From 572d34b946bae070debd42db1143034d9687e13f Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Tue, 31 Jan 2012 17:14:54 +0100 Subject: [PATCH] proc: unify mem_read() and mem_write() 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 Signed-off-by: Linus Torvalds --- fs/proc/base.c | 90 ++++++++++++++++++-------------------------------- 1 file changed, 32 insertions(+), 58 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index c3617ea7830b..be1909041685 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -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) { -- 2.20.1