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linux/arch/um/kernel/exitcode.c
Alexey Dobriyan 6613c5e860 uml: convert to seq_file/proc_fops
Convert code away from ->read_proc/->write_proc interfaces.  Switch to
proc_create()/proc_create_data() which make addition of proc entries
reliable wrt NULL ->proc_fops, NULL ->data and so on.

Problem with ->read_proc et al is described here commit
786d7e1612 "Fix rmmod/read/write races in
/proc entries"

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-15 08:53:25 -08:00

79 lines
1.6 KiB
C

/*
* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/types.h>
#include <asm/uaccess.h>
/*
* If read and write race, the read will still atomically read a valid
* value.
*/
int uml_exitcode = 0;
static int exitcode_proc_show(struct seq_file *m, void *v)
{
int val;
/*
* Save uml_exitcode in a local so that we don't need to guarantee
* that sprintf accesses it atomically.
*/
val = uml_exitcode;
seq_printf(m, "%d\n", val);
return 0;
}
static int exitcode_proc_open(struct inode *inode, struct file *file)
{
return single_open(file, exitcode_proc_show, NULL);
}
static ssize_t exitcode_proc_write(struct file *file,
const char __user *buffer, size_t count, loff_t *pos)
{
char *end, buf[sizeof("nnnnn\0")];
int tmp;
if (copy_from_user(buf, buffer, count))
return -EFAULT;
tmp = simple_strtol(buf, &end, 0);
if ((*end != '\0') && !isspace(*end))
return -EINVAL;
uml_exitcode = tmp;
return count;
}
static const struct file_operations exitcode_proc_fops = {
.owner = THIS_MODULE,
.open = exitcode_proc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
.write = exitcode_proc_write,
};
static int make_proc_exitcode(void)
{
struct proc_dir_entry *ent;
ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_fops);
if (ent == NULL) {
printk(KERN_WARNING "make_proc_exitcode : Failed to register "
"/proc/exitcode\n");
return 0;
}
return 0;
}
__initcall(make_proc_exitcode);