730760e90a
Some locking documentation and a cleanup. uml_exitcode is copied into a local before sprintf sees it, in case sprintf does anything non-atomic with it. The rest are comments about why certain globals don't need any kind of locking. Signed-off-by: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
77 lines
1.8 KiB
C
77 lines
1.8 KiB
C
/*
|
|
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
|
|
* Licensed under the GPL
|
|
*/
|
|
|
|
#include "linux/init.h"
|
|
#include "linux/ctype.h"
|
|
#include "linux/proc_fs.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 read_proc_exitcode(char *page, char **start, off_t off,
|
|
int count, int *eof, void *data)
|
|
{
|
|
int len, val;
|
|
|
|
/* Save uml_exitcode in a local so that we don't need to guarantee
|
|
* that sprintf accesses it atomically.
|
|
*/
|
|
val = uml_exitcode;
|
|
len = sprintf(page, "%d\n", val);
|
|
len -= off;
|
|
if(len <= off+count) *eof = 1;
|
|
*start = page + off;
|
|
if(len > count) len = count;
|
|
if(len < 0) len = 0;
|
|
return(len);
|
|
}
|
|
|
|
static int write_proc_exitcode(struct file *file, const char __user *buffer,
|
|
unsigned long count, void *data)
|
|
{
|
|
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 int make_proc_exitcode(void)
|
|
{
|
|
struct proc_dir_entry *ent;
|
|
|
|
ent = create_proc_entry("exitcode", 0600, &proc_root);
|
|
if(ent == NULL){
|
|
printk(KERN_WARNING "make_proc_exitcode : Failed to register "
|
|
"/proc/exitcode\n");
|
|
return(0);
|
|
}
|
|
|
|
ent->read_proc = read_proc_exitcode;
|
|
ent->write_proc = write_proc_exitcode;
|
|
|
|
return(0);
|
|
}
|
|
|
|
__initcall(make_proc_exitcode);
|
|
|
|
/*
|
|
* Overrides for Emacs so that we follow Linus's tabbing style.
|
|
* Emacs will notice this stuff at the end of the file and automatically
|
|
* adjust the settings for this buffer only. This must remain at the end
|
|
* of the file.
|
|
* ---------------------------------------------------------------------------
|
|
* Local variables:
|
|
* c-file-style: "linux"
|
|
* End:
|
|
*/
|