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6613c5e860
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>
79 lines
1.6 KiB
C
79 lines
1.6 KiB
C
/*
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* Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <linux/ctype.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/types.h>
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#include <asm/uaccess.h>
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/*
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* If read and write race, the read will still atomically read a valid
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* value.
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*/
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int uml_exitcode = 0;
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static int exitcode_proc_show(struct seq_file *m, void *v)
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{
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int val;
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/*
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* Save uml_exitcode in a local so that we don't need to guarantee
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* that sprintf accesses it atomically.
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*/
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val = uml_exitcode;
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seq_printf(m, "%d\n", val);
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return 0;
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}
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static int exitcode_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, exitcode_proc_show, NULL);
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}
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static ssize_t exitcode_proc_write(struct file *file,
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const char __user *buffer, size_t count, loff_t *pos)
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{
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char *end, buf[sizeof("nnnnn\0")];
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int tmp;
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if (copy_from_user(buf, buffer, count))
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return -EFAULT;
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tmp = simple_strtol(buf, &end, 0);
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if ((*end != '\0') && !isspace(*end))
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return -EINVAL;
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uml_exitcode = tmp;
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return count;
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}
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static const struct file_operations exitcode_proc_fops = {
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.owner = THIS_MODULE,
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.open = exitcode_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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.write = exitcode_proc_write,
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};
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static int make_proc_exitcode(void)
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{
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struct proc_dir_entry *ent;
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ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_fops);
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if (ent == NULL) {
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printk(KERN_WARNING "make_proc_exitcode : Failed to register "
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"/proc/exitcode\n");
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return 0;
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}
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return 0;
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}
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__initcall(make_proc_exitcode);
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