 = /dev/oldmem	Used by crashdump kernels to access

					the memory of the kernel that crashed.

		 12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore



  1 block	RAM disk

		  0 = /dev/ram0		First RAM disk

drivers/char/mem.c

+0 −47
Original line number Diff line number Diff line
@@ -21,7 +21,6 @@ 
#include <linux/ptrace.h>

#include <linux/device.h>

#include <linux/highmem.h>

#include <linux/crash_dump.h>

#include <linux/backing-dev.h>

#include <linux/bootmem.h>

#include <linux/splice.h>
@@ -357,40 +356,6 @@ static int mmap_kmem(struct file *file, struct vm_area_struct *vma) 
}

#endif



#ifdef CONFIG_CRASH_DUMP

/*

 * Read memory corresponding to the old kernel.

 */

static ssize_t read_oldmem(struct file *file, char __user *buf,

				size_t count, loff_t *ppos)

{

	unsigned long pfn, offset;

	size_t read = 0, csize;

	int rc = 0;



	while (count) {

		pfn = *ppos / PAGE_SIZE;

		if (pfn > saved_max_pfn)

			return read;



		offset = (unsigned long)(*ppos % PAGE_SIZE);

		if (count > PAGE_SIZE - offset)

			csize = PAGE_SIZE - offset;

		else

			csize = count;



		rc = copy_oldmem_page(pfn, buf, csize, offset, 1);

		if (rc < 0)

			return rc;

		buf += csize;

		*ppos += csize;

		read += csize;

		count -= csize;

	}

	return read;

}

#endif



#ifdef CONFIG_DEVKMEM

/*

 * This function reads the *virtual* memory as seen by the kernel.
@@ -772,7 +737,6 @@ static int open_port(struct inode *inode, struct file *filp) 
#define aio_write_zero	aio_write_null

#define open_mem	open_port

#define open_kmem	open_mem

#define open_oldmem	open_mem



static const struct file_operations mem_fops = {

	.llseek		= memory_lseek,
@@ -837,14 +801,6 @@ static const struct file_operations full_fops = { 
	.write		= write_full,

};



#ifdef CONFIG_CRASH_DUMP

static const struct file_operations oldmem_fops = {

	.read	= read_oldmem,

	.open	= open_oldmem,

	.llseek = default_llseek,

};

#endif



static const struct memdev {

	const char *name;

	umode_t mode;
@@ -866,9 +822,6 @@ static const struct memdev { 
#ifdef CONFIG_PRINTK

	[11] = { "kmsg", 0644, &kmsg_fops, NULL },

#endif

#ifdef CONFIG_CRASH_DUMP

	[12] = { "oldmem", 0, &oldmem_fops, NULL },

#endif

};



static int memory_open(struct inode *inode, struct file *filp)