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proc: unify mem_read() and mem_write()

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No functional changes, cleanup and preparation.

mem_read() and mem_write() are very similar. Move this code into the
new common helper, mem_rw(), which takes the additional "int write"
argument.

Cc: stable@kernel.org
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2012-01-31 17:14:54 +01:00 committed by Linus Torvalds
parent 71879d3cb3
commit 572d34b946
1 changed files with 32 additions and 58 deletions
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90
fs/proc/base.c
View file

@ -718,57 +718,13 @@ static int mem_open(struct inode* inode, struct file* file)
return 0;
}
static ssize_t mem_read(struct file * file, char __user * buf,
size_t count, loff_t *ppos)
static ssize_t mem_rw(struct file *file, char __user *buf,
size_t count, loff_t *ppos, int write)
{
int ret;
char *page;
unsigned long src = *ppos;
struct mm_struct *mm = file->private_data;
if (!mm)
return 0;
page = (char *)__get_free_page(GFP_TEMPORARY);
if (!page)
return -ENOMEM;
ret = 0;
while (count > 0) {
int this_len, retval;
this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
retval = access_remote_vm(mm, src, page, this_len, 0);
if (!retval) {
if (!ret)
ret = -EIO;
break;
}
if (copy_to_user(buf, page, retval)) {
ret = -EFAULT;
break;
}
ret += retval;
src += retval;
buf += retval;
count -= retval;
}
*ppos = src;
free_page((unsigned long) page);
return ret;
}
static ssize_t mem_write(struct file * file, const char __user *buf,
size_t count, loff_t *ppos)
{
int copied;
unsigned long addr = *ppos;
ssize_t copied;
char *page;
unsigned long dst = *ppos;
struct mm_struct *mm = file->private_data;
if (!mm)
return 0;
@ -779,30 +735,48 @@ static ssize_t mem_write(struct file * file, const char __user *buf,
copied = 0;
while (count > 0) {
int this_len, retval;
int this_len = min_t(int, count, PAGE_SIZE);
this_len = (count > PAGE_SIZE) ? PAGE_SIZE : count;
if (copy_from_user(page, buf, this_len)) {
if (write && copy_from_user(page, buf, this_len)) {
copied = -EFAULT;
break;
}
retval = access_remote_vm(mm, dst, page, this_len, 1);
if (!retval) {
this_len = access_remote_vm(mm, addr, page, this_len, write);
if (!this_len) {
if (!copied)
copied = -EIO;
break;
}
copied += retval;
buf += retval;
dst += retval;
count -= retval;
if (!write && copy_to_user(buf, page, this_len)) {
copied = -EFAULT;
break;
}
buf += this_len;
addr += this_len;
copied += this_len;
count -= this_len;
}
*ppos = dst;
*ppos = addr;
free_page((unsigned long) page);
return copied;
}
static ssize_t mem_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return mem_rw(file, buf, count, ppos, 0);
}
static ssize_t mem_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return mem_rw(file, (char __user*)buf, count, ppos, 1);
}
loff_t mem_lseek(struct file *file, loff_t offset, int orig)
{
switch (orig) {