/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: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Zhang 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 47 deletions

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 2ca6d7844ad9..f895a8c8a244 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -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)