[PATCH v2 1/7] /dev/oldmem: Remove the interface

From: Zhang Yanfei
Date: Sun May 26 2013 - 02:34:49 EST


From: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>

/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.

Suggested-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Zhang Yanfei <zhangyanfei@xxxxxxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/char/mem.c | 47 -----------------------------------------------
1 files changed, 0 insertions(+), 47 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1ccbe94..bbe8ab4 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)
--
1.7.1

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